Molecular sieve abstract
The present invention relates to a silicoaluminophosphate molecular
sieve comprising at least one intergrown phase of molecular sieves
having AEI and CHA framework types, wherein said intergrown phase
has an AEI/CHA ratio of from about 5/95 to 40/60 as determined by
DIFFaX analysis, using the powder X-ray diffraction pattern of a
calcined sample of said silicoaluminophosphate molecular sieve.
It also relates to methods for its preparation and to its use in
the catalytic conversion of methanol to olefins.
Molecular sieve claims
19. A process for making an olefin product from an oxygenate feedstock
comprising contacting said oxygenate feedstock with a catalyst comprising
a silicoaluminophosphate molecular sieve comprising at least one
intergrown phase of molecular sieves having AEI and CHA framework
types, wherein said intergrown phase has an AEI/CHA ratio of from
about 5/95 to 40/60 as determined by DIFFaX analysis, using the
powder X-ray diffraction pattern of a calcined sample of said silicoaluminophosphate
molecular sieve, under conditions effective to form an olefin product.
20. The process of claim 19 wherein the oxygenate is selected
from methanol; ethanol; n-propanol; isopropanol; C.sub.4-C.sub.20
alcohols; methyl ethyl ether; dimethyl ether; diethyl ether; di-isopropyl
ether; formaldehyde; dimethyl carbonate; dimethyl ketone; acetic
acid; and mixtures thereof.
21. The process of claim 20 wherein the oxygenate is selected
from methanol, dimethyl ether, and mixtures thereof.
22. The process of claim 19 wherein the oxygenate is methanol.
23. The process of claim 19 wherein the selectivity to ethylene
and propylene is equal to or greater than 75.0%.
24. The process of claim 23 wherein the ethylene to propylene
ratio is equal to or greater than 0.75.
25. The process of claim 24 wherein the selectivity to propane
is equal to or lower than 1.0%.
26. The process of claim 19 wherein the selectivity to propane
is equal to or smaller than 1.0%.
27. A silicoaluminophosphate molecular sieve exhibiting an X-ray
diffraction pattern having at least one reflection peak in each
of the following ranges in the 5 to 25 (2.theta.) range:
4 2.theta. (CuK.alpha.) 9.3-9.6 12.7-13.0 13.8-14.0 15.9-16.1 17.7-18.1
18.9-19.1 20.5-20.7 23.7-24.0
and having no reflection peak in the 9.8 to 12.0 (2.theta.) range.
28. The silicoaluminophosphate molecular sieve of claim 27 exhibiting
an X-ray diffraction pattern having no broad feature centered at
about 16.9 (2.theta.).
29. The silicoaluminophosphate molecular sieve of claim 28 wherein
the reflection peak in the 17.7-18.1 (2.theta.) range has a relative
intensity between 0.09 and 0.40 with respect to the reflection peak
at 17.9 (2.theta.) in the diffraction pattern of SAPO-34 all diffraction
patterns being normalized to the intensity value of the reflection
peak in the 20.5-20.7 (2.theta.) range.
30. The silicoaluminophosphate molecular sieve of claim 28 wherein
the reflection peak in the 17.7-18.1 (2.theta.) range has a relative
intensity between 0.10 and 0.35 with respect to the reflection peak
at 17.9 (2.theta.) in the diffraction pattern of SAPO-34 all diffraction
patterns being normalized to the intensity value of the reflection
peak in the 20.5-20.7 (2.theta.) range.
31. The silicoaluminophosphate molecular sieve of claim 28 wherein
the silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3) in
said silicoaluminophosphate molecular sieve ranges from 0.01 to
0.25.
32. The silicoaluminophosphate molecular sieve of claim 27 wherein
the silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3) in
said silicoaluminophosphate molecular sieve ranges from 0.02 to
0.20.
