U.S. patent application number 13/585640 was filed with the patent office on 2012-12-06 for system and method for ammonia synthesis.
This patent application is currently assigned to QUANTUMSPHERE, INC.. Invention is credited to R. Douglas Carpenter, Kevin Maloney.
Application Number | 20120308467 13/585640 |
Document ID | / |
Family ID | 42337108 |
Filed Date | 2012-12-06 |
United States Patent
Application |
20120308467 |
Kind Code |
A1 |
Carpenter; R. Douglas ; et
al. |
December 6, 2012 |
SYSTEM AND METHOD FOR AMMONIA SYNTHESIS
Abstract
Systems and methods are disclosed herein for synthesizing
ammonia using nano-size metal or metal alloy catalyst particles.
Hydrogen and nitrogen gases are passed through a system comprising,
for example, a bed of magnetite supporting nano-size iron or iron
alloy catalyst particles having an optional oxide layer that forms
the catalyst.
Inventors: |
Carpenter; R. Douglas;
(Tustin, CA) ; Maloney; Kevin; (Newport Beach,
CA) |
Assignee: |
QUANTUMSPHERE, INC.
Santa Ana
CA
|
Family ID: |
42337108 |
Appl. No.: |
13/585640 |
Filed: |
August 14, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13326135 |
Dec 14, 2011 |
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13585640 |
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13050823 |
Mar 17, 2011 |
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13326135 |
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12752018 |
Mar 31, 2010 |
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13050823 |
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12418356 |
Apr 3, 2009 |
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12752018 |
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12266477 |
Nov 6, 2008 |
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12418356 |
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60985855 |
Nov 6, 2007 |
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Current U.S.
Class: |
423/362 ;
422/148 |
Current CPC
Class: |
C01C 1/0411 20130101;
B82Y 40/00 20130101; Y02P 20/52 20151101; B01J 35/0013 20130101;
B01J 23/745 20130101 |
Class at
Publication: |
423/362 ;
422/148 |
International
Class: |
C01C 1/04 20060101
C01C001/04 |
Claims
1. A method of synthesizing ammonia comprising reacting a supply of
nitrogen gas in the presence of nano-sized metal catalyst particles
disposed on a ferrous support and in the presence of a nano-sized
promoter.
2. The method of claim 1, wherein the metal catalyst comprises an
oxide layer.
3. The method of claim 1, wherein the promoter comprises molecules
from Groups 1, 2, 6, 9, 13, 14 and/or the lanthanide series on the
periodic table.
4. An ammonia synthesis reactor comprising: nano-sized iron
catalyst particles and a nano-sized promoter disposed on a ferrous
support material within the reactor; at least one inlet configured
to introduce hydrogen gas and nitrogen gas to the nano-sized metal
catalyst particles; and at least one outlet configured to remove
ammonia gas generated in the presence of the nano-sized metal
catalyst particles, wherein the reactor is configured to operate at
a pressure less than about 500 atm.
5. The method of claim 4, wherein the metal catalyst comprises an
oxide layer.
6. The method of claim 4, wherein the promoter comprises molecules
from Groups 1, 2, 6, 9, 13, 14 and/or the lanthanide series on the
periodic table.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/326,135, filed Dec. 14, 2011, which is a
continuation of U.S. patent application Ser. No. 13/050,823, filed
Mar. 17, 2011, which is a continuation of U.S. patent application
Ser. No. 12/752,018, filed Mar. 31, 2010, which is a
continuation-in-part of U.S. patent application Ser. No.
12/418,356, filed Apr. 3, 2009, which is a continuation-in-part of
U.S. patent application Ser. No. 12/266,477, filed on Nov. 6, 2008,
which claims the benefit of Provisional Application No. 60/985,855,
filed on Nov. 6, 2007, the entire contents of each of which are
hereby incorporated by this express reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The disclosure relates generally to the synthesis of useful
chemical byproducts and, more specifically, to the synthesis of
ammonia using nano-size metal catalyst particles.
[0004] 2. Related Art
[0005] Ammonia synthesis is an important industrial process.
