U.S. patent application number 15/098450 was filed with the patent office on 2016-11-24 for processes using molecular sieve ssz-27.
The applicant listed for this patent is Chevron U.S.A. Inc.. Invention is credited to Robert James Saxton, Dan Xie, Stacey Ian Zones.
Application Number | 20160340197 15/098450 |
Document ID | / |
Family ID | 55913702 |
Filed Date | 2016-11-24 |
United States Patent
Application |
20160340197 |
Kind Code |
A1 |
Zones; Stacey Ian ; et
al. |
November 24, 2016 |
PROCESSES USING MOLECULAR SIEVE SSZ-27
Abstract
Uses for a new crystalline molecular sieve designated SSZ-27 are
disclosed. SSZ-27 is synthesized using a hexamethyl [4.3.3.0]
propellane-8,11-diammonium cation as a structure directing
agent.
Inventors: |
Zones; Stacey Ian; (San
Francisco, CA) ; Xie; Dan; (Richmond, CA) ;
Saxton; Robert James; (Pleasanton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chevron U.S.A. Inc. |
San Ramon |
CA |
US |
|
|
Family ID: |
55913702 |
Appl. No.: |
15/098450 |
Filed: |
April 14, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62165061 |
May 21, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J 29/72 20130101;
Y02P 30/42 20151101; Y02P 30/20 20151101; C07C 1/24 20130101; Y02P
20/152 20151101; B01J 29/78 20130101; Y02C 10/10 20130101; C01B
39/48 20130101; B01J 29/70 20130101; B01D 53/9413 20130101; Y02P
20/52 20151101; Y02P 30/40 20151101; B01D 2257/702 20130101; C07C
2529/70 20130101; B01D 2257/404 20130101; B01D 2255/50 20130101;
B01J 29/061 20130101; C07C 2529/72 20130101; C01B 39/46 20130101;
C07C 209/16 20130101; C07C 1/20 20130101; B01D 53/228 20130101;
B01D 2253/108 20130101; B01D 53/9486 20130101; B01D 2256/245
20130101; B01D 2257/504 20130101; C07C 1/20 20130101; C07C 11/04
20130101; C07C 1/20 20130101; C07C 11/06 20130101; C07C 1/20
20130101; C07C 11/08 20130101; C07C 209/16 20130101; C07C 211/04
20130101 |
International
Class: |
C01B 39/46 20060101
C01B039/46; C07C 209/16 20060101 C07C209/16; B01J 29/06 20060101
B01J029/06; C07C 1/24 20060101 C07C001/24; B01D 53/94 20060101
B01D053/94; B01J 29/70 20060101 B01J029/70 |
Claims
1. In a process for separating gases using a membrane containing a
molecular sieve, the improvement comprising using as the molecular
sieve a molecular sieve having in its calcined form, an X-ray
diffraction pattern including the lines listed in the following
table: TABLE-US-00005 2-Theta d-Spacing, nm Relative Intensity 7.50
.+-. 0.20 1.177 W 8.65 .+-. 0.20 1.021 W 9.47 .+-. 0.20 0.933 VS
9.94 .+-. 0.20 0.889 M 13.47 .+-. 0.20 0.657 M 14.86 .+-. 0.20
0.596 M 16.07 .+-. 0.20 0.551 W 16.37 .+-. 0.20 0.541 W 17.92 .+-.
0.20 0.495 W 19.92 .+-. 0.20 0.445 W 20.66 .+-. 0.20 0.430 W 21.14
.+-. 0.20 0.420 W 21.34 .+-. 0.20 0.416 W 22.07 .+-. 0.20 0.402 M
23.17 .+-. 0.20 0.384 M
2. A process for the production of light olefins from a feedstock
comprising an oxygenate or mixture of oxygenates, the process
comprising reacting the feedstock at effective conditions over a
catalyst comprising a molecular sieve having, in its calcined form,
an X-ray diffraction pattern including the lines listed in the
following table: TABLE-US-00006 2-Theta d-Spacing, nm Relative
Intensity 7.50 .+-. 0.20 1.177 W 8.65 .+-. 0.20 1.021 W 9.47 .+-.
0.20 0.933 VS 9.94 .+-. 0.20 0.889 M 13.47 .+-. 0.20 0.657 M 14.86
.+-. 0.20 0.596 M 16.07 .+-. 0.20 0.551 W 16.37 .+-. 0.20 0.541 W
17.92 .+-. 0.20 0.495 W 19.92 .+-. 0.20 0.445 W 20.66 .+-. 0.20
0.430 W 21.14 .+-. 0.20 0.420 W 21.34 .+-. 0.20 0.416 W 22.07 .+-.
0.20 0.402 M 23.17 .+-. 0.20 0.384 M
3. The process of claim 2, wherein the light olefins are ethylene,
propylene, butylene, or mixtures thereof.
4. The process of claim 2, wherein the oxygenate is methanol,
dimethyl ether, or a mixture thereof.
5. A process for producing methylamine or dimethylamine comprising
reacting methanol, dimethyl ether, or a mixture thereof, and
ammonia in the gaseous phase in the presence of a catalyst
comprising a molecular sieve having, in its calcined form, an X-ray
diffraction pattern including the lines listed in the following
table: TABLE-US-00007 2-Theta d-Spacing, nm Relative Intensity 7.50
.+-. 0.20 1.177 W 8.65 .+-. 0.20 1.021 W 9.47 .+-. 0.20 0.933 VS
9.94 .+-. 0.20 0.889 M 13.47 .+-. 0.20 0.657 M 14.86 .+-. 0.20
0.596 M 16.07 .+-. 0.20 0.551 W 16.37 .+-. 0.20 0.541 W 17.92 .+-.
0.20 0.495 W 19.92 .+-. 0.20 0.445 W 20.66 .+-. 0.20 0.430 W 21.14
.+-. 0.20 0.420 W 21.34 .+-. 0.20 0.416 W 22.07 .+-. 0.20 0.402 M
23.17 .+-. 0.20 0.384 M
6. A process for the reduction of oxides of nitrogen contained in a
gas stream, wherein the process comprises contacting the gas stream
with a molecular sieve having, in its calcined form, an X-ray
diffraction pattern including the lines listed in the following
table: TABLE-US-00008 2-Theta d-Spacing, nm Relative Intensity 7.50
.+-. 0.20 1.177 W 8.65 .+-. 0.20 1.021 W 9.47 .+-. 0.20 0.933 VS
9.94 .+-. 0.20 0.889 M 13.47 .+-. 0.20 0.657 M 14.86 .+-. 0.20
0.596 M 16.07 .+-. 0.20 0.551 W 16.37 .+-. 0.20 0.541 W 17.92 .+-.
0.20 0.495 W 19.92 .+-. 0.20 0.445 W 20.66 .+-. 0.20 0.430 W 21.14
.+-. 0.20 0.420 W 21.34 .+-. 0.20 0.416 W 22.07 .+-. 0.20 0.402 M
23.17 .+-. 0.20 0.384 M.
