U.S. patent application number 15/360721 was filed with the patent office on 2017-06-15 for three-way catalytic converter using nanoparticles.
The applicant listed for this patent is SDCmaterials, Inc.. Invention is credited to Maximilian A. BIBERGER, Xiwang QI.
Application Number | 20170167338 15/360721 |
Document ID | / |
Family ID | 50728131 |
Filed Date | 2017-06-15 |
United States Patent
Application |
20170167338 |
Kind Code |
A1 |
QI; Xiwang ; et al. |
June 15, 2017 |
THREE-WAY CATALYTIC CONVERTER USING NANOPARTICLES
Abstract
The present disclosure relates to a substrate comprising
nanomaterials for treatment of gases, washcoats for use in
preparing such a substrate, and methods of preparation of the
nanomaterials and the substrate comprising the nanomaterials. More
specifically, the present disclosure relates to a substrate
comprising nanomaterial for three-way catalytic converters for
treatment of exhaust gases.
Inventors: |
QI; Xiwang; (Scottsdale,
AZ) ; BIBERGER; Maximilian A.; (Scottsdale,
AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SDCmaterials, Inc. |
Tempe |
AZ |
US |
|
|
Family ID: |
50728131 |
Appl. No.: |
15/360721 |
Filed: |
November 23, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14846495 |
Sep 4, 2015 |
9533299 |
|
|
15360721 |
|
|
|
|
13801726 |
Mar 13, 2013 |
9156025 |
|
|
14846495 |
|
|
|
|
61729177 |
Nov 21, 2012 |
|
|
|
61729227 |
Nov 21, 2012 |
|
|
|
61735529 |
Dec 10, 2012 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 53/945 20130101;
Y02T 10/12 20130101; Y02A 50/2324 20180101; B01J 35/04 20130101;
Y10T 428/24149 20150115; B01J 37/0045 20130101; F01N 2510/068
20130101; B01D 2255/908 20130101; B01J 21/066 20130101; Y02T 10/22
20130101; B01D 2255/20715 20130101; B01D 2255/9022 20130101; B01J
35/023 20130101; B01J 37/08 20130101; F01N 3/0842 20130101; F01N
3/0864 20130101; B01D 2255/9202 20130101; B01J 23/42 20130101; B01J
23/63 20130101; B01J 37/0244 20130101; B01D 2255/1023 20130101;
B01D 2255/2042 20130101; B01J 23/44 20130101; B01J 35/0013
20130101; F01N 3/101 20130101; Y10T 428/25 20150115; B01D 2255/91
20130101; B01J 23/464 20130101; B01J 37/349 20130101; B01J 37/0228
20130101; B01D 2255/1021 20130101; B01D 2258/014 20130101; B01J
35/0006 20130101; B01D 53/00 20130101; B01D 2255/2065 20130101;
B01D 2255/407 20130101; Y02A 50/20 20180101; B01J 21/04 20130101;
B01D 2255/1025 20130101 |
International
Class: |
F01N 3/10 20060101
F01N003/10; B01J 21/04 20060101 B01J021/04; B01J 21/06 20060101
B01J021/06; B01J 23/42 20060101 B01J023/42; F01N 3/08 20060101
F01N003/08; B01J 23/46 20060101 B01J023/46; B01J 35/00 20060101
B01J035/00; B01J 37/02 20060101 B01J037/02; B01J 37/08 20060101
B01J037/08; B01D 53/94 20060101 B01D053/94; B01J 35/04 20060101
B01J035/04; B01J 23/44 20060101 B01J023/44 |
Claims
1. A coated substrate comprising: a first washcoat layer comprising
oxidative catalytically active particles, the oxidative
catalytically active particles comprising oxidative composite
nanoparticles bonded to first micron-sized carrier particles,
wherein the oxidative composite nanoparticles comprise a first
support nanoparticle and one or more oxidative catalyst
nanoparticles; and a second washcoat layer comprising reductive
catalytically active particles, the reductive catalytically active
particles comprising reductive composite nanoparticles bonded to
second micron-sized carrier particles, wherein the reductive
composite nanoparticles comprise a second support nanoparticle and
one or more reductive catalyst nanoparticles: wherein the first
washcoat layer is disposed underneath the second washcoat
layer.
2-3. (canceled)
4. The coated substrate of claim 1, wherein the oxidative catalyst
nanoparticles comprise platinum, palladium, or a mixture
thereof.
5. The coated substrate of claim 4, wherein the oxidative catalyst
nanoparticles comprise palladium.
6. The coated substrate of claim 1, wherein the first support
nanoparticles comprise aluminum oxide.
7. The coated substrate of claim 1, wherein the first micron-sized
carrier particles comprise aluminum oxide.
8. The coated substrate of claim 1, wherein the first micron-sized
carrier particle is pre-treated at a temperature range of about
700.degree. C. to about 1500.degree. C.
9. The coated substrate of claim 1, wherein the reductive catalyst
nanoparticles comprise rhodium.
10. The coated substrate of claim 1, wherein the second support
nanoparticles comprise cerium zirconium oxide.
11. The coated substrate of claim 1, wherein the second
micron-sized carrier particles comprise cerium zirconium oxide.
12. The coated substrate of claim 1, wherein the support
nanoparticles have an average diameter of 10 nm to 20 nm.
13. The coated substrate of claim 1, wherein the catalytic
nanoparticles have an average diameter of between 1 nm and 5
nm.
14. The coated substrate of claim 1, further comprising an oxygen
storage component.
15. The coated substrate of claim 14, wherein the oxygen storage
component is cerium zirconium oxide or cerium oxide.
16. The coated substrate of claim 1, further comprising a NOx
absorber component.
17. The coated substrate of claim 16, wherein the NOx absorber
component is nano-sized BaO.
18. The coated substrate of claim 16, wherein the NOx absorber
component is micron-sized BaO.
19. The coated substrate of claim 1, wherein the substrate
comprises cordierite.
20. The coated substrate of claim 1, wherein the substrate
comprises a grid array structure.
21. The coated substrate of claim 1, wherein: the coated substrate
has a platinum group metal loading of 4 g/l or less and a light-off
temperature for carbon monoxide at least 5.degree. C. lower than
the light-off temperature of a substrate with the same platinum
group metal loading deposited by wet-chemistry methods; the coated
substrate has a platinum group metal loading of 4 g/l or less and a
light-off temperature for hydrocarbon at least 5.degree. C. lower
than the light-off temperature of a substrate with the same
platinum group metal loading deposited by wet-chemistry methods; or
the coated substrate has a platinum group metal loading of 4 g/l or
less and a light-off temperature for nitrogen oxide at least
5.degree. C. lower than the light-off temperature of a substrate
with the same platinum group metal loading deposited by
wet-chemistry methods.
22-23. (canceled)
24. The coated substrate of claim 1, wherein the coated substrate
has a platinum group metal loading of about 3.0 g/l to about 4.0
g/l.
25. The coated substrate of claim 1, wherein said coated substrate
has a platinum group metal loading of about 3.0 g/l to about 4.0
g/l, and after 125,000 miles of operation in a vehicular catalytic
converter, the coated substrate has a light-off temperature for
carbon monoxide at least 5.degree. C. lower than a coated substrate
prepared by depositing platinum group metals by wet chemical
methods having the same platinum group metal loading after 125,000
miles of operation in a vehicular catalytic converter.
26. The coated substrate of claim 1, wherein a ratio of oxidative
catalytically active particles to reductive catalytically active
particles is between 6:1 and 40:1.
27. A catalytic converter comprising a coated substrate of claim
1.
28. An exhaust treatment system comprising a conduit for exhaust
gas and a catalytic converter comprising a coated substrate of
claim 1.
29. A vehicle comprising a catalytic converter according to claim
27.
30. A method of treating an exhaust gas, comprising contacting the
coated substrate of claim 1 with the exhaust gas.
31. (canceled)
32. A method of forming a coated substrate, the method comprising:
a) coating a substrate with a first washcoat composition comprising
oxidative catalytically active particles wherein the oxidative
catalytically active particles comprise oxidative composite
nanoparticles bonded to first micron-sized carrier particles, and
wherein the oxidative composite nanoparticles comprise a first
support nanoparticle and one or more oxidative catalyst
nanoparticles; and b) coating the substrate with a second washcoat
composition comprising reductive catalytically active particles
wherein the reductive catalytically active particles comprise
reductive composite nanoparticles bonded to second micron-sized
carrier particles, and wherein the reductive composite
nanoparticles comprise a second support nanoparticle and one or
more reductive catalyst nanoparticles; wherein the first washcoat
composition is coated onto the substrate prior to the second
washcoat composition.
33-34. (canceled)
35. A coated substrate comprising: a first washcoat layer
comprising oxidative catalytically active particles, the oxidative
catalytically active particles comprising oxidative composite
nanoparticles bonded to first micron-sized carrier particles,
wherein the oxidative composite nanoparticles comprise a first
support nanoparticle and one or more oxidative catalyst
nanoparticles; and a second washcoat layer comprising reductive
catalytically active particles, the reductive catalytically active
particles comprising reductive composite nanoparticles bonded to
second micron-sized carrier particles, wherein the reductive
composite nanoparticles comprise a second support nanoparticle and
one or more reductive catalyst nanoparticles: wherein the second
washcoat layer is disposed underneath the first washcoat layer.
36. The coated substrate of claim 35, wherein the oxidative
catalyst nanoparticles comprise platinum, palladium, or a mixture
thereof.
37. The coated substrate of claim 36, wherein the oxidative
catalyst nanoparticles comprise palladium.
38. The coated substrate of claim 35, wherein the first support
nanoparticles comprise aluminum oxide.
39. The coated substrate of claim 35, wherein the first
micron-sized carrier particles comprise aluminum oxide.
40. The coated substrate of claim 35, wherein the first
micron-sized carrier particle is pre-treated at a temperature range
of about 700.degree. C. to about 1500.degree. C.
41. The coated substrate of claim 35, wherein the reductive
catalyst nanoparticles comprise rhodium.
42. The coated substrate of claim 35, wherein the second support
nanoparticles comprise cerium zirconium oxide.
43. The coated substrate of claim 35, wherein the second
micron-sized carrier particles comprise cerium zirconium oxide.
44. The coated substrate of claim 35, wherein the support
nanoparticles have an average diameter of 10 nm to 20 nm.
45. The coated substrate of claim 35, wherein the catalytic
nanoparticles have an average diameter of between 1 nm and 5
nm.
46. The coated substrate of claim 35, further comprising an oxygen
storage component.
47. The coated substrate of claim 46, wherein the oxygen storage
component is cerium zirconium oxide or cerium oxide.
48. The coated substrate of claim 35, further comprising a NOx
absorber component.
49. The coated substrate of claim 48, wherein the NOx absorber
component is nano-sized BaO.
50. The coated substrate of claim 48, wherein the NOx absorber
component is micron-sized BaO.
51. The coated substrate of claim 35, wherein the substrate
comprises cordierite.
52. The coated substrate of claim 35, wherein the substrate
comprises a grid array structure.
53. The coated substrate of claim 35, wherein: the coated substrate
has a platinum group metal loading of 4 g/l or less and a light-off
temperature for carbon monoxide at least 5.degree. C. lower than
the light-off temperature of a substrate with the same platinum
group metal loading deposited by wet-chemistry methods; the coated
substrate has a platinum group metal loading of 4 g/l or less and a
light-off temperature for hydrocarbon at least 5.degree. C. lower
than the light-off temperature of a substrate with the same
platinum group metal loading deposited by wet-chemistry methods;
or; the coated substrate has a platinum group metal loading of 4
g/l or less and a light-off temperature for nitrogen oxide at least
5.degree. C. lower than the light-off temperature of a substrate
with the same platinum group metal loading deposited by
wet-chemistry methods.
54. The coated substrate of claim 35, wherein the coated substrate
has a platinum group metal loading of about 3.0 g/l to about 4.0
g/l.
55. The coated substrate of claim 35, wherein said coated substrate
has a platinum group metal loading of about 3.0 g/l to about 4.0
g/l, and after 125,000 miles of operation in a vehicular catalytic
converter, the coated substrate has a light-off temperature for
carbon monoxide at least 5.degree. C. lower than a coated substrate
prepared by depositing platinum group metals by wet chemical
methods having the same platinum group metal loading after 125,000
miles of operation in a vehicular catalytic converter.
56. The coated substrate of claim 35, wherein a ratio of oxidative
catalytically active particles to reductive catalytically active
particles is between 6:1 and 40:1.
57. A catalytic converter comprising a coated substrate of claim
35.
58. An exhaust treatment system comprising a conduit for exhaust
gas and a catalytic converter comprising a coated substrate of
claim 35.
59. A vehicle comprising a catalytic converter according to claim
57.
60. A method of treating an exhaust gas, comprising contacting the
coated substrate of claim 35 with the exhaust gas.
61. A method of forming a coated substrate, the method comprising:
a) coating a substrate with a first washcoat composition comprising
oxidative catalytically active particles, wherein the oxidative
catalytically active particles comprise oxidative composite
nanoparticles bonded to first micron-sized carrier particles, and
wherein the oxidative composite nanoparticles comprise a first
support nanoparticle and one or more oxidative catalyst
nanoparticles; and b) coating the substrate with a second washcoat
composition comprising reductive catalytically active particles,
wherein the reductive catalytically active particles comprise
reductive composite nanoparticles bonded to second micron-sized
carrier particles, and wherein the reductive composite
nanoparticles comprise a second support nanoparticle and one or
more reductive catalyst nanoparticles; wherein the second washcoat
composition is coated onto the substrate prior to the first
washcoat composition.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority benefit of U.S. Provisional
Patent Application No. 61/729,177, filed Nov. 21, 2012, U.S.
Provisional Patent Application No. 61/729,227 filed Nov. 21, 2012,
and U.S. Provisional Patent Application No. 61/735,529 filed Dec.
10, 2012. The entire contents of all of those applications are
hereby incorporated by reference herein.
TECHNICAL FIELD OF THE INVENTION
[0002] The present disclosure relates to the field of catalysts,
substrates including nanoparticles for gas treatment, and methods
of preparation of the same. More specifically, the present
disclosure relates to substrates including nanomaterial for
three-way catalytic converters.
BACKGROUND
[0003] Car exhaust often contains environmentally and biologically
harmful compositions, including hydrocarbons, carbon monoxide, and
nitrogen oxide. Some of these compositions come from incomplete
combustion of gasoline or other fuels. These compositions are often
formed in the high temperature environment of the engines.
[0004] Catalytic converters are used to convert these
environmentally and biologically harmful compositions into less or
non-environmentally harmful compositions, such as carbon dioxide,
water, nitrogen, and oxygen. A catalytic converter typically
includes a catalytic converter core that is coated with a
catalyst-containing washcoat. The core of the catalytic converter
normally includes a grid array structure that provides a large
surface area to support the catalysts. The washcoats generally
contain silica and alumina, which provide an even larger surface
area for active precious metal catalysts. The active precious metal
catalysts often include platinum, palladium, and rhodium. Other
metals that are also catalytically active can also be used as
catalysts, such as cerium, iron, manganese, and nickel.
[0005] Two types of catalytic converters are generally available,
two-way and three-way catalytic converters. The three-way catalytic
converter is widely used on gasoline engines to reduce the emission
of hydrocarbons, carbon monoxide, and nitrogen oxides. With the
assistance of the active catalysts, the carbon monoxide and
hydrocarbons are oxidized and converted into carbon dioxide, and
the nitrogen oxides are reduced and converted into nitrogen, as
shown below in the below Equations.
2CO+O.sub.2.fwdarw.+2CO.sub.2
C.sub.xH.sub.2+2+[(3x+1)/2]O.sub.2.fwdarw.xCO.sub.2+(x+1)H.sub.2O
2NO+2CO.fwdarw.2CO.sub.2+N.sub.2
C.sub.xH.sub.2x+2+NO.fwdarw.xCO.sub.2+H.sub.2O+N.sub.2
[0006] Traditionally, the three-way catalytic converters are
prepared by separately mixing oxidative precious metals, such as
platinum or palladium, with aluminum oxide, water, and other
components to make a slurry in one container and mixing reductive
precious metal, such as rhodium, with cerium zirconium oxide,
water, and other components to make a second slurry in a second
container. The slurries are normally referred to as oxidative and
reductive washcoats. A ceramic monolith, which can be cylindrically
shaped, having a grid array structure is dipped into one of the
washcoats to form a first catalytic layer on the ceramic monolith.
After drying and calcining, the ceramic monolith is dipped into
another washcoat to form a second layer on the ceramic monolith.
The ceramic monolith including the two washcoat layers is fitted
into a shell of a catalytic converter, which connects to the engine
for treating exhaust gas.
[0007] Catalytic converters made by traditional methods suffer from
problems. One big problem is that traditional catalysts age over
time, due to the exposure to the high temperature exhaust gases.
During normal operation, the temperature within a typical gasoline
engine catalytic converter can 1,000 degrees .degree. F., or in
some instances even higher. These high temperatures give the
precious metal nano-particles in the washcoat layer increased
mobility--which results in these particles moving more quickly
through the washcoat layers. When the precious metal nano-particles
encounter one another as they move through the washcoat layer, they
can sinter or coalesce into larger metal particles in a phenomenon
known as "aging." This aging phenomenon results in the loss of
available reactive surfaces of the precious metals. Accordingly,
through aging catalytic converters become less effective, the
light-off temperature starts to rise, and emissions levels start to
rise.
[0008] The aging phenomenon is even more of an issue in gasoline
engines that use three ways catalytic converters than in diesel
engines that can use two-way catalytic converters. This is because
the exhaust temperature of a gasoline exhaust is higher than the
temperature of a diesel exhaust. In addition, the three-way
catalytic converter has to deal with both the aging of the
oxidation and the reduction catalysts. To counteract these aging
effects, catalytic converter manufacturers can increase the amount
of precious metal particles initially present in the catalytic
converter. However, increasing the amount of precious metal in the
converter is both expensive and wasteful.
[0009] Accordingly, better materials and methods to prepare the
three-way active catalytic materials are needed.
SUMMARY
[0010] Described are coated substrates for use in three-way
catalytic converters. The coated substrates decrease the rate of
the aging phenomenon that plagues typical three-way catalytic
converters. This allows for both the oxidation and reduction
activity of three-way catalytic converters using these substrates
to remain stable when exposed to the high-temperature environment
of gasoline exhausts.
[0011] As described herein, the mobility of both the catalytically
active oxidation and reduction particles are constrained. This
means that the precious metals in the described washcoat mixtures
are less likely to sinter or coalesce into larger metal particles
and are less likely to have reduced catalytic activity as they age.
These improvements result in the reduction of pollution released to
the environment during the lifetime of the catalytic converter and
vehicle and/or decrease in the amount of precious metal oxidation
and reduction catalyst used to make an effective catalytic
converter.
[0012] The coated substrates for use in three-way catalytic
converters reduce emissions of hydrocarbons, carbon monoxide, and
nitrogen oxides. In certain embodiments, the coated substrates may
exhibit performance in converting hydrocarbons, carbon monoxide,
and nitrogen oxides that is comparable or better than present
commercial coated substrates with the same or less loading of
PGM.
[0013] The coated substrates include both oxidative catalytically
active particles and reductive catalytically active particles. The
oxidative catalytically active particles include oxidative
composite nanoparticles bonded to micron-sized carrier particles,
and the oxidative composite nanoparticles include a first support
nanoparticle and one or more oxidative nanoparticles. The reductive
catalytically active particles include reductive composite
nanoparticles bonded to micron-sized carrier particles. The
reductive composite nanoparticles include a second support
nanoparticle and one or more reductive nanoparticles. The oxidative
catalytically active particles and reductive catalytically active
particles may be effective to oxidize carbon monoxide and
hydrocarbons and reduce nitrogen oxides. The oxidative
catalytically active particles and reductive catalytically active
particles may be in the same or different washcoat layers as
described herein.
