U.S. patent application number 13/652669 was filed with the patent office on 2013-10-24 for phosphorus modified zeolite catalysts.
The applicant listed for this patent is TILMAN W. BEUTEL, MICHEL DAAGE, KARLTON J. HICKEY, STEPHEN J. McCARTHY, BEAU WALDRUP. Invention is credited to TILMAN W. BEUTEL, MICHEL DAAGE, KARLTON J. HICKEY, STEPHEN J. McCARTHY, BEAU WALDRUP.
Application Number | 20130281753 13/652669 |
Document ID | / |
Family ID | 47089187 |
Filed Date | 2013-10-24 |
United States Patent
Application |
20130281753 |
Kind Code |
A1 |
McCARTHY; STEPHEN J. ; et
al. |
October 24, 2013 |
PHOSPHORUS MODIFIED ZEOLITE CATALYSTS
Abstract
An unbound catalyst composition comprises a zeolite and
phosphorus in an amount between about 0.01 wt % and about 3 wt % of
the total catalyst composition. The catalyst composition, as
calcined at .about.1000.degree. F. (.about.538.degree. C.) for at
least .about.3 hours, can exhibit (i) 2,2-dimethylbutane
diffusivity >1.5.times.10.sup.-2 sec.sup.-1 when measured at
.about.120.degree. C. and .about.60 torr (.about.8 kPa), (ii) coke
deactivation rate constant <.about.0.15, and (iii) alpha value
at least 10, and further exhibiting at least one of: (a)
mesoporosity >0.2 ml/g; (b) microporous surface area at least
375 m.sup.2/g; and (c) coke deactivation rate constant <0.05
after steaming in .about.100% steam for .about.96 hours at
.about.1000.degree. F. (.about.538.degree. C.).
Inventors: |
McCARTHY; STEPHEN J.;
(Center Valley, PA) ; BEUTEL; TILMAN W.; (Neshanic
Station, NJ) ; DAAGE; MICHEL; (Hellertown, PA)
; HICKEY; KARLTON J.; (Boothwyn, PA) ; WALDRUP;
BEAU; (Luberton, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
McCARTHY; STEPHEN J.
BEUTEL; TILMAN W.
DAAGE; MICHEL
HICKEY; KARLTON J.
WALDRUP; BEAU |
Center Valley
Neshanic Station
Hellertown
Boothwyn
Luberton |
PA
NJ
PA
PA
TX |
US
US
US
US
US |
|
|
Family ID: |
47089187 |
Appl. No.: |
13/652669 |
Filed: |
October 16, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61548044 |
Oct 17, 2011 |
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61548052 |
Oct 17, 2011 |
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61548038 |
Oct 17, 2011 |
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61548015 |
Oct 17, 2011 |
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61548057 |
Oct 17, 2011 |
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61548064 |
Oct 17, 2011 |
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Current U.S.
Class: |
585/466 ; 502/60;
502/77 |
Current CPC
Class: |
B01J 2229/37 20130101;
B01J 35/1061 20130101; B01J 37/28 20130101; C10G 2400/02 20130101;
B01J 29/00 20130101; B01J 35/1019 20130101; B01J 37/0009 20130101;
B82Y 40/00 20130101; C07C 1/24 20130101; C07C 1/20 20130101; B01J
2229/186 20130101; Y02P 30/20 20151101; C10G 3/49 20130101; B01J
35/0026 20130101; B01J 35/1042 20130101; B01J 35/1038 20130101;
B01J 2229/42 20130101; B01J 37/0201 20130101; B01J 37/04 20130101;
C10G 2400/04 20130101; Y02P 20/10 20151101; B01J 29/40 20130101;
B01J 35/1085 20130101; B82Y 30/00 20130101; B01J 21/04 20130101;
B01J 35/002 20130101; B01J 35/1014 20130101; B01J 37/06 20130101;
C07C 2/864 20130101; B01J 29/83 20130101; B01J 35/1004 20130101;
C07C 1/22 20130101; C01B 39/54 20130101; B01J 2229/36 20130101;
C07C 41/09 20130101; C07C 41/09 20130101; C07C 43/043 20130101 |
Class at
Publication: |
585/466 ; 502/77;
502/60 |
International
Class: |
B01J 29/40 20060101
B01J029/40; C07C 2/86 20060101 C07C002/86 |
Claims
1. An unbound catalyst composition comprising a zeolite and
phosphorus in an amount between about 0.01 wt % and about 3 wt % of
the total catalyst composition, wherein the unbound catalyst, as
calcined at a temperature of at least about 1000.degree. F. (about
538.degree. C.) for at least about 3 hours, exhibits (i) a
diffusivity for 2,2-dimethylbutane of greater than
1.5.times.10.sup.-2 sec.sup.-1 when measured at a temperature of
about 120.degree. C. and a 2,2-dimethylbutane pressure of about 60
torr (about 8 kPa), (ii) a coke deactivation rate constant less
than about 0.15, and (iii) an alpha value of at least 10, and
wherein the unbound catalyst composition further exhibits at least
one of the following properties: (a) a mesoporosity of greater than
0.2 ml/g; (b) a microporous surface area of at least 375 m.sup.2/g;
and (c) a coke deactivation rate constant less than 0.05 after
steaming in approximately 100% steam for about 96 hours at about
1000.degree. F. (about 538.degree. C.).