7. The process of claim 6, conducted in the presence of oxygen.
8. The process of claim 6, wherein the molecular sieve contains one
or more metals selected from the group consisting of Cr, Mn, Re,
Mo, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Zn, Ga, In, Sn, and
mixtures thereof.
9. The process of claim 8, wherein the metal is present in an
amount of from 0.01 to 6 wt. %, based on the total weight of the
molecular sieve.
10. A process for treating exhaust gas that comprises a hydrocarbon
combustion product, the method comprising: (a) contacting the
exhaust gas with a molecular sieve for a period of time effective
to facilitate adsorption of the hydrocarbon combustion product by
the molecular sieve; (b) passing a purge gas through the molecular
sieve to remove adsorbed hydrocarbon combustion product therefrom;
and (c) contacting the purge gas containing the removed hydrocarbon
combustion product with a hydrocarbon conversion catalyst; wherein
the molecular sieve has in its calcined form, an X-ray diffraction
pattern including the lines listed in the following table:
TABLE-US-00009 2-Theta d-Spacing, nm Relative Intensity 7.50 .+-.
0.20 1.177 W 8.65 .+-. 0.20 1.021 W 9.47 .+-. 0.20 0.933 VS 9.94
.+-. 0.20 0.889 M 13.47 .+-. 0.20 0.657 M 14.86 .+-. 0.20 0.596 M
16.07 .+-. 0.20 0.551 W 16.37 .+-. 0.20 0.541 W 17.92 .+-. 0.20
0.495 W 19.92 .+-. 0.20 0.445 W 20.66 .+-. 0.20 0.430 W 21.14 .+-.
0.20 0.420 W 21.34 .+-. 0.20 0.416 W 22.07 .+-. 0.20 0.402 M 23.17
.+-. 0.20 0.384 M.
11. The process of claim 10, wherein the exhaust gas contains a
plurality of hydrocarbon combustion products.
12. The process of claim 10, wherein the hydrocarbon combustion
product is derived from the combustion of hydrocarbon fuel in an
engine.
13. The process of claim 12, wherein the engine is an internal
combustion engine.
14. The process of claim 13, wherein the internal combustion engine
includes an exhaust system and the process is utilized to reduce
cold start emission of hydrocarbons from the exhaust system.
15. The process of claim 19, wherein the molecular sieve contains a
metal cation selected from the group consisting of Mg, Ca, Mn, Fe,
Co, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, and mixtures thereof.
Description
TECHNICAL FIELD
[0001] This disclosure relates to uses for a new crystalline
molecular sieve designated SSZ-27, a method for preparing SSZ-27,
and uses for SSZ-27.
BACKGROUND
[0002] Molecular sieves are a class of important materials used in
the chemical industry for processes such as gas stream purification
and hydrocarbon conversion processes. Molecular sieves are porous
solids having interconnected pores of different sizes. Molecular
sieves typically have a one-, two- or three-dimensional crystalline
pore structure having pores of one or more molecular dimensions
that selectively adsorb molecules that can enter the pores, and
exclude those molecules that are too large. The pore size, pore
shape, interstitial spacing or channels, composition, crystal
morphology and structure are a few characteristics of molecular
sieves that determine their use in various hydrocarbon adsorption
and conversion processes.
[0003] For the petroleum and petrochemical industries, the most
commercially useful molecular sieves are known as zeolites. A
zeolite is an aluminosilicate having an open framework structure
formed from corner-sharing the oxygen atoms of [SiO.sub.4] and
[AlO.sub.4] tetrahedra. Mobile extra framework cations reside in
the pores for balancing charges along the zeolite framework. These
charges are a result of substitution of a tetrahedral framework
cation (e.g., Si.sup.4+) with a trivalent or pentavalent cation.
Extra framework cations counter-balance these charges preserving
the electroneutrality of the framework, and these cations are
exchangeable with other cations and/or protons.
[0004] Synthetic molecular sieves, particularly zeolites, are
typically synthesized by mixing sources of alumina and silica in an
aqueous media, often in the presence of a structure directing agent
or templating agent. The structure of the molecular sieve formed is
determined in part by the solubility of the various sources, the
silica-to-alumina ratio, the nature of the cation, the synthesis
conditions (temperature, pressure, mixing agitation), the order of
addition, the type of structure directing agent, and the like.
[0005] Although many different crystalline molecular sieves have
been discovered, there is a continuing need for new molecular
sieves with desirable properties for gas separation and drying,
hydrocarbon and chemical conversions, and other applications. New
molecular sieves may contain novel internal pore architectures,
providing enhanced selectivities in these processes.
SUMMARY
[0006] The present disclosure is directed to uses for a new family
of molecular sieves with unique properties, referred to herein as
"molecular sieve SSZ-27" or simply "SSZ-27."
[0007] In one aspect, there is provided a crystalline molecular
sieve having, in its calcined form, the X-ray diffraction lines of
Table 3.
[0008] In another aspect, there is provided a method of preparing a
crystalline molecular sieve by contacting under crystallization
conditions (1) at least one source of silicon; (2) at least one
source of aluminum; (3) at least one source of an element selected
from Groups 1 and 2 of the Periodic Table; (4) hydroxide ions; and
(5) hexamethyl [4.3.3.0] propellane-8,11-diammonium cations.
[0009] In yet another aspect, there is provided a process for
preparing a crystalline molecular sieve having, in its
as-synthesized form, the X-ray diffraction lines of Table 2, by:
(a) preparing a reaction mixture containing (1) at least one source
of silicon; (2) at least one source of aluminum; (3) at least one
source of an element selected from Groups 1 and 2 of the Periodic
Table; (4) hydroxide ions; (5) hexamethyl [4.3.3.0]
propellane-8,11-diammonium cations; and (6) water; and (b)
subjecting the reaction mixture to crystallization conditions
sufficient to form crystals of the molecular sieve.
[0010] The present disclosure also provides a novel molecular sieve
designated SSZ-27 having, in its as-synthesized, anhydrous form, a
composition, in terms of mole ratios, in the range:
Al.sub.2O.sub.3: 20-80 SiO.sub.2 or more preferably:
Al.sub.2O.sub.3: 20-35 SiO.sub.2.
[0011] The present disclosure provides processes using molecular
sieve SSZ-27.
DETAILED DESCRIPTION
Introduction
[0012] In preparing SSZ-27, a hexamethyl [4.3.3.0]
propellane-8,11-diammonium cation is used as a structure directing
agent ("SDA"), also known as a crystallization template. The SDA
useful for making SSZ-27 has the following structure (1):
##STR00001## [0013] hexamethyl[4.3.3.0]propellane-8,11-diammonium
cation including syn, syn; syn, anti; and anti, anti orientations
of the ammonium groups.