[0014] One embodiment of a coated substrate includes oxidative
catalytically active particles including oxidative composite
nanoparticles bonded to first micron-sized carrier particles,
wherein the oxidative composite nanoparticles include a first
support nanoparticle and one or more oxidative catalyst
nanoparticles, and reductive catalytically active particles
including reductive composite nanoparticles bonded to second
micron-sized carrier particles, wherein the reductive composite
nanoparticles include a second support nanoparticle and one or more
reductive catalyst nanoparticles.
[0015] In some embodiments, the coated substrate includes at least
two washcoat layers in which the oxidative catalytically active
particles are in one washcoat layer and the reductive catalytically
active particles are in another washcoat layer. In some
embodiments, the oxidative catalytically active particles and the
reductive catalytically active particles are in the same washcoat
layer.
[0016] In any of the embodiments, the oxidative catalyst
nanoparticles may include platinum, palladium, or a mixture
thereof. In any of the embodiments, the oxidative catalyst
nanoparticles may include palladium. In any of the embodiments, the
first support nanoparticles may include aluminum oxide. In any of
the embodiments, the first micron-sized carrier particles may
include aluminum oxide. In any of the embodiments, the first
micron-sized carrier particle may be pre-treated at a temperature
range of about 700.degree. C. to about 1200.degree. C. In any of
the embodiments, the reductive catalyst nanoparticles may include
rhodium. In any of the embodiments, the second support
nanoparticles may include cerium zirconium oxide. In any of the
embodiments, the second micron-sized carrier particle may include
cerium zirconium oxide. In any of the embodiments, the support
nanoparticles may have an average diameter of 10 nm to 20 nm. In
any of the embodiments, the catalytic nanoparticles may have an
average diameter of between 0.5 nm and 5 nm.
[0017] Any of the embodiments, may also include an oxygen storage
component. In some of these embodiments, the oxygen storage
component may be cerium zirconium oxide or cerium oxide.
[0018] Any of the embodiments, may also include a NOx absorber
component. In some of the embodiments, the NOx absorber may be
nano-sized BaO or micron-sized BaO. In some of the embodiments, the
nano-sized BaO is impregnated into micron-sized alumina particles.
In some of the embodiments, the NOx absorber may be both nano-sized
BaO and micron-sized BaO. In some of the embodiments using
nano-sized BaO impregnated into micron-sized alumina particles, the
nano-sized BaO comprises about 10% by weight and the alumina
comprises about 90% by weight. In some of the embodiments using
nano-sized BaO impregnated into micron-sized alumina particles, the
loading of the nano-sized BaO impregnated into micron-sized alumina
particles can comprise about 5 g/l to about 40 g/l, about 10 g/l to
about 35 g/l, about 10 g/l to about 20 g/l, or about 20 g/l to
about 35 g/l, or about 16 g/l, or about 30 g/l on the final
substrate. In some of the embodiments using nano-sized BaO
impregnated into micron-sized alumina particles, the loading of the
nano-sized BaO impregnated into micron-sized alumina particles can
comprise about 5 times to 20 times the PGM loading on the
substrate, about 8 times to 16 times the PGM loading on the
substrate, or about 12 times to 15 times the PGM loading on the
substrate. In some of the embodiments where 1.1 g/l PGM is loaded
on the substrate, the nano-sized BaO impregnated into micron-sized
alumina particles can comprise about 10 g/l to about 20 g/l, about
14 g/l to about 18 g/l, or about 16 g/l loading on the substrate.
In some of the embodiments where 2.5 g/l PGM is loaded on the
substrate, the nano-sized BaO impregnated into micron-sized alumina
particles can comprise about 20 g/l to about 40 g/l, about 25 g/l
to about 35 g/l, or about 30 g/l loading on the substrate.
[0019] In any of the embodiments, the substrate may include a
cordierite or a metal substrate. In any of the embodiments, the
substrate may include a grid array or foil structure.
[0020] In any of the embodiments of the coated substrate, the
coated substrate may have a platinum group metal loading of 4 g/l
or less and a light-off temperature for carbon monoxide at least
5.degree. C. lower than the light-off temperature of a substrate
with the same platinum group metal loading deposited by
wet-chemistry methods.
[0021] In any of the embodiments of the coated substrate, the
coated substrate may have a platinum group metal loading of 4 g/l
or less and a light-off temperature for hydrocarbon at least
5.degree. C. lower than the light-off temperature of a substrate
with the same platinum group metal loading deposited by
wet-chemistry methods.
[0022] In any of the embodiments of the coated substrate, the
coated substrate may have a platinum group metal loading of 4 g/l
or less and a light-off temperature for nitrogen oxide at least
5.degree. C. lower than the light-off temperature of a substrate
with the same platinum group metal loading deposited by
wet-chemistry methods.
[0023] In any of the embodiments of the coated substrate, the
coated substrate may have a platinum group metal loading of about
3.0 g/l to about 4.0 g/l. In any of the embodiments of the coated
substrate, the coated substrate may have a platinum group metal
loading of about 3.0 g/l to about 4.0 g/l, and after 125,000 miles
of operation in a vehicular catalytic converter, the coated
substrate has a light-off temperature for carbon monoxide at least
5.degree. C. lower than a coated substrate prepared by depositing
platinum group metals by wet chemical methods having the same
platinum group metal loading after 125,000 miles of operation in a
vehicular catalytic converter.
[0024] In any of the embodiments of the coated substrate, a ratio
of oxidative catalytically active particles to reductive
catalytically active particles is between 6:1 and 40:1.
[0025] A catalytic converter may include any of the embodiments of
the coated substrate. An exhaust treatment system may include a
conduit for exhaust gas and a catalytic converter including any of
the embodiments of the coated substrate. A vehicle may include a
catalytic converter including any of the embodiments of the coated
substrate.
[0026] A method of treating an exhaust gas may include contacting
the coated substrate of any of the embodiments of the coated
substrate with the exhaust gas. A method of treating an exhaust gas
may include contacting the coated substrate of any of the
embodiments of the coated substrate with the exhaust gas, wherein
the substrate is housed within a catalytic converter configured to
receive the exhaust gas.
[0027] In some embodiments, a method of forming a coated substrate
includes: a) coating a substrate with a washcoat composition
including oxidative catalytically active particles; wherein the
oxidative catalytically active particles include oxidative
composite nanoparticles bonded to micron-sized carrier particles,
and the oxidative composite nanoparticles include a first support
nanoparticle and one or more oxidative catalyst nanoparticles; and
b) coating the substrate with a washcoat composition including
reductive catalytically active particles; wherein the reductive
catalytically active particles include reductive composite
nanoparticles bonded to micron-sized carrier particles, and the
reductive composite nanoparticles include a second support
nanoparticle and one or more reductive catalyst nanoparticles.
[0028] In some embodiments, a method of forming a coated substrate
includes: a) coating a substrate with a washcoat composition
including oxidative catalytically active particles and reductive
catalytically active particles, wherein the oxidative catalytically
active particles include oxidative composite nanoparticles bonded
to micron-sized carrier particles, and the oxidative composite
nanoparticles include a first support nanoparticle and one or more
oxidative catalyst nanoparticle, and the reductive catalytically
active particles include reductive composite nanoparticles bonded
to micron-sized carrier particles, and the reductive composite
nanoparticles include a second support nanoparticle and one or more
reductive catalyst nanoparticle.
[0029] In some embodiments, a washcoat composition includes a
solids content of: 25-75% by weight of oxidative catalytic active
particles including composite oxidative nano-particles bonded to
micron-sized carrier particles, and the composite oxidative
nano-particles include a support nano-particle and a oxidative
catalytic nano-particle; 5-50% by weight of reductive catalytic
active particles including composite reductive nano-particles
bonded to micron-sized carrier particles, and the composite
reductive nano-particles include a support nano-particle and a
reductive catalytic nano-particle; 1-40% by weight of micron-sized
cerium zirconium oxide; 0.5-10% by weight of boehmite; and 1-25% by
weight micron-sized Al.sub.2O.sub.3.
[0030] For all methods, systems, compositions, and devices
described herein, the methods, systems, compositions, and devices
can either comprise the listed components or steps, or can "consist
essentially of" the listed components or steps. When a system,
composition, or device is described as "consisting essentially of"
the listed components, the system, composition, or device contains
the components listed, and may contain other components which do
not substantially affect the performance of the system,
composition, or device, but either do not contain any other
components which substantially affect the performance of the
system, composition, or device other than those components
expressly listed; or do not contain a sufficient concentration or
amount of the extra components to substantially affect the
performance of the system, composition, or device. When a method is
described as "consisting essentially of" the listed steps, the
method consists of the steps listed, and may contain other steps
that do not substantially affect the outcome of the method, but the
method does not contain any other steps which substantially affect
the outcome of the method other than those steps expressly
listed.
[0031] The systems, compositions, substrates, and methods described
herein, including any embodiment of the invention as described
herein, may be used alone or may be used in combination with other
systems, compositions, substrates, and methods.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 shows a graphic illustration of a catalytic converter
with a coated substrate comprising oxidative catalytically active
particles and reductive catalytically active particles contained in
separate washcoat layers in accordance with the present
disclosure.
[0033] FIG. 2 is a flow chart illustrating a preparation method of
a coated substrate comprising oxidative catalytically active
particles and reductive catalytically active particles contained in
separate washcoat layers in accordance with the present
disclosure.
[0034] FIG. 3 shows a graphic illustration of a catalytic converter
with a coated substrate comprising oxidative catalytically active
particles and reductive catalytically active particles contained in
the same washcoat layer in accordance with the present
disclosure.
[0035] FIG. 4 is a flow chart illustrating a preparation method of
a coated substrate comprising oxidative catalytically active
particles and reductive catalytically active particles contained in
the same washcoat layer in accordance with the present
disclosure.
DETAILED DESCRIPTION
[0036] Described are three-way catalytic converters and methods of
making the three-way catalytic converters by combining the washcoat
layers that include both oxidative catalytically active particles
and reductive catalytically active particles. Also described are
composite nanoparticle catalysts, washcoat formulations, coated
substrates, and catalytic converters, and methods of making and
using these composite nanoparticle catalysts, washcoat
formulations, coated substrates, and catalytic converters. The
described three-way catalytic converters are more stable, and age
less, than typical three-way catalytic converters that rely on wet
chemistry methods. Accordingly, less precious metal oxidation and
reduction catalyst may be used in these three-way catalytic
converters.
[0037] In addition, the described substrates, composite
nanoparticle catalysts and washcoat solutions provide for increased
performance relative to prior catalysts and washcoat formulations
when used to produce catalytic converters, allowing for the
production of catalytic converters having reduced light-off
temperatures, reduced emissions, and/or reduced platinum group
metal loading requirements, as compared to catalytic converters
having catalysts prepared using wet-chemistry methods. The
described coated substrates include one or more washcoat layers in
which the mobility of both the catalytically active oxidation and
the catalytically active reduction particles are constrained when
exposed to the high temperatures encountered in exhaust from
gasoline engines. Because of this constrained mobility, the
precious metals in the described layers are less likely to sinter
or coalesce into larger metal particles and the reduction in
catalytic activity as they age is reduced as compared to
conventional three-way catalytic converters. These improvements
result in the reduction of pollution released to the environment
during the lifetime of the catalytic converter. In addition, less
precious metal oxidation and reduction catalyst can be used to make
an effective catalytic converter.
[0038] Composite nanoparticles include catalytic nanoparticles and
support nanoparticles that are bonded together to form nano-on-nano
composite nano particles. These composite nano particles are then
bonded to a micron-sized carrier particle to form micron-sized
catalytically active particles. The composite nano-particles may be
produced, for example, in a plasma reactor so that consistent and
tightly bonded nano-on-nano composite particles are produced. These
composite particles can then be bonded to micron-sized carrier
particles to produce micron-sized catalytically active particles
bearing composite nanoparticles, which may offer better initial
(engine start-up) performance, better performance over the lifetime
of the catalyst, and/or less decrease in performance over the life
of the catalyst as compared to previous catalysts used in catalytic
converters, such as catalysts prepared using wet-chemistry
methods.
[0039] Further, the three-way catalytic converter can include one
or more layers of washcoats on a catalyst substrate, such as a
catalytic converter substrate. In some embodiments, the micron
particles bearing composite oxidative nanoparticles and micron
particles bearing composite reductive nanoparticles are in the same
washcoat layer. In some embodiments, the micron particles bearing
composite oxidative nanoparticles and micron particles bearing
composite reductive nanoparticles are in separate washcoat layers.
When the micron particles bearing composite oxidative nanoparticles
and micron particles bearing composite reductive nanoparticles are
in separate washcoat layers, the order and placement of these two
layers on a substrate may vary in different embodiments and, in
further embodiments, additional washcoat formulations/layers may
also be used over, under, or between these washcoat layers, for
example, a corner-fill washcoat layer which may be initially
deposited on the substrate to be coated. In other embodiments, the
two layers can be directly disposed on each other, that is, there
are no intervening layers between the first and second washcoat
layers. The described washcoat formulations may include a lower
amount of platinum group metals and/or offer better performance
when compared to previous washcoat formulations, particularly when
these described washcoat formulations utilize the micron-sized
particles bearing composite nanoparticles.
[0040] Various aspects of the disclosure can be described through
the use of flowcharts. Often, a single instance of an aspect of the
present disclosure is shown. As is appreciated by those of ordinary
skill in the art, however, the protocols, processes, and procedures
described herein can be repeated continuously or as often as
necessary to satisfy the needs described herein. Additionally, it
is contemplated that certain method steps can be performed in
alternative sequences to those disclosed in the flowcharts.
[0041] When numerical values are expressed herein using the term
"about" or the term "approximately," it is understood that both the
value specified, as well as values reasonably close to the value
specified, are included. For example, the description "about
50.degree. C." or "approximately 50.degree. C." includes both the
disclosure of 50.degree. C. itself, as well as values close to
50.degree. C. Thus, the phrases "about X" or "approximately X"
include a description of the value X itself. If a range is
indicated, such as "approximately 50.degree. C. to 60.degree. C.,"
it is understood that both the values specified by the endpoints
are included, and that values close to each endpoint or both
endpoints are included for each endpoint or both endpoints; that
is, "approximately 50.degree. C. to 60.degree. C." is equivalent to
reciting both "50.degree. C. to 60.degree. C." and "approximately
50.degree. C. to approximately 60.degree. C."
[0042] By "substantial absence of any platinum group metals" it is
meant that less than about 5%, less than about 2%, less than about
1%, less than about 0.5%, less than about 0.1%, less than about
0.05%, less than about 0.025%, or less than about 0.01% of platinum
group metals are present by weight. Preferably, substantial absence
of any platinum group metals indicates that less than about 1% of
platinum group metals are present by weight.
[0043] By "substantially free of" a specific component, a specific
composition, a specific compound, or a specific ingredient in
various embodiments, is meant that less than about 5%, less than
about 2%, less than about 1%, less than about 0.5%, less than about
0.1%, less than about 0.05%, less than about 0.025%, or less than
about 0.01% of the specific component, the specific composition,
the specific compound, or the specific ingredient is present by
weight. Preferably, "substantially free of" a specific component, a
specific composition, a specific compound, or a specific ingredient
indicates that less than about 1% of the specific component, the
specific composition, the specific compound, or the specific
ingredient is present by weight.
[0044] It should be noted that, during fabrication, or during
operation (particularly over long periods of time), small amounts
of materials present in one washcoat layer may diffuse, migrate, or
otherwise move into other washcoat layers. Accordingly, use of the
terms "substantial absence of" and "substantially free of" is not
to be construed as absolutely excluding minor amounts of the
materials referenced.
[0045] By "substantially each" of a specific component, a specific
composition, a specific compound, or a specific ingredient in
various embodiments, it is meant that at least about 95%, at least
about 98%, at least about 99%, at least about 99.5%, at least about
99.9%, at least about 99.95%, at least about 99.975%, or at least
about 99.99% of the specific component, the specific composition,
the specific compound, or the specific ingredient is present by
number or by weight. Preferably, substantially each" of a specific
component, a specific composition, a specific compound, or a
specific ingredient is meant that at least about 99% of the
specific component, the specific composition, the specific
compound, or the specific ingredient is present by number or by
weight.
[0046] This disclosure provides several embodiments. It is
contemplated that any features from any embodiment can be combined
with any features from any other embodiment. In this fashion,
hybrid configurations of the disclosed features are within the
scope of the present invention.
[0047] It is understood that reference to relative weight
percentages in a composition assumes that the combined total weight
percentages of all components in the composition add up to 100. It
is further understood that relative weight percentages of one or
more components may be adjusted upwards or downwards such that the
weight percent of the components in the composition combine to a
total of 100, provided that the weight percent of any particular
component does not fall outside the limits of the range specified
for that component.
[0048] This disclosure refers to both particles and powders. These
two terms are equivalent, except for the caveat that a singular
"powder" refers to a collection of particles. The present invention
can apply to a wide variety of powders and particles. The terms
"nano-particle," "nano-size particle," and "nano-sized particle"
are generally understood by those of ordinary skill in the art to
encompass a particle on the order of nanometers in diameter,
typically between about 0.5 nm to 500 nm, about 1 nm to 500 nm,
about 1 nm to 100 nm, or about 1 nm to 50 nm. Preferably, the
nano-particles have an average grain size less than 250 nanometers
and an aspect ratio between one and one million. In some
embodiments, the nano-particles have an average grain size of about
50 nm or less, about 30 nm or less, or about 20 nm or less. In
additional embodiments, the nano-particles have an average diameter
of about 50 nm or less, about 30 nm or less, or about 20 nm or
less. The aspect ratio of the particles, defined as the longest
dimension of the particle divided by the shortest dimension of the
particle, is preferably between one and one hundred, more
preferably between one and ten, yet more preferably between one and
two. "Grain size" is measured using the ASTM (American Society for
Testing and Materials) standard (see ASTM E112-10). When
calculating a diameter of a particle, the average of its longest
and shortest dimension is taken; thus, the diameter of an ovoid
particle with long axis 20 nm and short axis 10 nm would be 15 nm.
The average diameter of a population of particles is the average of
diameters of the individual particles, and can be measured by
various techniques known to those of skill in the art.
[0049] In additional embodiments, the nano-particles have a grain
size of about 50 nm or less, about 30 nm or less, or about 20 nm or
less. In additional embodiments, the nano-particles have a diameter
of about 50 nm or less, about 30 nm or less, or about 20 nm or
less.
[0050] The terms "micro-particle," "micro-size particle,"
"micro-sized particle," "micron-particle," "micron-size particle,"
and "micron-sized particle" are generally understood to encompass a
particle on the order of micrometers in diameter, typically between
about 0.5 .mu.m to 1000 .mu.m, about 1 .mu.m to 1000 .mu.m, about 1
.mu.m to 100 .mu.m, or about 1 .mu.m to 50 .mu.m. Additionally, the
term "platinum group metals" (abbreviated "PGM") used in this
disclosure refers to the collective name used for six metallic
elements clustered together in the periodic table. The six platinum
group metals are ruthenium, rhodium, palladium, osmium, iridium,
and platinum.
Composite Nanoparticle Catalyst
[0051] Three-way catalytic converters may be formed from two
different types of composite nanoparticles. One type of composite
nanoparticles is an oxidative composite nanoparticle. Another type
of composite nanoparticle is a reductive composite
nanoparticle.
[0052] A composite nanoparticle catalyst may include a catalytic
nanoparticle attached to a support nanoparticle to form a
"nano-on-nano" composite nanoparticle. Multiple nano-on-nano
particles may then be bonded to a micron-sized carrier particle to
form a composite micro/nanoparticle, that is, a micro-particle
bearing composite nanoparticles. These composite
micro/nanoparticles may be used in washcoat formulations and
catalytic converters as described herein. The use of these
particles can reduce requirements for platinum group metal content
and/or significantly enhance performance, particularly in terms of
reduced light-off temperature, as compared with currently available
commercial catalytic converters prepared by wet-chemistry methods.