2. The catalyst composition of claim 1, wherein the alpha value is
at least 20.
3. The catalyst composition of claim 1, wherein the alpha value is
at least 50.
4. The catalyst composition of claim 1, wherein the mesoporosity is
greater than 0.3 ml/g.
5. The catalyst composition of claim 1, wherein the microporous
surface area is at least 380 m.sup.2/g.
6. The catalyst composition of claim 1, wherein the
2,2-dimethylbutane diffusivity is at least 1.7.times.10.sup.-2
sec.sup.-1, when measured at a temperature of about 120.degree. C.
and a 2,2-dimethylbutane pressure of about 60 torr (about 8
kPa).
7. The catalyst composition of claim 1, wherein the
2,2-dimethylbutane diffusivity is at least 2.times.10.sup.-2
sec.sup.-1, when measured at a temperature of about 120.degree. C.
and a 2,2-dimethylbutane pressure of about 60 torr (about 8
kPa).
8. The catalyst composition of claim 1, wherein the coke
deactivation rate constant is less than or equal to 0.04 after
steaming in approximately 100% steam for about 96 hours at about
1000.degree. F. (about 538.degree. C.).
9. The catalyst composition of claim 1, wherein the composition has
at least two of said properties (a) to (c).
10. The catalyst composition of claim 1, wherein said zeolite has a
constraint index from about 1 to about 12.
11. The catalyst composition of claim 1, wherein said zeolite
comprises ZSM-5.
12. The catalyst composition of claim 1, wherein a silica to
alumina molar ratio of zeolite is from about 40 to about 200.
13. The catalyst composition of claim 1, wherein the phosphorus is
present in an amount between about 0.05 wt % and about 2 wt % of
the total catalyst composition.
14. A process for organic compound conversion employing contacting
a feedstock with the catalyst composition of claim 13 under organic
compound conversion conditions.
15. The process of claim 14, wherein said organic compound
conversion comprises the conversion of methanol to hydrocarbons
boiling in the gasoline boiling range.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/548,044, filed on Oct. 17, 2011, the entire
contents of which are hereby incorporated by reference herein.
[0002] This application also claims the benefit of related U.S.
Provisional Application Nos. 61/548,015, 61/548,038, 61/548,052,
61/548,057, and 61/548,064, each filed on Oct. 17, 2011, the entire
contents of each of which are hereby also incorporated by reference
herein. This application is also related to five other co-pending
U.S. utility applications, each filed on even date herewith and
claiming the benefit to the aforementioned provisional patent
applications, and which are entitled "Process for Producing
Phosphorus Modified Zeolite Catalysts", "Process for Producing
Phosphorus Modified Zeolite Catalysts", "Phosphorus Modified
Zeolite Catalysts", "Phosphorus Modified Zeolite Catalysts", and
"Selective Dehydration of Alcohols to Dialkyl Ethers",
respectively, the entire contents of each of which utility patents
are hereby further incorporated by reference herein.
FIELD OF THE INVENTION
[0003] This disclosure relates to phosphorus modified zeolite
catalysts and their use in organic conversion reactions, such as
the conversion of methanol to gasoline and diesel boiling range
hydrocarbons.
BACKGROUND OF THE INVENTION
[0004] Phosphorus modification is a known method of improving the
performance of zeolite catalysts for a variety of chemical
processes including, for example, the conversion of methanol to
hydrocarbons and the methylation of toluene to produce xylenes. For
example, U.S. Pat. Nos. 4,590,321 and 4,665,251 disclose a process
for producing aromatic hydrocarbons by contacting one or more
non-aromatic compounds, such as propane, propylene, or methanol,
with a catalyst containing a zeolite, such as ZSM-5, together with
a binder or matrix material resistant to the temperature and other
conditions employed in the process. The zeolite is modified with
phosphorus oxide by impregnating the zeolite with a source of
phosphate ions, such as an aqueous solution of an ammonium
phosphate, followed by calcination. The phosphorus oxide
modification is said to render the zeolite more active and/or
benzene selective in the aromatization reaction.
[0005] U.S. Pat. Nos. 6,423,879 and 6,504,072 disclose a process
for the selective production of para-xylene which comprises
reacting toluene with methanol in the presence of a catalyst
comprising a porous crystalline material having a Diffusion
Parameter for 2,2 dimethylbutane of about 0.1-15 sec.sup.-1 when
measured at a temperature of 120.degree. C. and a 2,2
dimethylbutane pressure of 60 torr (8 kPa). The porous crystalline
material is preferably a medium-pore zeolite, particularly ZSM-5,
which has been severely steamed at a temperature of at least
950.degree. C. and which has been combined with about 0.05 to about
20 wt % of at least one oxide modifier, preferably an oxide of
phosphorus, to control reduction of the micropore volume of the
material during the steaming step. The porous crystalline material
is normally combined with a binder or matrix material, preferably
silica or a kaolin clay.