[0014] The SDA dication is associated with anions which may be any
anion that is not detrimental to the formation of SSZ-27.
Representative anions include elements from Group 17 of the
Periodic Table (e.g., fluoride, chloride, bromide and iodide),
hydroxide, sulfate, tetrafluoroboroate, acetate, carboxylate, and
the like. As used herein, the numbering scheme for the Periodic
Table Groups is as disclosed in Chem. Eng. News, 63(5), 27
(1985).
[0015] Reaction Mixture
[0016] In general, SSZ-27 is prepared by: (a) preparing a reaction
mixture containing (1) at least one source of silicon; (2) at least
one source of aluminum; (3) at least one source of an element
selected from Groups 1 and 2 of the Periodic Table; (4) hydroxide
ions; (5) hexamethyl [4.3.3.0] propellane-8,11-diammonium cations;
and (6) water; and (b) subjecting the reaction mixture to
crystallization conditions sufficient to form crystals of the
molecular sieve.
[0017] The composition of the reaction mixture from which the
molecular sieve is formed, in terms of mole ratios, is identified
in Table 1 below
TABLE-US-00001 TABLE 1 Components Broad Exemplary
SiO.sub.2/Al.sub.2O.sub.3 20 to 80 20 to 35 M/SiO.sub.2 0.05 to
0.50 0.15 to 0.30 Q/SiO.sub.2 0.10 to 0.40 0.10 to 0.30
OH/SiO.sub.2 0.25 to 0.60 0.25 to 0.50 H.sub.2O/SiO.sub.2 10 to 60
20 to 50
wherein Q is a hexamethyl [4.3.3.0] propellane-8,11-diammonium
cation and M is selected from the group consisting of elements from
Groups 1 and 2 of the Periodic Table.
[0018] Sources useful herein for silicon include fumed silica,
precipitated silicates, silica hydrogel, silicic acid, colloidal
silica, tetra-alkyl orthosilicates (e.g., tetraethyl
orthosilicate), and silica hydroxides.
[0019] Sources useful for aluminum include oxides, hydroxides,
acetates, oxalates, ammonium salts and sulfates of aluminum.
Typical sources of aluminum oxide include aluminates, alumina, and
aluminum compounds such as aluminum chloride, aluminum sulfate,
aluminum hydroxide, kaolin clays, and other zeolites. An example of
the source of aluminum oxide is zeolite Y.
[0020] As described herein above, for each embodiment described
herein, the reaction mixture can be formed using at least one
source of an element selected from Groups 1 and 2 of the Periodic
Table (referred to herein as M). In one sub-embodiment, the
reaction mixture is formed using a source of an element from Group
1 of the Periodic Table. In another sub-embodiment, the reaction
mixture is formed using a source of sodium (Na). Any M-containing
compound which is not detrimental to the crystallization process is
suitable. Sources for such Groups 1 and 2 elements include oxides,
hydroxides, nitrates, sulfates, halides, acetates, oxalates, and
citrates thereof.
[0021] For each embodiment described herein, the molecular sieve
reaction mixture can be supplied by more than one source. Also, two
or more reaction components can be provided by one source.
[0022] The reaction mixture can be prepared either batch wise or
continuously. Crystal size, morphology and crystallization time of
the molecular sieve described herein can vary with the nature of
the reaction mixture and the crystallization conditions.
[0023] Crystallization and Post-Synthesis Treatment
[0024] In practice, the molecular sieve is prepared by: (a)
preparing a reaction mixture as described herein above; and (b)
subjecting the reaction mixture to crystallization conditions
sufficient to form crystals of the molecular sieve (see, e.g., H.
Robson, Verified Syntheses of Zeolitic Materials, Second Revised
Edition, Elsevier, 2001).
[0025] The reaction mixture is maintained at an elevated
temperature until the crystals of the molecular sieve are formed.
The hydrothermal crystallization is usually conducted under
pressure, and usually in an autoclave so that the reaction mixture
is subject to autogenous pressure, at a temperature between
150.degree. C. and 180.degree. C., e.g., from 170.degree. C. to
175.degree. C.
[0026] The reaction mixture can be subjected to mild stirring or
agitation during the crystallization step. It will be understood by
one skilled in the art that the molecular sieves described herein
can contain impurities, such as amorphous materials, unit cells
having framework topologies which do not coincide with the
molecular sieve, and/or other impurities (e.g., organic
hydrocarbons).
[0027] During the hydrothermal crystallization step, the molecular
sieve crystals can be allowed to nucleate spontaneously from the
reaction mixture. The use of crystals of the molecular sieve as
seed material can be advantageous in decreasing the time necessary
for complete crystallization to occur. In addition, seeding can
lead to an increased purity of the product obtained by promoting
the nucleation and/or formation of the molecular sieve over any
undesired phases. When used as seeds, seed crystals are added in an
amount between 1% and 10% of the weight of the source for silicon
used in the reaction mixture.
[0028] Once the molecular sieve crystals have formed, the solid
product is separated from the reaction mixture by standard
mechanical separation techniques such as filtration. The crystals
are water-washed and then dried to obtain the as-synthesized
molecular sieve crystals. The drying step can be performed at
atmospheric pressure or under vacuum.
[0029] The molecular sieve can be used as-synthesized, but
typically will be thermally treated (calcined). The term
"as-synthesized" refers to the molecular sieve in its form after
crystallization, prior to removal of the SDA cation. The SDA can be
removed by thermal treatment (e.g., calcination), preferably in an
oxidative atmosphere (e.g., air, gas with an oxygen partial
pressure of greater than 0 kPa) at a temperature readily
determinable by one skilled in the art sufficient to remove the SDA
from the molecular sieve. The SDA can also be removed by photolysis
techniques (e.g., exposing the SDA-containing molecular sieve
product to light or electromagnetic radiation that has a wavelength
shorter than visible light under conditions sufficient to
selectively remove the organic compound from the molecular sieve)
as described in U.S. Pat. No. 6,960,327.
[0030] The molecular sieve can subsequently be calcined in steam,
air or inert gas at temperatures ranging from 200.degree. C. to
800.degree. C. for periods of time ranging from 1 to 48 hours, or
more. Usually, it is desirable to remove the extra-framework cation
(e.g., Na.sup.+) by ion exchange and replace it with hydrogen,
ammonium, or any desired metal-ion. Particularly preferred cations
are those which tailor the catalytic activity for certain
hydrocarbon conversion reactions. These include hydrogen, rare
earth metals and metals of Groups 2 to 15 of the Periodic Table of
the Elements.
[0031] Where the molecular sieve formed is an intermediate
material, the target molecular sieve can be achieved using
post-synthesis techniques such as heteroatom lattice substitution
techniques in order to achieve a higher SiO.sub.2/Al.sub.2O.sub.3
ratio. The target molecular sieve can also be achieved by removing
heteroatoms from the lattice by known techniques such as acid
leaching.