This is particularly significant and striking for a three-way
catalytic converter, which functions in the high temperature
environment produced by a gasoline engine and includes both
oxidation and reduction catalytically active particles. The
wet-chemistry methods generally involve use of a solution of
platinum group metal ions or metal salts, which are impregnated
into supports (typically micron-sized particles), and reduced to
platinum group metal in elemental form for use as the catalyst. For
example, a solution of chloroplatinic acid, H.sub.2PtCl.sub.6, can
be applied to alumina micro-particles, followed by drying and
calcining, resulting in precipitation of platinum onto the alumina.
The platinum group metals deposited by wet-chemical methods onto
metal oxide supports, such as alumina and cerium zirconium oxide,
are mobile at high temperatures, such as temperatures encountered
in catalytic converters. That is, at the high temperatures of a
three-way catalytic converter that is used for gasoline engines,
the PGM atoms can migrate over the surface on which they are
deposited, and will clump together with other PGM atoms. The
finely-divided portions of PGM combine into larger and larger
agglomerations of platinum group metal as the time of exposure to
high temperature increases. This agglomeration leads to reduced
catalyst surface area and degrades the performance of the catalytic
converter. This phenomenon is referred to as "aging" of the
catalytic converter.
[0053] In contrast, the composite platinum group metal catalysts
are prepared by plasma-based methods. In one embodiment, the
platinum group nano-sized metal particle is deposited on a
nano-sized metal oxide support, which has much lower mobility than
the PGM deposited by wet chemistry methods. The resulting
plasma-produced catalysts age at a much slower rate than the
wet-chemistry produced catalysts. Thus, catalytic converters using
plasma-produced catalysts can maintain a larger surface area of
exposed catalyst to gases emitted by the engine over a longer
period of time, leading to better emissions performance.
Oxidative Composite Nanoparticle (Oxidative Nano-on-Nano
Particle)
[0054] As discussed above, one type of composite nanoparticles is
an oxidative composite nanoparticle catalyst. An oxidative
composite nanoparticle may include one or more oxidative catalyst
nanoparticles attached to a first support nanoparticle to form an
oxidative "nano-on-nano" composite nanoparticle. Platinum (Pt) and
palladium (Pd) are oxidative to the hydrocarbon gases and carbon
monoxide. In certain embodiments, the oxidative nanoparticle is
platinum. In other embodiments, the oxidative nanoparticle is
palladium. A suitable support nanoparticle for the oxidative
catalyst nanoparticle includes, but is not limited to, nano-sized
aluminum oxide (alumina or Al.sub.2O.sub.3).
[0055] Each oxidative catalyst nanoparticle may be supported on a
first support nanoparticle. The first support nanoparticle may
include one or more oxidative nanoparticles. The oxidative catalyst
nanoparticles on the first support nanoparticle may include
platinum, palladium, or a mixture thereof. At the high temperatures
involved in gasoline exhaust engines both palladium and platinum
are effective oxidative catalysts. Accordingly, in some
embodiments, the oxidative catalyst is palladium alone, which is
presently more widely available and less expensive. However, in
some embodiments platinum alone may be used or in combination with
palladium. For example, the first support nanoparticle may contain
a mixture of 2:1 to 40:1 palladium to platinum.
Reductive Composite Nanoparticle (Reductive Nano-on-Nano
Particle)
[0056] As discussed above, another type of composite nanoparticles
is a reductive composite nanoparticle catalyst. A reductive
composite nanoparticle may include one or more reductive catalyst
nanoparticles attached to a second support nanoparticle to form a
reductive "nano-on-nano" composite nanoparticle. Rhodium (Rh) is
reductive to the nitrogen oxides in fuel-rich conditions. In
certain embodiments, the reductive catalyst nanoparticle is
rhodium. The second support may be the same or different than the
first support. A suitable second support nanoparticle for the
reductive nanoparticle includes, but is not limited to, nano-sized
cerium zirconium oxide (CeO.sub.2.ZrO.sub.2).
[0057] Each reductive catalyst nanoparticle may be supported on a
second support nanoparticle. The second support nanoparticle may
include one or more reductive catalyst nanoparticles. The ratios of
rhodium to cerium zirconium oxide and sizes of the reductive
composite nanoparticle catalyst are further discussed below in the
sections describing production of composite nanoparticles by
plasma-based methods and production of micron-sized carrier
particles bearing composite nanoparticles.
Barium-Oxide Nano-Particles and Micron-Particles
[0058] Barium oxide nanoparticles may be combined with porous
micron supports as described below, and may be included in the
oxidative washcoat layer, the reductive washcoat layer, or both the
oxidative and reductive washcoat layers. As an alternative
embodiment, micron-sized barium oxide particles may be included in
the oxidative washcoat layer, the reductive washcoat layer, or both
the oxidative and reductive washcoat layers. In another alternative
embodiment, both barium oxide nanoparticles and barium oxide micron
particles may be included in the oxidative washcoat layer, the
reductive washcoat layer, or both the oxidative and reductive
washcoat layers. When the oxidative and reductive particles are in
the same layer, barium-oxide nanoparticles and/or barium-oxide
micron particles may be included in this combination layer.
[0059] The barium oxide is an absorber that binds and holds NOx
compounds, particularly NO.sub.2, and sulfur compounds such
SO.sub.x, particularly SO.sub.2, during lean burn times of engine
operation. These compounds are then released and reduced by the
catalysts during a period of rich engine operation.
Production of Composite Nanoparticles by Plasma-Based Methods
("Nano-on-Nano" Particles or "NN" Particles)
[0060] The oxidative composite nanoparticle catalysts and reductive
composite nanoparticle catalysts are produced by plasma-based
methods. These particles have many advantageous properties as
compared to catalysts produced by wet chemistry. For example, the
precious metals in the composite nanoparticle catalysts are
relatively less mobile under the high temperature environment of a
three-way catalytic converter than the precious metals in washcoat
mixtures used in typical commercial three-way catalytic converters
that are produced using wet chemistry methods.
[0061] Both the oxidative composite nanoparticles and the reductive
composite nanoparticles may be formed by plasma reactor methods.
These methods include feeding platinum group metal(s) and support
material into a plasma gun, where the materials are vaporized.
Plasma guns such as those disclosed in US 2011/0143041 can be used,
and techniques such as those disclosed in U.S. Pat. No. 5,989,648,
U.S. Pat. No. 6,689,192, U.S. Pat. No. 6,755,886, and US
2005/0233380 can be used to generate plasma. A working gas, such as
argon, is supplied to the plasma gun for the generation of plasma;
in one embodiment, an argon/hydrogen mixture (in the ratio of 10:2
Ar/H.sub.2) may be used as the working gas.
[0062] The platinum group metal or metals (such as rhodium,
palladium, platinum, or platinum/palladium in any ratio, such as
2:1 up to 40:1 platinum:palladium by weight), generally in the form
of metal particles of about 1 to 6 microns in diameter, can be
introduced into the plasma reactor as a fluidized powder in a
carrier gas stream such as argon. Metal oxide, typically aluminum
oxide or cerium zirconium oxide in a particle size of about 15 to
25 microns diameter, is also introduced as a fluidized powder in
carrier gas. However, other methods of introducing the materials
into the reactor can be used, such as in a liquid slurry.
Typically, for oxidative composite nanoparticles, palladium,
platinum, or a mixture thereof is deposited on aluminum oxide.
Typically, for reductive composite nanoparticles, rhodium is
deposited on cerium zirconium oxide.
[0063] For preparation of oxidative composite nanoparticles, a
composition of 1% to 5% platinum group metal(s) and 55% to 99%
metal oxide (by weight) is typically used. Examples of ranges of
materials that can be used for oxidative composite nanoparticles in
which palladium is the oxidation catalyst are from about 1% to 20%
palladium, to 80% to 99% aluminum oxide; and 5%-20% palladium to
80%-95% aluminum oxide. Examples of ranges of materials that can be
used for oxidative composite nanoparticles in which platinum is the
oxidation catalyst are from about 35% to 45% platinum to 55% to 65%
aluminum oxide. Examples of ranges of materials that can be used
for oxidative composite nanoparticles in which both platinum and
palladium are the oxidation catalyst are from about 23.3% to about
30% platinum, 11.7% to 15% palladium, and 55% to 65% aluminum
oxide. In a certain embodiment, a composition contains about 26.7%
platinum, 13.3% palladium, and 60% aluminum oxide.
[0064] Examples of ranges of materials that can be used for
reductive composite nanoparticles are from about 1% to about 10%
rhodium and 90% to 99% cerium zirconium oxide. In a certain
embodiment, the composition contains about 5% rhodium and 95%
cerium zirconium oxide.
[0065] In a plasma reactor, any solid or liquid materials are
rapidly vaporized or turned into plasma. The kinetic energy of the
superheated material, which can reach temperatures of 20,000 to
30,000 Kelvin, ensures extremely thorough mixture of all
components.
[0066] The superheated material of the plasma stream is then
quenched rapidly; using such methods as the turbulent quench
chamber disclosed in US 2008/0277267. Argon quench gas at high flow
rates, such as 2400 to 2600 liters per minute, may be injected into
the superheated material. The material may be further cooled in a
cool-down tube, and collected and analyzed to ensure proper size
ranges of material.
[0067] The plasma production method described above produces highly
uniform composite nanoparticles, where the composite nanoparticles
comprise a catalytic nanoparticle bonded to a support nanoparticle.
The catalytic nanoparticle comprises the platinum group metal or
metals, such as Pd, Pt, or Rh. In some embodiments, the catalytic
nanoparticles have an average diameter or average grain size
between approximately 0.3 nm and approximately 10 nm, preferably
between approximately 1 nm to approximately 5 nm, that is,
approximately 3 nm+/-2 nm. In some embodiments, the support
nanoparticles, comprising the metal oxide such as aluminum oxide or
cerium zirconium oxide, have an average diameter of approximately
20 nm or less, or approximately 15 nm or less, or between
approximately 10 nm and approximately 20 nm, that is, approximately
15 nm+/-5 nm, or between approximately 10 nm and approximately 15
nm, that is, approximately 12.5 nm+/-2.5 nm. In some embodiments,
the support nano-particles, comprising the metal oxide such as
aluminum oxide or cerium zirconium oxide, have a diameter of
approximately 20 nm or less, or approximately 15 nm or less, or
between approximately 10 nm and approximately 20 nm, that is,
approximately 15 nm+/-5 nm, or between approximately 10 nm and
approximately 15 nm, that is, approximately 12.5 nm+/-2.5 nm.
[0068] The Pd-alumina, Pt-alumina, and Pt/Pd-alumina composite
nanoparticles, when produced under reducing conditions, such as by
using argon/hydrogen working gas, results in a partially reduced
alumina surface on the support nano-particle to which the PGM
nano-particle is bonded, as described in US 2011/0143915 at
paragraphs 0014-0022. The partially reduced alumina surface, or
Al.sub.2O.sub.(3-x) where x is greater than zero, but less than
three, inhibits migration of the platinum group metal on the
alumina surface at high temperatures. This in turn limits the
agglomeration of platinum group metal when the particles are
exposed to prolonged elevated temperatures. Such agglomeration is
undesirable for many catalytic applications, as it reduces the
surface area of PGM catalyst available for reaction.
[0069] The composite nanoparticles comprising two nanoparticles
(catalytic or support) are referred to as "nano-on-nano" particles
or "NN" particles.
Production of Micron-Sized Carrier Particles Bearing Composite
Nanoparticles ("Nano-on-Nano-on-Micro" Particles or "NNm".TM.
Particles)
[0070] The composite nanoparticles (nano-on-nano particles) may be
further bonded to micron-sized carrier particles to produce
composite micro/nanoparticles, referred to as
"nano-on-nano-on-micro" particles or "NNm".TM. particles, which are
catalytically active particles.
[0071] An oxidative catalytically active particle includes an
oxidative catalyst nanoparticle (such as palladium, platinum or a
mixture thereof) and nano-sized metal oxide (such as nano-sized
aluminum oxide or nano-sized cerium zirconium oxide) which are
bonded to a micron-sized carrier particle (such as micron-sized
aluminum oxide or micron-sized cerium zirconium oxide). A reductive
catalytically active particle includes a reductive catalyst
nanoparticle (such as rhodium) and a nano-sized metal oxide (such
as nano-sized cerium zirconium oxide) which are bonded to
micron-sized carrier particles (such as micron-sized cerium
zirconium oxide).
[0072] The micron-sized particles can have an average size between
about 1 micron and about 100 microns, such as between about 1
micron and about 10 microns, between about 3 microns and about 7
microns, or between about 4 microns and about 6 microns.
[0073] In general, the nano-on-nano-on-micro particles are produced
by a process of suspending the composite nanoparticles
(nano-on-nano particles) in water, adjusting the pH of the
suspension to between about 2 and about 7, between about 3 and
about 5, or about 4, adding one or more surfactants to the
suspension (or, alternatively, adding the surfactants to the water
before suspending the composite nano-particles in the water) to
form first solution. The process includes sonicating the composite
nanoparticle suspension, applying the suspension to micron-sized
metal oxide particles until the point of incipient wetness, thereby
impregnating the micron-sized particles with composite
nanoparticles and nano-sized metal oxide.
[0074] In some embodiments, the micron-sized metal oxide particles
are pre-treated with a gas at high temperature. The pretreatment of
the micron-sized metal oxide particles allows the
nano-on-nano-on-micro particles to withstand the high temperatures
of an engine. Without pretreatment, the nano-on-nano-on-micro
particles would more likely change phase on exposure to high
temperature compared to the nano-on-nano-on-micro particles that
have been pretreated. In some embodiments, pretreatment includes
exposure of the micron-sized metal oxide particles at temperatures,
such as about 700.degree. C. to about 1500.degree. C.; 700.degree.
C. to about 1400.degree. C.; 700.degree. C. to about 1300.degree.
C.; and 700.degree. C. to about 1200.degree. C. In some
embodiments, pretreatment includes exposure of the micron-sized
metal oxide particles at temperatures, such as about 700.degree.
C., 1110.degree. C., 1120.degree. C., 1130.degree. C., 1140.degree.
C., 1150.degree. C., 1155.degree. C., 1160.degree. C., 1165.degree.
C., 1170.degree. C., 1175.degree. C., 1180.degree. C., 1190.degree.
C., and 1200.degree. C.
[0075] The process includes drying the micron-sized metal oxide
particles which have been impregnated with composite nanoparticles
and nano-sized metal oxide, and calcining the micron-sized metal
oxide particles which have been impregnated with composite
nanoparticles and nano-sized metal oxide.
[0076] Typically, the composite nanoparticles and nano-sized metal
oxide are suspended in water, and the suspension is adjusted to
have a pH of between about 2 and about 7, preferably between about
3 and about 5, more preferably a pH of about 4 (the pH is adjusted
with acetic acid or another organic acid). Dispersants and/or
surfactants may be added to the composite nanoparticles and
nano-sized metal oxide. Surfactants suitable for use include
Jeffsperse.RTM. X3202 (Chemical Abstracts Registry No. 68123-18-2,
and described as 4,4'-(1-methylethylidene)bis-phenol polymer with
2-(chloromethyl)oxirane, 2-methyloxirane, and oxirane),
Jeffsperse.RTM. X3204, and Jeffsperse.RTM. X3503 surfactants from
Huntsman (JEFFSPERSE is a registered trademark of Huntsman
Corporation, The Woodlands, Tex., United States of America for
chemicals for use as dispersants and stabilizers), which are
nonionic polymeric dispersants. Other suitable surfactants include
Solsperse.RTM. 24000 and Solsperse.RTM. 46000 from Lubrizol
(SOLSPERSE is a registered trademark of Lubrizol Corporation,
Derbyshire, United Kingdom for chemical dispersing agents). The
Jeffsperse.RTM. X3202 surfactant, Chemical Abstracts Registry No.
68123-18-2 (described as 4,4'-(1-methylethylidene)bis-phenol
polymer with 2-(chloromethyl)oxirane, 2-methyloxirane, and
oxirane), is preferred. The surfactant may be added in a range, for
example, of about 0.5% to about 5%, with about 2% being a typical
value.
[0077] The mixture of aqueous surfactants and composite
nanoparticles and nano-sized metal oxide may be sonicated to
disperse the composite nanoparticles and nano-sized metal oxide.
The quantity of composite nanoparticles and nano-sized metal oxide
in the dispersion may be in the range of about 2% to about 15% (by
mass).
General Procedures for Preparation of Catalysts for Oxidation
Reaction
[0078] To prepare an oxidative catalytically active particle, a
dispersion of oxidative composite nanoparticles may be applied to
porous, micron-sized Al.sub.2O.sub.3, which may be purchased, for
example, from companies such as Rhodia or Sasol. The porous,
micron-sized, Al.sub.2O.sub.3 powders may be stabilized with a
small percentage of lanthanum (about 2% to about 4% La). One
commercial alumina powder suitable for use is MI-386, which may be
purchased from Grace Davison or Rhodia. The usable surface for this
powder, defined by pore sizes greater than 0.28 .mu.m, is
approximately 2.8 m.sup.2/g. The ratio of composite nano-particles
used to micron-sized carrier particles used may be from about 3:100
to about 10:100, about 5:100 to about 8:100, or about 6.5:100, in
terms of (weight of composite nanoparticle):(weight of micron
carrier particle). In some embodiments, about 8 grams of composite
nano-particles may be used with about 122 grams of carrier
micro-particles. The aqueous dispersion of composite nanoparticles
may be applied in small portions (such as by dripping or other
methods) to the micron-sized powder until the point of incipient
wetness, producing a material similar to damp sand as described
below.
[0079] In some instances, the sizes of the nano-sized oxidative
catalysts, for example Pd, Pt or Pt/Pd are about 1 nm and the sizes
of the nano-sized Al.sub.2O.sub.3 are about 10 nm. In some
instances, the sizes of the nano-sized oxidative catalysts are
approximately 1 nm or less and the sizes of the nano-sized
Al.sub.2O.sub.3 are approximately 10 nm or less. In some instances,
Pd is used as the oxidative catalyst and the weight ratio of
nano-sized Pd:nano-sized Al.sub.2O.sub.3 is about 5%:95%. In some
instances, the weight percentage of nano-sized Pd is between about
5% to about 20% of nano-sized Pd on nano-sized Al.sub.2O.sub.3. The
nano-on-nano material that contains nano-sized Pd on nano-sized
Al.sub.2O.sub.3 shows a dark black color. In some instances, Pt is
used as the oxidative catalyst and the weight ratio of nano-sized
Pt:nano-sized Al.sub.2O.sub.3 is about 40%: 60%.
[0080] A solution containing dispersed nano-on-nano material can be
prepared by sonication process to disperse nano-on-nano particles
into water with pH .about.4. Then 100 g of micron-sized MI386
Al.sub.2O.sub.3 is put into a mixer, and 100 g dispersion
containing the nano-on-nano material is injected into the mixing
Al.sub.2O.sub.3, which is known as incipient wetness process.
[0081] Next, the wet powder is dried at 60.degree. C. in a
convection oven overnight until it is fully dried.
[0082] Next, calcination is performed. The dried powder from the
previous step, that is, the nanomaterials on the micron-sized
material, is baked at 550.degree. C. for two hours under ambient
air condition. During the calcination, the surfactant is burned off
and the nanomaterials are glued or fixed onto the surface of the
micron-materials or the surface of the pores of the
micron-materials. One explanation for why the nanomaterials can be
glued or fixed more permanently onto the micron-material during the
calcination is because oxygen-oxygen (O--O) bonds, oxide-oxide
bonds, or covalent bonds are formed during the calcination. The
oxide-oxide bonds can be formed between the nanomaterials
(nano-on-nano with nano-on-nano, nano-on-nano with nano-sized
Al.sub.2O.sub.3, and nano-sized Al.sub.2O.sub.3 with nano-sized
Al.sub.2O.sub.3), between the nanomaterials and the
micron-materials, and between the micron-materials themselves. The
oxide-oxide bond formation is sometimes referred to as a solid
state reaction. At this stage, the material produced contains a
micron-particle based material having nano-on-nano and
n-Al.sub.2O.sub.3 randomly distributed on the surface.
[0083] The oxidative NNm.TM. particles may contain from about 0.5%
to about 5% palladium by weight, or in another embodiment from
about 1% to 3% by weight, or in another embodiment, about 1.2% to
2.5% by weight, of the total mass of the NNm.TM. particle.