Ammonia is produced in huge quantities worldwide, for use in the
fertilizer industry, as a precursor for nitric acid and nitrates
for the explosives industry, and as a raw material for various
industrial chemicals.
[0006] Despite an energy production cost of about 35 to 50 GJ per
ton of ammonia, the Haber-Bosch process is the most widespread
ammonia manufacturing process used today. The Haber-Bosch process
was invented in the early 1900s in Germany and is fundamental to
modern chemical engineering.
[0007] The Haber-Bosch process uses an iron catalyst to improve
NH.sub.3 yields. Being a transition metal with partially occupied
d-bands, iron represents a surface suitable for adsorption and
dissociation of N.sub.2 molecules. An example of a commonly used
iron catalyst is reduced magnetite ore (Fe.sub.3O.sub.4) enriched
("promoted") with oxides of, for example, aluminum, potassium,
calcium, magnesium, or silicon.
[0008] In the Haber-Bosch process, ammonia is synthesized using
hydrogen (H.sub.2) and nitrogen (N.sub.2) gases according to the
net reaction (N.sub.2+3H.sub.2.fwdarw.2NH.sub.3). The mechanism for
iron-catalyzed ammonia synthesis is stated below in four dominant
reaction steps, wherein "ads" denotes a species adsorbed on the
iron catalyst and "g" denotes a gas phase species:
N.sub.2(ads).fwdarw.2N(ads) (1)
H.sub.2(ads).fwdarw.2H(ads) (2)
N(ads)+3H(ads).fwdarw.NH.sub.3(ads) (3)
NH.sub.3(ads).fwdarw.NH.sub.3(g) (4)
The rate limiting step in the conversion of nitrogen and hydrogen
into ammonia has been determined to be the adsorption and
dissociation of the nitrogen on the catalyst surface. Thermodynamic
equilibrium of the reaction is shifted towards ammonia product by
high pressure and low temperature. However, in practice, both high
pressures and temperatures are used due to a sluggish reaction
rate. Due to overall low reaction efficiency when hydrogen and
nitrogen are first passed over the catalyst bed, most ammonia
production plants utilize multiple adiabatically heated catalyst
beds with cooling between beds, typically with axial or radial
flow. High pressure favors the adsorption process as well, but at a
cost of increased operational and capital costs.
[0009] At pressures above 750 atm, there is an almost 100%
conversion of reactants to the ammonia product. Because there are
difficulties associated with containing larger amounts of materials
at this high pressure, lower pressures of about 150 to 250 atm are
used industrially. By using a pressure of around 200 atm and a
temperature of about 500.degree. C., the yield of ammonia is about
10 to 20%, while costs and safety concerns in the plant and during
operation of the plant are minimized. Nevertheless, due in part to
high pressures used in the process, ammonia production requires
reactors with heavily-reinforced walls, piping and fittings, as
well as a series of powerful compressors, all with high capital
cost. In addition, generation of those high pressures during plant
operation requires a large expenditure in energy.
[0010] In an effort to reduce the energy requirements of this
process, the Kellogg Advanced Ammonia Process (KAAP) was developed
using a ruthenium catalyst supported on carbon. The KAAP catalyst
is reported to be 40% more active than the traditional iron
catalysts. Use of this catalyst allowed the reactor pressure to be
reduced, but the high cost of the precious metal ruthenium catalyst
and the sensitivity of the catalyst to impurities in the hydrogen
feed stock have prevented widespread use for ammonia synthesis.
Other catalysts being studied include cobalt doped with ruthenium,
but few encouraging results have been exhibited to date. Thus,
after almost 90 years of ammonia synthesis, the Haber-Bosch process
remains the most commonly used ammonia synthesis mechanism.
[0011] For the last 100 years, iron-based catalysts have been used
in industrial ammonia synthesis. This catalyst is prepared by
melting magnetite (Fe.sub.3O.sub.4) with a promoter compounds, for
example potassium or calcium, and solidifying. The resulting porous
material is then crushed into granules, generally in the size range
of 1-10 millimeters. Active catalyst is then produced by reduction
of iron oxides with hydrogen and nitrogen gas mixture, to give
porous iron, and unreduced promoter oxides. Approximately 50% of
this catalyst is void volume.