[0032] The molecular sieve made from the process disclosed herein
can be formed into a wide variety of physical shapes. Generally
speaking, the molecular sieve can be in the form of a powder, a
granule, or a molded product, such as extrudate having a particle
size sufficient to pass through a 2-mesh (Tyler) screen and be
retained on a 400-mesh (Tyler) screen. In cases where the catalyst
is molded, such as by extrusion with an organic binder, the
molecular sieve can be extruded before drying or dried (or
partially dried) and then extruded.
[0033] The molecular sieve can be composited with other materials
resistant to the temperatures and other conditions employed in
organic conversion processes. Such matrix materials include active
and inactive materials and synthetic or naturally occurring
zeolites as well as inorganic materials such as clays, silica and
metal oxides. Examples of such materials and the manner in which
they can be used are disclosed in U.S. Pat. Nos. 4,910,006 and
5,316,753.
[0034] Characterization of the Molecular Sieve
[0035] SSZ-27 has, in its as-synthesized, anhydrous form, a
composition, in terms of mole ratios, in the range:
Al.sub.2O.sub.3: 20-80 SiO.sub.2 or more preferably:
Al.sub.2O.sub.3: 20-35 SiO.sub.2.
[0036] Molecular sieves synthesized by the process disclosed herein
are characterized by their X-ray diffraction (XRD) pattern. The
product of the synthesis reaction is a crystalline molecular sieve
containing within its pore structure hexamethyl [4.3.3.0]
propellane-8,11-diammonium cations. The resultant as-synthesized
material has an X-ray diffraction pattern which is distinguished
from the patterns of other known as-synthesized or thermally
treated crystalline materials by the lines listed in Table 2
below.
TABLE-US-00002 TABLE 2 Characteristic Peaks for As-Synthesized
SSZ-27 2-Theta.sup.(a) d-Spacing, nm Relative Intensity.sup.(b)
7.57 1.167 W 8.62 1.025 W 9.35 0.946 M 9.83 0.900 W 13.55 0.653 W
14.80 0.598 W 15.27 0.580 W 16.25 0.545 W 17.72 0.500 W 19.76 0.449
M 20.50 0.433 W 21.08 0.421 S 21.30 0.417 M 21.93 0.405 S 22.95
0.387 VS .sup.(a).+-.0.20 .sup.(b)The powder XRD patterns provided
are based on a relative intensity scale in which the strongest line
in the powder X-ray pattern is assigned a value of 100: W = weak
(>0 to .ltoreq.20); M = medium (>20 to .ltoreq.40); S =
strong (>40 to .ltoreq.60); VS = very strong (>60 to
.ltoreq.100).
[0037] The X-ray diffraction pattern of the calcined form of SSZ-27
includes the lines listed in Table 3 below:
TABLE-US-00003 TABLE 3 Characteristic Peaks for Calcined SSZ-27
2-Theta.sup.(a) d-Spacing, nm Relative Intensity.sup.(b) 7.50 1.177
W 8.65 1.021 W 9.47 0.933 VS 9.94 0.889 M 13.47 0.657 M 14.86 0.596
M 16.07 0.551 W 16.37 0.541 W 17.92 0.495 W 19.92 0.445 W 20.66
0.430 W 21.14 0.420 W 21.34 0.416 W 22.07 0.402 M 23.17 0.384 M
.sup.(a).+-.0.20 .sup.(b)The powder XRD patterns provided are based
on a relative intensity scale in which the strongest line in the
powder X-ray pattern is assigned a value of 100: W = weak (>0 to
.ltoreq.20); M = medium (>20 to .ltoreq.40); S = strong (>40
to .ltoreq.60); VS = very strong (>60 to .ltoreq.100).
[0038] The powder X-ray diffraction patterns presented herein were
collected by standard techniques. The radiation was CuK.sub..alpha.
radiation. The peak heights and the positions, as a function of
2.theta. where .theta. is the Bragg angle, were read from the
relative intensities of the peaks (adjusting for background), and
d, the interplanar spacing corresponding to the recorded lines, can
be calculated.
[0039] Minor variations in the diffraction pattern can result from
variations in the mole ratios of the framework species of the
particular sample due to changes in lattice constants. In addition,
sufficiently small crystals will affect the shape and intensity of
peaks, leading to significant peak broadening. Minor variations in
the diffraction pattern can also result from variations in the
organic compound used in the preparation. Calcination can also
cause minor shifts in the XRD pattern. Notwithstanding these minor
perturbations, the basic crystal lattice structure remains
unchanged.
[0040] Processes Using SSZ-27
[0041] SSZ-27 is useful as an adsorbent for gas separations. SSZ-27
can also be used as a catalyst for converting oxygenates (e.g.,
methanol) to olefins and for making small amines. SSZ-27 can be
used to reduce oxides of nitrogen in a gas streams, such as
automobile exhaust. SSZ-27 can also be used to as a cold start
hydrocarbon trap in combustion engine pollution control systems.
SSZ-27 is particularly useful for trapping C.sub.3 fragments.
[0042] Gas Separation
[0043] SSZ-100 can be used to separate gases. For example, it can
be used to separate carbon dioxide from natural gas. Typically, the
molecular sieve is used as a component in a membrane that is used
to separate the gases. Examples of such membranes are disclosed in
U.S. Pat. No. 6,508,860.
[0044] Oxygenate Conversion
[0045] SSZ-27 is useful in the catalytic conversion of oxygenates
to one or more light olefins, i.e., C.sub.2, C.sub.3 and/or C.sub.4
olefins. As used herein, the term "oxygenates" is defined to
include aliphatic alcohols, ethers, carbonyl compounds (aldehydes,
ketones, carboxylic acids, carbonates, and the like), and also
compounds containing hetero-atoms, such as, halides, mercaptans,
sulfides, amines, and mixtures thereof. The aliphatic moiety will
normally contain from 1 to 10 carbon atoms, such as from 1 to 4
carbon atoms.
[0046] Representative oxygenates include lower straight chain or
branched aliphatic alcohols, their unsaturated counterparts, and
their nitrogen, halogen and sulfur analogues. Examples of suitable
oxygenate compounds include methanol, ethanol, n-propanol,
isopropanol, C.sub.4-C.sub.10 alcohols, methyl ethyl ether,
dimethyl ether, diethyl ether, diisopropyl ether, methyl mercaptan,
methyl sulfide, methyl amine, ethyl mercaptan, diethyl sulfide,
diethyl amine, ethyl chloride, formaldehyde, dimethyl carbonate,
dimethyl ketone, acetic acid, n-alkyl amines, n-alkyl halides,
n-alkyl sulfides having n-alkyl groups of comprising the range of
from 3 to 10 carbon atoms, and mixtures thereof. Particularly
suitable oxygenate compounds are methanol, dimethyl ether, or
mixtures thereof, most preferably methanol. As used herein, the
term "oxygenate" designates only the organic material used as the
feed. The total charge of feed to the reaction zone may contain
additional compounds, such as diluents.
