U.S. patent application number 13/652660 was filed with the patent office on 2013-05-16 for process for producing phosphorus modified zeolite catalysts.
This patent application is currently assigned to EXXONMOBIL RESEARCH AND ENGINEERING COMPANY. The applicant listed for this patent is ExxonMobil Research and Engineering Company. Invention is credited to PATRICIA A. BIELENBERG, GUANG CAO, STEPHEN J. McCARTHY, Beau Waldrup.
Application Number | 20130123557 13/652660 |
Document ID | / |
Family ID | 47089187 |
Filed Date | 2013-05-16 |
United States Patent
Application |
20130123557 |
Kind Code |
A1 |
McCARTHY; STEPHEN J. ; et
al. |
May 16, 2013 |
PROCESS FOR PRODUCING PHOSPHORUS MODIFIED ZEOLITE CATALYSTS
Abstract
In a process for producing a phosphorus-modified zeolite
catalyst, zeolite crystals can be formed into a shaped catalyst
body either in the absence of a separate inorganic oxide binder or
in the presence of a separate inorganic oxide binder that is
substantially free of aluminum. After converting the zeolite
crystals to the hydrogen form and removing any organic directing
agent employed in the synthesis of the zeolite crystals, the shaped
catalyst body can be treated with an aqueous solution of a
phosphorus compound, and the treated catalyst body can be heated to
remove the water and to convert the phosphorus compound to an oxide
form.
Inventors: |
McCARTHY; STEPHEN J.;
(Center Valley, PA) ; CAO; GUANG; (Princeton,
NJ) ; BIELENBERG; PATRICIA A.; (Houston, TX) ;
Waldrup; Beau; (Lumberton, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Research and Engineering Company; |
Annandale |
NJ |
US |
|
|
Assignee: |
EXXONMOBIL RESEARCH AND ENGINEERING
COMPANY
Annandale
NJ
|
Family ID: |
47089187 |
Appl. No.: |
13/652660 |
Filed: |
October 16, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61548038 |
Oct 17, 2011 |
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61548044 |
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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61548052 |
Oct 17, 2011 |
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Current U.S.
Class: |
585/407 ;
423/700; 423/702; 502/60; 502/64; 502/77; 585/475; 585/752;
585/899 |
Current CPC
Class: |
C07C 1/22 20130101; B01J
37/06 20130101; B82Y 40/00 20130101; B01J 21/04 20130101; C10G
2400/04 20130101; B82Y 30/00 20130101; B01J 35/1038 20130101; B01J
35/1061 20130101; C10G 3/49 20130101; B01J 29/40 20130101; B01J
2229/186 20130101; B01J 2229/37 20130101; B01J 2229/42 20130101;
B01J 35/1004 20130101; Y02P 30/20 20151101; B01J 37/0009 20130101;
B01J 29/00 20130101; B01J 35/1019 20130101; B01J 29/83 20130101;
B01J 35/1085 20130101; B01J 37/28 20130101; C01B 39/54 20130101;
B01J 35/002 20130101; B01J 2229/36 20130101; C07C 1/24 20130101;
B01J 37/04 20130101; B01J 35/1042 20130101; C07C 1/20 20130101;
C07C 2/864 20130101; B01J 35/1014 20130101; C07C 41/09 20130101;
B01J 35/0026 20130101; Y02P 20/10 20151101; C10G 2400/02 20130101;
B01J 37/0201 20130101; C07C 41/09 20130101; C07C 43/043
20130101 |
Class at
Publication: |
585/407 ;
585/475; 585/899; 585/752; 423/702; 423/700; 502/60; 502/64;
502/77 |
International
Class: |
B01J 29/83 20060101
B01J029/83; C07C 1/22 20060101 C07C001/22 |
Claims
1. A process for producing a phosphorus-modified zeolite catalyst,
said process comprising: (a) forming zeolite crystals into a shaped
catalyst body either in the absence of a separate inorganic oxide
binder or in the presence of a separate inorganic oxide binder
which is substantially free of aluminum; (b) converting the zeolite
crystals to the hydrogen form; (c) removing any organic directing
agent employed in the synthesis of the zeolite crystals; (d)
treating the shaped catalyst body with an aqueous solution of a
phosphorus compound; and (e) heating the treated catalyst body to
remove the water and convert the phosphorus compound to an oxide
form.