33. The silicoaluminophosphate molecular sieve of claim 27 wherein
the silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3) in
said silicoaluminophosphate molecular sieve ranges from 0.03 to
0.19.
34. The silicoaluminophosphate molecular sieve of claim 28 wherein
the molecular sieve is comprised of crystalline plates, platelets
or stacked platelets.
35. The silicoaluminophosphate molecular sieve of claim 34 wherein
the average smallest crystal dimenstion is less than 0.1 micron.
36. A catalyst comprising the silicoaluminophosphate molecular
sieve of claim 28 and a binder.
37. A method for preparing the molecular sieve of claim 1 that
comprises (a) combining a reactive source of silicon, a reactive
source of phosphorus and a hydrated aluminum oxide in the presence
of an organic structure directing agent (template) to form a mixture;
(b) mixing and heating continuously the mixture prepared at step
a) up to the crystallization temperature; (c) maintaining the mixture
at the crystallization temperature and under stirring for a period
of time of from 2 to 150 hours; (d) recovering crystals of the silicoaluminophosphate
molecular sieve (e) wherein the mixture prepared at step a) has
a molar composition within the following ranges:P.sub.2O.sub.5:Al.sub.2O.sub.3
from 0.6:1 to 1.2:1SiO.sub.2:Al.sub.2O.sub.3 from 0.005:1 to 0.35:1H.sub.2O:Al.sub.2O.s-
ub.3 from 10:1 to 40:1and the template is a tetraethylammonium compound.
38. The method for preparing the molecular sieve of claim 37 wherein
the crystallization temperature is between about 120.degree. C.
and 250.degree. C., preferably from 130.degree. C. and 200.degree.
C., most preferably from 150.degree. C. to 185.degree. C.
39. The method for preparing the molecular sieve of claim 37 wherein
step b) is carried out for a period of from about 5 to about 16
hours, preferably of from about 6 to 12 hours.
40. The method for preparing the molecular sieve of claim 38 wherein
the template is a tetraethylammonium compound, preferably tetraethylammonium
hydroxide.
41. The method for preparing the molecular sieve of claim 37 wherein
the hydrated aluminum oxide is pseudoboehmite.
42. The method for preparing the molecular sieve of claim 37 wherein
SAPO-34 seeds are combined with the reactive source of silicon,
the reactive source of phosphorus, the hydrated aluminum oxide and
the organic structure directing agent (template).
Molecular sieve description
[0001] This application claims priority to U.S. Provisional Patent
Application No. 60/272061 filed Mar. 1 2001 and U.S. patent
application Ser. No. 09/924016 filed Aug. 7 2001 which is fully
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to new silicoaluminophosphate molecular
sieves, to methods of making them and to their use in a method of
making an olefin product by contacting these silicoaluminophosphate
molecular sieves with an oxygenate feedstock. In particular, this
invention relates to silicoaluminophosphate molecular sieves comprising
at least one intergrown phase of AEI and CHA molecular sieves.
BACKGROUND OF THE INVENTION
[0003] Silicoaluminophosphate (SAPO) molecular sieves contain a
three-dimensional microporous crystal framework structure of [SiO.sub.2],
[AlO.sub.2] and [PO.sub.2] corner sharing tetrahedral units. The
[PO.sub.2] tetrahedral units are provided by a variety of compositions
including phosphoric acid, organic phosphates such as triethyl phosphate,
and aluminophosphates. The [AlO.sub.2] tetrahedral units are provided
by a variety of compositions including aluminum alkoxides such as
aluminum isopropoxide, aluminum phosphates, aluminum hydroxide,
sodium aluminate, and pseudoboehmite. The [SiO.sub.2] tetrahedral
units are provided by a variety of compositions including silica
sols and silicon alkoxides such as tetraethylorthosilicate and fumed
silica.