[0006] U.S. Pat. No. 7,304,194 discloses a process for the
hydrothermal treatment of a phosphorus-modified ZSM-5 catalyst. In
the process, ZSM-5 having a silica/alumina mole ratio of at least
about 250 and a phosphorus content of from at least about 0.08 g
P/g zeolite to about 0.15 g P/g zeolite is calcined at a
temperature of at least 300.degree. C. and then contacted with
steam at a temperature of from about 150.degree. C. about
250.degree. C. The steamed, phosphorus modified zeolite is said to
exhibit improved para-selectivity and methanol selectivity when
used as a catalyst in toluene methylation reactions. The steamed,
phosphorus modified zeolite may be used as a catalyst in unbound
form or in combination with a binder material, such as alumina,
clay, and silica.
[0007] In addition, U.S. Pat. No. 7,285,511 discloses a process of
modifying a zeolite catalyst to increase its para-xylene
selectivity in toluene methylation reactions, wherein the method
comprises forming a slurry consisting essentially of a binder-free
ZSM-5-type zeolite having a SiO.sub.2/Al.sub.2O.sub.3 mole ratio of
from about 250 to about 1000 and an aqueous solution of a
phosphorus-containing compound; and removing water from the slurry
to provide a non-steamed, phosphorus treated ZSM-5 zeolite having a
phosphorus content of from 0.04 g P/g zeolite or more and a pore
volume of from 0.2 ml/g or less. The resultant phosphorus treated
ZSM-5 can be used as a toluene methylation catalyst either in
unbound form or may be composited with a binder, such as alumina,
clay, or silica.
[0008] In certain organic conversion processes, such as the
conversion of methanol to gasoline and diesel boiling range
hydrocarbons, the hydrothermal stability of the catalyst is of
vital importance, since steam dealumination of a zeolite is
irreversible and can drastically reduce catalyst life. However,
although phosphorus modification is effective in enhancing zeolite
hydrothermal stability, it has now been found that binders added to
improve cohesive strength of the final catalyst, can negatively
impact the utility of phosphorus modification. Thus, with certain
binders, especially alumina-containing binders, the phosphorus can
preferentially migrate to the binder alumina and can thus increase
the coke selectivity of the catalyst. According to the invention,
an unbound phosphorus modified zeolite catalyst composition has now
been identified that can tend to exhibit higher steam stability and
lower coke deactivation rates in methanol conversion reactions than
other phosphorus modified compositions. The present catalyst
composition can therefore be particularly attractive for use in the
conversion of methanol to gasoline and diesel boiling range
hydrocarbons and/or in other processes where high temperature steam
is present.
SUMMARY
[0009] In one aspect, the invention resides in an unbound catalyst
composition comprising a zeolite and phosphorus in an amount
between about 0.1 and about 3 wt % of the total catalyst
composition, the composition having an alpha value of at least 20
and at least one, and preferably at least two, of the following
properties:
[0010] (a) a mesoporosity of greater than 0.2 ml/g;
[0011] (b) a microporous surface area of at least 375
m.sup.2/g;
[0012] (c) a diffusivity for 2,2-dimethylbutane of greater than
1.times.10.sup.-2 sec.sup.-1 when measured at a temperature of
.about.120.degree. C. and a 2,2-dimethylbutane pressure of
.about.60 torr (.about.8 kPa); and
[0013] (d) a coke deactivation rate constant less than or equal to
0.06 after steaming in .about.100% steam for .about.96 hours at
.about.1000.degree. F. (.about.538.degree. C.).
[0014] Conveniently, the catalyst composition can have an alpha
value of at least 40, such as at least 75.
[0015] Conveniently, the catalyst composition can have a
mesoporosity of greater than 0.3 ml/g and a microporous surface
area of at least 380 m.sup.2/g.
[0016] In one embodiment, the catalyst composition can have a
diffusivity for 2,2-dimethylbutane of greater than
1.25.times.10.sup.-2 sec.sup.-1, such as greater than
1.5.times.10.sup.-2 sec.sup.-1, when measured at a temperature of
.about.120.degree. C. and a 2,2-dimethylbutane pressure of
.about.60 torr (.about.8 kPa).
[0017] Typically, the catalyst composition can have a coke
deactivation rate constant less than or equal to 0.05.
[0018] In one embodiment, the zeolite of the catalyst composition
can have a constraint index of about 1 to about 12. Conveniently,
the zeolite can have a silica to alumina molar ratio of zeolite
from about 40 to about 200 and can generally comprise or be
ZSM-5.
[0019] In one embodiment, the catalyst composition can comprise
phosphorus in an amount between about 0.01 and about 2 wt % of the
total catalyst composition.
[0020] In a further aspect, the invention can reside in use of the
unbound catalyst composition described herein in organic conversion
reactions, such as the conversion of methanol to hydrocarbons
boiling in the gasoline boiling range.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a graph comparing the alpha values of the calcined
catalyst extrudates of Examples 1-6.
[0022] FIG. 2 is a graph comparing the alpha values of the calcined
catalyst extrudates of Examples 1-6 after steaming at
.about.1000.degree. F. (.about.538.degree. C.) in .about.100% steam
for .about.96 hours.