2. The process of claim 1, wherein the zeolite crystals are formed
into a shaped catalyst body in the presence of a separate inorganic
oxide binder which contains less than 5 wt % of aluminum.
3. The process of claim 1, wherein the zeolite crystals are mixed
with a silica binder prior to the forming (a).
4. The process of claim 1, wherein the forming (a) is accomplished
by extrusion.
5. The process of claim 1, wherein the converting (b) is
accomplished before the forming (a).
6. The process of claim 5, wherein the removing (c) is accomplished
before t forming (a).
7. The process of claim 1, wherein the treating (d) is accomplished
by impregnation with an aqueous solution of a phosphorus
oxyacid.
8. The process of claim 1, Wherein the heating in (e) is conducted
at a temperature from about 350.degree. C. to about 650.degree. C.
for a time of about 0.2 hours to about 5.0 hours.
9. The process of claim 1, wherein the zeolite has a molar ratio of
silica to alumina from about 20 to about 200.
10. The process of claim 1, wherein the zeolite has a molar ratio
of silica to alumina from about 20 to about 150.
11. The process of claim 1, wherein the zeolite comprises
ZSM-5.
12. A phosphorus-modified zeolite catalyst produced by the process
of claim 11.
13. A process for organic compound conversion employing contacting
a feedstock with the phosphorus-modified zeolite catalyst of claim
12 under organic compound conversion conditions.
14. The process of claim 13, 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. 61/548,038, 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, 61/548,044, 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", "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 a process for producing
phosphorus modified zeolite catalysts.
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, composited
with an inorganic oxide binder. The catalyst is modified with
phosphorus by impregnation with a source of phosphate ions, such as
an aqueous solution of an ammonium phosphate, followed by
calcination to produce phosphorus oxide in an amount of about 0.05%
to 50%, preferably from about 0.7% to about 15%, by weight of the
catalyst composite.
[0005] In addition, U.S. Pat. No. 7,662,737 discloses a process for
producing a bound phosphorus-modified zeolite catalyst, in which a
zeolite, such as ZSM-5, which may be in the NH.sub.4.sup.+ or the
H.sup.+ form, is slurried with an aqueous solution of a phosphorus
compound and then water is removed from the slurry to form a
phosphorus-modified zeolite. The phosphorus-modified, pre-calcined
zeolite is then mixed with an acid-treated inorganic oxide binder
material selected from alumina, clay, aluminum phosphate and/or
silica-alumina. After optional extrusion, the zeolite-binder
mixture is heated at a temperature of about 400.degree. C. or
higher to form a bound zeolite catalyst, typically from 0.01 to
about 0.15 gram of phosphorus per gram of zeolite. The catalyst is
particularly intended for use in the alkylation of toluene with
methanol to produce xylenes, but is also said to be useful in MTG
processes. Similar processes of producing phosphorus-modified
toluene methylation catalysts are disclosed in U.S. Pat. Nos.
7,368,410 and 7,507,685, and in U.S. Patent Application Publication
Nos. 2007/0149384, 2008/0275280, and 2009/0036723.
[0006] 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. A
similar process of producing a phosphorus-modified toluene
methylation catalyst is disclosed in U.S. Pat. No. 7,399,727.
[0007] U.S. Pat. No 6,504,072 discloses selective production of
para-xylene by the reaction of toluene with methanol over a
severely steamed ZSM-5 catalyst combined with oxide modifier,
preferably an oxide of phosphorus, to control the reduction of the
micropore volume of the catalyst during the steaming step.
Incorporation of phosphorus in the catalyst is conveniently
accomplished by contacting the ZSM-5, either alone or in
combination with a binder or matrix material, with a solution of an
appropriate phosphorus compound, followed by drying and calcining
to convert the phosphorus to an oxide form.
[0008] One desirable result of modifying a zeolite catalyst by the
addition of phosphorus can be that the tendency for the zeolite to
lose its catalytic activity when exposed to high temperature steam
can be reduced. There is, however, significant interest in the
development of phosphorus-modified zeolite catalysts in which the
steam stabilization resulting from the phosphorus addition can be
improved/maximized.
[0009] According to the present invention, it has now been found
that a zeolite catalyst with improved steam stability can be
produced by phosphorus treatment of a zeolite catalyst which is
self-bound or is combined with a binder that is substantially free
of aluminum.