[0004] Aluminophosphate (ALPO) molecular sieves are crystalline
microporous oxides which can have an AlPO.sub.4 framework. ALPOs
can have additional elements within the framework, typically have
uniform pore dimensions ranging from about 3 Angstroms to about
10 Angstroms.
[0005] Light olefins, particularly ethylene and propylene, can
be produced by contacting a feedstock containing oxygenated organic
compounds, such as methanol or dimethyl ether, with a SAPO and/or
ALPO-containing catalyst. See for example U.S. Pat. No. 4499327.
[0006] SAPO-34 and SAPO-18 have been reported as suitable catalysts
for light olefin production from methanol. SAPO-34 belongs to the
family of molecular sieves having the structure type of the zeolitic
mineral chabazite (CHA). The preparation and characterization of
SAPO-34 has been reported in several publications, including U.S.
Pat. No. 4440871; J. Chen et al. in "Studies in Surface Science
and Catalysis", Vol. 84 pp. 1731-1738; U.S. Pat. No. 5279810;
J. Chen et al. in "Journal of Physical Chemistry", Vol.
98 pp. 10216-10224 (1994); J. Chen et al. in "Catalysis Letters",
Vol. 28 pp. 241-248 (1994); A. M. Prakash et al. in "Journal
of the Chemical Society, Faraday Transactions" Vol. 90(15),
pp. 2291-2296 (1994); Yan Xu et al. in "Journal of the Chemical
Society, Faraday Transactions" Vol. 86(2), pp. 425-429 (1990),
all of which are herein fully incorporated by reference.
[0007] SAPO-18 belongs to the family of molecular sieves having
the AEI structure type. Other molecular sieves with the AEI structure
type are ALPO-18 and RUW-18. The preparation and characterization
of molecular sieves with AEI structure type has been reported in
several publications, including U.S. Pat. No. 4440871; J. Chen
et al. in "Studies in Surface Science and Catalysis",
Vol. 84 pp. 1731-1738; U.S. Pat. No. 5279810; J. Chen et al.
in "Journal of Physical Chemistry", Vol. 98 pp. 10216-10224
(1994); J. Chen et al. in "Catalysis Letters", Vol. 28
pp. 241-248 (1994); pp. 2291-2296 (1994); Yan Xu et al. in "Journal
of the Chemical Society, Faraday Transactions" Vol. 86(2),
pp. 425-429 (1990); U.S. Pat. No. 5609843 all of which are herein
fully incorporated by reference.
[0008] International Application PCT/NO97/00272 published as WO
98/15496 relates to a molecular sieve that is a mixed phase comprising
silicoaluminophosphates of AEI and CHA structure, referred to as
RUW-19. RUW-19 is said to produce an X-ray diffractogram that includes
peaks at the following 2.theta. values: 9.3-9.5 10.4-10.6 12.7-12.9
13.8-14.0 15.9-16.1 16.7-16.9 18.9-19.0 20.5-10.7 21.0-21.3
23.7-24.0 25.7-26.0 30.9-31.1. FIG. 1 of this publication shows
the XRD-traces in the 15-33 (2.theta.) region for RUW-19 (examples
1 to 3), SAPO-18 (example 4), SAPO-34 (example 5) and a physical
mixture of SAPO-18 and SAPO-34 (example 6). This publication suggests
that RUW-19 is different from a physical mixture of SAPO-18 and
SAPO-34. RUW-19 has peaks characteristic of an AEI structure type
molecular sieve, except that the broad feature centered at about
16.9 (2.theta.) in RUW-19 replaces the pair of reflections centered
at about 17.0 (2.theta.) in SAPO-18 or AEI. Also, RUW-19 does not
have the reflections associated with SAPO-34 or CHA centered at
17.8 (2.theta.) and 24.8 (2.theta.). According to WO 98/15496 RUW-19
is suitable for the conversion of methanol to olefins. Throughout
this description, the XRD reflection values are referred to as (2.theta.),
which is synonymous to the expression "degrees 2.theta.".