[0012] Improvements to Haber-Bosch catalysts focus on the addition
of promoters for improved activity ammonia synthesis. U.S. Pat.
Nos. 4,789,657 and 3,951,862 describe processes of preparing a
magnetite-based ammonia synthesis catalyst via the melting of iron
oxide with other compounds, such as Al.sub.2O.sub.3, K.sub.2O, CaO,
MgO, and SiO.sub.2, and grinding into granules. U.S. Pat. No.
5,846,507 describes an iron composition having a non-stoichiometric
oxide content and additional promoters, prepared by melting.
Suggestions of reducing the processing pressures have been made,
but have not been achieved economically.
[0013] Non-ferrous metal oxides may also be incorporated into the
granules. For example, U.S. Pat. No. 6,716,791 describes the
addition of cobalt and titanium oxides in a 0.1-3.0% weight ratio
as additional promoters to aluminum, potassium, calcium, and
magnesium. U.S. Pat. No. 3,653,831 describes the addition of
platinum to improve reaction efficiency, however given the expense
of platinum this may not be feasible at large scales. Other
promoters, such as cerium described in U.S. Pat. No. 3,992,328 have
also been shown to increase activity. Other improvements include
alternative catalysts, such as those described in U.S. Pat. Nos.
4,163,775 and 4,179,407. These supported catalysts include
ruthenium, rhodium, lanthanides and alloys.
[0014] Ideally, highly active ammonia catalysts can be used without
significant changes to the many existing ammonia plants that exist
today; the best candidates would be a "drop in" solution for
existing manufacturers. Retrofit and reconstruction of these plants
could be costly should there be a need to change design based on
catalyst properties, such as space velocity. The best candidate
catalyst would exhibit increased activity, have similar basic
properties as compared to existing catalysts, and reduce operating
costs. Non-ferrous catalysts in the above referenced prior art do
not overcome all of these constraints because 1) catalyst cost
increases more than catalyst efficiency, 2) the catalyst may not
have the same properties that allow for seamless operation in
existing ammonia production plants, or 3) the catalyst may have
high activity but do not meet long term durability
requirements.
SUMMARY
[0015] The invention described herein comprises the synthesis of
ammonia by providing core-shell iron/iron oxide nanoparticles on
ferrous catalysts to improve catalytic activity while maintaining
durability. In various embodiments herein, systems and methods for
the synthesis of ammonia are disclosed that are capable of being
used in both traditional and new ammonia reactor bed designs. The
function of the nano-size catalyst particles is improved by
dispersing or separating the particles using a support material,
thereby reducing or eliminating sintering of adjacent particles.
The result are systems and methods that can operate at much lower
pressures than the Haber-Bosch process and that can maintain
catalysis efficiency over time.
[0016] In at least one embodiment of the present invention, methods
of synthesizing ammonia are provided comprising reacting a supply
of nitrogen gas and hydrogen gas in the presence of nano-sized
metal catalyst particles disposed on a support material that is
configured to disperse the catalyst particles, wherein the reaction
proceeds at a pressure less than about 500 atm., preferably less
than about 200 atm., and more preferably less than about 100
atm.