[0047] In the present oxygenate conversion process, a feedstock
comprising an organic oxygenate, optionally with one or more
diluents, is contacted in the vapor phase in a reaction zone with a
catalyst comprising the molecular sieve disclosed herein at
effective process conditions so as to produce the desired olefins.
Alternatively, the process may be carried out in a liquid or a
mixed vapor/liquid phase. When the process is carried out in the
liquid phase or a mixed vapor/liquid phase, different conversion
rates and selectivities of feedstock-to-product may result
depending upon the catalyst and the reaction conditions.
[0048] When present, the diluent(s) is generally non-reactive to
the feedstock or molecular sieve catalyst composition and is
typically used to reduce the concentration of the oxygenate in the
feedstock. Non-limiting examples of suitable diluents include
helium, argon, nitrogen, carbon monoxide, carbon dioxide, water,
essentially non-reactive paraffins (especially alkanes such as
methane, ethane, and propane), essentially non-reactive aromatic
compounds, and mixtures thereof. The most preferred diluents are
water and nitrogen, with water being particularly preferred.
Diluent(s) may comprise from 1 to 99 mole % of the total feed
mixture.
[0049] The temperature employed in the oxygenate conversion process
may vary over a wide range, such as from 200.degree. C. to
1000.degree. C. (e.g., from 250.degree. C. to 800.degree. C., from
250.degree. C. to 750.degree. C., from 300.degree. C. to
650.degree. C., from 350.degree. C. to 600.degree. C., or from
400.degree. C. to 600.degree. C.).
[0050] Light olefin products will form, although not necessarily in
optimum amounts, at a wide range of pressures, including autogenous
pressures and pressures in the range of from 0.1 to 10 MPa (e.g.,
from 7 kPa to 5 MPa, or from 50 kPa to 1 MPa). The foregoing
pressures are exclusive of diluent, if any is present, and refer to
the partial pressure of the feedstock as it relates to oxygenate
compounds and/or mixtures thereof. Lower and upper extremes of
pressure may adversely affect selectivity, conversion, coking rate,
and/or reaction rate; however, light olefins such as ethylene still
may form.
[0051] The process should be continued for a period of time
sufficient to produce the desired olefin products. The reaction
time may vary from tenths of seconds to a number of hours. The
reaction time is largely determined by the reaction temperature,
the pressure, the catalyst selected, the weight hourly space
velocity, the phase (liquid or vapor) and the selected process
design characteristics.
[0052] A wide range of weight hourly space velocities (WHSV) for
the feedstock will function in the present process. WHSV is defined
as weight of feed (excluding diluent) per hour per weight of a
total reaction volume of molecular sieve catalyst (excluding inerts
and/or fillers). The WHSV generally should be in the range of from
0.01 h.sup.-1 to 500 h.sup.-1 (e.g., from about 0.5 to 300
h.sup.-1, or from 0.1 to 200 h.sup.-1).
[0053] The molecular sieve catalyst can be incorporated into solid
particles in which the catalyst is present in an amount effective
to promote the desired conversion of oxygenates to light olefins.
In one aspect, the solid particles comprise a catalytically
effective amount of the catalyst and at least one matrix material
selected from the group consisting of binder materials, filler
materials and mixtures thereof to provide a desired property or
properties, e.g., desired catalyst dilution, mechanical strength
and the like to the solid particles. Such matrix materials are
often, to some extent, porous in nature and can or cannot be
effective to promote the desired reaction. Filler and binder
materials include, for example, synthetic and naturally occurring
substances such as metal oxides, clays, silicas, aluminas,
silica-aluminas, silica-magnesias, silica-zirconias, silica-thorias
and the like. If matrix materials are included in the catalyst
composition, the molecular sieve desirably comprises from 1 to 99
wt. % (e.g., from 5 to 90 wt. % or from 10 to 80 wt. %) of the
total composition.
[0054] Synthesis of Amines
[0055] SSZ-27 can be used in a catalyst to prepare methylamine or
dimethylamine. Dimethylamine is generally prepared in industrial
quantities by continuous reaction of methanol (and/or dimethyl
ether) and ammonia in the presence of a silica-alumina catalyst.
The reactants are typically combined in the vapor phase, at
temperatures of from 300.degree. C. to 500.degree. C., and at
elevated pressures. Such a process is disclosed in U.S. Pat. No.
4,737,592.
[0056] The catalyst is used in its acid form. Acid forms of
molecular sieves can be prepared by a variety of techniques.
Desirably, the molecular sieve used to prepare dimethylamine will
be in the hydrogen form, or have an alkali or alkaline earth metal,
such as Na, K, Rb, or Cs, ion-exchanged into it.
[0057] The process disclosed herein involves reacting methanol,
dimethyl ether, or a mixture thereof and ammonia in amounts
sufficient to provide a carbon/nitrogen (C/N) ratio of from 0.2 to
1.5, e.g., from 0.5 to 1.2. The reaction is conducted at a
temperature of from 250.degree. C. to 450.degree. C., e.g., from
300.degree. C. to 400.degree. C. Reaction pressures can vary from 7
to 7000 kPa, e.g., from 70 to 3000 kPa. A methanol and/or dimethyl
ether space time of from 0.01 to 80 h.sup.-1 (e.g., from 0.10 to
1.5 h.sup.-1) is typically used. This space time is calculated as
the mass of catalyst divided by the mass flow rate of
methanol/dimethyl ether introduced into the reactor.
[0058] Reduction of Oxides of Nitrogen
[0059] SSZ-27 can be used for the catalytic reduction of the oxides
of nitrogen in a gas stream. The catalyst comprises one or more
metals supported on the molecular sieve support. Any suitable metal
may be selected. Metals particularly effective for use during
selective catalytic reduction include metals selected from the
group consisting of Cr, Mn, Re, Mo, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt,
Cu, Ag, Zn, Ga, In, Sn, and mixtures thereof. In one embodiment,
the one or more metals is selected from the group consisting of Cr,
Mn, Fe, Co, Rh, Ni, Pd, Pt, Cu, and mixtures thereof. Preferably,
the metal is selected from Mn, Fe, Co, Pt, and Cu. More preferably,
the one or more metals may be selected from the group consisting of
Fe, Cu, and mixtures thereof. In an exemplary embodiment, the metal
is Cu.
[0060] Any suitable and effective amount of at least one metal may
be used in the catalyst. The total amount of the metal(s) that may
be included in the molecular sieve may be from 0.01 to 20 wt. %
(e.g., from 0.1 to 10 wt. %, from 0.5 to 5 wt. %, from 1 to 3 wt.
%, or from 1.5 to 2.5 wt. %), based on the total weight of the
catalyst.