[0084] The oxidative NNm.TM. particles may contain from about 1% to
about 6% platinum by weight, of the total mass of the NNm.TM.
particle.
General Procedures for Preparation of Catalysts for Reduction
Reaction
[0085] To prepare a reductive catalytically active particle, a
dispersion of reductive composite nanoparticles may be applied to
porous, micron-sized cerium zirconium oxide. A preferred reductive
PGM is rhodium.
[0086] The micron-sized carrier particles, impregnated with the
composite reductive nanoparticles and nano-sized metal oxide, may
then be dried (for example, at about 30.degree. C. to about
95.degree. C., preferably about 60.degree. C. to about 70.degree.
C., at atmospheric pressure or at reduced pressure such as from
about 1 pascal to about 90,000 pascal). After drying, the particles
may then be calcined (at elevated temperatures, such as from
400.degree. C. to about 700.degree. C., preferably about
500.degree. C. to about 600.degree. C., more preferably at about
540.degree. C. to about 560.degree. C., still more preferably at
about 550.degree. C. to about 560.degree. C., or at about
550.degree. C.; at atmospheric pressure or at reduced pressure, for
example, from about 1 pascal to about 90,000 pascal, in ambient
atmosphere or under an inert atmosphere such as nitrogen or argon)
to yield the composite micro/nano-particles, also referred to as
nano-on-nano-on-micro particles, or NNm.TM. particles. The drying
step may be performed before the calcining step to remove the water
before heating at the higher calcining temperatures; this avoids
boiling of the water, which would disrupt the impregnated
nano-particles which are lodged in the pores of the micron-sized
carrier.
[0087] The catalyst for reduction reactions can be made using the
procedures similar to the procedure of making the catalyst for
oxidation reactions. The nano-on-nano materials, nano-sized Rh on
nano-sized cerium zirconium oxide, can be obtained and prepared
using the method described above. In some instances, the sizes of
the nano-sized Rh are about 1 nm and the sizes of the nano-sized
cerium zirconium oxide are about 10 nm. In some instances, the
sizes of the nano-sized Rh are approximately 1 nm or less and the
sizes of the nano-sized cerium zirconium oxide are approximately 10
nm or less. In some instances, the weight ratio of nano-sized
Rh:nano-sized cerium zirconium oxide is about 5%:95%. In some
instances, the weight percentage of nano-sized Rh is between about
5% to about 20% nano-sized Rh on nano-sized cerium zirconium
oxide.
[0088] Next, calcination can be performed. The dried powder from
the previous step, that is, the nanomaterials on the micron-sized
material, can be baked at 550.degree. C. for two hours under
ambient air condition. During the calcination, the surfactant is
evaporated and the nanomaterials are glued or fixed onto the
surface of the micron-materials or the surface of the pores of the
micron-materials. At this stage, the material produced (a catalytic
active material) contains a micron-particle based material
(micron-sized cerium zirconium oxide) having nano-on-nano
(nano-sized Rh on nano-sized cerium zirconium oxide) and nano-sized
cerium zirconium oxide randomly distributed on the surface.
[0089] The reductive NNm.TM. particles may contain from about 0.1%
to 1.0% rhodium by weight, or in another embodiment from about 0.2%
to 0.5% by weight, or in another embodiment, about 0.3% by weight,
of the total mass of the NNm.TM. particle. The NNm.TM. particles
can then be used for formulations for coating substrates, where the
coated substrates may be used in catalytic converters.
[0090] Examples of production of NNm.TM. material are described in
the following co-owned patents and patent applications, the
disclosures of which are hereby incorporated by reference in their
entirety: U.S. Patent Publication No. 2005/0233380, U.S. Patent
Publication No. 2006/0096393, U.S. patent application Ser. No.
12/151,810, U.S. patent application Ser. No. 12/152,084, U.S.
patent application Ser. No. 12/151,809, U.S. Pat. No. 7,905,942,
U.S. patent application Ser. No. 12/152,111, U.S. Patent
Publication 2008/0280756, U.S. Patent Publication 2008/0277270,
U.S. patent application Ser. No. 12/001,643, U.S. patent
application Ser. No. 12/474,081, U.S. patent application Ser. No.
12/001,602, U.S. patent application Ser. No. 12/001,644, U.S.
patent application Ser. No. 12/962,518, U.S. patent application
Ser. No. 12/962,473, U.S. patent application Ser. No. 12/962,490,
U.S. patent application Ser. No. 12/969,264, U.S. patent
application Ser. No. 12/962,508, U.S. patent application Ser. No.
12/965,745, U.S. patent application Ser. No. 12/969,503, and U.S.
patent application Ser. No. 13/033,514, WO 2011/081834
(PCT/US2010/59763) and US 2011/0143915 (U.S. patent application
Ser. No. 12/962,473).
NNm.TM. Particles with Inhibited Migration of Platinum Group
Metals
[0091] The oxidative NNm.TM. particles including an aluminum oxide
micron-sized carrier particle bearing composite nano-particles,
where the composite nano-particles are produced under reducing
conditions, are particularly advantageous for use in catalytic
converter applications. The platinum group metal of the catalytic
nano-particle has a greater affinity for the partially reduced
Al.sub.2O.sub.(3-x) surface of the support nano-particle than for
the Al.sub.2O.sub.3 surface of the micron-sized carrier particles.
Thus, at elevated temperatures, neighboring PGM nanoparticles bound
to neighboring Al.sub.2O.sub.(3-x) support nano-particles are less
likely to migrate on the Al.sub.2O.sub.3 micron-sized carrier
particle surface and agglomerate into larger catalyst clumps. Since
the larger agglomerations of catalyst have less surface area, and
are less effective as catalysts, the inhibition of migration and
agglomeration provides a significant advantage for the NNm.TM.
particles. In contrast, palladium and platinum particles deposited
by wet-chemical precipitation onto alumina support demonstrate
higher mobility and migration, forming agglomerations of catalyst
and leading to decreased catalytic efficacy over time (that is,
catalyst aging).
Barium-Oxide Particles
[0092] Barium-oxide nano particles and barium-oxide micron
particles may be produced by the plasma-based methods described
above with respect to the oxidative and reductive nano-on-nano
particles. The barium-oxide feed material can be fed into the into
a plasma gun, where the material is vaporized.
[0093] In some embodiments, the barium-oxide nanoparticles have an
average diameter of approximately 20 nm or less, or approximately
15 nm or less, or between approximately 10 nm and approximately 20
nm, that is, approximately 15 nm+/-5 nm, or between approximately
10 nm and approximately 15 nm, that is, approximately 12.5 nm+/-2.5
nm. In some embodiments, the barium-oxide nano-particles have a
diameter of approximately 20 nm or less, or approximately 15 nm or
less, or between approximately 10 nm and approximately 20 nm, that
is, approximately 15 nm+/-5 nm, or between approximately 10 nm and
approximately 15 nm, that is, approximately 12.5 nm+/-2.5 nm.
[0094] In some embodiments, the barium-oxide micron particles have
an average diameter of approximately 10 .mu.m or less, or
approximately 8 .mu.m or less, or approximately 5 .mu.m or less, or
approximately 2 .mu.m or less, or approximately 1.5 .mu.m or less,
or approximately 1 .mu.m or less, or approximately 0.5 .mu.m or
less. In some embodiments, the barium-oxide micron particles have
an average diameter between approximately 6 .mu.m and approximately
10 .mu.m, that is, approximately 8 .mu.m+/-2 .mu.m, or between
approximately 7 .mu.m and approximately 9 .mu.m, that is,
approximately 8 .mu.m+/-1 .mu.m. In some embodiments, the
barium-oxide micron particles have an average diameter between
approximately 0.5 .mu.m and approximately 2 .mu.m, that is,
approximately 1.25 .mu.m+/-0.75 .mu.m, or between approximately 1.0
.mu.m and approximately 1.5 .mu.m, that is, approximately 1.25
.mu.m+/-0.25 .mu.m.
[0095] The barium-oxide nano particles may be impregnated into
micron-sized alumina supports. The procedure for impregnating these
supports may be similar to the process described above with respect
to impregnating the oxidative composite nanoparticles into
micron-sized Al.sub.2O.sub.3 supports. Preferably, the barium-oxide
nano-particles are prepared by applying a dispersion of
barium-oxide nanoparticles to porous, micron-sized Al.sub.2O.sub.3,
as described with respect to the oxidative nanoparticles. The
porous, micron-sized, Al.sub.2O.sub.3 powders may be stabilized
with a small percentage of lanthanum (about 2% to about 4% La). One
commercial alumina powder suitable for use is MI-386.
[0096] Exemplary ranges for the nano-sized BaO-alumina ratio
include 1-20% BaO to 80% to 99% aluminum oxide micron support;
2-15% BaO to 85% to 98% aluminum oxide micron support; 5%-12% BaO
to 88% to 95% aluminum oxide micron support; and about 10% BaO to
about 90% aluminum oxide micron support, expressed as weight
percentages. In one embodiment, the nano-BaO-impregnated aluminum
oxide comprises 10%, or about 10%, nano-BaO by weight and 90%, or
about 90%, aluminum oxide by weight.
[0097] Barium-oxide micron particles are used simply by adding them
to the washcoat when desired, in the amount desired, along with the
other solid ingredients.
Substrates
[0098] The initial substrate is preferably a catalytic converter
substrate that demonstrates good thermal stability, including
resistance to thermal shock, and to which the described washcoats
can be affixed in a stable manner. Suitable substrates include, but
are not limited to, substrates forming from cordierite or other
ceramic materials, and substrates formed from metal. The substrates
may include a grid array structure, or coiled foil structure, which
provides numerous channels and results in a high surface area. The
high surface area of the coated substrate with its applied
washcoats in the catalytic converter provides for effective
treatment of the exhaust gas flowing through the catalytic
converter.
[0099] A corner fill layer, or a buffer layer or adhesion layer
such as a thin Boehmite layer, may be applied to the substrate
prior to applying any of the active washcoat layers, but is not
required. The cordierite substrates used for gasoline engines using
a three way washcoat typically has about 900 channels per square
inch (cpsi), with a 2.5 mil wall thickness.
Washcoat Comprising Nano-on-Nano-on-Micro Particles
[0100] The catalytically active particles bound to support
particles and can be applied to a substrate of a catalytic
converter as part of a washcoat. The catalytically active particles
are reactive to different gases in the exhausts. For example,
catalytically active particles containing platinum or palladium
nanoparticles are oxidative to the hydrocarbon gases and carbon
monoxide and catalytically active particles containing rhodium are
reductive to the nitrogen oxides.
[0101] The washcoat may contain oxidative nanoparticles, reductive
nanoparticles or both oxidative nanoparticles and reductive
nanoparticles. A washcoat containing oxidative nanoparticles on
micron supports or reductive nanoparticles on micron supports may
be used to coat a substrate such that the oxidative catalytically
active particles bearing composite nanoparticles and reductive
catalytically active particles bearing composite nanoparticles are
in separate washcoat layers on a substrate. In alternative
embodiments, a washcoat containing oxidative nanoparticles on
micron supports and reductive nanoparticles on micron supports may
be used to coat a substrate such that the oxidative catalytically
active particles bearing composite nanoparticles and reductive
catalytically active particles bearing composite nanoparticles are
in the same layer on a substrate.
[0102] The washcoat layers can include materials that are less
active or inert to exhausts. Such materials can be incorporated as
supports for the reactive catalysts or to provide surface area for
the precious metals. In some embodiments, the catalyst-containing
washcoat composition further includes "spacer" or "filler"
particles, where the spacer particles may, for example, be ceramic,
metal oxide, or metallic particles. In some embodiments, the spacer
particles may be alumina or boehmite.
[0103] In certain embodiments, the washcoat layer can contain an
oxygen storage component. An oxygen storage component has oxygen
storage capacity with which the catalyst can accumulate oxygen when
exhaust gas is in an oxygen-excess state (oxidative atmosphere),
and releases the accumulated oxygen when exhaust gas is in a
oxygen-deficient state (reductive atmosphere). With an oxygen
storage component, carbon monoxide and hydrocarbons can be
efficiently oxidized to CO.sub.2 even in an oxygen-deficient state.
Materials such as cerium oxide (CeO.sub.2, also referred to as
"ceria") and cerium zirconium oxide (CeO.sub.2--ZrO.sub.2) can be
used as oxygen storage components. In some embodiments,
micron-sized cerium zirconium oxide is included in the washcoat as
an oxygen storage component.
[0104] In certain embodiments, the washcoat layer can contain an
absorber to bind NO.sub.x and SO.sub.x compounds. In some
embodiments, the nano barium-oxide particles or micron-sized
barium-oxide particles used with the alumina supports are included
in the washcoat as an absorber.
[0105] In the following descriptions, the percentages of the
components of the washcoat compositions are provided in terms of
the amount of solids present in the washcoat compositions, as the
washcoat compositions can be provided in an aqueous suspension or,
in some instances, as dry powder. The catalyst layer (or
catalyst-containing layer) refers to the catalyst-containing
washcoat composition after it has been applied to the substrate,
dried, and calcined. The catalyst layer referred to herein
encompasses a layer including oxidative catalytically active
particles or a layer including reductive catalytically active
particles or a washcoat layer including oxidative catalytically
active particles and reductive catalytically active particles.
[0106] The following Table 1 provides embodiments of different
washcoat layer configurations:
TABLE-US-00001 TABLE 1 Washcoat Configurations Two-layer washcoat
configurations-separate One-layer washcoat configurations-combined
oxidation and reduction washcoat layers oxidation and reduction
washcoat layer Two-layer washcoat configuration using One layer
washcoat configuration using alumina filler without BaO alumina
filler without BaO 1a) Substrate-Oxidizing Washcoat Layer- 5)
Substrate-Combined Oxidizing/Reducing Reducing Washcoat Layer
Washcoat Layer (MI-386 alumina filler without BaO) (MI-386 alumina
filler without BaO) 1b) Substrate-Reducing Washcoat Layer-
Oxidizing Washcoat Layer (MI-386 alumina filler without BaO)
Two-layer washcoat configuration using nano- One-layer washcoat
configuration using nano- BaO-bearing alumina filler BaO-bearing
alumina filler 2a) Substrate-Oxidizing Washcoat Layer- 6)
Substrate-Combined Oxidizing/Reducing Reducing Washcoat Layer
Washcoat Layer (nano-BaO-bearing MI-386 alumina filler)
(nano-BaO-bearing MI-386 alumina filler) 2b) Substrate-Reducing
Washcoat Layer- Oxidizing Washcoat Layer (nano-BaO-bearing MI-386
alumina filler) Two-layer washcoat configuration using One-layer
washcoat configuration using micron-BaO mixed with alumina filler
micron-BaO mixed with alumina filler 3a) Substrate-Oxidizing
Washcoat Layer- 7) Substrate-Combined Oxidizing/Reducing Reducing
Washcoat Layer Washcoat Layer (micron-BaO mixed with MI-386 alumina
filler) (micron-BaO mixed with MI-386 alumina filler) 3b)
Substrate-Reducing Washcoat Layer- Oxidizing Washcoat Layer
(micron-BaO mixed with MI-386 alumina filler) Two-layer washcoat
configuration using One-layer washcoat configuration using alumina
filler with nano-BaO and with alumina filler with both nano-BaO and
admixed micron-BaO micron-BaO 4a) Substrate-Oxidizing Washcoat
Layer- 8) Substrate-Combined Oxidizing/Reducing Reducing Washcoat
Layer Washcoat Layer (admixed micron-BaO and/or nano-BaO-bearing
(admixed micron-BaO and nano-BaO-bearing MI-386 alumina filler)
MI-386 alumina filler) 4b) Substrate-Reducing Washcoat Layer-
Oxidizing Washcoat Layer (admixed micron-BaO and/or
nano-BaO-bearing MI-386 alumina filler)
Two Layer Washcoat Configurations-Separate Oxidation and Reduction
Washcoat Layers Oxidation Washcoat Components
[0107] In some embodiments, the oxidizing washcoat layer in the two
layer configurations (configurations 1a, 1b, 3a and 3b in Table 1)
comprises, consists essentially of, or consists of oxidizing
nano-on-nano-on-micro (NNm.TM.) particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant particles
with or without BaO (for example MI-386). The composition of the
oxidizing washcoat components and the reducing washcoat components
may be as described below regardless of the order in which the
washcoats are deposited.
[0108] In some embodiments, the NNm.TM. particles make up between
approximately 35% to approximately 75% by weight of the combination
of the NNm.TM. particles, cerium-zirconium oxide particles,
boehmite particles, and alumina filler/sealant particles. In some
embodiments, the NNm.TM. particles make up between approximately
45% to approximately 65% by weight of the combination of the
NNm.TM. particles, cerium-zirconium oxide particles, boehmite
particles, and alumina filler/sealant particles. In some
embodiments, the NNm.TM. particles make up between approximately
50% to approximately 60% by weight of the combination of the
NNm.TM. particles, cerium-zirconium oxide particles, boehmite
particles, and alumina filler/sealant particles. In some
embodiments, the NNm.TM. particles make up about 55% by weight of
the combination of the NNm.TM. particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant
particles. Preferably, the catalytically active particle in the
oxidizing NNm.TM. particles is palladium at a loading of 1.5-2 wt %
in the NNm.TM. particles. Palladium, platinum and platinum and
palladium/platinum mixtures may also be used in the loadings
described previously.
[0109] The micron-sized porous cerium-zirconium oxide particles
described with respect to the reducing NNm.TM. support particles
may be used for the micron-sized porous cerium-zirconium oxide
component in the oxidizing washcoat formulation. In some
embodiments, the micron-sized porous cerium-zirconium oxide
particles make up between approximately 5% to approximately 25% by
weight of the combination of the NNm.TM. particles,
cerium-zirconium oxide particles, boehmite particles, and alumina
filler/sealant particles. In some embodiments, the micron-sized
porous cerium-zirconium oxide particles make up between
approximately 10% to approximately 20% by weight of the combination
of the NNm.TM. particles, cerium-zirconium oxide particles,
boehmite particles, and alumina filler/sealant particles. In some
embodiments, the micron-sized porous cerium-zirconium oxide
particles make up between approximately 12% to approximately 17% by
weight of the combination of the NNm.TM. particles,
cerium-zirconium oxide particles, boehmite particles, and alumina
filler/sealant particles. In some embodiments, the micron-sized
porous cerium-zirconium oxide particles make up about 15% by weight
of the combination of the NNm.TM. particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant
particles.
[0110] In some embodiments, the boehmite particles make up between
approximately 0.5% to approximately 10% by weight of the
combination of the NNm.TM. particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the boehmite particles make up
between approximately 1% to approximately 7% by weight of the
combination of the NNm.TM. particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the boehmite particles make up
between approximately 2% to approximately 5% by weight of the
combination of the NNm.TM. particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the boehmite particles make up
about 3% by weight of the combination of the NNm.TM. particles,
cerium-zirconium oxide particles, boehmite particles, and alumina
filler/sealant particles.
[0111] In some embodiments, the alumina filler/sealant particles
make up between approximately 10% to approximately 40% by weight of
the combination of the NNm.TM. particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the alumina filler/sealant
particles make up between approximately 20% to approximately 35% by
weight of the combination of the NNm.TM. particles,
cerium-zirconium oxide particles, boehmite particles, and alumina
filler/sealant particles. In some embodiments, the alumina
filler/sealant particles make up between approximately 25% to
approximately 30% by weight of the combination of the NNm.TM.
particles, cerium-zirconium oxide particles, boehmite particles,
and alumina filler/sealant particles. In some embodiments, the
alumina filler/sealant particles make up about 27% by weight of the
combination of the NNm.TM. particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant
particles. The alumina filler/sealant particles may be porous
lanthanum-stabilized alumina, for example MI-386. In some
embodiments, a different filler particle may be used in place of
some or all of the alumina particles.