SUMMARY OF THE INVENTION
[0010] In one aspect, the invention resides in a process for
producing a phosphorus-modified zeolite catalyst, said process
comprising: (a) forming as-synthesized zeolite crystals into a
shaped catalyst body either in the absence of a separate inorganic
oxide binder or in the presence of a separate inorganic oxide
binder which is substantially free of aluminum; (b) converting the
zeolite crystals to the hydrogen form; (c) removing any organic
directing agent employed in the synthesis of the zeolite crystals;
(d) treating the shaped catalyst body with an aqueous solution of a
phosphorus compound; and (e) heating the treated catalyst body to
remove water and convert the phosphorus compound to an oxide
form.
[0011] Conveniently, the zeolite crystals can be formed into a
shaped catalyst body in the presence of a separate inorganic oxide
binder containing less than 5 wt %, for example less than 3 wt %,
of aluminum.
[0012] Conveniently, the forming (a) can be accomplished by
extrusion.
[0013] In some embodiments, the zeolite crystals can be mixed with
a silica binder prior to the forming (a).
[0014] Additionally or alternately in some embodiments, the
converting (b) can be accomplished before the forming (a).
[0015] Additionally or alternately in some embodiments, the
removing (c) can be accomplished before the forming (a).
[0016] Conveniently, the treating (d) can be accomplished by
impregnation, such as with an aqueous solution of a phosphorus
oxyacid.
[0017] Conveniently, the catalyst body can comprise from about 0.1
wt % to about 3 wt % of elemental phosphorus present as an oxide of
phosphorus.
[0018] Conveniently, the heating in (e) can be conducted at a
temperature from about 350.degree. C. to about 650.degree. C. for a
time from about 0.2 hours to about 5.0 hours.
[0019] Conveniently, the zeolite can have a molar ratio of silica
to alumina from about 20 to about 200, e.g., from about 20 to about
150.
[0020] Conveniently, the zeolite can comprise, consist essentially
of, or be ZSM-5.
[0021] In further aspects, the invention can reside in a
phosphorus-modified zeolite catalyst produced by the process
described herein, and/or in use of the catalyst in organic
conversion reactions, especially in a process for conversion of
methanol to hydrocarbons.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] Described herein is a process for producing a
phosphorus-modified zeolite catalyst. In the present process, the
phosphorus incorporation can be accomplished after the zeolite has
been formed into a shaped catalyst body, either in the absence of a
separate inorganic oxide binder (self-bound) or in the presence of
a separate inorganic oxide binder which can advantageously be
substantially free of aluminum. In particular, it has been found
that, by omitting the binder or by employing a binder that is
substantially aluminum-free, the thermal stability of the catalyst
can be significantly improved, as compared with a conventional
alumina-bound catalyst containing the same amount of
phosphorus.
[0023] The present process can be employed to produce a
phosphorus-modified zeolite catalyst containing any known zeolite
or mixture of zeolites. In one embodiment, the catalyst described
herein can comprise, consist essentially of, or be at least one
medium pore zeolite having a Constraint Index of 2-12 (as defined
in U.S. Pat. No. 4,016,218), Suitable medium pore molecular sieves
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.
[0024] Additionally or alternately, the catalyst described herein
can comprise one or more large pore zeolites having a Constraint
Index less than 2. Suitable large pore molecular sieves can
include, but are not limited to, zeolite beta, zeolite Y,
Ultrastable Y (USY), Dealuminized Y (Deal Y), mordenite, ZSM-3,
ZSM-4, ZSM-18, ZSM-20, and the like, and combinations thereof.
ZSM-14 is described in U.S. Pat. No. 3,923,636. ZSM-20 is described
in U.S. Pat. No. 3,972,983. Zeolite beta is described in U.S. Pat.
Nos. 3,308,069, and RE 28,341. Low sodium Ultrastable Y molecular
sieve (USY) is described in U.S. Pat. Nos. 3,293,192 and 3,449,070.
Deluminized Y zeolite (Deal Y) may be prepared by the method found
in U.S. Pat. No. 3,442,795. Zeolite UHP-Y is described in U.S. Pat.
No. 4,401,556. Mordenite is a naturally occurring material but is
also available in synthetic forms, such as TEA-mordenite (i.e.,
synthetically prepared from a reaction mixture comprising a
tetraethylammonium directing agent), which is disclosed in U.S.