[0061] The molecular sieve acts as a support for the metal, e.g.,
the metal may be inside the pore(s) and/or may be on the external
surface of the molecular sieve. In an exemplary embodiment, a
significant amount of the metal(s) resides inside the pores.
[0062] The metal(s) may also be included in the molecular sieve
and/or supported by the molecular sieve using any feasible method.
For example, the metal can be added after the molecular sieve has
been synthesized, e.g., by incipient wetness or exchange process;
or can be added during molecular sieve synthesis.
[0063] The molecular sieve catalysts may be used in any suitable
form. For example, the molecular sieve catalyst may be used in
powder form, as extrudates, as pellets, or in any other suitable
form.
[0064] The molecular sieve catalysts for use herein may be coated
on a suitable substrate monolith or can be formed as extruded-type
catalysts, but are preferably used in a catalyst coating. In one
embodiment, the molecular sieve catalyst is coated on a
flow-through monolith substrate (i.e., a honeycomb monolithic
catalyst support structure with many small, parallel channels
running axially through the entire part) or filter monolith
substrate, such as a wall-flow filter, etc. The molecular sieve
catalyst for use herein may be coated, e.g., as a washcoat
component, on a suitable monolith substrate, such as a metal or
ceramic flow through monolith substrate or a filtering substrate,
such as a wall-flow filter or sintered metal or partial filter
(such as those disclosed in WO 01/80978 or EP 1057519).
Alternatively, the molecular sieves for use herein may be
synthesized directly onto the substrate and/or may be formed into
an extruded-type flow through catalyst.
[0065] Washcoat compositions containing the molecular sieves for
use herein for coating onto the monolith substrate for
manufacturing extruded type substrate monoliths may comprise a
binder, such as alumina, silica, (non-molecular sieve)
silica-alumina, naturally occurring clays, such as TiO.sub.2,
ZrO.sub.2, SnO.sub.2, CeO.sub.2, or mixtures thereof.
[0066] According to one embodiment, a method of using the catalyst
comprises exposing a catalyst to at least one reactant in a
chemical process. In other words, a method for reducing NO.sub.x in
a gas comprises exposing the gas having at least one reactant, such
as NO.sub.x, to a catalyst. As used herein, a chemical process for
reducing NO.sub.x in a gas can include any suitable chemical
process using a catalyst comprising a molecular sieve or zeolite.
Typical chemical processes include, but are not limited to, exhaust
gas treatment such as selective catalytic reduction using
nitrogenous reductants, lean NO.sub.x catalyst, catalyzed soot
filter, or a combination of any one of these with a NO.sub.x
adsorber catalyst or a three-way catalyst (TWC), e.g.,
NAC+(downstream)SCR or TWC+(downstream)SCR.
[0067] A method of treating NO.sub.x in an exhaust gas of a lean
burn internal combustion engine is to store the NO.sub.x from a
lean gas in a basic material and then to release the NO.sub.x from
the basic material and reduce it periodically using a rich gas. The
combination of a basic material (such as an alkali metal, alkaline
earth metal, or a rare earth metal), and a precious metal (such as
platinum), and possibly also a reduction catalyst component (such
as rhodium) is typically referred to as a NO adsorber catalyst
(NAC), a lean NO.sub.x trap (LNT), or a NO.sub.x storage/reduction
catalyst (NSRC). As used herein, NO.sub.x storage/reduction
catalyst, NO.sub.x trap, and NO.sub.x adsorber catalyst (or their
acronyms) may be used interchangeably.
[0068] Under certain conditions, during the periodically rich
regeneration events, NH.sub.3 may be generated over a NO.sub.x
adsorber catalyst. The addition of a SCR catalyst downstream of the
NO.sub.x adsorber catalyst may improve the overall system NO.sub.x
reduction efficiency. In the combined system, the SCR catalyst is
capable of storing the released NH.sub.3 from the NAC catalyst
during rich regeneration events and utilizes the stored NH.sub.3 to
selectively reduce some or all of the NO.sub.x that slips through
the NAC catalyst during the normal lean operation conditions. As
used herein, such combined systems may be shown as a combination of
their respective acronyms, e.g., NAC+SCR or LNT+SCR.
[0069] The catalysts may be effective in reducing or lean
conditions, e.g., as encountered in engine emissions. For example,
the lean portion of the cycle may consist of exposure to about 200
ppm NO, 10% O.sub.2, 5% H.sub.2O, 5% CO.sub.2 in N.sub.2, and the
rich portion of the cycle may consist of exposure to about 200 ppm
NO, 5000 ppm C.sub.3H.sub.6, 1.3% H.sub.2, 4% CO, 1% O.sub.2, 5%
H.sub.2O, 5% CO.sub.2 in N.sub.2. A reducing atmosphere is an
atmosphere having a lambda value of less than 1, i.e., the redox
composition is net reducing. A lean atmosphere is one having a
lambda value of greater than 1, i.e., the redox composition is net
oxidizing. The catalysts described herein may be particularly
effective when exposed to a reducing atmosphere, more particularly
a high temperature reducing atmosphere, such as when encountered
during the rich phase of a lean/rich excursion cycle.
[0070] A method for reducing NO.sub.x in a gas comprises exposing
the gas having at least one reactant to a catalyst. The reactant
may include any reactants typically encountered in the chemical
processes above. Reactants may include a selective catalytic
reductant, such as ammonia. Selective catalytic reduction may
include (1) using ammonia or a nitrogenous reductant or (2) a
hydrocarbon reductant (the latter also known as lean NO.sub.x
catalysis). Other reactants may include nitrogen oxides and oxygen.
In an exemplary embodiment, the catalysts described herein are used
during selective catalytic reduction of NO.sub.x with ammonia.
[0071] The at least one reactant, e.g., nitrogen oxides, is reduced
with the reducing agent at a temperature of at least 100.degree. C.
(e.g., from 150.degree. C. to 750.degree. C., or from 175.degree.
C. to 550.degree. C.).
[0072] For a reactant including nitrogen oxides, the reduction of
nitrogen oxides may be carried out in the presence of oxygen or in
the absence of oxygen. The source of nitrogenous reductant can be
ammonia, hydrazine, ammonium carbonate, ammonium carbamate,
ammonium hydrogen carbonate, ammonium formate or any suitable
ammonia precursor, such as urea.
[0073] The method may be performed on a gas derived from a
combustion process, such as from an internal combustion engine
(whether mobile or stationary), a gas turbine and coal or oil fired
power plants. The method may also be used to treat gas from
industrial processes such as refining, from refinery heaters and
boilers, furnaces, the chemical processing industry, coke ovens,
municipal waste plants and incinerators, coffee roasting plants,
etc.
[0074] In a particular embodiment, the method is used for treating
exhaust gas from a vehicular internal combustion engine with a
lean/rich cycle, such as a diesel engine, a gasoline engine, or an
engine powered by liquid petroleum gas or natural gas.