[0017] In certain embodiments and applications, the reaction
proceeds cost effectively at pressures less than about 10 atm. In
certain embodiments of the inventive methods, at least a portion of
the nano-sized metal catalyst particles are selected from the group
consisting of iron, cobalt, ruthenium, alloys thereof, and mixtures
thereof. In certain embodiments, at least a portion of the
nano-sized metal catalyst particles comprise a metal core and an
oxide shell. In certain embodiments, the support material comprises
a porous structure. In certain embodiments, the support material
comprises a matrix, tubes, granules, a honeycomb, or the like. In
certain embodiments, the support material comprises magnetite or
other ferrous materials, silicon nitride, silicon carbide, silicon
dioxide, aluminum oxide, and/or cordierite, as examples. In certain
embodiments, the support material is configured to separate the
catalyst nano-particles. In certain embodiments, the support
material further comprises promoter molecules located adjacent the
surface of the nano-sized metal catalyst particles. In certain
embodiments, at least a portion of the promoter molecules comprise
one or more of the elements selected from the group consisting of
Groups 1, 2, 6, 9, 13, 14 and the lanthanide series on the periodic
table, including but not limited to aluminum, potassium, calcium,
magnesium, and/or silicon. It should also be recognized that
oxides, including core-shell oxides, of promoter material are also
contemplated for promoting ammonia synthesis. In one embodiment, at
least some portion of the promoter comprises nano-scale material to
further enhance interaction between the promoter particle and the
nano-catalyst. Preferably, the promoter particle size is about 100
nanometers or smaller, although large nanoscale particles are also
suitable for enhanced promotion. In certain embodiments, the
nanosized metal catalyst particles are disposed in a bed, with or
without the support material.
[0018] In at least one embodiment of the present invention, an
ammonia synthesis reactor is provided, with nano-sized metal
catalyst particles disposed within the reactor, wherein the
catalyst particles may be disposed on a support material that is
configured to disperse the catalyst particles. In certain
embodiments of the reactor, at least a portion of the nano-sized
metal catalyst particles are selected from the group consisting of
iron, cobalt, ruthenium, alloys thereof, and mixtures thereof. In
certain embodiments, at least a portion of the nano-sized metal
catalyst particles comprise a metal core and an oxide shell. In
certain embodiments, the support material comprises a porous
structure. In certain embodiments, the support material comprises a
matrix, tubes, granules, a honeycomb, or the like. In certain
embodiments, the support material comprises magnetite or other
ferrous materials, silicon nitride, silicon carbide, silicon
dioxide, aluminum oxide, or cordierite, by way of example. In
certain embodiments, the support material is configured to separate
the catalyst particles.
[0019] The reactor further comprises at least one inlet for
providing hydrogen gas and nitrogen gas to the nano-sized metal
catalyst particles and at least one outlet for removing ammonia gas
generated in the presence of the nano-sized metal catalyst
particles. The reactor is configured to operate at a pressure less
than about 500 atm., preferably less than about 200 atm., and more
preferably less than about 100 atm. In certain embodiments, the
reactor is a plug flow reactor, a packed bed reactor, an adiabatic
reactor, or an isothermal reactor. In certain embodiments, the
nano-sized metal catalyst particles are disposed in a packed bed
within the reactor. In certain embodiments, the support material
further comprises promoter molecules located adjacent the surface
of the nano-sized metal catalyst particles. In certain embodiments,
at least a portion of the promoter molecules are selected from the
group consisting of aluminum, potassium, calcium, magnesium, and
silicon.
[0020] In at least one embodiment of the present invention, a
NO.sub.x remediation system is provided that comprises a hydrogen
gas supply and a nitrogen gas supply. The system further comprises
a reactor in fluid communication with the hydrogen gas supply and
the nitrogen gas supply comprising nano-sized metal catalyst
particles, wherein the nano-sized metal catalyst particles are
disposed on a support material that is configured to disperse the
catalyst particles, and wherein the reactor is configured to
generate ammonia gas at a pressure less than about 500 atm.,
preferably less than about 200 atm., and more preferably less than
about 100 atm. The system further comprises an exhaust supply
configured to provide a gas stream comprising NO.sub.x emissions
and a selective catalytic reduction (SCR) system in fluid
communication with the reactor and the exhaust supply, wherein the
SCR system is configured to facilitate the reaction of the ammonia
gas and the NO.sub.x emissions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a schematic of a reactor comprising a bed of
nano-sized metal catalyst particles.
[0022] FIG. 2 is an SEM of nano-sized ferrous catalyst particles
with an oxide layer.
[0023] The features mentioned above in the summary, along with
other features of the inventions disclosed herein, are described
below with reference to the drawings. The illustrated embodiments
in the figures listed below are intended to illustrate, but not to
limit, the inventions.