[0023] FIG. 3 is a graph comparing the alpha, alpha zero and coke
deactivation rate constant values of the calcined catalyst
extrudates of Examples 4-6.
[0024] FIG. 4 is a graph comparing the alpha, alpha zero and coke
deactivation rate constant values of the calcined catalyst
extrudates of Examples 4-6 after steaming at .about.1000.degree. F.
(.about.538.degree. C.) in .about.100% steam for .about.96
hours.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] Described herein is an unbound phosphorus-stabilized zeolite
catalyst composition and its use in a variety of organic conversion
reactions, particularly, but not exclusively, in the conversion of
methanol to hydrocarbons boiling in the gasoline boiling range. In
some cases, the present catalyst composition can alternatively be
referred to as being self-bound. The terms "unbound" and
"self-bound" are intended to be synonymous and mean that the
present catalyst composition can be advantageously free of any of
the inorganic oxide binders, such as alumina and/or silica,
frequently combined with zeolite catalysts to enhance their
physical properties.
[0026] The zeolite employed in the present catalyst composition can
generally comprise at least one medium pore aluminosilicate zeolite
having a Constraint Index of 1-12 (as defined in U.S. Pat. No.
4,016,218). Suitable zeolites can include, but are not limited to,
ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-48, and the
like, and combinations thereof. ZSM-5 is described in detail in
U.S. Pat. Nos. 3,702,886 and RE 29,948. ZSM-11 is described in
detail in U.S. Pat. No. 3,709,979. ZSM-12 is described in U.S. Pat.
No. 3,832,449. ZSM-22 is described in U.S. Pat. No. 4,556,477.
ZSM-23 is described in U.S. Pat. No. 4,076,842. ZSM-35 is described
in U.S. Pat. No. 4,016,245. ZSM-48 is more particularly described
in U.S. Pat. No. 4,234,231. In a preferred embodiment, the zeolite
can comprise or be ZSM-5.
[0027] The chemical composition of the zeolite is not necessarily
critical, although the zeolite can advantageously contain
sufficient aluminum to provide the phosphorus-stabilized zeolite
catalyst with an initial alpha value, before any steaming, of at
least 10, for example of at least 20 or at least 50. Alpha value
can be a measure of the acid activity of a zeolite catalyst, as
compared with a standard silica-alumina catalyst. The alpha test is
described in U.S. Pat. No. 3,354,078; in the Journal of Catalysis,
v. 4, p. 527 (1965); v. 6, p. 278 (1966); and v. 61, p. 395 (1980),
each incorporated herein by reference as to that description. The
experimental conditions of the test used herein include a constant
temperature of -538.degree. C. and a variable flow rate as
described in detail in the Journal of Catalysis, v. 61, p. 395. The
higher alpha values correspond with a more active cracking
catalyst. In certain embodiments, a zeolite having the desired
activity can have a silica to alumina molar ratio from about 40 to
about 200.
[0028] When used in the present catalyst composition, the zeolite
can advantageously be present at least partly in the hydrogen form.
Depending on the conditions used to synthesize the zeolite, this
may require converting the zeolite from, for example, the alkali
(sodium) form. This can readily be achieved by ion exchange to
convert the zeolite to the ammonium form, followed by calcination
in air or an inert atmosphere, e.g., at a temperature from about
400.degree. C. to about 700.degree. C., to convert the ammonium
form to the active hydrogen form.
[0029] To enhance the steam stability of the zeolite without
excessive loss of its initial acid activity, the present catalyst
composition can contain phosphorus in an amount between about 0.01
wt % and about 3 wt %, for example between about 0.05 wt % and
about 2 wt %, elemental phosphorus, by weight of the total catalyst
composition. The phosphorus can be added to the catalyst
composition at any stage during synthesis of the zeolite and/or
formulation of the zeolite into the catalyst composition.
Generally, phosphorus addition can be achieved by spraying and/or
impregnating the catalyst composition (and/or a precursor thereto)
with a solution of a phosphorus compound. Suitable phosphorus
compounds can include, but are not limited to, phosphonic,
phosphinous, phosphorus, and phosphoric acids, salts and esters of
such acids, phosphorous halides, and the like, as well as
combinations thereof. After phosphorus treatment, the catalyst can
generally be calcined, e.g., in air at a temperature from about
400.degree. C. to about 700.degree. C., to convert the phosphorus
to an oxide form.
[0030] The catalyst composition can employ the phosphorus treated
zeolite in its original crystalline form and/or after formulation
into catalyst particles, such as by extrusion. A process for
producing zeolite extrudates in the absence of a binder, e.g., is
disclosed in U.S. Pat. No. 4,582,815, the entire contents of which
are incorporated herein by reference.