[0075] For a reactant including nitrogen oxides, the nitrogenous
reductant may be metered into the flowing exhaust gas only when it
is determined that the molecular sieve catalyst is capable of
catalyzing NO.sub.x reduction at or above a desired efficiency,
such as at above 100.degree. C., above 150.degree. C., or above
175.degree. C. The determination by the control means can be
assisted by one or more suitable sensor inputs indicative of a
condition of the engine selected from the group consisting of:
exhaust gas temperature, catalyst bed temperature, accelerator
position, mass flow of exhaust gas in the system, manifold vacuum,
ignition timing, engine speed, lambda value of the exhaust gas, the
quantity of fuel injected in the engine, the position of the
exhaust gas recirculation (EGR) valve and thereby the amount of EGR
and boost pressure.
[0076] Metering may be controlled in response to the quantity of
nitrogen oxides in the exhaust gas determined either directly
(using a suitable NO.sub.x sensor) or indirectly, such as using
pre-correlated look-up tables or maps--stored in the control
means--correlating any one or more of the abovementioned inputs
indicative of a condition of the engine with predicted NO.sub.x
content of the exhaust gas.
[0077] The molecular sieve supported metal catalysts described
herein may exhibit improved NH.sub.3--SCR activity, good thermal
stability, good hydrothermal stability, and tolerate repeated
lean/rich high temperature aging.
[0078] Treatment of Engine Exhaust (Cold Start Emissions)
[0079] SSZ-27 can also be used as a hydrocarbon trap, particularly
for reducing the emissions associated with the combustion of
hydrocarbon fuels.
[0080] Increasingly lower emissions standards for vehicles are
forcing automobile and catalyst manufacturers to focus on reducing
cold start hydrocarbon emissions since a large portion of
hydrocarbon emissions occur during the cold start period.
Consequently, control of emissions during the cold start operation
of a vehicle containing an internal combustion engine is essential.
Vehicles equipped with a conventional three-way catalytic converter
typically contain precious metals supported on a washcoat layer,
which in turn is deposited on a monolithic carrier. Fresh catalysts
start to operate at about 170.degree. C., while aged catalysts work
only at about 200.degree. C. to 225.degree. C. These catalysts
usually require at least 1-2 minutes before reaching such
temperatures, and during this "cold start" period, 70% to 80% of
the tailpipe hydrocarbon emissions occur. Such cold start emissions
often result in failure in the cycle of the U.S. Federal Test
Procedure (FTP), a standardized laboratory method for new vehicles
testing that is based on two simulated environments; namely, city
and highway, in which prototypes of new vehicle models are driven
by a trained driver in a laboratory on a dynamometer. At lower
temperatures where the catalyst in a catalytic converter is not
able to effectively convert incompletely burned hydrocarbons to
final combustion products, a hydrocarbon adsorber system should
trap hydrocarbons exhausted from the engine before they reach the
catalytic converter by adsorbing the incompletely burned
hydrocarbons. In the ideal case, desorption should occur at
temperatures exceeding catalyst light-off.
[0081] The critical factors for any emission hydrocarbon trap are
the adsorption capacity of the adsorbent, the desorption
temperature at which adsorbed hydrocarbons are desorbed and passed
to the catalytic converter (must be higher than the catalyst
operating temperature), and the hydrothermal stability of the
adsorbent. Molecular sieves such as zeolites have generally been
found to be useful adsorbents for this application in part due to
their hydrothermal stability under these conditions compared to
other materials.
[0082] A method of treating exhaust gas is disclosed that comprises
a hydrocarbon combustion product is provided, the method comprising
contacting the exhaust gas with molecular sieve SSZ-27 for a time
period effective to facilitate adsorption of the hydrocarbon
combustion product by the molecular sieve; passing a purge gas
through the molecular sieve to remove adsorbed hydrocarbon
combustion product therefrom; and contacting the purge gas
containing the removed hydrocarbon combustion product with a
hydrocarbon conversion catalyst. The phrase "method of treating
exhaust gas" generally refers to a method of reducing the emission
of exhaust gas pollutants, particularly those associated with the
incomplete combustion of hydrocarbon fuels. While not exclusively
limited thereto, the treatment method is primarily directed to
reducing the emission of incompletely combusted exhaust gas
components, such as occur during the cold start operation of an
internal combustion engine.
[0083] Exhaust gases produced from the combustion of a hydrocarbon
fuels in an internal combustion engine contain a plurality of
combustion components, typically including linear and branched
chain non-aromatic hydrocarbons, cycloaliphatic hydrocarbons,
aromatic hydrocarbons, polycyclic hydrocarbons and mixtures
thereof, as well as non-hydrocarbon components such as carbon
dioxide, water, nitrogen oxides and sulfur dioxide. Included within
such emissions compounds are aromatic hydrocarbons such as toluene,
xylene, benzene and mixtures thereof; linear and branched
hydrocarbons such as methane, ethane, ethylene, propane, propylene,
butane, pentane, hexane, heptane, octane; cycloaliphatic
hydrocarbons such as cyclohexane; and additional fuel additives
such as alcohols and methyl tertiary butyl ether (MTBE). The method
disclosed herein may be advantageously utilized to reduce such
hydrocarbon emissions, particularly during cold start operation of
an internal combustion engine, without being necessarily limited to
a particular hydrocarbon fuel. Typical hydrocarbon fuels benefiting
from the present invention include gasolines, diesel fuels,
aviation fuels, and the like.
[0084] The method may be applied as a batch process in which the
adsorbent is contacted with the exhaust gas batchwise or as a
continuous or semi-continuous process in which the exhaust gas
continuously or semi-continuously flows through the molecular
sieve. For example, the method may be applied as a continuous
process for purifying the exhaust gas from an internal combustion
engine in which a hydrocarbon fuel is combusted. In such a
continuous process, the exhaust gas may be first passed from the
source, such as from an internal combustion engine, to an adsorbent
molecular sieve (i.e., SSZ-27), so that components in the exhaust
gas, particularly hydrocarbons, are adsorbed by the molecular
sieve. Depending on the application, the adsorbed components are
typically subsequently desorbed from the molecular sieve and
brought into contact with a catalyst. In the case of an exhaust gas
purification system, SSZ-27 may be utilized to adsorb partially
combusted hydrocarbon components from the exhaust gas of an
internal combustion engine by contacting the molecular sieve with
the exhaust gas upstream of a catalytic converter. As the molecular
sieve and the catalyst subsequently heat up due to continued
throughflow of the exhaust gas, the components adsorbed onto the
molecular sieve are desorbed into the exhaust gas stream and passed
on to the converter. The desorbed hydrocarbon components are then
converted by the catalyst due to the improved hydrocarbon
conversion efficiency of the catalyst at higher operating
temperatures.