[0112] In the oxidizing washcoat from 0 to 100% of the alumina
filler/sealant particles may be alumina impregnated with nano-sized
BaO particles, alumina mixed with micron-sized BaO particles, or
both alumina impregnated with nano-sized BaO particles and admixed
with micron-sized BaO particles. In some embodiments, from 1 wt
%-100 wt %, from 20 wt %-wt 80%, or from 30 wt %-60 wt %
micron-sized BaO may be used in place of non-BaO-impregnated
alumina. In some embodiments, a 50:50 mixture of regular MI-386 and
BaO impregnated MI-386 (impregnated with nano-sized BaO particles),
or a 50:50 mixture of MI-386 and micron-sized BaO particles, or a
mixture of MI-386 impregnated with nano-sized BaO particles and
admixed with micron-sized BaO particles, may be used for this
component of the washcoat. In some embodiments, the alumina can
comprise from 5% to 30% nano-BaO-impregnated alumina and from 70%
to 95% non-BaO-impregnated alumina. In some embodiments, the
alumina can comprise from 5% to 20% nano-BaO-impregnated alumina
and from 80% to 95% non-BaO-impregnated alumina. In some
embodiments, the alumina can comprise from 8% to 16%
nano-BaO-impregnated alumina and from 84% to 92%
non-BaO-impregnated alumina. In one embodiment, 12%, or about 12%,
nano-BaO-impregnated alumina is mixed with 88%, or about 88%,
alumina without impregnated BaO. In one embodiment, 10%, or about
10%, nano-BaO-impregnated alumina is mixed with 90%, or about 90%,
alumina without impregnated BaO.
[0113] In some embodiments, the alumina can comprise from 5% to 30%
micron-sized BaO and from 70% to 95% non-BaO-impregnated alumina.
In some embodiments, the alumina can comprise from 5% to 20%
micron-sized BaO and from 80% to 95% non-BaO-impregnated alumina.
In some embodiments, the alumina can comprise from 8% to 16%
micron-sized-BaO and from 84% to 92% non-BaO-impregnated alumina.
In one embodiment, 12%, or about 12%, micron-sized BaO is mixed
with 88%, or about 88%, alumina without impregnated BaO. In one
embodiment, 10%, or about 10%, micron-sized BaO is mixed with 90%,
or about 90%, alumina without impregnated BaO.
[0114] The ranges for the nano-sized BaO-alumina ratio, that is,
the amount of nano-BaO impregnated into the alumina, include 1-20%
BaO to 80% to 99% aluminum oxide micron support; 2-15% BaO to 85%
to 98% aluminum oxide micron support; 5%-12% BaO to 88% to 95%
aluminum oxide micron support; and about 10% BaO to about 90%
aluminum oxide micron support, expressed as weight percentages. In
one embodiment, the nano-BaO-impregnated aluminum oxide comprises
10%, or about 10%, nano-BaO by weight and 90%, or about 90%,
aluminum oxide by weight.
Reducing Washcoat Components
[0115] In some embodiments, the reducing washcoat layer in the two
layer configurations (configurations 1a, 1b, 3a and 3b in Table 1)
comprises, consists essentially of, or consists of reducing
nano-on-nano-on-micro (NNm.TM.) particles, boehmite particles, and
alumina filler/sealant particles with or without BaO (for example
MI-386).
[0116] In some embodiments, the reducing NNm.TM. particles make up
between approximately 50% to approximately 95% by weight of the
combination of the NNm.TM. particles, boehmite particles, and
alumina filler/sealant particles. In some embodiments, the NNm.TM.
particles make up between approximately 60% to approximately 90% by
weight of the combination of the NNm.TM. particles, boehmite
particles, and alumina filler/sealant particles. In some
embodiments, the NNm.TM. particles make up between approximately
75% to approximately 85% by weight of the combination of the
NNm.TM. particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the NNm.TM. particles make up about
80% by weight of the combination of the NNm.TM. particles, boehmite
particles, and alumina filler/sealant particles. Preferably, the
catalytically active particle in the NNm.TM. particles is rhodium
at a loading of about 0.3 wt % in the NNm.TM. particles other
loadings described previously may also be used.
[0117] In some embodiments, the boehmite particles make up between
approximately 0.5% to approximately 10% by weight of the
combination of the NNm.TM. particles, boehmite particles, and
alumina filler/sealant particles. In some embodiments, the boehmite
particles make up between approximately 1% to approximately 7% by
weight of the combination of the NNm.TM. particles, boehmite
particles, and alumina filler/sealant particles. In some
embodiments, the boehmite particles make up between approximately
2% to approximately 5% by weight of the combination of the NNm.TM.
particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the boehmite particles make up
about 3% by weight of the combination of the NNm.TM. particles,
boehmite particles, and alumina filler/sealant particles.
[0118] In some embodiments, the alumina filler/sealant particles
make up between approximately 5% to approximately 30% by weight of
the combination of the NNm.TM. particles, boehmite particles, and
alumina filler/sealant particles. In some embodiments, the alumina
filler/sealant particles make up between approximately 10% to
approximately 25% by weight of the combination of the NNm.TM.
particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the alumina filler/sealant
particles make up between approximately 15% to approximately 20% by
weight of the combination of the NNm.TM. particles, boehmite
particles, and alumina filler/sealant particles. In some
embodiments, the alumina filler/sealant particles make up about 17%
by weight of the combination of the NNm.TM. particles, boehmite
particles, and alumina filler/sealant particles. The alumina
filler/sealant particles may be porous lanthanum-stabilized
alumina, for example MI-386. In some embodiments, a different
filler particle may be used in place of some or all of the alumina
particles.
[0119] In the reducing washcoat from 0 to 100% of the alumina
filler/sealant particles may be alumina impregnated with nano-sized
BaO particles, alumina mixed with micron-sized BaO particles, or
both alumina impregnated with nano-sized BaO particles and admixed
with micron-sized BaO particles. In some embodiments, from 1 wt
%-100 wt %, from 20 wt %-wt 80%, or from 30 wt %-60 wt %
micron-sized BaO may be used in place of non-BaO-impregnated
alumina. In some embodiments, a 50:50 mixture of regular MI-386 and
BaO impregnated MI-386 (impregnated with nano-sized BaO particles),
or a 50:50 mixture of MI-386 and micron-sized BaO particles, or a
mixture of MI-386 impregnated with nano-sized BaO particles and
admixed with micron-sized BaO particles, may be used for this
component of the washcoat. In some embodiments, the alumina can
comprise from 5% to 30% nano-BaO-impregnated alumina and from 70%
to 95% non-BaO-impregnated alumina. In some embodiments, the
alumina can comprise from 5% to 20% nano-BaO-impregnated alumina
and from 80% to 95% non-BaO-impregnated alumina. In some
embodiments, the alumina can comprise from 8% to 16%
nano-BaO-impregnated alumina and from 84% to 92%
non-BaO-impregnated alumina. In one embodiment, 12%, or about 12%,
nano-BaO-impregnated alumina is mixed with 88%, or about 88%,
alumina without impregnated BaO. In one embodiment, 10%, or about
10%, nano-BaO-impregnated alumina is mixed with 90%, or about 90%,
alumina without impregnated BaO.
[0120] In some embodiments, the alumina can comprise from 5% to 30%
micron-sized BaO and from 70% to 95% non-BaO-impregnated alumina.
In some embodiments, the alumina can comprise from 5% to 20%
micron-sized BaO and from 80% to 95% non-BaO-impregnated alumina.
In some embodiments, the alumina can comprise from 8% to 16%
micron-sized-BaO and from 84% to 92% non-BaO-impregnated alumina.
In one embodiment, 12%, or about 12%, micron-sized BaO is mixed
with 88%, or about 88%, alumina without impregnated BaO. In one
embodiment, 10%, or about 10%, micron-sized BaO is mixed with 90%,
or about 90%, alumina without impregnated BaO.
[0121] The ranges for the nano-sized BaO-alumina ratio, that is,
the amount of nano-BaO impregnated into the alumina, include 1-20%
BaO to 80% to 99% aluminum oxide micron support; 2-15% BaO to 85%
to 98% aluminum oxide micron support; 5%-12% BaO to 88% to 95%
aluminum oxide micron support; and about 10% BaO to about 90%
aluminum oxide micron support, expressed as weight percentages. In
one embodiment, the nano-BaO-impregnated aluminum oxide comprises
10%, or about 10%, nano-BaO by weight and 90%, or about 90%,
aluminum oxide by weight.
One Layer Washcoat Configuration: Combined Washcoat Components
[0122] In some embodiments, the combined washcoat layer in the one
layer configurations (configurations 2 and 4 in Table 1) comprises,
consists essentially of, or consists of oxidizing
nano-on-nano-on-micro (NNm.TM.) particles, reducing
nano-on-nano-on-micro (NNm.TM.) particles, cerium-zirconium oxide
particles, boehmite particles, and alumina filler/sealant particles
with or without BaO (for example MI-386).
[0123] In some embodiments, the oxidizing NNm.TM. particles make up
between approximately 25% to approximately 75% by weight of the
combination of the oxidizing NNm.TM. particles, reducing NNm.TM.
particles, cerium-zirconium oxide particles, boehmite particles,
and alumina filler/sealant particles. In some embodiments, the
oxidizing NNm.TM. particles make up between approximately 35% to
approximately 55% by weight of the combination of the oxidizing
NNm.TM. particles, reducing NNm.TM. particles, cerium-zirconium
oxide particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the oxidizing NNm.TM. particles
make up between approximately 40% to approximately 50% by weight of
the combination of the oxidizing NNm.TM. particles, reducing
NNm.TM. particles, cerium-zirconium oxide particles, boehmite
particles, and alumina filler/sealant particles. In some
embodiments, the oxidizing NNm.TM. particles make up about 45% by
weight of the combination of the oxidizing NNm.TM. particles,
reducing NNm.TM. particles, cerium-zirconium oxide particles,
boehmite particles, and alumina filler/sealant particles.
Preferably, the catalytically active particle in the oxidizing
NNm.TM. particles is palladium at a loading of 1.3-2.0 wt % in the
NNm.TM. particles. Palladium, platinum and platinum and
palladium/platinum mixtures may also be used in the loadings
described previously.
[0124] In some embodiments, the reducing NNm.TM. particles make up
between approximately 5% to approximately 50% by weight of the
combination of the oxidizing NNm.TM. particles, reducing NNm.TM.
particles, cerium-zirconium oxide particles, boehmite particles,
and alumina filler/sealant particles. In some embodiments, the
reducing NNm.TM. particles make up between approximately 10% to
approximately 40% by weight of the combination of the oxidizing
NNm.TM. particles, reducing NNm.TM. particles, cerium-zirconium
oxide particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the reducing NNm.TM. particles make
up between approximately 20% to approximately 30% by weight of the
combination of the oxidizing NNm.TM. particles, reducing NNm.TM.
particles, cerium-zirconium oxide particles, boehmite particles,
and alumina filler/sealant particles. In some embodiments, the
reducing NNm.TM. particles make up about 25% by weight of the
combination of the oxidizing NNm.TM. particles, reducing NNm.TM.
particles, cerium-zirconium oxide particles, boehmite particles,
and alumina filler/sealant particles. Preferably, the catalytically
active particle in the reducing NNm.TM. particles is rhodium at a
loading of 0.3-wt % in the reducing NNm.TM. particles. Preferably,
the catalytically active particle in the reducing NNm.TM. particles
is rhodium at a loading of about 0.3 wt % in the reducing NNm.TM.
particles. Other loadings described previously may also be
used.
[0125] The micron-sized porous cerium-zirconium oxide particles
described with respect to the reducing NNm.TM. support particles
may be used for the micron-sized porous cerium-zirconium oxide
component in the combined washcoat formulation. In some
embodiments, the micron-sized porous cerium-zirconium oxide
particles make up between approximately 1% to approximately 40% by
weight of the combination of the oxidizing NNm.TM. particles,
reducing NNm.TM. particles, cerium-zirconium oxide particles,
boehmite particles, and alumina filler/sealant particles. In some
embodiments, the micron-sized porous cerium-zirconium oxide
particles make up between approximately 5% to approximately 30% by
weight of the combination of the oxidizing NNm.TM. particles,
reducing NNm.TM. particles, cerium-zirconium oxide particles,
boehmite particles, and alumina filler/sealant particles. In some
embodiments, the micron-sized porous cerium-zirconium oxide
particles make up between approximately 10% to approximately 20% by
weight of the combination of the oxidizing NNm.TM. particles,
reducing NNm.TM. particles, cerium-zirconium oxide particles,
boehmite particles, and alumina filler/sealant particles. In some
embodiments, the micron-sized porous cerium-zirconium oxide
particles make up about 15% by weight of the combination of the
oxidizing NNm.TM. particles, reducing NNm.TM. particles,
cerium-zirconium oxide particles, boehmite particles, and alumina
filler/sealant particles.
[0126] In some embodiments, the boehmite particles make up between
approximately 0.5% to approximately 10% by weight of the
combination of the oxidizing NNm.TM. particles, reducing NNm.TM.
particles, cerium-zirconium oxide particles, boehmite particles,
and alumina filler/sealant particles. In some embodiments, the
boehmite particles make up between approximately 1% to
approximately 7% by weight of the combination of the oxidizing
NNm.TM. particles, reducing NNm.TM. particles, cerium-zirconium
oxide particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the boehmite particles make up
between approximately 2% to approximately 5% by weight of the
combination of the oxidizing NNm.TM. particles, reducing NNm.TM.
particles, cerium-zirconium oxide particles, boehmite particles,
and alumina filler/sealant particles. In some embodiments, the
boehmite particles make up about 3% by weight of the combination of
the oxidizing NNm.TM. particles, reducing NNm.TM. particles,
cerium-zirconium oxide particles, boehmite particles, and alumina
filler/sealant particles.
[0127] In some embodiments, the alumina filler/sealant particles
make up between approximately 1% to approximately 25% by weight of
the combination of the oxidizing NNm.TM. particles, reducing
NNm.TM. particles, cerium-zirconium oxide particles, boehmite
particles, and alumina filler/sealant particles. In some
embodiments, the alumina filler/sealant particles make up between
approximately 5% to approximately 20% by weight of the combination
of the oxidizing NNm.TM. particles, reducing NNm.TM. particles,
cerium-zirconium oxide particles, boehmite particles, and alumina
filler/sealant particles. In some embodiments, the alumina
filler/sealant particles make up between approximately 10% to
approximately 15% by weight of the combination of the oxidizing
NNm.TM. particles, reducing NNm.TM. particles, cerium-zirconium
oxide particles, boehmite particles, and alumina filler/sealant
particles. In some embodiments, the alumina filler/sealant
particles make up about 12% by weight of the combination of the
oxidizing NNm.TM. particles, reducing NNm.TM. particles,
cerium-zirconium oxide particles, boehmite particles, and alumina
filler/sealant particles. The alumina filler/sealant particles may
be porous lanthanum-stabilized alumina, for example MI-386. In some
embodiments, a different filler particle may be used in place of
some or all of the alumina particles.
[0128] In the combination washcoat from 0 to 100% of the alumina
filler/sealant particles may be alumina impregnated with nano-sized
BaO particles, alumina mixed with micron-sized BaO particles, or
both alumina impregnated with nano-sized BaO particles and admixed
with micron-sized BaO particles. In some embodiments, from 1 wt
%-100 wt %, from 20 wt %-wt 80%, or from 30 wt %-60 wt %
micron-sized BaO may be used in place of non-BaO-impregnated
alumina. In some embodiments, a 50:50 mixture of regular MI-386 and
BaO impregnated MI-386 (impregnated with nano-sized BaO particles),
or a 50:50 mixture of MI-386 and micron-sized BaO particles, or a
mixture of MI-386 impregnated with nano-sized BaO particles and
admixed with micron-sized BaO particles, may be used for this
component of the washcoat. In some embodiments, the alumina can
comprise from 5% to 30% nano-BaO-impregnated alumina and from 70%
to 95% non-BaO-impregnated alumina. In some embodiments, the
alumina can comprise from 5% to 20% nano-BaO-impregnated alumina
and from 80% to 95% non-BaO-impregnated alumina. In some
embodiments, the alumina can comprise from 8% to 16%
nano-BaO-impregnated alumina and from 84% to 92%
non-BaO-impregnated alumina. In one embodiment, 12%, or about 12%,
nano-BaO-impregnated alumina is mixed with 88%, or about 88%,
alumina without impregnated BaO. In one embodiment, 10%, or about
10%, nano-BaO-impregnated alumina is mixed with 90%, or about 90%,
alumina without impregnated BaO.
[0129] In some embodiments, the alumina can comprise from 5% to 30%
micron-sized BaO and from 70% to 95% non-BaO-impregnated alumina.
In some embodiments, the alumina can comprise from 5% to 20%
micron-sized BaO and from 80% to 95% non-BaO-impregnated alumina.
In some embodiments, the alumina can comprise from 8% to 16%
micron-sized-BaO and from 84% to 92% non-BaO-impregnated alumina.
In one embodiment, 12%, or about 12%, micron-sized BaO is mixed
with 88%, or about 88%, alumina without impregnated BaO. In one
embodiment, 10%, or about 10%, micron-sized BaO is mixed with 90%,
or about 90%, alumina without impregnated BaO.
[0130] The ranges for the nano-sized BaO-alumina ratio, that is,
the amount of nano-BaO impregnated into the alumina, include 1-20%
BaO to 80% to 99% aluminum oxide micron support; 2-15% BaO to 85%
to 98% aluminum oxide micron support; 5%-12% BaO to 88% to 95%
aluminum oxide micron support; and about 10% BaO to about 90%
aluminum oxide micron support, expressed as weight percentages. In
one embodiment, the nano-BaO-impregnated aluminum oxide comprises
10%, or about 10%, nano-BaO by weight and 90%, or about 90%,
aluminum oxide by weight.
[0131] In some embodiments, the catalyst-containing washcoat
composition is mixed with water and acid, such as acetic acid,
prior to the coating of the substrate with the catalyst-containing
washcoat composition, thereby forming an aqueous mixture of the
catalyst-containing washcoat composition, water, and acid. This
aqueous mixture of the catalyst-containing washcoat composition,
water, and acid is then applied to the substrate (where the
substrate may or may not already have other washcoat layers applied
to it). In some embodiments, the pH of this aqueous mixture is
adjusted to a pH level of about 2 to about 7 prior to it being
applied to the substrate. In some embodiments, the pH of this
aqueous mixture is adjusted to a pH level of about 4 prior to it
being applied to the substrate. In some embodiments, the viscosity
of the aqueous washcoat is adjusted by mixing with a cellulose
solution, with corn starch, or with similar thickeners. In some
embodiments, the viscosity is adjusted to a value between about 300
cP to about 1200 cP.
[0132] In some embodiments, the oxidizing catalyst, palladium or
platinum, containing washcoat composition comprises a thickness of
approximately 50 g/l to approximately 300 g/l, such as
approximately 150 g/l to approximately 250 g/l, approximately 175
g/l to approximately 225 g/l, or approximately 185 g/l to
approximately 210 g/l, or about 200 g/l palladium or platinum.
[0133] In some embodiments, the reducing catalyst, rhodium
containing washcoat composition comprises a thickness of 10 g/l to
approximately 150 g/l, such as approximately 50 g/l to
approximately 120 g/l, approximately 60 g/l to approximately 100
g/l, or approximately 70 g/l to approximately 90 g/l, or about 80
g/l rhodium.
Procedure for Preparation of Washcoat: Containing Catalysts for
Oxidation Reaction
[0134] The oxidative nano-on-nano-on micro catalytically active
material (for example nano-Pd or nano-Pt-on-nano-on-micro) can be
mixed with La stabilized micron-sized Al.sub.2O.sub.3, boehmite,
and water to form a washcoat slurry. In some instances, the mixture
contains about 55% by weight of the catalytic active material
(nano-on-nano and nano-sized Al.sub.2O.sub.3 without precious
metal), about 27% by weight of the micron-sized Al.sub.2O.sub.3,
about 3% by weight boehmite, and 15% micron CZ. In some instances,
the washcoat is adjusted to have a pH of 4 or approximately 4.