[0031] In addition to the alpha value, the phosphorus-stabilized
zeolite catalyst composition employed herein can advantageously
exhibit both (i) a diffusivity for 2,2-dimethylbutane of greater
than 1.5.times.10.sup.-2 sec.sup.-1, for example at least
1.7.times.10.sup.-2 sec.sup.-1 or at least 2.times.10.sup.-2
sec.sup.-1, when measured at a temperature of about 120.degree. C.
and a 2,2-dimethylbutane pressure of about 60 tort (about 8 kPa)
and (ii) a coke deactivation rate constant, as calcined, of less
than 0.2, e.g., less than about 0.15 or less than about 0.12. The
phosphorus-stabilized zeolite catalyst composition employed herein
can additionally or alternately be characterized by at least one,
and preferably at least two or in some embodiments all, of the
following properties: (a) a mesoporosity of greater than 0.2 ml/g,
for example greater than 0.3 ml/g; (b) a microporous surface area
of at least 375 m.sup.2/g, for example at least 380 m.sup.2/g; and
(c) a coke deactivation rate constant less than or equal to 0.06,
for example less than or equal to 0.05, less than 0.05, less than
or equal to 0.04, or less than 0.04, after steaming in .about.100%
steam for about 96 hours at about 1000.degree. F. (about
538.degree. C.). It should be understood by one of ordinary skill
in the art that properties (a) and (b) above, unlike property (c),
are measured before any steaming of the catalyst composition.
[0032] Of these properties, mesoporosity and diffusivity for
2,2-dimethylbutane can be determined by a number of factors,
including, for a given zeolite, crystal size. Microporous surface
area can be determined by the pore size of the zeolite and the
availability of the zeolite pores at the surfaces of the catalyst
particles. Producing a zeolite catalyst with the desired minimum
mesoporosity, microporous surface area, and 2,2-dimethylbutane
diffusivity should be well within the expertise of anyone of
ordinary skill in zeolite chemistry.
[0033] The coke deactivation rate constant can be a measure of the
rate at which the catalyst deactivates when subjected to a routine
alpha test and is defined in the Examples.
[0034] The phosphorus-modified zeolite catalyst described herein
can be particularly useful in any organic conversion process where
the hydrothermal stability of the catalyst is important. Examples
of such processes can include, but are not necessarily limited to,
fluid catalytic cracking of heavy hydrocarbons to gasoline and
diesel boiling range hydrocarbons, methylation and
disproportionation of toluene to produce xylenes, n-paraffin (e.g.,
C.sub.6 and higher) cyclization, conversion of methanol to gasoline
and diesel boiling range hydrocarbons, and the like, and
combinations and/or integrations thereof.
[0035] The invention can additionally or alternately include one or
more of the following embodiments.
Embodiment 1
[0036] An unbound catalyst composition comprising a zeolite and
phosphorus in an amount between about 0.01 wt % and about 3 wt % of
the total catalyst composition, wherein the unbound catalyst, as
calcined at a temperature of at least about 1000.degree. F. (about
538.degree. C.) for at least about 3 hours, exhibits (i) a
diffusivity for 2,2-dimethylbutane of greater than
1.5.times.10.sup.-2 sec.sup.-1 when measured at a temperature of
about 120.degree. C. and a 2,2-dimethylbutane pressure of about 60
torr (about 8 kPa), (ii) a coke deactivation rate constant less
than about 0.15, and (iii) an alpha value of at least 10, and
wherein the unbound catalyst composition further exhibits at least
one of the following properties: (a) a mesoporosity of greater than
0.2 ml/g; (b) a microporous surface area of at least 375 m.sup.2/g;
and (c) a coke deactivation rate constant less than 0.05 after
steaming in approximately 100% steam for about 96 hours at about
1000.degree. F. (about 538.degree. C.).
Embodiment 2
[0037] The catalyst composition of embodiment 1, wherein the as
calcined alpha value is at least 20, e.g., at least 50.
Embodiment 3
[0038] The catalyst composition of any one of the previous
embodiments, wherein the mesoporosity is greater than 0.3 ml/g.
Embodiment 4
[0039] The catalyst composition of any one of the previous
embodiments, wherein the microporous surface area is at least 380
m.sup.2/g.
Embodiment 5
[0040] The catalyst composition of any one of the previous
embodiments, wherein the 2,2-dimethylbutane diffusivity is at least
1.7.times.10.sup.-2 sec.sup.-1, e.g., at least 2.times.10.sup.-2
sec.sup.-1, when measured at a temperature of about 120.degree. C.
and a 2,2-dimethylbutane pressure of about 60 torr (about 8
kPa).
Embodiment 6
[0041] The catalyst composition of any one of the previous
embodiments, wherein the coke deactivation rate constant is less
than 0.04 after steaming in approximately 100% steam for about 96
hours at about 1000.degree. F. (about 538.degree. C.).
Embodiment 7
[0042] The catalyst composition of any one of the previous
embodiments, wherein the composition has at least two of said
properties (a) to (c), e.g., all three of said properties (a) to
(c).
Embodiment 8
[0043] The catalyst composition of any one of the previous
embodiments, The catalyst composition of claim 1, wherein said
zeolite has a constraint index from about 1 to about 12.
Embodiment 9
[0044] The catalyst composition of any one of the previous
embodiments, wherein said zeolite comprises or is ZSM-5.
Embodiment 10
[0045] The catalyst composition of any one of the previous
embodiments, wherein a silica, to alumina molar ratio of zeolite is
from about 40 to about 200.
Embodiment 11
[0046] The catalyst composition of any one of the previous
embodiments, wherein the phosphorus is present in an amount between
about 0.05 wt % and about 2 wt % of the total catalyst
composition.