DETAILED DESCRIPTION
[0024] In various embodiments, systems and methods of ammonia
production are provided. Referring first FIG. 1, an example system
10 is shown comprising at least one reactor 12. In preferred
embodiments, the reactor 12 comprises a plug flow reactor. One or
more alternative reactors can be used instead of or in conjunction
with a plug flow reactor, for example, packed bed, adiabatic,
and/or iso-thermal reactors. As an example, one or more reactors
can be connected in series.
[0025] N.sub.2 gas 3 and H.sub.2 gas 5 are introduced into the at
least one reactor 12. The gases pass through a bed 14 of supported
nano-sized metal catalyst particles disposed within the at least
one reactor 12. A stream of NH.sub.3 gas 17 exits the at least one
reactor 12. In certain embodiments, the stream of NH.sub.3 gas 17
can be collected in a reservoir of water (not shown) after suitable
cooling, to take advantage of the extensive solubility of ammonia
in water.
[0026] In certain embodiments, the supported nano-sized metal
catalyst particles are disposed on the walls of the at least one
reactor 14. In certain embodiments, the supported nano-sized metal
catalyst particles are disposed within or on channels in the
reactor 14. In certain embodiments, the supported nano-sized metal
catalyst particles are piled in a packed bed configuration within
the reactor. Alternative configurations for arranging the supported
particles within the at least one reactor 14 can also be used. As
used herein, "bed" 14 is used to refer to any suitable arrangement
of supported nano-sized metal catalyst particles within the at
least one reactor 14 and is not intended to be limited to a packed
bed configuration.
[0027] The N.sub.2 gas 3 and H.sub.2 gas 5 are introduced into the
at least one reactor 12 at a pressure below about 200 atm,
preferably below about 100 atm, and more preferably between about 1
atm and 20 atm (e.g., between about 3 and 10 atm). Additional
examples of pressures which have been demonstrated to be suitable
for ammonia synthesis are about 4 atm and about 7 atm. In certain
embodiments, the gases are heated to temperatures between about
200.degree. C. and 600.degree. C., and preferably between about
400.degree. C. and 450.degree. C. In certain embodiments, the gases
3, 5 are heated before entering the bed 14. In certain embodiments,
the gases are heated inside the bed 14. In certain embodiments, the
molar ratio of N.sub.2 gas 3 to H.sub.2 gas 5 introduced into the
reactor 12 is about 1:10, 1:5, 1:2, or 1:1. Preferably, the molar
ratio of N.sub.2 gas 3 to H.sub.2 gas 5 is about 1:3.
[0028] In certain embodiments, the N.sub.2 gas 3 can be removed
from compressed air using an oxygen exclusion membrane. It is
desirable to remove oxygen gas from the N.sub.2 gas 3 feed because
oxygen can reduce the efficiency of the reactions described above
(e.g., by a side reaction to form water). In certain embodiments,
the H.sub.2 gas 5 can be obtained from reformed natural gas. In
preferred embodiments, the H.sub.2 gas 5 is provided by
electrolysis of water.
[0029] Nano-sized metal catalyst particles as used herein refer to
metal nanoparticles, metal alloy nanoparticles, nanoparticles
having a metal or metal alloy core and an oxide shell, or mixtures
thereof. The particles are preferably generally spherical, as shown
in FIG. 2. Preferably the individual nanoparticles have a diameter
less than about 50 nm, more preferably between about 15 and 25 nm,
and most preferably between about 1 and 15 nm. These particles can
be produced by vapor condensation in a vacuum chamber. A preferable
vapor condensation process yielding highly uniform metal
nanoparticles is described in U.S. Pat. No. 7,282,167 to Carpenter,
which is hereby expressly incorporated by reference in its
entirety.
[0030] The nano-sized metal catalyst particles are disposed on a
support material configured to disperse or separate the particles.