Procedure for Preparation of Washcoat Containing Catalysts for
Reduction Reaction
[0135] The reductive nano-on-nano-on micro catalytically active
material (for example Rh) can be mixed with micron-sized cerium
zirconium oxide, boehmite, and water to form a washcoat slurry. In
some instances, the mixture comprises 80% by weight of the
catalytic active material (for example nano-rhodium on nano CZ on
micro-CZ), 3% by weight of boehmite, and 17% MI 386
Al.sub.2O.sub.3. In some instances, the washcoat is adjusted to
have a pH of 4 or approximately 4.
Coated Substrate with Separate Layers of Oxidative Nanoparticles
and Reductive Nanoparticles
[0136] The oxidative and reductive nanoparticles may be in the same
or different layers. Preferably, the ratio of oxidative
nanoparticles to reductive nanoparticles is between 2:1 and 100:1,
is between 3:1 and 70:1, or is between 6:1 and 40:1.
Oxidation and Reduction Catalysts in Different Layers
[0137] A coated substrate may include a first layer washcoat
containing oxidative catalytically active nanoparticles and a
second layer washcoat containing reductive catalytically active
nanoparticles. In certain embodiments, the oxidative catalytically
active nanoparticles do not react with the reductive catalytically
active nanoparticles.
[0138] The washcoat containing catalysts for oxidation and the
washcoat containing catalysts for reduction can be applied to a
monolith of a grid array structure, for example a honeycomb
structure. In some instances, the washcoats can form a layered
structure in the channels of the monolith. In some instances, the
washcoat that contains catalysts for oxidation reactions can be
applied first. In some instances, the washcoat that contains
catalysts for reduction reaction can be applied first. The
application of the washcoat onto the monolith can be achieved, for
example, by dipping the monolith into a washcoat slurry. After the
slurry is dried, the monolith can be baked in an oven at
550.degree. C. for one hour. Next, the monolith can be dipped into
the second washcoat slurry. After the slurry of the second dip is
dried, the monolith can be baked in the oven again at 550.degree.
C. for one hour.
[0139] A person having ordinary skill in the art would be able to
use typical methods or procedures to apply the washcoat prepared
according to the procedures described above to make a catalytic
converter, which can be used in various fields, such as for a
catalytic converter for diesel engines and/or other motor
vehicles.
Oxidation and Reduction Catalysts in the Same Layer
[0140] The following are experimental procedures for making a
coated substrate containing a oxidative catalytically active
particles and reductive catalytically active particles in the same
washcoat layer. The oxidative and reductive catalytic active
material is mixed with micron-sized cerium zirconium oxide,
micron-sized aluminum oxide, boehmite, and water to form a washcoat
slurry. In some embodiments, the washcoat is adjusted to have a pH
of about 4.
[0141] The washcoat contains catalysts for both oxidation and
reduction reactions can be applied to a monolith of a grid array
structure in a single set of procedure. The application of the
washcoat onto the monolith can be achieved by dipping the monolith
into a washcoat slurry. After the slurry is dried, the monolith is
baked in an oven at 550.degree. C. for one hour.
[0142] A person who has ordinary skill in the art would be able to
use typical methods or procedures to apply the washcoat prepared
according to the procedures described above to make a catalytic
converter, which can be used in various field, such as the
catalytic converter for diesel engines and/or other motor
vehicles.
[0143] FIG. 1 shows a graphic illustration of a catalytic converter
100 in accordance with embodiments of the present disclosure. The
catalytic converter 100 can be installed in a motor vehicle 102.
The motor vehicle 102 includes an engine 104. The engine can
combust fossil fuel, diesel, or gasoline and generate energy and
waste gas. The waste gas or exhausts are treated by the catalytic
converter 100. The catalytic converter 100 can contain a grid array
structure 106. The grid array structure can be coated with a first
layer of washcoat 108 and a second layer of washcoat 150. The
positions of the first layer 108 and the second layer 150 of the
washcoat may be interchangeable, so that the first layer can be on
top of the second layer in some embodiments and the second layer
can be on top of the first layer in alternative embodiments. In
certain embodiments, the second layer covers at least a portion of
the substrate, and the first layer covers at least a portion of the
second layer. In certain embodiments, the first layer covers at
least a portion of the substrate, and the second layer covers at
least a portion of the first layer.
[0144] The washcoats 108, 150 can contain different chemical
compositions. The compositions contained in the washcoat 108 can be
reactive to gases that exist in the exhausts different from the
gases to which the composition of washcoat 150 is reactive. In some
embodiments, washcoat 108 contains active catalytic materials 120,
cerium zirconium oxide 122, Boehmite 126, and/or other materials.
The active catalytic materials 120 can contain a micron-sized
support 110. The nanoparticles can be immobilized onto the
micron-sized support 110 to prevent the clustering or sintering of
the nanomaterials. The nanomaterials can include an oxidative
catalyst, such as Pd nanoparticles 116, precious metal support in
nano-sized 118, such as nano-sized aluminum oxide, and nano-sized
aluminum oxide 114 without any active catalytic materials coupled
to it. As shown in FIG. 1, the active catalytic material 120 can
include precious metal nanoparticles 116 on nano-sized
Al.sub.2O.sub.3 118 (e.g., nano-on-nano or n-on-n material 130).
The nano-on-nano material 130 is randomly distributed on the
surface of micron-sized Al.sub.2O.sub.3 112.
[0145] In some embodiments, washcoat 150 contains active catalytic
materials 152, micron-sized aluminum oxide 154, boehmite 156,
and/or other materials. The active catalytic materials 152 can
contain a micron-sized support 160. The nanomaterials can be
immobilized on the micron-sized support 160 to prevent the
clustering or sintering of the nanomaterials. The nanomaterials can
include a reductive catalyst, such as nano-sized Rh nanoparticles
162, nano-sized precious metal support 164, such as nano-sized
cerium zirconium oxide, and nano-sized cerium zirconium oxide 166
that does contain any active catalytic materials.
[0146] FIG. 2 is a flow chart illustrating a three-way catalyst
system preparation method 500 in accordance with embodiments of the
present disclosure. The three-way catalyst system includes both
oxidative catalytically active particles and reductive
catalytically active particles in separate washcoat layers on a
substrate.
[0147] The three-way catalyst system preparation method 500 can
start from Step 502. At Step 504, a catalyst for oxidation reaction
is prepared. At Step 506, a first washcoat containing the catalyst
for oxidation reaction is prepared. At Step 508, a catalyst for
reduction reaction is prepared. At Step 510, a second washcoat
containing the catalyst for reduction reaction is prepared. At Step
512, either the first washcoat or the second washcoat is applied to
a substrate. At Step 514, the substrate is dried. At Step 516, the
washcoat-covered substrate is baked in an oven allowing the
formation of the oxide-oxide bonds, resulting in immobilized
nanoparticles. At Step 520, the other washcoat is applied on the
substrate. At Step 522, the substrate is dried. At Step 524, the
washcoat-covered substrate oxidative catalytically active particles
and reductive catalytically active particles contained in separate
layers is baked in an oven allowing the formation of the
oxide-oxide bonds. The method 500 ends at Step 526. The oxide-oxide
bonds formed during the baking process firmly retain the
nanoparticles, so that the chances for the oxidative nanoparticles
and/or the reductive nanoparticles to move at high temperature and
to encounter and react with each other are avoided.
Coated Substrate with Oxidative Nanoparticles and Reductive
Nanoparticles in the Same Layer
[0148] In certain embodiments, the coated substrate includes a
washcoat layer that contains both oxidative catalytically active
particles and reductive catalytically active particles. In certain
embodiments, the oxidative catalytically active nanoparticles do
not react or couple with the reductive catalytically active
nanoparticles, though being in the same layer.
[0149] FIG. 3 shows a graphic illustration of the catalytic
converter 100 in accordance with some embodiments. The catalytic
converter 100 can be installed in a motor vehicle 102. The motor
vehicle 102 includes an engine 104. The engine can combust fossil
fuel, diesel, or gasoline and generate energy and exhaust gas. The
waste gas or exhausts are treated by the catalytic converter 100.
The catalytic converter 100 can comprise a grid array structure
106. The grid array structure can be coated with a layer of
washcoat 108 that contains both oxidative catalytically active
particles and reductive catalytically active particles.
[0150] The washcoat 108 can contain different chemical
compositions. The different compositions contained in the washcoat
108 can be reactive to different gases that exist in the exhausts.
In some embodiments, the washcoat 108 contains oxidative
compositions 110 and reductive compositions 112. In some
embodiments, the washcoat 108 also contains Boehmite 114,
micron-sized cerium zirconium oxide 116, and micron-sized aluminum
oxide 120.
[0151] The active catalytic materials 110 can contain a
micron-sized support 122, such as micron-sized aluminum oxide. The
nanomaterials can be immobilized onto the micron-sized support 122
to prevent the clustering or sintering of the nanomaterials. The
nanomaterials can include precious metals, such as Pd nanoparticles
124, precious metal support in nano-sized 126, such as nano-sized
aluminum oxide, and nano-sized aluminum oxide 128 that does not
contain any active catalytic materials. As shown in FIG. 3, the
precious metal nanoparticles 124 on the nano-sized Al.sub.2O.sub.3
126 (nano-on-nano material 130) can be mixed with nano-sized
Al.sub.2O.sub.3 128 to be randomly distributed on the surface of
the micron-sized Al.sub.2O.sub.3 122 forming the active catalytic
material 110. The nano-sized Al.sub.2O.sub.3 128 can be aluminum
oxide nanoparticle having no active catalytic material on the
surface.
[0152] The active catalytic materials 112 can contain a
micron-sized support 132, such as micron-sized cerium zirconium
oxide. The nanomaterials can be immobilized on the micron-sized
support 132 to prevent the clustering or sintering of the
nanomaterials. The nanomaterials can include precious metals that
have ability to be a reductive catalyst, such as Rh nanoparticles
134, precious metal support in nano-sized 136, such as nano-sized
cerium zirconium oxide, and nano-sized cerium zirconium oxide 138
that does not contain active catalytic materials on the surface. As
shown in FIG. 3, the precious metal nanoparticles 134 on the
nano-sized cerium zirconium oxide 136 (nano-on-nano material) can
be mixed with nano-sized cerium zirconium oxide 138 to be randomly
distributed on the surface of the micron-sized cerium zirconium
oxide 132, forming the active catalytic material 112.
[0153] FIG. 4 is a flow chart illustrating a three-way catalytic
system preparation method 200 in accordance with some embodiments.
Compared to traditional methods, in method 200, a three-way
catalytic system with oxidative catalytically active particles and
reductive catalytically active particles contained in the same
layer is prepared by using a "one-dip" process. The one dip process
can be used to apply a mixture containing both oxidative
catalytically active particles and reductive catalytically active
particles onto a substrate by performing a dipping procedure
once.
[0154] The three-way catalytic system preparation method 200 can
start at Step 202. At Step 204, an oxidative catalytically active
particle is prepared. At Step 206, a reductive catalytically active
particle is prepared is prepared. At Step 208, the oxidative
catalytically active particles and the reductive catalytically
active particles are mixed to form a three-way catalytic material.
At Step 210, water is added to the catalytic material form a
washcoat slurry. At Step 212, a substrate is dipped into the
slurry, allowing the three-way catalytic material to stay on the
substrate. A person who has ordinary skill in the art would
appreciate that any methods are able to be used to apply the
washcoat slurry onto the substrate. For example, the washcoat is
able to be sprayed to make it stay on the substrate. At Step 214,
the washcoat-covered substrate is dried. At Step 216, the substrate
is baked in an oven. At Step 218, the substrate is fitted into a
catalytic converter. At Step 220, a three-way catalytic converter
with oxidative catalytically active particles and reductive
catalytically active particles contained in the same layer is
formed. The method 200 can end at Step 222. The oxide-oxide bonds
formed during the baking process firmly retain the nanoparticles,
so that the chances for the oxidative nanoparticles and/or the
reductive nanoparticles to move at high temperature and to
encounter and react with each other are avoided.
Exhaust Systems, Vehicles, and Emissions Performance
[0155] Three-way conversion (TWC) catalysts have utility in a
number of fields including the treatment of exhaust gas streams
from internal combustion engines, such as automobile, truck and
other gasoline-fueled engines. Emission standards for unburned
hydrocarbons, carbon monoxide and nitrogen oxide contaminants have
been set by various governments and must be met by older as well as
new vehicles. In order to meet such standards, catalytic converters
containing a TWC catalyst are located in the exhaust gas line of
internal combustion engines. Such catalysts promote the oxidation
by oxygen in the exhaust gas stream of unburned hydrocarbons and
carbon monoxide as well as the reduction of nitrogen oxides to
nitrogen.
[0156] In some embodiments, a coated substrate as disclosed herein
is housed within a catalytic converter in a position configured to
receive exhaust gas from an internal combustion engine, such as in
an exhaust system of an internal combustion engine. The catalytic
converter can be used with the exhaust from a gasoline engine. The
catalytic converter can be installed on a vehicle containing a
gasoline engine.
[0157] The coated substrate is placed into a housing, such as that
shown in FIGS. 1 and 3, which can in turn be placed into an exhaust
system (also referred to as an exhaust treatment system) of a
gasoline internal combustion. The exhaust system of the internal
combustion engine receives exhaust gases from the engine, typically
into an exhaust manifold, and delivers the exhaust gases to an
exhaust treatment system. The exhaust system can also include other
components, such as oxygen sensors, HEGO (heated exhaust gas
oxygen) sensors, UEGO (universal exhaust gas oxygen) sensors,
sensors for other gases, and temperature sensors. The exhaust
system can also include a controller such as an engine control unit
(ECU), a microprocessor, or an engine management computer, which
can adjust various parameters in the vehicle (fuel flow rate,
fuel/air ratio, fuel injection, engine timing, valve timing, etc.)
in order to optimize the components of the exhaust gases that reach
the exhaust treatment system, so as to manage the emissions
released into the environment.
[0158] "Treating" an exhaust gas, such as the exhaust gas from a
gasoline engine refers to having the exhaust gas proceed through an
exhaust system (exhaust treatment system) prior to release into the
environment.
[0159] When used in a catalytic converter, the substrates coated
with the washcoat formulations including nano-on-nano-on-micro
particles disclosed herein provide a significant improvement over
other catalytic converters. The coated substrates may exhibit
performance in converting hydrocarbons, carbon monoxide, and
nitrogen oxides that is comparable or better than present
commercial coated substrates using wet chemistry techniques with
the same or less loading of PGM.
[0160] In some embodiments, catalytic converters and exhaust
treatment systems employing the coated substrates disclosed herein
display emissions of 3400 mg/mile or less of CO emissions and 400
mg/mile or less of NO.sub.x emissions; 3400 mg/mile or less of CO
emissions and 200 mg/mile or less of NO.sub.x emissions; or 1700
mg/mile or less of CO emissions and 200 mg/mile or less of NO.sub.x
emissions. The disclosed coated substrates, used as catalytic
converter substrates, can be used in an emission system to meet or
exceed these standards.
[0161] Emissions limits for Europe are summarized at the URL
europa.eu/legislation_summaries/environment/air_pollution/128186_en.htm.
The Euro 5 emissions standards, in force as of September 2009,
specify a limit of 500 mg/km of CO emissions, 180 mg/km of NO.sub.x
emissions, and 230 mg/km of HC (hydrocarbon)+NO.sub.x emissions.
The Euro 6 emissions standards, scheduled for implementation as of
September 2014, specify a limit of 500 mg/km of CO emissions, 80
mg/km of NO.sub.x emissions, and 170 mg/km of HC
(hydrocarbon)+NO.sub.x emissions. The disclosed catalytic converter
substrates can be used in an emission system to meet or exceed
these standards.
[0162] In some embodiments, a catalytic converter made with a
coated substrate of the invention, loaded with 4.0 g/l of PGM or
less displays a carbon monoxide light-off temperature at least 5
degrees C. lower than a catalytic converter made with wet chemistry
methods and having the same or similar PGM loading. In some
embodiments, a catalytic converter made with a coated substrate of
the invention, loaded with 4.0 g/l of PGM or less, displays a
carbon monoxide light-off temperature at least 10 degrees C. lower
than a catalytic converter made with wet chemistry methods and
having the same or similar PGM loading. In some embodiments, a
catalytic converter made with a coated substrate of the invention,
loaded with 4.0 g/l of PGM or less, displays a carbon monoxide
light-off temperature at least 15 degrees C. lower than a catalytic
converter made with wet chemistry methods and having the same or
similar PGM loading. In some embodiments, the catalytic converter
made with a coated substrate of the invention demonstrates any of
the foregoing performance standards after about 50,000 km, about
50,000 miles, about 75,000 km, about 75,000 miles, about 100,000
km, about 100,000 miles, about 125,000 km, about 125,000 miles,
about 150,000 km, or about 150,000 miles of operation (for both the
catalytic converter made with a coated substrate of the invention
and the comparative catalytic converter).
[0163] In some embodiments, a catalytic converter made with a
coated substrate of the invention, loaded with 4.0 g/l of PGM or
less, displays a hydrocarbon light-off temperature at least 5
degrees C. lower than a catalytic converter made with wet chemistry
methods and having the same or similar PGM loading. In some
embodiments, a catalytic converter made with a coated substrate of
the invention, loaded with 4.0 g/l of PGM or less, displays a
hydrocarbon light-off temperature at least 10 degrees C. lower than
a catalytic converter made with wet chemistry methods and having
the same or similar PGM loading. In some embodiments, a catalytic
converter made with a coated substrate of the invention, loaded
with 4.0 g/l of PGM or less, displays a hydrocarbon light-off
temperature at least 15 degrees C. lower than a catalytic converter
made with wet chemistry methods and having the same or similar PGM
loading. In some embodiments, the catalytic converter made with a
coated substrate of the invention demonstrates any of the foregoing
performance standards after about 50,000 km, about 50,000 miles,
about 75,000 km, about 75,000 miles, about 100,000 km, about
100,000 miles, about 125,000 km, about 125,000 miles, about 150,000
km, or about 150,000 miles of operation (for both the catalytic
converter made with a coated substrate of the invention and the
comparative catalytic converter).
[0164] In some embodiments, a catalytic converter made with a
coated substrate of the invention, loaded with 4.0 g/l of PGM or
less, displays a nitrogen oxide light-off temperature at least 5
degrees C. lower than a catalytic converter made with wet chemistry
methods and having the same or similar PGM loading. In some
embodiments, a catalytic converter made with a coated substrate of
the invention, loaded with 4.0 g/l of PGM or less, displays a
nitrogen oxide light-off temperature at least 10 degrees C. lower
than a catalytic converter made with wet chemistry methods and
having the same or similar PGM loading. In some embodiments, a
catalytic converter made with a coated substrate of the invention,
loaded with 4.0 g/l of PGM or less, displays a nitrogen oxide
light-off temperature at least 15 degrees C. lower than a catalytic
converter made with wet chemistry methods and having the same or
similar PGM loading. In some embodiments, the catalytic converter
made with a coated substrate of the invention demonstrates any of
the foregoing performance standards after about 50,000 km, about
50,000 miles, about 75,000 km, about 75,000 miles, about 100,000
km, about 100,000 miles, about 125,000 km, about 125,000 miles,
about 150,000 km, or about 150,000 miles of operation (for both the
catalytic converter made with a coated substrate of the invention
and the comparative catalytic converter).
[0165] In some embodiments, a catalytic converter made with a
coated substrate of the invention, loaded with 3.0 g/l of PGM or
less, displays a carbon monoxide light-off temperature at least 5
degrees C. lower than a catalytic converter made with wet chemistry
methods and having the same or similar PGM loading. In some
embodiments, a catalytic converter made with a coated substrate of
the invention, loaded with 3.0 g/l of PGM or less, displays a
carbon monoxide light-off temperature at least 10 degrees C. lower
than a catalytic converter made with wet chemistry methods and
having the same or similar PGM loading. In some embodiments, a
catalytic converter made with a coated substrate of the invention,
loaded with 3.0 g/l of PGM or less, displays a carbon monoxide
light-off temperature at least 15 degrees C. lower than a catalytic
converter made with wet chemistry methods and having the same or
similar PGM loading. In some embodiments, the catalytic converter
made with a coated substrate of the invention demonstrates any of
the foregoing performance standards after about 50,000 km, about
50,000 miles, about 75,000 km, about 75,000 miles, about 100,000
km, about 100,000 miles, about 125,000 km, about 125,000 miles,
about 150,000 km, or about 150,000 miles of operation (for both the
catalytic converter made with a coated substrate of the invention
and the comparative catalytic converter).