[0085] The method disclosed herein may also be carried out
sequentially and continuously with a flowing exhaust gas, that is,
wherein the exhaust gas continuously flows through the molecular
sieve and then through a downstream catalytic converter. In this
regard, the exhaust gas may also essentially function as the purge
gas for removing exhaust components desorbed from the molecular
sieve. A separate purge gas stream, or a separate purge gas stream
in conjunction with the exhaust gas stream, may also be used to
remove the desorbed exhaust gas components, including, without
limitation, air such as secondary air that is added to the exhaust
gas stream, an inert gas, or a mixture thereof.
[0086] The use of SSZ-27 in batch and semi-continuous systems is
also within the scope of this disclosure. For example, in a batch
process SSZ-27 may be contacted with a portion of the exhaust gas
such that the exhaust gas components, particularly incompletely
combusted hydrocarbon components produced during cold start
operation of an internal combustion engine, are adsorbed onto the
molecular sieve. Thereafter, when the operating temperature of a
catalyst such as in a catalytic converter has been reached, the
adsorbed components may be purged using a purge gas and passed to
the catalyst for conversion to exhaust gas emission products.
Similarly, in a semi-continuous process, the exhaust gas may be
initially passed through the molecular sieve and subsequently
through a downstream catalyst. After a period of time (e.g., when
the catalyst light-off temperature is reached), the exhaust gas may
be re-directed to pass only through the catalyst, such that the
molecular sieve is bypassed. A purge gas such as air may then be
passed through the molecular sieve to desorb the exhaust gas
components adsorbed onto the molecular sieve.
[0087] In one embodiment, the SSZ-27 molecular sieve may also
contain a metal cation selected from rare earth, Group 2 metals,
Groups 6-12 metals, and mixtures thereof (e.g., the metal cation
may be selected from Mg, Ca, Mn, Fe, Co, Ni, Pd, Pt, Cu, Ag, Au,
Zn, Cd, and mixtures thereof). In an alternate embodiment, the
molecular sieve contains a metal selected from Cu, Ag, Au and
mixtures thereof.
[0088] Although the molecular sieve may be utilized to adsorb
exhaust gas components by itself, it may also be utilized in an
adsorbent material that comprises the molecular sieve along with
additional materials such as binders and clays. The adsorbent
material may also comprise one or more catalysts in conjunction
with the molecular sieve. Such catalysts are generally known in the
art and are not specifically limited for use herein in conjunction
with the adsorbent material. Other adsorbent materials may also be
included along with molecular sieve SSZ-27 if desired, including
without limitation molecular sieves having a framework type such
as, e.g., AEI, AFX, *BEA, CHA, CON, IFR, MTT, MWW, MTW, SEW, SFE,
SFF, SFG, SFH, SFN, SFS, *SFV, SSY, STF, STT, -SVR, and mixtures
thereof, and the like.
EXAMPLES
[0089] The following illustrative examples are intended to be
non-limiting.
Example 1
Synthesis of SSZ-27
[0090] 1 mmole of the SDA in the OH form, in 2.5 g of water, was
added into a Teflon liner for a 23 mL Parr reactor. Next, 2 g of 1
N NaOH solution was added, followed by 1 g of water, and Na--Y
zeolite (CBV100, Zeolyst International, SiO.sub.2/Al.sub.2O.sub.3
mole ratio=5.1) as the aluminum source. Finally, 0.60 g of
CAB-O-SIL.RTM. M5 fumed silica (Cabot Corporation) was added. The
liner was capped and placed within a Parr steel autoclave reactor.
The autoclave was then fixed in a rotating spit (43 rpm) within an
oven heated at 170.degree. C. for 7-10 days. The solid products
were recovered, washed thoroughly with deionized water and
dried.
[0091] The resulting product was analyzed by powder XRD and
indicated that the material is unique.
Example 2
Seeded Synthesis of SSZ-27
[0092] Example 1 was repeated with the exception that
as-synthesized zeolite from Example 1 was added to the reaction
mixture as seed material (2% of the weight of the silicon source).
The crystallization was complete in 6-7 days, as confirmed by
powder XRD.
Example 3
Calcination of SSZ-27
[0093] The as-synthesized product of Example 1 was calcined inside
a muffle furnace under a flow of air heated to 595.degree. C. at a
rate of 1.degree. C./minute and held at 595.degree. C. for 5 hours,
cooled and then analyzed by powder XRD. The powder XRD pattern of
the resulting product indicated that the material remains stable
after calcination to remove the organic SDA.
Example 4
Ammonium-Ion Exchange of SSZ-27
[0094] The calcined material from Example 3 (Na-SSZ-27) was treated
with 10 mL (per g of zeolite) of a 1 N ammonium nitrate solution at
90.degree. C. for 2 hours. The solution was cooled, decanted off
and the same process repeated.
[0095] The product (NH.sub.4--SSZ-27) after drying was subjected to
a micropore volume analysis using N.sub.2 as adsorbate and via the
BET method. The zeolite exhibited a micropore volume of 0.11
cm.sup.3/g and indicates that SSZ-27 has microporous character.
Example 5
Methanol Conversion
[0096] The product made in Example 4 was pelletized at 5 kpsi,
crushed and meshed to 20-40. 0.25 g of catalyst (diluted 4:1 v/v
with alundum) was centered in a stainless steel downflow reactor in
a split tube furnace. The catalyst was pre-heated in-situ under
flowing nitrogen at 400.degree. C. A feed of 10% methanol in
nitrogen was introduced into the reactor at a rate of 1.0 h.sup.-1
WHSV.
[0097] Reaction data was collected using a plug flow and an Agilent
on-line gas chromatograph with an FID detector. Reaction products
were analyzed at 60 minutes and 120 minutes on an HP-PLOT Q column.
The results are summarized in Table 4.
TABLE-US-00004 TABLE 4 Product 1 Hour Data 2 Hour Data Methane 9.0
4.5 Ethane 13.3 2.2 Ethylene 13.5 33.8 Propane 3.3 11.9 Propylene
4.8 28.3 Summed Butanes/Butenes 11.5 13.5 Summed Pentanes/Pentenes
25.0 5.5
[0098] The products shown in Table 4 are consistent with those for
a small pore zeolite in terms of product shape-selectivity in the
reaction of methanol being catalytically converted to olefins of
mostly C.sub.2-C.sub.4 size.
[0099] As used herein, the term "comprising" means including
elements or steps that are identified following that term, but any
such elements or steps are not exhaustive, and an embodiment can
include other elements or steps.
[0100] Unless otherwise specified, the recitation of a genus of
elements, materials or other components, from which an individual
component or mixture of components can be selected, is intended to
include all possible sub-generic combinations of the listed
components and mixtures thereof.
[0101] All documents cited in this application are herein
incorporated by reference in their entirety to the extent such
disclosure is not inconsistent with this text.
* * * * *