Embodiment 12
[0047] A process for organic compound conversion employing
contacting a feedstock with the catalyst composition of any one of
the previous embodiments under organic compound conversion
conditions.
Embodiment 13
[0048] The process of embodiment 12, wherein said organic compound
conversion comprises the conversion of methanol to hydrocarbons
boiling in the gasoline boiling range.
[0049] The invention will now be more particularly described with
reference to the following non-limiting Examples and the
accompanying drawings.
EXAMPLES
Examples 1-3
Production of Self-Bound ZSM-5 Catalysts
[0050] ZSM-5 crystal (.about.1.4 kg on a solids basis) was added to
a mixer and dry mulled. Then, approximately 190 grams of deionized
water was added during mulling. After about 10 minutes, .about.28
grams of .about.50 wt % caustic solution mixed with about 450 grams
of deionized water were added to the mixture and mulled for an
additional .about.5 minutes. The mixture was then extruded into
.about. 1/10'' quadralobes. The extrudates were dried overnight
(.about.8-16 hours) at .about.250.degree. F. (.about.121.degree.
C.) and then calcined in nitrogen for .about.3 hours at
.about.1000.degree. F. (.about.538.degree. C.). The extrudates were
then exchanged twice with a 1N solution of ammonium nitrate. The
exchanged crystal was dried overnight at .about.250.degree. F.
(.about.121.degree. C.) and then calcined in air for .about.3 hours
at .about.1000.degree. F. (.about.538.degree. C.). Three different
ZSM-5 crystals were self-bound using the described procedure. These
catalysts were analyzed using nitrogen porosimetry and inductively
coupled plasma (ICP) elemental analysis, and the results are
summarized in Table 1 below.
Examples 4-6
Phosphorus Addition to Self-Bound ZSM-5 Catalysts
[0051] Each of the self-bound catalysts of Examples 1-3 was
impregnated via incipient wetness with .about.1.2 wt % phosphorus
using a solution of phosphoric acid. The impregnated crystals were
then dried overnight (.about.8-16 hours) at .about.250.degree. F.
(.about.121.degree. C.) and then calcined in air for .about.3 hours
at .about.1000.degree. F. (.about.538.degree. C.). The resultant
P-containing catalysts were again analyzed using nitrogen
porosimetry and ICP elemental analysis, and the results are also
summarized in Table 1 below.
Examples 7-42
Steam Deactivation of Self-Bound ZSM5 Catalysts
[0052] The catalysts of Examples 1-6 were steamed in .about.100%
steam for about 96 hours at .about.1000.degree. F.
(.about.538.degree. C.). The resultant steamed catalysts were again
analyzed using nitrogen porosimetry and ICP elemental analysis, and
the results are further summarized in Table 1 below.
Example 13
2,2-Dimethylbutane Sorption
[0053] The hydrocarbon diffusivity, expressed as the inverse of the
characteristic diffusion time, D/r.sup.2, was determined by the
rate of 2,2-dimethylbutane (2,2-DMB) uptake for each of the
catalysts of Examples 1-12. Prior to hydrocarbon adsorption, about
50 mg of the sample was heated in air to .about.500.degree. C.,
e.g., to remove moisture and any hydrocarbon or coke impurities.
For 2,2-DMB adsorption, the sample was cooled to .about.120.degree.
C. after the air calcination step and then exposed to a flow of
.about.60 torr (.about.8 kPa) of 2,2-DMB in nitrogen. Again, the
results are summarized in Table 1.
Example 14
Alpha Testing
[0054] The catalysts of Examples 1-12 were screened for acid
activity with hexane cracking in a routine alpha test at standard
conditions (.about.100 torr, or .about.13 kPa, hexane vapor
pressure in He carrier gas flowing through a reactor held at
.about.1000.degree. F., or .about.538.degree. C.). During the test,
the flow rate was adjusted to achieve a conversion of between about
5% and about 15%. Four data points were taken at .about.4,
.about.1, .about.18, and .about.25 minutes at relatively constant
flow. The Alpha value represented the ratio of the first order rate
constant, at .about.18 minutes, for n-hexane cracking, relative to
a silica-alumina standard.
[0055] The alpha value was determined as follows:
.alpha.=A*ln(1-X)/.tau.
where [0056] A--Reference rate constant [0057] X--Fractional
Conversion [0058] .tau.--Residence Time
[0059] The four Alpha values were then plotted as a function of
time and fitted by an exponential function to determine the rate of
coke deactivation:
.alpha.=.alpha..sub.o*exp(-ct.sup.1/3)
where [0060] .alpha..sub.o--Alpha zero measured at time=0 [0061]
c--Coke deactivation rate constant [0062] t--time, min
[0063] The results of the alpha testing are also summarized in
Table 1 and FIGS. 1-4. From these results, it can be seen that the
initial alpha values of both the phosphorus-free and the
phosphorus-containing catalysts were roughly proportional to the
amount of free aluminum in the catalyst. Free aluminum is defined
herein as the total aluminum minus the phosphorus content.