[0166] In some embodiments, a catalytic converter made with a
coated substrate of the invention, loaded with 3.0 g/l of PGM or
less, displays a hydrocarbon light-off temperature at least 5
degrees C. lower than a catalytic converter made with wet chemistry
methods and having the same or similar PGM loading. In some
embodiments, a catalytic converter made with a coated substrate of
the invention, loaded with 3.0 g/l of PGM or less, displays a
hydrocarbon light-off temperature at least 10 degrees C. lower than
a catalytic converter made with wet chemistry methods and having
the same or similar PGM loading. In some embodiments, a catalytic
converter made with a coated substrate of the invention, loaded
with 3.0 g/l of PGM or less, displays a hydrocarbon light-off
temperature at least 15 degrees C. lower than a catalytic converter
made with wet chemistry methods and having the same or similar PGM
loading. In some embodiments, the catalytic converter made with a
coated substrate of the invention demonstrates any of the foregoing
performance standards after about 50,000 km, about 50,000 miles,
about 75,000 km, about 75,000 miles, about 100,000 km, about
100,000 miles, about 125,000 km, about 125,000 miles, about 150,000
km, or about 150,000 miles of operation (for both the catalytic
converter made with a coated substrate of the invention and the
comparative catalytic converter).
[0167] In some embodiments, a catalytic converter made with a
coated substrate of the invention, loaded with 3.0 g/l of PGM or
less, displays a nitrogen oxide light-off temperature at least 5
degrees C. lower than a catalytic converter made with wet chemistry
methods and having the same or similar PGM loading. In some
embodiments, a catalytic converter made with a coated substrate of
the invention, loaded with 3.0 g/l of PGM or less, displays a
nitrogen oxide light-off temperature at least 10 degrees C. lower
than a catalytic converter made with wet chemistry methods and
having the same or similar PGM loading. In some embodiments, a
catalytic converter made with a coated substrate of the invention,
loaded with 3.0 g/l of PGM or less, displays a nitrogen oxide
light-off temperature at least 15 degrees C. lower than a catalytic
converter made with wet chemistry methods and having the same or
similar PGM loading. In some embodiments, the catalytic converter
made with a coated substrate of the invention demonstrates any of
the foregoing performance standards after about 50,000 km, about
50,000 miles, about 75,000 km, about 75,000 miles, about 100,000
km, about 100,000 miles, about 125,000 km, about 125,000 miles,
about 150,000 km, or about 150,000 miles of operation (for both the
catalytic converter made with a coated substrate of the invention
and the comparative catalytic converter).
[0168] In some embodiments, a catalytic converter made with a
coated substrate of the invention displays a carbon monoxide
light-off temperature within +/-2 degrees C. of the carbon monoxide
light-off temperature of a catalytic converter made with wet
chemistry methods, while the catalytic converter made with a coated
substrate employing about 30 to 40% less catalyst than the
catalytic converter made with wet chemistry methods. In some
embodiments, the catalytic converter made with a coated substrate
of the invention demonstrates this performance after about 50,000
km, about 50,000 miles, about 75,000 km, about 75,000 miles, about
100,000 km, about 100,000 miles, about 125,000 km, about 125,000
miles, about 150,000 km, or about 150,000 miles of operation (for
both the catalytic converter made with a coated substrate of the
invention and the comparative catalytic converter).
[0169] In some embodiments, a catalytic converter made with a
coated substrate of the invention displays a carbon monoxide
light-off temperature within +/-1 degrees C. of the carbon monoxide
light-off temperature of a catalytic converter made with wet
chemistry methods, while the catalytic converter made with a coated
substrate employing about 30 to 40% less catalyst than the
catalytic converter made with wet chemistry methods. In some
embodiments, the catalytic converter made with a coated substrate
of the invention demonstrates this performance after about 50,000
km, about 50,000 miles, about 75,000 km, about 75,000 miles, about
100,000 km, about 100,000 miles, about 125,000 km, about 125,000
miles, about 150,000 km, or about 150,000 miles of operation (for
both the catalytic converter made with a coated substrate of the
invention and the comparative catalytic converter).
[0170] In some embodiments, a catalytic converter made with a
coated substrate of the invention displays a carbon monoxide
light-off temperature within +/-2 degrees C. of the hydrocarbon
light-off temperature of a catalytic converter made with wet
chemistry methods, while the catalytic converter made with a coated
substrate employing about 30 to 40% less catalyst than the
catalytic converter made with wet chemistry methods. In some
embodiments, the catalytic converter made with a coated substrate
of the invention demonstrates this performance after about 50,000
km, about 50,000 miles, about 75,000 km, about 75,000 miles, about
100,000 km, about 100,000 miles, about 125,000 km, about 125,000
miles, about 150,000 km, or about 150,000 miles of operation (for
both the catalytic converter made with a coated substrate of the
invention and the comparative catalytic converter).
[0171] In some embodiments, a catalytic converter made with a
coated substrate of the invention displays a carbon monoxide
light-off temperature within +/-1 degrees C. of the hydrocarbon
light-off temperature of a catalytic converter made with wet
chemistry methods, while the catalytic converter made with a coated
substrate employing about 30 to 40% less catalyst than the
catalytic converter made with wet chemistry methods. In some
embodiments, the catalytic converter made with a coated substrate
of the invention demonstrates this performance after about 50,000
km, about 50,000 miles, about 75,000 km, about 75,000 miles, about
100,000 kin, about 100,000 miles, about 125,000 km, about 125,000
miles, about 150,000 km, or about 150,000 miles of operation (for
both the catalytic converter made with a coated substrate of the
invention and the comparative catalytic converter).
[0172] In some embodiments, a catalytic converter made with a
coated substrate of the invention displays a carbon monoxide
light-off temperature within +/-2 degrees C. of the nitrogen oxide
light-off temperature of a catalytic converter made with wet
chemistry methods, while the catalytic converter made with a coated
substrate employing about 30 to 40% less catalyst than the
catalytic converter made with wet chemistry methods. In some
embodiments, the catalytic converter made with a coated substrate
of the invention demonstrates this performance after about 50,000
km, about 50,000 miles, about 75,000 km, about 75,000 miles, about
100,000 km, about 100,000 miles, about 125,000 km, about 125,000
miles, about 150,000 km, or about 150,000 miles of operation (for
both the catalytic converter made with a coated substrate of the
invention and the comparative catalytic converter).
[0173] In some embodiments, a catalytic converter made with a
coated substrate of the invention displays a carbon monoxide
light-off temperature within +/-4 degrees C. of the nitrogen oxide
light-off temperature of a catalytic converter made with wet
chemistry methods, while the catalytic converter made with a coated
substrate employing about 30 to 40% less catalyst than the
catalytic converter made with wet chemistry methods. In some
embodiments, the catalytic converter made with a coated substrate
of the invention demonstrates this performance after about 50,000
km, about 50,000 miles, about 75,000 km, about 75,000 miles, about
100,000 km, about 100,000 miles, about 125,000 km, about 125,000
miles, about 150,000 km, or about 150,000 miles of operation (for
both the catalytic converter made with a coated substrate of the
invention and the comparative catalytic converter).
[0174] In some embodiments, a catalytic converter made with a
coated substrate of the invention employed on a gasoline engine or
gasoline vehicle complies with United States EPA emissions
requirements, while using at least about 30% less, up to about 30%
less, at least about 40% less, up to about 40% less, at least about
50% less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which complies with the same standard. In
some embodiments, the coated substrate is used in a catalytic
converter to meet or exceed these standards. The emissions
requirements can be intermediate life requirements or full life
requirements. The requirements can be TLEV requirements, LEV
requirements, or ULEV requirements. In some embodiments, the
catalytic converter made with a coated substrate of the invention
demonstrates any of the foregoing performance standards after about
50,000 km, about 50,000 miles, about 75,000 km, about 75,000 miles,
about 100,000 km, about 100,000 miles, about 125,000 km, about
125,000 miles, about 150,000 km, or about 150,000 miles of
operation (for both the catalytic converter made with a coated
substrate of the invention and the comparative catalytic
converter).
[0175] In some embodiments, a catalytic converter made with a
coated substrate of the invention employed on a gasoline engine or
gasoline vehicle complies with EPA TLEV/LEV intermediate life
requirements. In some embodiments, a catalytic converter made with
a coated substrate of the invention employed on a gasoline engine
or gasoline vehicle complies with EPA TLEV/LEV full life
requirements. In some embodiments, a catalytic converter made with
a coated substrate of the invention employed on a gasoline engine
or gasoline vehicle complies with EPA ULEV intermediate life
requirements. In some embodiments, a catalytic converter made with
a coated substrate of the invention employed on a gasoline engine
or gasoline vehicle complies with EPA ULEV full life requirements.
In some embodiments, the coated substrate is used in a catalytic
converter to meet or exceed these standards. In some embodiments,
the catalytic converter made with a coated substrate of the
invention demonstrates any of the foregoing performance standards
after about 50,000 km, about 50,000 miles, about 75,000 km, about
75,000 miles, about 100,000 km, about 100,000 miles, about 125,000
km, about 125,000 miles, about 150,000 km, or about 150,000 miles
of operation.
[0176] In some embodiments, a catalytic converter made with a
coated substrate of the invention employed on a gasoline engine or
gasoline vehicle complies with EPA TLEV/LEV intermediate life
requirements, while using at least about 30% less, up to about 30%
less, at least about 40% less, up to about 40% less, at least about
50% less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which complies with that standard. In some
embodiments, a catalytic converter made with a coated substrate of
the invention employed on a gasoline engine or gasoline vehicle
complies with EPA TLEV/LEV full life requirements, while using at
least about 30% less, up to about 30% less, at least about 40%
less, up to about 40% less, at least about 50% less, or up to about
50% less, platinum group metal or platinum group metal loading, as
compared to a catalytic converter made with wet chemistry methods
which complies with that standard. In some embodiments, a catalytic
converter made with a coated substrate of the invention employed on
a gasoline engine or gasoline vehicle complies with EPA ULEV
intermediate life requirements, while using at least about 30%
less, up to about 30% less, at least about 40% less, up to about
40% less, at least about 50% less, or up to about 50% less,
platinum group metal or platinum group metal loading, as compared
to a catalytic converter made with wet chemistry methods which
complies with that standard. In some embodiments, a catalytic
converter made with a coated substrate of the invention employed on
a gasoline engine or gasoline vehicle complies with EPA ULEV full
life requirements, while using at least about 30% less, up to about
30% less, at least about 40% less, up to about 40% less, at least
about 50% less, or up to about 50% less, platinum group metal or
platinum group metal loading, as compared to a catalytic converter
made with wet chemistry methods which complies with that standard.
In some embodiments, a catalytic converter made with a coated
substrate of the invention employed on a gasoline engine or
gasoline vehicle complies with EPA SULEV intermediate life
requirements, while using at least about 30% less, up to about 30%
less, at least about 40% less, up to about 40% less, at least about
50% less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which complies with that standard. In some
embodiments, a catalytic converter made with a coated substrate of
the invention employed on a gasoline engine or gasoline vehicle
complies with EPA SULEV full life requirements, while using at
least about 30% less, up to about 30% less, at least about 40%
less, up to about 40% less, at least about 50% less, or up to about
50% less, platinum group metal or platinum group metal loading, as
compared to a catalytic converter made with wet chemistry methods
which complies with that standard. In some embodiments, the coated
substrate is used in a catalytic converter to meet or exceed these
standards. In some embodiments, the catalytic converter made with a
coated substrate of the invention demonstrates any of the foregoing
performance standards after about 50,000 km, about 50,000 miles,
about 75,000 km, about 75,000 miles, about 100,000 km, about
100,000 miles, about 125,000 km, about 125,000 miles, about 150,000
km, or about 150,000 miles of operation (for both the catalytic
converter made with a coated substrate of the invention and the
comparative catalytic converter). In some embodiments, the
requirements above are those for light duty vehicles. In some
embodiments, the requirements above are those for light duty
trucks. In some embodiments, the requirements above are those for
medium duty vehicles.
[0177] In some embodiments, a catalytic converter made with a
coated substrate of the invention employed on a gasoline engine or
gasoline vehicle complies with Euro 5 requirements. In some
embodiments, a catalytic converter made with a coated substrate of
the invention employed on a gasoline engine or gasoline vehicle
complies with Euro 6 requirements. In some embodiments, the coated
substrate is used in a catalytic converter to meet or exceed these
standards. In some embodiments, the catalytic converter made with a
coated substrate of the invention demonstrates any of the foregoing
performance standards after about 50,000 km, about 50,000 miles,
about 75,000 km, about 75,000 miles, about 100,000 km, about
100,000 miles, about 125,000 km, about 125,000 miles, about 150,000
km, or about 150,000 miles of operation.
[0178] In some embodiments, a catalytic converter made with a
coated substrate of the invention employed on a gasoline engine or
gasoline vehicle complies with Euro 5 requirements, while using at
least about 30% less, up to about 30% less, at least about 40%
less, up to about 40% less, at least about 50% less, or up to about
50% less, platinum group metal or platinum group metal loading, as
compared to a catalytic converter made with wet chemistry methods
which complies with Euro 5 requirements. In some embodiments, the
coated substrate is used in a catalytic converter to meet or exceed
these standards. In some embodiments, the catalytic converter made
with a coated substrate of the invention demonstrates any of the
foregoing performance standards after about 50,000 km, about 50,000
miles, about 75,000 km, about 75,000 miles, about 100,000 km, about
100,000 miles, about 125,000 km, about 125,000 miles, about 150,000
km, or about 150,000 miles of operation (for both the catalytic
converter made with a coated substrate of the invention and the
comparative catalytic converter).
[0179] In some embodiments, a catalytic converter made with a
coated substrate of the invention employed on a gasoline engine or
gasoline vehicle complies with Euro 6 requirements, while using at
least about 30% less, up to about 30% less, at least about 40%
less, up to about 40% less, at least about 50% less, or up to about
50% less, platinum group metal or platinum group metal loading, as
compared to a catalytic converter made with wet chemistry methods
which complies with Euro 6 requirements. In some embodiments, the
coated substrate is used in a catalytic converter to meet or exceed
these standards. In some embodiments, the catalytic converter made
with a coated substrate of the invention demonstrates any of the
foregoing performance standards after about 50,000 km, about 50,000
miles, about 75,000 km, about 75,000 miles, about 100,000 km, about
100,000 miles, about 125,000 km, about 125,000 miles, about 150,000
km, or about 150,000 miles of operation (for both the catalytic
converter made with a coated substrate of the invention and the
comparative catalytic converter).
[0180] In some embodiments, a catalytic converter made with a
coated substrate of the invention employed on a gasoline engine or
gasoline vehicle displays carbon monoxide emissions of 4200 mg/mile
or less. In some embodiments, a catalytic converter made with a
coated substrate of the invention and employed on a gasoline engine
or gasoline vehicle displays carbon monoxide emissions of 3400
mg/mile or less. In some embodiments, a catalytic converter made
with a coated substrate of the invention and employed on a gasoline
engine or gasoline vehicle displays carbon monoxide emissions of
2100 mg/mile or less. In another embodiment, a catalytic converter
made with a coated substrate of the invention and employed on a
gasoline engine or gasoline vehicle displays carbon monoxide
emissions of 1700 mg/mile or less. In some embodiments, the coated
substrate is used in a catalytic converter to meet or exceed these
standards. In some embodiments, the catalytic converter made with a
coated substrate of the invention demonstrates any of the foregoing
performance standards after about 50,000 km, about 50,000 miles,
about 75,000 km, about 75,000 miles, about 100,000 km, about
100,000 miles, about 125,000 km, about 125,000 miles, about 150,000
km, or about 150,000 miles of operation.
[0181] In some embodiments, a catalytic converter made with a
coated substrate of the invention and employed on a gasoline engine
or gasoline vehicle displays carbon monoxide emissions of 500 mg/km
or less. In some embodiments, a catalytic converter made with a
coated substrate of the invention and employed on a gasoline engine
or gasoline vehicle displays carbon monoxide emissions of 375 mg/km
or less. In some embodiments, a catalytic converter made with a
coated substrate of the invention and employed on a gasoline engine
or gasoline vehicle displays carbon monoxide emissions of 250 mg/km
or less. In some embodiments, the coated substrate is used in a
catalytic converter to meet or exceed these standards. In some
embodiments, the catalytic converter made with a coated substrate
of the invention demonstrates any of the foregoing performance
standards after about 50,000 km, about 50,000 miles, about 75,000
km, about 75,000 miles, about 100,000 km, about 100,000 miles,
about 125,000 km, about 125,000 miles, about 150,000 km, or about
150,000 miles of operation.
[0182] In some embodiments, a catalytic converter made with a
coated substrate of the invention and employed on a gasoline engine
or gasoline vehicle displays NO.sub.x emissions of 180 mg/km or
less. In some embodiments, a catalytic converter made with a coated
substrate of the invention and employed on a gasoline engine or
gasoline vehicle displays NO.sub.x emissions of 80 mg/km or less.
In some embodiments, a catalytic converter made with a coated
substrate of the invention and employed on a gasoline engine or
gasoline vehicle displays NO.sub.x emissions of 40 mg/km or less.
In some embodiments, the coated substrate is used in a catalytic
converter to meet or exceed these standards. In some embodiments,
the catalytic converter made with a coated substrate of the
invention demonstrates any of the foregoing performance standards
after about 50,000 km, about 50,000 miles, about 75,000 km, about
75,000 miles, about 100,000 km, about 100,000 miles, about 125,000
km, about 125,000 miles, about 150,000 km, or about 150,000 miles
of operation.
[0183] In some embodiments, a catalytic converter made with a
coated substrate of the invention and employed on a gasoline engine
or gasoline vehicle displays NO.sub.x plus HC emissions of 230
mg/km or less. In some embodiments, a catalytic converter made with
a coated substrate of the invention and employed on a gasoline
engine or gasoline vehicle displays NO.sub.x plus HC emissions of
170 mg/km or less. In some embodiments, a catalytic converter made
with a coated substrate of the invention and employed on a gasoline
engine or gasoline vehicle displays NO.sub.x plus HC emissions of
85 mg/km or less. In some embodiments, the coated substrate is used
in a catalytic converter to meet or exceed these standards. In some
embodiments, the catalytic converter made with a coated substrate
of the invention demonstrates any of the foregoing performance
standards after about 50,000 km, about 50,000 miles, about 75,000
km, about 75,000 miles, about 100,000 km, about 100,000 miles,
about 125,000 km, about 125,000 miles, about 150,000 km, or about
150,000 miles of operation.
[0184] In some embodiments, a catalytic converter made with a
coated substrate and employed on a gasoline engine or gasoline
vehicle displays carbon monoxide emissions of 500 mg/km or less,
while using at least about 30% less, up to about 30% less, at least
about 40% less, up to about 40% less, at least about 50% less, or
up to about 50% less, platinum group metal or platinum group metal
loading, as compared to a catalytic converter made with wet
chemistry methods which displays the same or similar emissions. In
some embodiments, a catalytic converter made with a coated
substrate of the invention and employed on a gasoline engine or
gasoline vehicle displays carbon monoxide emissions of 375 mg/km or
less, while using at least about 30% less, up to about 30% less, at
least about 40% less, up to about 40% less, at least about 50%
less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which displays the same or similar emissions.
In some embodiments, a catalytic converter made with a coated
substrate of the invention and employed on a gasoline engine or
gasoline vehicle displays carbon monoxide emissions of 250 mg/km or
less, while using at least about 30% less, up to about 30% less, at
least about 40% less, up to about 40% less, at least about 50%
less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which displays the same or similar emissions.