Pat. Nos. 3,766,093 and 3,894,104.
[0025] Further additionally or alternately, the catalyst described
herein can comprise at least one molecular sieve of the MCM-22
family. As used herein, the term "molecular sieve of the MCM-22
family" (or "material of the MCM-22 family" or "MCM-22 family
material" or "MCM-22 family zeolite") includes one or more of:
[0026] molecular sieves made from a common first degree crystalline
building block unit cell, which unit cell has the MWW framework
topology. (A unit cell is a spatial arrangement of atoms which if
tiled in three-dimensional space describes the crystal structure.
Such crystal structures are discussed in the "Atlas of Zeolite
Framework Types", Fifth Edition, 2001, the entire contents of which
are incorporated by reference herein); [0027] molecular sieves made
from a common second degree building block, being a 2-dimensional
tiling of such MWW framework topology unit cells, forming a
monolayer of one unit cell thickness, preferably one c-unit cell
thickness; [0028] molecular sieves made from common second degree
building blocks, being layers of one or more than one unit cell
thickness, wherein the layer of more than one unit cell thickness
can be made from stacking, packing, or binding at least two
monolayers of one unit cell thickness. The stacking of such second
degree building blocks can be in a regular fashion, an irregular
fashion, a random fashion, or any combination thereof; and [0029]
molecular sieves made by any regular or random 2-dimensional or
3-dimensional combination of unit cells having the MWW framework
topology.
[0030] Molecular sieves of the MCM-22 family can include those
molecular sieves having an X-ray diffraction pattern including
d-spacing maxima at 12.4.+-.0.25, 6.9.+-.0.15, 3.57.+-.0.07 and
3.42.+-.0.07 Angstroms. The X-ray diffraction data used to
characterize the material can be obtained by standard techniques
using the K-alpha doublet of copper as incident radiation and a
diffractometer equipped with a scintillation counter and associated
computer as the collection system.
[0031] Materials of the MCM-22 family can additionally or
alternately include, but are not limited to, MCM-22 (described in
U.S. Pat. No. 4,954,325), PSF-3 (described in U.S. Pat. No.
4,439,409), SSZ-25 (described in U.S. Pat. No. 4,826,667), ERR-1
(described in European Patent No. 0293032). ITQ-1 (described in
U.S. Pat. No. 6,077,498), ITQ-2 (described in International Patent
Publication No. WO97/17290), MCM-36 (described in U.S. Pat. No.
5,250,277), MCM-49 (described in U.S. Pat. No. 5,236,575), MCM-56
(described in U.S. Pat. No. 5,362,697), UZM-8 (described in U.S.
Pat. No. 6,756,030), and mixtures thereof.
[0032] In certain preferred embodiments, the catalyst described
herein can comprise or be ZSM-5. Additionally or alternately, the
catalyst described herein can comprise or be a zeolite having a
silica to alumina molar ratio from about 20 to about 200, for
example from about 20 to about 150.
[0033] In addition to the zeolite, the catalyst employed in the
present process may contain a separate inorganic oxide binder that
is substantially free of aluminum. By "substantially free" is meant
the separate inorganic oxide binder should contain less than 5 wt %
of aluminum, for example less than 3 wt %, less than 1 wt %, less
than 0.5 wt %, less than 0.3 wt %, less than 0.1 wt %, less than
0.05 wt %, or completely free of measurable aluminum. Examples of
suitable inorganic oxide binders can include, but are not
necessarily limited to, silica, titanic, zirconia, and the like,
and mixtures thereof with each other and other metal oxides (again
typically not including alumina). The inorganic oxide binder can be
present in an amount from about 5 wt % to about 65 wt %, for
example from about 10 wt % to about 35 wt %, of the total catalyst.
Alternatively, the present zeolite catalyst may be formed into a
shaped catalyst body without the aid of a separate binder, i.e.,
the catalyst may be self-bound. For more information on the
production of silica-rich catalysts, reference is directed to U.S.
Pat. No. 4,582 815, the entire contents of which are incorporated
herein by reference.