[0064] It can also be seen that the non-phosphorus stabilized
catalysts of Examples 1-3 exhibited high initial alpha values
(.about.1100, .about.540, and .about.410, respectively) but their
steamed counterparts of Examples 7-9 showed a marked decrease in
alpha values (to .about.7, .about.14, and .about.4,
respectively).
[0065] For the phosphorus stabilized catalysts of Examples 4-6,
although the initial alpha values were slightly lower (.about.700,
.about.200, and .about.160, respectively) than their
phosphorus-free counterparts, the steamed versions of Examples
10-12 exhibited better retention of alpha value (.about.58,
.about.95, and .about.100, respectively) than their steamed
phosphorus-free counterparts.
[0066] From FIGS. 3 and 4, it can be seen that, for the steamed
catalysts of Examples 7-12, the phosphorus-stabilized self-bound
ZSM-5 catalysts with Si/Al.sub.2 ratios of at least 20, a calcined
2,2-DMB diffusivity of at least 10,000 10.sup.-6 sec.sup.-1, and a
mesoporsity of at least 0.2 ml/g exhibited the best combination of
alpha value retention on steaming and low coke deactivation rate.
As shown in FIG. 4, the catalyst of Example 11 exhibited
essentially no coke deactivation.
TABLE-US-00001 TABLE 1 Meso-PV, Alpha Deactivation 2,2-DMB Rate
2,2-DMB Diffusivity Microporous Surface Ex. Si/Al P/Al ml/g Alpha
Constant (mg/g/min.sup.0.5) (10.sup.-6 sec.sup.-1) Area, m.sup.2/g
1 ~14 0 ~0.087 ~1100 ~13 ~601 ~424 2 ~25 0 ~0.340 ~540 ~61 ~13500
~401 3 ~36 0 ~0.049 ~410 ~2 ~19 ~309 4 ~14 ~0.4 ~0.074 ~700 ~0.138
~9 ~376 ~360 5 ~25 ~0.7 ~0.341 ~200 ~0.103 ~74 ~21400 ~396 6 ~36
~1.0 ~0.044 ~160 ~0.049 ~1 ~7 ~253 7 ~14 0 ~0.089 ~7 ~14 ~808 ~320
8 ~25 0 ~0.422 ~14 ~114 ~50500 ~300 9 ~36 0 ~0.048 ~4 ~4 ~70 ~361
10 ~14 ~0.4 ~0.076 ~58 ~0.173 ~9 ~396 ~297 11 ~25 ~0.7 ~0.373 ~95
~0.001 ~69 ~18200 ~283 12 ~36 ~1.0 ~0.038 ~100 ~0.085 ~3 ~26
~322
Example 15
Preparation of P-Modified ZSM-5/Versal-300 Alumina Catalyst
[0067] A mixture of .about.80 wt % of as-synthesized NaZSM-5
zeolite (having a silica to alumina molar ratio of about 50 and
containing the organic directing agent used in its synthesis) was
blended in a muller with .about.20 wt % of Versal.TM.-300 alumina
binder. The blend was extruded and the resultant extrudate sample
was calcined in nitrogen for .about.3 hours at .about.1000.degree.
F. (.about.538.degree. C.) to decompose the organic template. The
calcined extrudate was then exchanged with an ammonium nitrate
solution to convert the zeolite from the sodium to the ammonium
form, whereafter the extrudate was calcined in air for another
.about.3 hours at .about.1000.degree. F. (.about.538.degree. C.) to
convert the zeolite from the ammonium to the hydrogen form. At the
same time, any carbonaceous deposits (e.g., from the decomposition
of the organic template and/or from the ammonium nitrate exchange)
were removed by oxidation. The thus obtained
H-ZSM-5-Al.sub.2O.sub.3 extrudate was then impregnated with
phosphoric acid to a target level of .about.0.96 wt % phosphorus
via aqueous incipient wetness impregnation. The sample was dried
and then calcined in air for another .about.3 hours at
.about.1000.degree. F. (.about.538.degree. C.). The resultant
product was labeled Catalyst A'' and had the properties summarized
in Table 2 below.
Example 16
Preparation of P-Modified Unbound ZSM-5 Catalyst
[0068] A sample of as-synthesized NaZSM-5 zeolite was extruded
without the use of binder. The sample was calcined in nitrogen for
.about.3 hours at .about.1000.degree. F. (.about.538.degree. C.),
exchanged with an ammonium nitrate solution, and calcined in air
for another .about.3 hours at .about.1000.degree. F.
(.about.538.degree. C.). The extrudate was impregnated with
phosphoric acid to a target level of .about.1.2 wt % phosphorus via
aqueous incipient wetness impregnation. The sample was dried and
then calcined for another .about.3 hours at .about.1000.degree. F.
(.about.538.degree. C.). The resultant product was labeled Catalyst
B'' and had the properties summarized in Table 2 below.
Example 17
Preparation of P-Modified Unbound Small Crystal ZSM-5 Catalyst
[0069] A sample of as-synthesized small crystal NaZSM-5 zeolite was
extruded without the use of binder. The sample was calcined in
nitrogen for .about.3 hours at .about.1000.degree. F.