[0009] In the conversion of methanol to olefins, SAPO-34 exhibits
relatively high product selectivity to ethylene and propylene, and
low product selectivity to paraffin and olefin with four or more
carbons (C.sub.4.sup.+ olefin). Catalysts containing SAPO-34 are
thus particularly suited for the conversion of methanol to olefin.
Despite its good performances, carbonaceous deposits, commonly referred
to as coke, quickly form in the catalytic cages of SAPO-34. Eventually,
the presence of too much coke will clog up the cage and deactivate
the catalyst. Also, despite its low product selectivity to paraffin,
SAPO-34 still produces by-products. Separating by-products from
the desired ethylene and propylene adds additional cost to the methanol
to olefin conversion process. Therefore, there is a need to find
new molecular sieves that have good product selectivity and produce
few by-products.
SUMMARY OF THE INVENTION
[0010] The present invention relates to silicoaluminophosphate
molecular sieves comprising at least one intergrown phase of molecular
sieves having AEI and CHA framework types, wherein said intergrown
phase has an AEI/CHA ratio of from about 5/95 to 40/60 as determined
by DIFFaX analysis, using the powder X-ray diffraction pattern of
a calcined sample of said silicoaluminophosphate molecular sieve.
[0011] The silicoaluminophosphate molecular sieves of the present
invention exhibit characteristic X-ray diffraction features. In
an embodiment of the invention, the molecular sieves of the invention
possess silica to alumina molar ratios (SiO.sub.2/Al.sub.2O.sub.3)
ranging from 0.01 to 0.25.
[0012] The molecular sieves of the present invention may conveniently
be prepared by a process that comprises a) combining a reactive
source of silicon, a reactive source of phosphorus and a hydrated
aluminum oxide in the presence of an organic structure directing
agent (template) to form a mixture; b) mixing and heating continuously
the mixture prepared at step a) up to the crystallization temperature;
c) maintaining the mixture at the crystallization temperature and
under stirring for a period of time of from 2 to 150 hours; d) recovering
crystals of the silicoaluminophosphate molecular sieve wherein the
mixture prepared at step a) has a molar composition within the following
ranges:
P.sub.2O.sub.5:Al.sub.2O.sub.3 from 0.6:1 to 1.2:1
SiO.sub.2:Al.sub.2O.sub.3 from 0.005:1 to 0.35:1
H.sub.2O:Al.sub.2O.sub.3 from 10:1 to 40:1
[0013] and the template is a tetraethylammonium compound. In an
embodiment of the invention, the organic structure directing agent
is tetraethylammonium hydroxide.
[0014] The silicoaluminophosphate molecular sieves of the present
invention exhibit good catalytic performances in processes for making
olefin products from an oxygenate feedstock, such as a feedstock
comprising methanol.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIGS. 1a and 1b show DIFFaX simulated diffraction patterns
for intergrown phases having various AEI/CHA ratios;
[0016] FIG. 2 shows the XRD diffraction pattern of a silicoaluminophosphate
according to the invention, of MTO-RUW-356 of WO 98/15496 and DIFFaX
simulated diffraction patterns for intergrown phases having various
AEI/CHA ratios;
[0017] FIG. 3 shows DIFFaX simulated diffraction patterns in the
15 to 19 2.theta. range for intergrown phases having various AEI/CHA
ratios;
[0018] FIG. 4a shows a SEM picture of a crystalline silicoaluminophosphate
molecular sieve according to the invention, obtained on a JEOL JSM-6340F
Field Emission Scanning Electron Microscope, using a magnification
of 20000 times at a voltage of 2 keV.