[0034] To produce the desired phosphorus-modified catalyst,
as-synthesized crystals of the target zeolite can be formed into a
slurry with a solvent, generally water, and, where applicable, a
substantially aluminum-free inorganic oxide binder. The resultant
slurry can then formed into a shaped catalyst body, generally by
extrusion, and the catalyst body can then be treated with an
aqueous solution of a phosphorus compound, such as a phosphorus
oxyacid. Phosphorus treatment can conveniently be accomplished by
impregnation. After phosphorus treatment, the treated catalyst body
can be heated to remove the water and to convert the phosphorus
compound to an oxide form. Heating can be conducted, advantageously
in an oxidizing environment such as in air, at a temperature from
about 350.degree. C. to about 650.degree. C. for an appropriate
time, e.g., from about 0.2 hours to about 5.0 hours. Typically, the
final catalyst can comprise from about 0.1 wt % to about 3 wt % of
elemental phosphorus, present as an oxide of phosphorus.
[0035] Generally, but not always, the as-synthesized zeolite
crystals used to produce the desired catalyst can contain an
organic directing agent used in the synthesis of the zeolite. Such
directing agents can frequently block the pores of the zeolite and
so should generally be removed before the zeolite is used
catalytically. In this case, although the directing agent can be
removed prior to formation of the shaped catalyst body, in some
preferred embodiments, the directing agent can be removed by
heating the shaped catalyst body in an oxidizing or non-oxidizing
environment (e.g., in air) at a temperature from about 400.degree.
C. to about 820.degree. C. for an appropriate time, e.g., from
about 0.3 hours to about 3 hours. Typically, heating to remove the
organic directing agent can be conducted before phosphorus
treatment of the shaped catalyst body.
[0036] In addition, many zeolite synthesis processes can be
conducted under alkaline conditions in the presence of alkali metal
ions, especially sodium ions. In this case, the as-synthesized
zeolite crystals can often be in the sodium form and so should be
converted to the catalytically active hydrogen form before use.
Such conversion can typically be achieved by ion exchange with
ammonium cations and heating to drive off the ammonia, thus leaving
the H.sup.+ form of the zeolite. Again, although these steps can be
conducted on the as-synthesized zeolite crystals before catalyst
formation, in some preferred embodiments, ammonium exchange and
subsequent conversion to the hydrogen form can be conducted on the
shaped catalyst body. Typically, conversion of the zeolite to the
hydrogen form can be conducted before phosphorus treatment of the
shaped catalyst body, but after removal of the organic directing
agent employed in the synthesis of the zeolite.
[0037] The phosphorus-modified ZSM-5 catalyst produced by the
present process 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.
[0038] The invention can additionally or alternately include one or
more of the following embodiments.
[0039] EMBODIMENT 1. A process for producing a phosphorus-modified
zeolite catalyst, said process comprising: (a) forming zeolite
crystals into a shaped catalyst body either in the absence of a
separate inorganic oxide binder or in the presence of a separate
inorganic oxide binder which is substantially free of aluminum; (b)
converting the zeolite crystals to the hydrogen form; (c) removing
any organic directing agent employed in the synthesis of the
zeolite crystals; (d) treating the shaped catalyst body with an
aqueous solution of a phosphorus compound; and (e) heating the
treated catalyst body to remove the water and convert the
phosphorus compound to an oxide form.
[0040] EMBODIMENT 2. The process of embodiment 1, wherein the
zeolite crystals are formed into a shaped catalyst body in the
presence of a separate inorganic oxide hinder which contains less
than 5 wt % of aluminum.
[0041] EMBODIMENT 3. The process of any one of the previous
embodiments, wherein the zeolite crystals are mixed with a silica
binder prior to the forming (a).
[0042] EMBODIMENT 4. The process of any one of the previous
embodiments, wherein the forming (a) is accomplished by
extrusion.
[0043] EMBODIMENT 5. The process of any one of the previous
embodiments, wherein the converting (b) is accomplished before the
forming (a).
[0044] EMBODIMENT 6. The process of embodiment 5, wherein the
removing (c) is accomplished before the forming (a).
[0045] EMBODIMENT 7. The process of any one of the previous
embodiments, wherein the treating (d) is accomplished by
impregnation, e.g., with an aqueous solution of a phosphorus
oxyacid.
[0046] EMBODIMENT 8. The process of any one of the previous
embodiments, wherein the heating in (e) is conducted at a
temperature from about 350.degree. C. to about 650.degree. C. for a
time of about 0.2 hours to about 5.0 hours.