It was surprisingly discovered that a reactor 12 comprising a
packed bed of unsupported nano-sized metal catalyst particles
nanoparticles tended to lose catalysis efficiency over time. At
high temperatures, the nanoparticles sintered with adjacent
nanoparticles, reducing the overall area available for reaction on
the particles' surfaces. The reduction of surface area due to
temperature-induced sintering resulted in a loss of catalytic
activity over time.
[0031] Experiments confirmed that sintering could be minimized and
catalysis efficiency could be maintained by disposing the
nano-sized metal catalyst particles on a support material, thereby
dispersing or separating adjacent nanoparticles. Suitable
structures for the support material include, but are not limited
to, silicon nitride, silicon carbide, silicon dioxide (silica), and
aluminum oxide (alumina) matrices, granules, or tubes. An example
of a suitable support material is silica or alumina granules about
30 microns in diameter or Si.sub.3N.sub.4 microtubes. Another
example of a suitable support material is a cordierite honeycomb.
In certain embodiments, a porous material (e.g., porous granules)
can be used.
[0032] In certain embodiments, the support material can further
comprise promoter molecules disposed on or near the surface of the
support material that contact, and in certain embodiments, are
fused to the outer surface of the catalyst particles. Examples of
suitable promoter molecules include, but are not limited to,
aluminum, potassium, calcium, magnesium, and silicon. Promoter
molecules can advantageously increase the catalytic activity of
nitrogen absorption and reaction with hydrogen during ammonia
synthesis by facilitating electron transfer.
[0033] In preferred embodiments, the nano-sized metal catalyst
particles comprise nano-sized ferrous (iron or iron alloy) catalyst
particles. Other suitable metals can include cobalt, ruthenium, and
alloys thereof. Mixtures of suitable metal catalyst particles can
also be used in certain embodiments. For example, certain
embodiments can comprise a mixture of nano-sized iron and cobalt
catalyst particles, a mixture of cobalt and ruthenium catalyst
particles, a mixture of iron and ruthenium catalyst particles, or a
mixture of iron, cobalt, and ruthenium catalyst particles.
[0034] As described above, in certain embodiments, at least a
portion of the nano-sized catalyst particles have a metal or metal
oxide core and an oxide shell. In preferred embodiments, the
nano-sized ferrous catalyst particles comprise an iron or iron
alloy core and an oxide shell. An oxide shell can advantageously
provide means for stabilizing the metal or metal oxide core.
Preferably, the oxide shell has a shell thickness between about 0.5
and 25 nm, more preferably between about 0.5 and 10 nm, and most
preferably between about 0.5 and 1.5 nm. Examples of nano-sized
ferrous catalyst particles comprising an oxide coating thickness
between about 0.5 and 1.5 nm are shown in FIG. 2. These particles
can be produced by vapor condensation in a vacuum chamber, and the
oxide layer thickness can be controlled by introduction of air or
oxygen into the chamber as the particles are formed.
[0035] In certain embodiments, NO.sub.x remediation systems are
provided. These systems can be integrated, for example, with
internal combustion engines. In at least one embodiment, a vehicle
comprising an on-board NO.sub.x remediation system is provided. The
NO.sub.x remediation systems disclosed herein advantageously reduce
or eliminate NO.sub.x emissions from internal combustion engines by
introducing ammonia or urea (which is produced by reaction of
ammonia and carbon dioxide) into the exhaust stream.
[0036] An example NO.sub.x remediation system comprises a reactor
as described above. H.sub.2 and N.sub.2 gases are passed to the
reactor, which comprises a bed of supported nano-sized metal
catalyst particles. As described above, H.sub.2 gas can be produced
by an electrolyzer system. In certain embodiments in which a
NO.sub.x remediation system is onboard a vehicle, the electrolyzer
is powered by the vehicle's battery and/or engine alternator.
N.sub.2 gas can be obtained by processing compressed air (e.g.,
from the brake system) through an oxygen exclusion filter. A stream
of NH.sub.3 is produced by the reactor.