[0019] FIG. 4b shows a TEM picture of a crystalline silicoaluminophosphate
molecular sieve according to the invention; and
[0020] FIG. 5 shows the XRD diffraction pattern of a silicoaluminophosphate
molecular sieve according to the invention and, by way of comparison,
of MTO-RUW-356 and MTO-RUW-335T of WO 98/15496.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention relates to a silicoaluminophosphate
molecular sieve comprising at least one intergrown phase of molecular
sieves having AEI and CHA framework types, wherein said intergrown
phase has an AEI/CHA ratio of from about 5/95 to 40/60 as determined
by DIFFaX analysis, using the powder X-ray diffraction pattern of
a calcined sample of said silicoaluminophosphate molecular sieve.
[0022] Intergrown molecular sieve phases are disordered planar
intergrowths of molecular sieve frameworks. We refer to the "Catalog
of Disordered Zeolite Structures", 2000 Edition, published
by the Structure Commission of the International Zeolite Association
and to the "Collection of Simulated XRD Powder Patterns for
Zeolites", M. M. J. Treacy and J. B. Higgins, 2001 Edition,
published on behalf of the Structure Commission of the International
Zeolite Association for a detailed explanation on intergrown molecular
sieve phases.
[0023] Regular crystalline solids are periodically ordered in three
dimensions. Structurally disordered structures show periodic ordering
in dimensions less than three, i.e. in two, one or zero dimensions.
This phenomenon is called stacking disorder of structurally invariant
Periodic Building Units. Crystal structures built from Periodic
Building Units are called end-member structures- if periodic ordering
is achieved in all three dimensions. Disordered structures are those
where the stacking sequence of the Periodic Building Units deviates
from periodic ordering up to statistic stacking sequences.
[0024] The molecular sieves of the present invention are disordered
planar intergrowths of end-member structures AEI and CHA. We refer
to A. Simmen et al. in Zeolites (1991), Vol. 11 pp. 654-661 describing
the structure of molecular sieves with AEI and CHA framework types.
For AEI and CHA, the Periodic Building Unit is a double six ring
layer. There are two types of layers "a" and "b",
which are identical except "b" is the mirror image of
"a" (180.degree. rotation about the plane normal or mirror
operation perpendicular to the plane normal). When layers of the
same type stack on top of one another, i.e. aaa or bbb, the framework
type CHA is generated. When layers "a" and "b"
alternate, ie, abab, the framework type AEI is generated. The molecular
sieves of the present invention are made of stackings of layers
"a" and "b" which contain regions of CHA framework
type and regions of AEI framework type. Each change of CHA to AEI
framework type is a stacking disorder or planar fault.
[0025] Preferably, the molecular sieves of the invention possess
an AEI/CHA ratio of from about 7/93 to 38/62 more preferably from
about 8/92 to 35/65 even more preferably from about 9/91 to 33/67
most preferably from about 10/90 to 30/70 as determined by DIFFaX
analysis, using the powder X-ray diffraction pattern of a calcined
sample of said silicoaluminophosphate molecular sieve.
[0026] In the case of crystals with planar faults, interpretation
of XRD diffraction diffraction patterns requires an ability to simulate
the effects of stacking disorder. DIFFaX is a computer program based
on a mathematical model for calculating intensities from crystals
containing planar faults (see M. M. J. Tracey et al., Proceedings
of the Royal Chemical Society, London, A (1991), Vol. 433 pp.499-520).
DIFFaX is the simulation program selected by and available from
the International Zeolite Association to simulate the XRD powder
patterns for intergrown phases of zeolites (see "Collection
of Simulated XRD Powder Patterns for Zeolites"by M. M. J. Treacy
and J. B. Higgins, 2001 Fourth Edition, published on behalf of
the Structure Commission of the International Zeolite Association).
It has also been used to theoretically study intergrown phases of
AEI, CHA, tmm and KFI, as reported by K. P. Lillerud et al. in "Studies
in Surface Science and Catalysis", 1994 Vol. 84 pp. 543-550.
DIFFaX is a well-known and established method to characterize crystalline
materials with planar faults such as the intergrown molecular sieves
of the present invention.