[0047] EMBODIMENT 9. The process of any one of the previous
embodiments, wherein the zeolite has a molar ratio of silica to
alumina from about 20 to about 200, e.g., from about 20 to about
150.
[0048] EMBODIMENT 10. The process of any one of the previous
embodiments, wherein the zeolite comprises ZSM-5.
[0049] EMBODIMENT 11. A phosphorus-modified zeolite catalyst
produced by the process of any one of the previous embodiments,
[0050] EMBODIMENT 12. A process for organic compound conversion
employing contacting a feedstock with the phosphorus-modified
zeolite catalyst of embodiment 11 under organic compound conversion
conditions.
[0051] EMBODIMENT 13. The process of embodiment 12, wherein said
organic compound conversion comprises the conversion of methanol to
hydrocarbons boiling in the gasoline boiling range.
[0052] The invention will now be more particularly described with
reference to the following non-limiting Examples and the
accompanying drawings.
EXAMPLES
[0053] In the Examples, the ZSM-5 crystal employed was an
as-synthesized sodium form ZSM-5 having a silica to alumina molar
ratio of about 50, produced using tetrapropylammonium bromide as a
structure directing agent.
[0054] In the Examples, alpha values are used to provide an
indication of the catalytic cracking activity of a catalyst,
compared to a standard catalyst, and to help assess the relative
rate constant (rate of normal hexane conversion per volume of
catalyst per unit time). The alpha value is based on the activity
of a silica-alumina cracking catalyst taken as an alpha of 1 (Rate
Constant.apprxeq.0.016 sec.sup.-1). The Alpha Test is described in
U.S. Pat. No. 3,354,078; in the Journal of Catalysis, 4, 527
(1965); 6, 278 (1966); and 61, 395 (1980), each incorporated herein
by reference as to that description. The experimental conditions of
the test used herein include .about.100 torr (.about.13 kPa) hexane
vapor pressure in He carrier gas flowing through a reactor held at
.about.1000.degree. F. (.about.538.degree. C.).
Example 1
Phosphorus Addition to Zeolite During Extrusion with Alumina
[0055] Alumina (.about.200 grams on solids basis) was first added
to a mixer and dry Deionized water (.about.100 grams) was then
added to moisten the alumina, followed by addition of an amount of
phosphoric acid (.about.0, .about.61, .about.122, or .about.183.2
grams, respectively, on solids basis) to achieve targeted
phosphorus levels. Na-ZSM-5 crystals (.about.800 grams on solids
basis) and additional deionized water were then added, and the
mixtures were mulled for .about.10-30 minutes to achieve the
desired consistency for extrusion, Mixtures with four different
phosphorus levels (.about.0, .about.1.7, .about.3.4, and .about.4.2
wt %, respectively) were thereby prepared. Each mixture was then
extruded into .about. 1/16'' cylinders. The extrudates were dried
overnight (.about.8-16 hours) at .about.250.degree. F.
(.about.121.degree. C.) and then precalcined in nitrogen for
.about.3 hours at .about.1000.degree. F. (.about.538.degree. C.).
Each extrudate was then exchanged twice with a 1N aqueous solution
of ammonium nitrate. The resultant exchanged catalyst 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.).
Example 2
Phosphorus Addition to Alumina-bound Zeolite
[0056] ZSM-5 (.about.800 grams on solids basis) and Versal.TM. 300
alumina (.about.200 grams on solids basis) were added to a mixer
and dry mulled. While mulling, .about.492 grams of deionized water
were added to achieve the desired consistency for extrusion. The
mixture was then extruded into .about. 1/16'' cylinders, The
extrudates were dried overnight (.about.8-16 hours) at
.about.250.degree. F. (.about.121.degree. C.) and then precalcined
in nitrogen for .about.3 hours at .about.1000.degree. F.
(.about.538.degree. C.). The extrudate was then exchanged twice
with a 1N aqueous solution of ammonium nitrate. The exchanged
catalyst 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.). The extrudate
was then impregnated via incipient wetness with targeted levels of
.about.2, .about.4, or .about.6 wt % phosphorus (actual levels as
indicated in Table 1 below) using an aqueous solution of phosphoric
acid. The impregnated crystal was then dried at .about.250.degree.
F. (.about.121.degree. C.) overnight and then calcined in air for
.about.3 hours at .about.1000.degree. F. (.about.538.degree.
C.).