[0037] The NH.sub.3 stream is combined with exhaust from the
internal combustion engine and directed into a selective catalytic
reduction (SCR) catalyst and filter. Preferably, the SCR catalyst
comprises supported zeolites and nano-sized metal catalyst
particles such as nano-sized vanadium or vanadium alloy catalyst
particles. In certain embodiments, the SCR catalyst operates at a
temperature between about 200.degree. C. and 800.degree. C. and
more preferably between about 400.degree. C. and 600.degree. C.
[0038] To determine how much NH.sub.3 is required for NO.sub.x
reduction, in certain embodiments there is provided an electronic
controller that uses the engine RPM and manifold pressure along
with data from a NO.sub.x sensor on the exhaust of the SCR catalyst
to increase or decrease the amount of current to the electrolyzer
controlling the hydrogen input to the low pressure ammonia
generator. The larger the amount of ammonia generated, the greater
the overall NO.sub.x reduction in the exhaust stream.
EXAMPLE 1
[0039] Synthesis of NH.sub.3 was performed over a bed of nano-sized
ferrous catalyst particles, manufactured using the vapor
condensation process described in U.S. Pat. No. 7,282,167 to
Carpenter, and supported with silicon nitride tubes. The nano-sized
ferrous catalyst particles comprised an oxide coating between about
0.5 and 1.5 nanometer thickness. The particles had average
diameters from 15 to 25 nanometers.
[0040] The supported nano-sized ferrous catalyst particles were
piled in a packed bed configuration within a plug flow reactor
system. Hydrogen and nitrogen gases were introduced into to plug
flow reactor system as described above at pressures between about
10 atm and 20 atm and a temperature of about 450.degree. C.
[0041] Ammonia was detected and alkalinity tests conducted with pH
paper yielded a pH of 11, typical of ammoniacal solutions in water.
The experiment established the production of ammonia from hydrogen
and nitrogen at vastly reduced pressures, as compared to industrial
processes for ammonia synthesis, by a factor of 15 to 30. The
kinetic rate of the adsorption and disassociation of the nitrogen
and hydrogen was increased by as much as three orders of
magnitude.
EXAMPLE 2
[0042] Synthesis of ammonia was performed over a bed of nano-sized
ferrous catalyst particles, manufactured using the vapor
condensation process described in U.S. Pat. No. 7,282,167 to
Carpenter, and supported on SG9801R promoted iron from BASF. The
nano-sized ferrous catalyst particles comprised an oxide coating
between about 0.5 and 1.5 nanometer thickness rendering them air
safe for mixing. The particles had an average diameter from 15 to
30 nanometers. The nano-sized iron and iron support particles were
blended for 2 minutes at 20G with an acoustic mixer to distribute
the nano-sized particles onto the support iron particles.
[0043] Supported nano-sized ferrous catalyst particles were piled
in a packed bed configuration within a plug flow reactor system.
The supported nano-sized iron particles were reduced in a stream of
hydrogen gas at 300.degree. C. Hydrogen and nitrogen gasses were
introduced into the plug flow reactor system as described above at
pressures between about 5 atm and 10 atm and a temperature of
350.degree. C. to 450.degree. C.
[0044] Ammonia production was quantified by bubbling the mixture of
gasses flowing from the reactor through a measured amount of dilute
sulfuric acid containing a phenolphthalein indicator and recording
the time required to reach a pink end point. The experiment
established the production of ammonia from hydrogen and nitrogen at
vastly reduced pressures, as compared to industrial processes for
ammonia synthesis, by a factor of 15 to 30. The kinetic rate of the
adsorption and disassociation of the nitrogen and hydrogen was
increased by as much as three orders of magnitude compared to
conventional iron catalysts.
[0045] The foregoing description is that of preferred embodiments
having certain features, aspects, and advantages. Various changes
and modifications also may be made to the above-described
embodiments without departing from the spirit and scope of the
inventions. For example, it is contemplated that nano-sized
materials made from processes other than the ones described in U.S.
Pat. No. 7,282,167 to Carpenter would still achieve some or all of
the advantages described above or inherent herein, including cost
effective ammonia synthesis. It is also contemplated that pressures
well below prior art conventional processing of 200 atmospheres can
be achieved using the inventive process herein.
* * * * *