[0027] FIGS. 1a and 1b show the simulated diffraction patterns
obtained for intergrown phases having various AEI/CHA ratios. FIG.
1a shows the diffraction patterns in the 15 to 35 (2.theta.) range
simulated by DIFFaX for intergrown phases with AEI/CHA ratios of
0/100 (CHA end-member), 10/90 (AEI/CHA=0.11), 20/80 (AEI/CHA=0.25),
30/70 (AEI/CHA=0.41), 40/60 (AEI/CHA=0.67), 50/50 (AEI/CHA=1.00)
and 60/40 (AEI/CHA=1.50). FIG. 1b shows the diffraction patterns
in the range of 5 to 20 (2.theta.) simulated by DIFFaX for intergrown
phases with AEI/CHA ratios of 0/100 (CHA end-member), 10/90 (AEI/CHA=0.11),
20/80 (AEI/CHA=0.25), 50/50 (AEI/CHA=1.0), 70/30 (AEI/CHA=2.33),
80/20 (AEI/CHA=4.0), 100/0 (AEI end-member). All XRD diffraction
patterns are normalized between 0 and 1. Normalized intensity values
are determined by normalizing the intensities of the diffraction
peaks to the intensity value of the reflection in the 20.5-20.7
(2.theta.) range. For example, if the peak in the 20.5-20.7 (2.theta.)
range has an absolute intensity of 50 counts and the peak at 26.0
(2.theta.) has an absolute intensity of 16 counts, then the normalized
intensity of the peak at 26.0 (2.theta.) is 0.32. Normalization
of intensity values allows for the comparison between diffraction
patterns of the intensity of an X-ray diffraction peak at certain
2.theta. value.
[0028] As the ratio of AEI increases relative to CHA in the intergrown
phase, one can observe a decrease in intensity of certain peaks,
for example, the peak at about 2.theta.=25.0 and an increase in
intensity of other peaks, for example the peak at about 2.theta.=17.05
and the shoulder at 2.theta.=21.2. Intergrown phases with AEI/CHA
ratios of 50/50 and above (AEI/CHA >1.0) show a broad feature
centered at about 16.9 (2.theta.).
[0029] FIG. 2 shows the powder XRD diffraction pattern of a silicoaluminophosphate
according to the present invention (Sample B) and, by way of comparison,
the XRD diffraction pattern of MTO-RUW-356 described in example
1 and FIG. 1 of WO 98/15496 as well as DIFFaX simulated diffraction
patterns for intergrowths with varying AEI/CHA ratios. The diffraction
pattern of MTO-RUW-356 was digitized and re-normalized. DIFFaX analysis
indicates that Sample B according to the present invention has an
AEI/CHA ratio of 25/75 (AEI/CHA ratio of 0.33) and that MTO-RUW-356
has an AEI/CHA ratio of 70/30 (AEI/CHA ratio of 2.3). MTO-RUW-356
has a broad feature centered at about 16.9 (2.theta.).
[0030] The silicoaluminophosphates of the present invention are
characterized by powder XRD diffraction patterns obtained from samples
after calcination and avoiding re-hydration after calcination, having
at least the reflections in the 5 to 25 (2.theta.) range as shown
in Table 1:
1TABLE 1 2.theta. (CuK.alpha.) 9.3-9.6 12.7-13.0 13.8-14.0 15.9-16.1
17.7-18.1 18.9-19.1 20.5-20.7 23.7-24.0
[0031] The XRD diffraction patterns of the intergrown phases of
AEI/CHA according to the present invention are also characterized
by the absence of peaks in the 9.8 to 12.0 (2.theta.) range and
the absence of any broad feature centered at about 16.9 (2.theta.).
A further characteristic is the presence of a peak in the 17.7 to
18.1 (2.theta.) range. The reflection peak in the 17.7-18.1 (2.theta.)
range has a relative intensity between 0.09 and 0.4 preferably
between 0.1 and 0.35 with respect to the reflection peak at 17.9
(2.theta.) in the diffraction pattern of SAPO-34 all diffraction
patterns being normalized to the intensity value of the reflection
peak in the 20.5-20.7 (2.theta.) range.