Example 3
Phosphorous Addition to Silica-bound Zeolite
[0057] ZSM-5 (.about.800 grams on solids basis) and Ultrasil.TM.
VN3SP silica (.about.100 grams on solids basis) were added to a
mixer and dry mulled. Ludox.TM.-40 silica (.about.100 grams) was
then added to the mixture followed by the addition of .about.60
grams of .about.50 wt % caustic (NaOH) solution. While mulling,
.about.85 grams of deionized water were added to achieve the
desired consistency for extrusion. The mixture was then extruded
into .about. 1/16'' cylinders. The extrudates were dried overnight
(.about.8-16 hours) at .about.250.degree. F. (.about.121.degree.
C.) and then precalcined in nitrogen for .about.3 hours at
.about.1000.degree. F. (.about.538.degree. C.). The extrudate was
then exchanged twice with a 1N aqueous solution of ammonium
nitrate. The exchanged catalyst 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.). The extrudate was then impregnated via
incipient wetness with targeted levels of .about.2, .about.4, or
.about.6 wt % phosphorus (actual levels as indicated in Table 1
below) using an aqueous solution of phosphoric acid. The
impregnated crystal was then dried at .about.250.degree. F.
(.about.121.degree. C.) overnight and then calcined in air for
.about.3 hours at .about.1000.degree. F. (.about.538.degree.
C.).
Example 4
Phosphorous Addition to Self-bound Zeolite
[0058] ZSM-5 crystal (.about.1,4 kg on solids basis) was added to a
mixer and dry mulled. Approximately 190 grams of deionized water
was then added during mulling. After about 10 minutes, .about.28
grams of .about.50 wt % caustic (NaOH) solution mixed with
approximately 450 grams of 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 precalcined in nitrogen for
.about.3 hours at .about.1000.degree. F. (.about.538.degree. C.).
The extrudate was then exchanged twice with a 1N aqueous solution
of ammonium nitrate. The exchanged catalyst was dried overnight at
.about.250.degree. F. (.about.121.degree. C.) and then calcined in
air for .about.3 hours at .about.4000.degree. F.
(.about.538.degree. C.). The extrudate was then impregnated via
incipient wetness with targeted levels of .about.2, .about.4, or
.about.6 wt % phosphorus (actual levels as indicated in Table 1
below) using an aqueous solution of phosphoric acid. The
impregnated crystal was then dried at .about.250.degree. F.
(.about.121.degree. C.) overnight and then calcined in air for
.about.3 hours at .about.1000.degree. F.
Example 5
Measurement of Hexane Cracking Activity of P-stabilized
Catalysts
[0059] The ZSM-5 containing extrudates of Examples 1-4 were
analyzed for phosphorus content and steamed for .about.96 hours at
.about.1000.degree. F. (.about.538.degree. C.) and .about.14.7 psia
steam partial pressure. The as-prepared and steamed catalysts were
then screened for acidic activity with hexane cracking measurements
in a routine Alpha test. The Alpha values and phosphorus levels of
the extrudates from Examples 1-4 are shown in Table 1 below. The
results show that the alumina-containing catalysts from Examples 1
and 2 have much lower alpha activity than the silica and self-bound
catalysts from Examples 3 and 4 after steaming. Both silica and
self-bound catalysts with approximately 0.8 wt % P retain
.about.110 alpha value after steaming as compared to the same
catalysts with no P that retain .about.14 and .about.11 alpha value
after steaming.
TABLE-US-00001 TABLE 1 Phosphorus Alpha value Alpha value Catalyst
wt % (as prepared) (as steamed) Example 1a 0.0 ~300 ~13 Example 1b
~1.7 ~270 ~5.3 Example 1c ~3.4 ~250 ~12 Example 1d ~4.2 ~240 ~19
Example 2a 0.0 ~320 ~13 Example 2b ~2.7 ~340 ~22 Example 2c ~4.2
~210 ~38 Example 2d ~5.3 ~160 ~79 Example 3a 0.0 ~580 ~14 Example
3b ~0.8 ~240 ~110 Example 3c ~1.6 ~170 ~96 Example 3d ~2.4 ~99 ~26
Example 4a 0.0 ~540 ~11 Example 4b ~0.84 ~290 ~110 Example 4c ~1.67
~160, ~210 ~85 Example 4d ~2.47 ~70 ~47, ~29
[0060] 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.
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