In some embodiments, the coated substrate is used in a catalytic
converter to meet or exceed these standards. In some embodiments,
the catalytic converter made with a coated substrate of the
invention demonstrates any of the foregoing performance standards
after about 50,000 km, about 50,000 miles, about 75,000 km, about
75,000 miles, about 100,000 km, about 100,000 miles, about 125,000
km, about 125,000 miles, about 150,000 km, or about 150,000 miles
of operation (for both the catalytic converter made with a coated
substrate of the invention and the comparative catalytic
converter).
[0185] In some embodiments, a catalytic converter made with a
coated substrate of the invention and employed on a gasoline engine
or gasoline vehicle displays NO.sub.x emissions of 180 mg/km or
less, while using at least about 30% less, up to about 30% less, at
least about 40% less, up to about 40% less, at least about 50%
less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which displays the same or similar emissions.
In some embodiments, a catalytic converter made with a coated
substrate of the invention and employed on a gasoline engine or
gasoline vehicle displays NO.sub.x emissions of 80 mg/km or less,
while using at least about 30% less, up to about 30% less, at least
about 40% less, up to about 40% less, at least about 50% less, or
up to about 50% less, platinum group metal or platinum group metal
loading, as compared to a catalytic converter made with wet
chemistry methods which displays the same or similar emissions. In
some embodiments, a catalytic converter made with a coated
substrate of the invention and employed on a gasoline engine or
gasoline vehicle displays NO.sub.x emissions of 40 mg/km or less,
while using at least about 30% less, up to about 30% less, at least
about 40% less, up to about 40% less, at least about 50% less, or
up to about 50% less, platinum group metal or platinum group metal
loading, as compared to a catalytic converter made with wet
chemistry methods which displays the same or similar emissions. In
some embodiments, the coated substrate is used in a catalytic
converter to meet or exceed these standards. In some embodiments,
the catalytic converter made with a coated substrate of the
invention demonstrates any of the foregoing performance standards
after about 50,000 km, about 50,000 miles, about 75,000 km, about
75,000 miles, about 100,000 km, about 100,000 miles, about 125,000
km, about 125,000 miles, about 150,000 km, or about 150,000 miles
of operation (for both the catalytic converter made with a coated
substrate of the invention and the comparative catalytic
converter).
[0186] In some embodiments, a catalytic converter made with a
coated substrate of the invention and employed on a gasoline engine
or gasoline vehicle displays NO), plus HC emissions of 230 mg/km or
less, while using at least about 30% less, up to about 30% less, at
least about 40% less, up to about 40% less, at least about 50%
less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which displays the same or similar emissions.
In some embodiments, a catalytic converter made with a coated
substrate of the invention and employed on a gasoline engine or
gasoline vehicle displays NO.sub.x plus HC emissions of 170 mg/km
or less, while using at least about 30% less, up to about 30% less,
at least about 40% less, up to about 40% less, at least about 50%
less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which displays the same or similar emissions.
In some embodiments, a catalytic converter made with a coated
substrate of the invention and employed on a gasoline engine or
gasoline vehicle displays NO.sub.x plus HC emissions of 85 mg/km or
less, while using at least about 30% less, up to about 30% less, at
least about 40% less, up to about 40% less, at least about 50%
less, or up to about 50% less, platinum group metal or platinum
group metal loading, as compared to a catalytic converter made with
wet chemistry methods which displays the same or similar emissions.
In some embodiments, the coated substrate is used in a catalytic
converter to meet or exceed these standards. In some embodiments,
the catalytic converter made with a coated substrate of the
invention demonstrates any of the foregoing performance standards
after about 50,000 km, about 50,000 miles, about 75,000 km, about
75,000 miles, about 100,000 km, about 100,000 miles, about 125,000
km, about 125,000 miles, about 150,000 km, or about 150,000 miles
of operation (for both the catalytic converter made with a coated
substrate of the invention and the comparative catalytic
converter).
[0187] In some embodiments, for the above-described comparisons,
the thrifting (reduction) of platinum group metal for the catalytic
converters made with substrates of the invention is compared with
either 1) a commercially available catalytic converter, made using
wet chemistry, for the application disclosed (e.g., for use on a
gasoline engine or gasoline vehicle), or 2) a catalytic converter
made with wet chemistry, which uses the minimal amount of platinum
group metal to achieve the performance standard indicated.
[0188] In some embodiments, for the above-described comparisons,
both the coated substrate according to the invention, and the
catalyst used in the commercially available catalytic converter or
the catalyst prepared using wet chemistry methods, are aged (by the
same amount) prior to testing. In some embodiments, both the coated
substrate according to the invention, and the catalyst substrate
used in the commercially available catalytic converter or the
catalyst substrate prepared using wet chemistry methods, are aged
to about (or up to about) 50,000 kilometers, about (or up to about)
50,000 miles, about (or up to about) 75,000 kilometers, about (or
up to about) 75,000 miles, about (or up to about) 100,000
kilometers, about (or up to about) 100,000 miles, about (or up to
about) 125,000 kilometers, about (or up to about) 125,000 miles,
about (or up to about) 150,000 kilometers, or about (or up to
about) 150,000 miles. In some embodiments, for the above-described
comparisons, both the coated substrate according to the invention,
and the catalyst substrate used in the commercially available
catalytic converter or the catalyst substrate prepared using wet
chemistry methods, are artificially aged (by the same amount) prior
to testing. In some embodiments, they are artificially aged by
heating to about 400.degree. C., about 500.degree. C., about
600.degree. C., about 700.degree. C., about 800.degree. C., about
900.degree. C., about 1000.degree. C., about 1100.degree. C., or
about 1200.degree. C. for about (or up to about) 4 hours, about (or
up to about) 6 hours, about (or up to about) 8 hours, about (or up
to about) 10 hours, about (or up to about) 12 hours, about (or up
to about) 14 hours, about (or up to about) 16 hours, about (or up
to about) 18 hours, about (or up to about) 20 hours, about (or up
to about) 22 hours, or about (or up to about) 24 hours, or about
(or up to about) 50 hours In some embodiments, they are
artificially aged by heating to about 800.degree. C. for about 16
hours.
[0189] In some embodiments, for the above-described comparisons,
the thrifting (reduction) of platinum group metal for the catalytic
converters made with substrates of the invention is compared with
either 1) a commercially available catalytic converter, made using
wet chemistry, for the application disclosed (e.g., for use on a
gasoline engine or gasoline vehicle), or 2) a catalytic converter
made with wet chemistry, which uses the minimal amount of platinum
group metal to achieve the performance standard indicated, and
after the coated substrate according to the invention and the
catalytic substrate used in the commercially available catalyst or
catalyst made using wet chemistry with the minimal amount of PGM to
achieve the performance standard indicated are aged as described
above.
[0190] In some embodiments, for the above-described catalytic
converters employing the coated substrates of the invention, for
the exhaust treatment systems using catalytic converters employing
the coated substrates of the invention, and for vehicles employing
these catalytic converters and exhaust treatment systems, the
catalytic converter is employed as a diesel oxidation catalyst
along with a diesel particulate filter, or the catalytic converter
is employed as a diesel oxidation catalyst along with a diesel
particulate filter and a selective catalytic reduction unit, to
meet or exceed the standards for CO and/or NO.sub.R, and/or HC
described above.
EXEMPLARY EMBODIMENTS
[0191] The invention is further described by the following
embodiments.
Embodiment 1
[0192] In one embodiment, the invention provides a coated substrate
comprising: oxidative catalytically active particles comprising
oxidative composite nanoparticles bonded to first micron-sized
carrier particles, wherein the oxidative composite nanoparticles
comprise a first support nanoparticle and one or more oxidative
catalyst nanoparticles; and reductive catalytically active
particles comprising reductive composite nanoparticles bonded to
second micron-sized carrier particles, wherein the reductive
composite nanoparticles comprise a second support nanoparticle and
one or more reductive catalyst nanoparticles.
Embodiment 2
[0193] In a further embodiment of embodiment 1, the coated
substrate comprises at least two washcoat layers in which the
oxidative catalytically active particles are in one washcoat layer
and the reductive catalytically active particles are in another
washcoat layer.
Embodiment 3
[0194] In a further embodiment of embodiment 1, the oxidative
catalytically active particles and the reductive catalytically
active particles are in the same washcoat layer.
Embodiment 4
[0195] In a further embodiment of any one of embodiments 1, 2, or
3, the oxidative catalyst nanoparticles comprise platinum,
palladium, or a mixture thereof.
Embodiment 5
[0196] In a further embodiment of any one of embodiments 1, 2, or
3, the oxidative catalyst nanoparticles comprise palladium.
Embodiment 6
[0197] In a further embodiment of any one of embodiments 1-5,
embodiments, the first support nanoparticles comprise aluminum
oxide.
Embodiment 7
[0198] In a further embodiment of any one of embodiments 1-6, the
first micron-sized carrier particles comprise aluminum oxide.
Embodiment 8
[0199] In a further embodiment of any one of embodiments 1-7, the
first micron-sized carrier particle is pre-treated at a temperature
range of about 700.degree. C. to about 1500.degree. C.
Embodiment 9
[0200] In a further embodiment of any one of embodiments 1-8, the
reductive catalyst nanoparticles comprise rhodium.
Embodiment 10
[0201] In a further embodiment of any one of embodiments 1-9, the
second support nanoparticles comprise cerium zirconium oxide.
Embodiment 11
[0202] In a further embodiment of any one of embodiments 1-10, the
second micron-sized carrier particles comprise cerium zirconium
oxide.
Embodiment 12
[0203] In a further embodiment of any one of embodiments 1-11, the
support nanoparticles have an average diameter of 10 nm to 20
nm.
Embodiment 13
[0204] In a further embodiment of any one of embodiments 1-12, the
catalytic nanoparticles have an average diameter of between 1 nm
and 5 nm.
Embodiment 14
[0205] In a further embodiment of any one of embodiments 1-13, the
embodiment further comprises an oxygen storage component.
Embodiment 15
[0206] In a further embodiment of embodiment 14, the oxygen storage
component is cerium zirconium oxide or cerium oxide.
Embodiment 16
[0207] In a further embodiment of any one of embodiments 1-15, the
embodiment further comprises a NOx absorber component.
Embodiment 17
[0208] In a further embodiment of embodiment 16, the NOx absorber
is nano-sized BaO.
Embodiment 18
[0209] In a further embodiment of embodiment 16, the NOx absorber
is micron-sized BaO.
Embodiment 19
[0210] In a further embodiment of any one of embodiments 1-18, the
substrate comprises cordierite.
Embodiment 20
[0211] In a further embodiment of any one of embodiments 1-19, the
substrate comprises a grid array structure.
Embodiment 21
[0212] In a further embodiment of any one of embodiments 1-20, the
coated substrate has a platinum group metal loading of 4 g/l or
less and a light-off temperature for carbon monoxide at least
5.degree. C. lower than the light-off temperature of a substrate
with the same platinum group metal loading deposited by
wet-chemistry methods.
Embodiment 22
[0213] In a further embodiment of any one of embodiments 1-20, the
coated substrate has a platinum group metal loading of 4 g/l or
less and a light-off temperature for hydrocarbon at least 5.degree.
C. lower than the light-off temperature of a substrate with the
same platinum group metal loading deposited by wet-chemistry
methods.
Embodiment 23
[0214] In a further embodiment of any one of embodiments 1-20, the
coated substrate has a platinum group metal loading of 4 g/l or
less and a light-off temperature for nitrogen oxide at least
5.degree. C. lower than the light-off temperature of a substrate
with the same platinum group metal loading deposited by
wet-chemistry methods.
Embodiment 24
[0215] In a further embodiment of any one of embodiments 1-23, the
coated substrate has a platinum group metal loading of about 3.0
g/l to about 4.0 g/l.
Embodiment 25
[0216] In a further embodiment of any one of embodiments 1-24, the
coated substrate has a platinum group metal loading of about 3.0
g/l to about 4.0 g/l, and after 125,000 miles of operation in a
vehicular catalytic converter, the coated substrate has a light-off
temperature for carbon monoxide at least 5.degree. C. lower than a
coated substrate prepared by depositing platinum group metals by
wet chemical methods having the same platinum group metal loading
after 125,000 miles of operation in a vehicular catalytic
converter.
Embodiment 26
[0217] In a further embodiment of any one of embodiments 1-25, the
ratio of oxidative catalytically active particles to reductive
catalytically active particles is between 6:1 and 40:1.
Embodiment 27
[0218] A catalytic converter comprising a coated substrate of any
of embodiments 1-26.
Embodiment 28
[0219] An exhaust treatment system comprising a conduit for exhaust
gas and a catalytic converter comprising a coated substrate as in
any one of embodiments 1-26.
Embodiment 29
[0220] A vehicle comprising a catalytic converter according to
embodiment 27.
Embodiment 30
[0221] A method of treating an exhaust gas, comprising contacting
the coated substrate as in any one of embodiments 1-26 with the
exhaust gas.
Embodiment 31
[0222] A method of treating an exhaust gas, comprising contacting
the coated substrate as in any one of embodiments 1-26 with the
exhaust gas, wherein the substrate is housed within a catalytic
converter configured to receive the exhaust gas.
Embodiment 32
[0223] In another embodiment, the invention provides a method of
forming a coated substrate, the method comprising: a) coating a
substrate with a washcoat composition comprising oxidative
catalytically active particles; wherein the oxidative catalytically
active particles comprise oxidative composite nanoparticles bonded
to micron-sized carrier particles, and the oxidative composite
nanoparticles comprise a first support nanoparticle and one or more
oxidative catalyst nanoparticles; and b) coating the substrate with
a washcoat composition comprising reductive catalytically active
particles; wherein the reductive catalytically active particles
comprise reductive composite nanoparticles bonded to micron-sized
carrier particles, and the reductive composite nanoparticles
comprise a second support nanoparticle and one or more reductive
catalyst nanoparticles.
Embodiment 33
[0224] In another embodiment, the invention provides a method of
forming a coated substrate, the method comprising: a) coating a
substrate with a washcoat composition comprising oxidative
catalytically active particles and reductive catalytically active
particles; wherein the oxidative catalytically active particles
comprise oxidative composite nanoparticles bonded to micron-sized
carrier particles, and the oxidative composite nanoparticles
comprise a first support nanoparticle and one or more oxidative
catalyst nanoparticles; and the reductive catalytically active
particles comprise reductive composite nanoparticles bonded to
micron-sized carrier particles, and the reductive composite
nanoparticles comprise a second support nanoparticle and one or
more reductive catalyst nanoparticles.
Embodiment 34
[0225] In another embodiment, the invention provides a washcoat
composition comprising a solids content of: 25-75% by weight of
oxidative catalytic active particles comprising composite oxidative
nano-particles bonded to micron-sized carrier particles, and the
composite oxidative nano-particles comprise a support nano-particle
and an oxidative catalytic nano-particle; 5-50% by weight of
reductive catalytic active particles comprising composite reductive
nano-particles bonded to micron-sized carrier particles, and the
composite reductive nano-particles comprise a support nano-particle
and a reductive catalytic nano-particle; 1-40% by weight of
micron-sized cerium zirconium oxide; 0.5-10% by weight of boehmite;
and 1-25% by weight micron-sized Al.sub.2O.sub.3.
EXPERIMENTAL SECTION
Comparison of Catalytic Converter Performance to Commercially
Available Catalytic Converters
[0226] The table below illustrates the performance of a coated
substrate in a catalytic converter, where the coated substrate is
prepared according to one embodiment of the present invention,
compared to a commercially available catalytic converter having a
substrate prepared using wet-chemistry methods. The coated
substrates are artificially aced and tested.
TABLE-US-00002 TABLE 2 SDC Catalyst compared to Commercial
Catalytic Converter at Same PGM Loadings PGM load- Catalytic ing
CO-T.sub.50 CO-T.sub.50 HC-T.sub.50 HC-T.sub.50 NO-T.sub.50
NO-T.sub.50 converter (g/l) fresh aged fresh aged fresh aged
Commer- 2.1 164 224 172 227 165 220 cial- (14:1) Compar- ative
Example 1 Example 2.1 180 203 181 206 182 207 2 (14:1)
[0227] In Table 2, a study of catalysts was performed to compare a
catalytic converter containing the coated substrate prepared
according to one embodiment of the present invention with a
commercial catalytic converter. The catalytic converters contained
the same PGM loading. The ratios show the PGM loading and indicate
the ratio of palladium to rhodium. The light off temperature
(T.sub.50) of carbon monoxide (CO), hydrocarbons (HC), and nitrogen
oxide (NO) were measured and shown above. Based on the results in
Table 2, a catalytic converter containing the coated substrate of
Example 2, which was prepared according to the present invention,
showed significantly better performance including lower light off
temperatures after aging than the commercially available catalytic
converter of Comparative Example 1 with the same loading of
PGM.
TABLE-US-00003 TABLE 3 SDC Catalyst compared to Commercial
Catalytic Converter PGM load- Catalytic ing CO-T.sub.50 CO-T.sub.50
HC-T.sub.50 HC-T.sub.50 NO-T.sub.50 NO-T.sub.50 converter (g/l)
fresh aged fresh aged fresh aged Commer- 2.1 164 224 172 227 165
220 cial- (14:1) Compar- ative Example 3 Example 1.3 200 222 201
225 203 222 4 (14:1)
[0228] In Table 3, a study of catalysts was performed to compare a
catalytic converter containing the coated substrate prepared
according to one embodiment of the present invention with a
commercial catalytic converter. Example 4, which is a catalytic
converter containing a coated substrate prepared according to one
embodiment of the present invention contained a lower PGM loading
than the commercially available catalytic converter of Comparative
Example 3. The ratios shown the PGM loading indicate the ratio of
palladium to rhodium. The light off temperature (T.sub.50) of
carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxide (NO)
were measured and shown above. Based on the results in Table 3, the
catalytic converter of Example 4 prepared according to an
embodiment of the present invention showed similar performance
compared to the commercial catalytic converter of Comparative
Example 3, which had a higher loading of PGM. This shows that the
disclosed catalytic converters reduce the need for platinum group
metals.
Comparison of Catalytic Converter Performance Described Herein to
Commercially Available Catalytic Converters
[0229] Table 4 shows a comparison of certain properties of a
catalyst prepared according to the present invention ("SDCmaterials
Catalyst") versus a commercially available catalytic converter
having a substrate prepared using wet-chemistry methods
("Commercial TWC Catalyst" or "Comm. Catalyst"). The coated
substrates are artificially aged and tested in a fashion as
described above. The catalyst prepared according to the present
invention demonstrated lower light-off temperatures (50% conversion
temperatures) for carbon monoxide (CO) (36.degree. C. lower),
hydrocarbons (HC) (40.degree. C. lower), and nitric oxide (NO)
(11.degree. C. lower). The catalyst prepared according to the
present invention demonstrated also displayed about 2.2 times the
oxygen storage capacity of the catalytic converter prepared via wet
chemistry methods.
TABLE-US-00004 TABLE 4 SDC Catalyst compared to Commercial
Catalytic Converter: Lightoff, Oxygen Storage Aged CO- Aged HC-
Aged NO- Oxygen PGM T.sub.50 Light T.sub.50 Light T.sub.50 Light
Storage Loading Temp. in .degree. C. Temp. in .degree. C. Temp. in
.degree. C. Capacity Commercial 100% x.degree. C. y.degree. C.
z.degree. C. 1 TWC Catalyst SDCmaterials 66% x.degree.
C.-36.degree. C. y.degree. C.-40.degree. C. z.degree. C.-11.degree.
C. 2.2x of Catalyst (of Comm. Comm. Catalyst) Catalyst
[0230] The following description is presented to enable one of
ordinary skill in the art to make and use the invention and is
provided in the context of a patent application and its
requirements. Various modifications to the described embodiments
will be readily apparent to those persons skilled in the art and
the generic principles herein may be applied to other embodiments.
Thus, the present invention is not intended to be limited to the
embodiment shown but is to be accorded the widest scope consistent
with the principles and features described herein. Finally, the
entire disclosure of the patents and publications referred in this
application are hereby incorporated herein by reference.
* * * * *