[0032] FIG. 3 illustrates the evolution of these XRD features in
the 15 to 19 (2.theta.) range for AEI/CHA ratios of 0/100 (CHA end-member),
10/90 (AEI/CHA=0.11), 20/80 (AEI/CHA=0.25), 30/70 (AEI/CHA=0.41),
40/60 (AEI/CHA=0.67), 50/50 (AEI/CHA=1.00) and 60/40 (AEI/CHA=1.50).
[0033] The silicoaluminophosphate molecular sieves of the present
invention comprise at least one intergrown phase of AEI and CHA
molecular sieves. Preferably the CHA molecular sieve is SAPO-34
and the AEI molecular sieve is selected from SAPO-18 ALPO-18 or
a mixture of SAPO-18 and ALPO-18. Preferably, the silicoaluminophosphates
of the present invention have a silica to alumina molar ratios (SiO.sub.2/Al.sub.2O.sub.-
3) ranging from 0.01 to 0.25 more preferably from 0.02 to 0.20
even more preferably from 0.03 to 0.19 most preferably from 0.03
to 0.08. The silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3)
is conveniently determined by chemical analysis.
[0034] In one embodiment, the silicoaluminophosphates of the present
invention are prepared by submitting a mixture comprising a reactive
source of silicon, a reactive source of aluminum and a reactive
source of phosphorus, in the presence of an organic structure directing
agent (template) to hydrothermal treatment under autogenous pressure.
[0035] The molecular sieves of the present invention may conveniently
be prepared by a process that comprises
[0036] a) combining a reactive source of silicon, a reactive source
of phosphorus and a hydrated aluminum oxide in the presence of an
organic structure directing agent (template) to form a mixture;
[0037] b) mixing and heating continuously the mixture prepared
at step a) up to the crystallization temperature;
[0038] c) maintaining the mixture at the crystallization temperature
and under stirring for a period of time of from 2 to 150 hours;
[0039] d) recovering crystals of the silicoaluminophosphate molecular
sieve wherein the mixture prepared at step a) has a molar composition
within the following ranges:
P.sub.2O.sub.5:Al.sub.2O.sub.3 from 0.6:1 to 1.2:1
SiO.sub.2:Al.sub.2O.sub.3 from 0.005:1 to 0.35:1
H.sub.2O:Al.sub.2O.sub.3 from 10:1 to 40:1
[0040] and the template is a tetraethylammonium compound.
[0041] Preferably, the mixture prepared at step a) has a molar
composition within the following ranges:
P.sub.2O.sub.5:Al.sub.2O.sub.3 from 0.8:1 to 1.1:1
SiO.sub.2:Al.sub.2O.sub.3 from 0.01:1 to 0.3:1 most preferably
from 0.015:1 to 0.25:1
H.sub.2O:Al.sub.2O.sub.3 from 10:1 to 40:1.
[0042] It will be understood that the molar ratio of silica to
alumina in the reaction mixture will influence the silica to alumina
ratio of the molecular sieve after synthesis.
[0043] The reactive source of silicon used in the preparation of
the silicoaluminophosphates of the invention may be a silicate,
e.g., fumed silica, such as Aerosil (available form Degussa), a
tetraalkyl orthosilicate, or an aqueous colloidal suspension of
silica, for example one sold by E.I. du Pont de Nemours under the
tradename Ludox.
[0044] Examples of suitable hydrated aluminum oxides that may be
used according to the present invention include boehmite and pseudoboehmite.
Preferably, pseudoboehmite is used.