(.about.538.degree. C.), exchanged with an ammonium nitrate
solution, and calcined in air for another .about.3 hours at
.about.1000.degree. F. (.about.538.degree. C.). The extrudate was
impregnated with phosphoric acid to a target level of .about.1.2 wt
% phosphorus via aqueous incipient wetness impregnation. The sample
was dried and then calcined for another .about.3 hours at
.about.1000.degree. F. (.about.538.degree. C.). The resultant
product was labeled Catalyst C'' and had the properties summarized
in Table 2 below.
Example 18
Preparation of P-Modified Silica-Bound ZSM-5 Catalyst
[0070] A mixture of .about.80 wt % as-synthesized small crystal
NaZSM-5 zeolite was extruded with .about.20 wt % Ultrasil.TM.
silica. The sample was calcined in nitrogen for .about.3 hours at
.about.1000.degree. F. (.about.538.degree. C.), exchanged with an
ammonium nitrate solution, and calcined in air for another .about.3
hours at .about.1000.degree. F. (.about.538.degree. C.). The
extrudate was impregnated with phosphoric acid to a target level of
.about.0.96 wt % phosphorus via aqueous incipient wetness
impregnation. The sample was dried and then calcined for another
.about.3 hours at .about.1000.degree. F. (.about.538.degree. C.).
The resultant product was labeled Catalyst D'' and had the
properties summarized in Table 2 below.
Example 19
Preparation of P-Modified Silica-Bound ZSM-5 Catalyst
[0071] A mixture of .about.80 wt % of as-synthesized NaZSM-5
zeolite (having a silica to alumina molar ratio of about 28 and
containing the organic directing agent used in its synthesis) was
blended in a muller with .about.20 wt % of Ultrasil.TM. silica
binder. The blend was extruded and the resultant extrudate sample
was calcined in nitrogen for .about.3 hours at .about.1000.degree.
F. (.about.538.degree. C.). The calcined extrudate was then
exchanged with an ammonium nitrate solution, and then calcined in
air for another .about.3 hours at .about.1000.degree. F.
(.about.538.degree. C.). The extrudate was then impregnated with
phosphoric acid to a target level of .about.0.96 wt % phosphorus
via aqueous incipient wetness impregnation. The sample was dried
and then calcined in air for another .about.3 hours at
.about.1000.degree. F. (.about.538.degree. C.). The resultant
product was labeled Catalyst E and had the properties summarized in
Table 2 below.
TABLE-US-00002 TABLE 2 Binder Binder content, P (wt % based Cat
Si/Al.sub.2 type wt % on zeolite) A'' ~50 Al.sub.2O.sub.3 ~20 ~1.0
B'' ~50 N/A 0 ~1.2 C'' ~50 N/A 0 ~1.2 D'' ~50 SiO.sub.2 ~20 ~1.0 E
~28 SiO.sub.2 ~20 ~1.0
Example 20
Microporous Surface Area
[0072] The MTG reaction generally takes place inside the zeolite
micropores. It can, therefore, be beneficial to improve/maximize
the zeolitic micropore volume in order to achieve maximum MTG
activity. Samples of Catalysts A'', B'', C'', D'', and E from
Examples 15-19 were calcined for .about.6 hours at
.about.1000.degree. F. (.about.538.degree. C.) in air prior to
measurement of the micropore surface are by N.sub.2-BET. The
micropore surface areas were normalized by the zeolite content
present in the extrudates. Preferred catalyst extrudates exhibited
a micropore surface area of at least 375 m.sup.2/g zeolite.
Example 21
Characterizations of Samples from Examples 15-19
[0073] For the samples made according to Examples 15-19 and
detailed in Table 2 above (A'', B'', C'', D'', and E,
respectively), the following tests were conducted. Alpha testing
and coke resistance testing (in order to measure coke deactivation
rate constants) was done according to Example 14, on samples that
were treated by steaming in .about.100% H.sub.2O atmosphere for
.about.96 hours at .about.1000.degree. F. (.about.538.degree. C.).
Coke resistance testing was additionally done for these samples,
however, on as calcined samples (not steamed). Microporous surface
area testing was done according to Example 20, on as calcined
samples. Diffusivity testing for 2,2-dimethylbutane was done
according to Example 13, on samples that were calcined in air for
.about.6 hours at .about.1000.degree. F. (.about.538.degree. C.)
prior to measurement. The results of these characterizations are
shown in Table 3 below.
TABLE-US-00003 TABLE 3 2,2-DMB Alpha Surface Diffus. Coke Deact.
Coke Deact. value (as area (*10.sup.-2 Rate Const. Rate Const.
Catalyst steamed) (m.sup.2/g) sec.sup.-1) (steamed) (as calcined)
A'' 33 385 1.42 0.43 0.30 B'' 103 429 2.14 0.01 0.10 C'' 81 385
2.51 0.02 0.02 D'' 100 409 1.76 0.01 0.03 E 128 386 0.03 0.05
0.22
[0074] While the present invention has been described and
illustrated by reference to particular embodiments, those of
ordinary skill in the art will appreciate that the invention lends
itself to variations not necessarily illustrated herein. For this
reason, then, reference should be made solely to the appended
claims for purposes of determining the true scope of the present
invention.
* * * * *