[0045] The organic structure directing agent, also called template,
is a tetraethyl ammonium compound selected from the group of tetraethyl
ammonium hydroxide (TEAOH), tetraethyl ammonium phosphate, tetraethyl
ammonium fluoride, tetraethyl ammonium bromide, tetraethyl ammonium
chloride, tetraethyl ammonium acetate. Most preferably, the template
is tetraethyl ammonium hydroxide.
[0046] In order to prepare the silicoaluminophosphates of the invention,
the reaction mixture obtained by mixing the reactive sources of
alumina, silica, phosphorus and organic structure directing agent
is submitted to hydrothermal treatment. The reaction mixture is
heated continuously up to the crystallization temperature that may
range from about 120.degree. C. and 250.degree. C., preferably from
130.degree. C. and 200.degree. C., most preferably from 150.degree.
C. to 185.degree. C. Heating up to the crystallization temperature
is typically carried for a period of time ranging from about 5 to
about 16 hours, preferably from about 6 to 12 hours, most preferably
from about 6 to 9 hours.
[0047] The temperature may be increased stepwise or continuously.
However, continuous heating is preferred. The reaction may be kept
static, tumbled or stirred during heat-up. Preferably, the reaction
is tumbled or stirred, most preferably stirred.
[0048] The temperature is then maintained at the crystallization
temperature for a period of time ranging from 2 to 150 hours, the
crystallization time depending mainly on the crystallization temperature.
Heat is applied for a period of time effective to form crystalline
product. In a specific embodiment, the reaction is kept at the crystallization
temperature for a period of from 20 to 60 hours.
[0049] The silicoaluminophosphate synthesis may be aided by seeds
form a previous synthesis or by seeds of another molecular sieve,
conveniently, SAPO-34 seeds. Hydrothermal treatment may be carried
out with or without agitation, for example stirring or tumbling
(rotating the vessel about a horizontal axis), but is preferably
carried out with agitation. Preferably, the mixture is stirred during
the period required to heat the reaction mixture to the crystallization
temperature and for the period of crystallization.
[0050] Typically, the crystalline molecular sieve product is formed
as a slurry and can be recovered by standard means, such as by centrifugation
or filtration. The separated molecular sieve product can also be
washed, recovered by centrifugation or filtration and dried.
[0051] As a result of the molecular sieve crystallization process,
the recovered molecular sieve contains within its pores at least
a portion of the template used. The crystalline structure essentially
wraps around the template, and the template should be removed to
obtain catalytic activity. In a preferred embodiment, activation
is performed in such a manner that the template is removed from
the molecular sieve, leaving active catalytic sites with the microporous
channels of the molecular sieve open for contact with a feedstock.
The activation process is typically accomplished by calcining, or
essentially heating the molecular sieve comprising the template
at a temperature of from 200 to 800.degree. C. in the presence of
an oxygen-containing gas. In some cases, it may be desirable to
heat the molecular sieve in an environment having a low oxygen concentration.
This type of process can be used for partial or complete removal
of the template from the intracrystalline pore system. In other
cases, particularly with smaller templates, complete or partial
removal from the sieve can be accomplished by conventional desorption
processes.
[0052] The crystalline silicoaluminophosphate molecular sieves
of the present invention are typically plates, platelets or stacked
platelets. These plates, platelets of stacked platelets can be seen
as flattened cubes with the smallest dimension being defined as
Z and the largest dimension being defined as Y, preferably with
Z/Y less than 1. Preferably, Z/Y is between 0.05 and 0.5. FIG. 4
shows an electron microscopy picture of a crystalline silicoaluminophosphate
molecular sieve according to the invention. Preferably, the average
smallest crystal dimension of the molecular sieve of the invention
is less than 0.1 micron.
[0053] Once the molecular sieve is made, it can be formulated into
a catalyst by combining the molecular sieve with other materials
that provide additional hardness or catalytic activity to the finished
catalyst product. When combined with these other materials, the
resulting composition is typically referred to as a silicoaluminophosphate
catalyst, with the catalyst comprising the SAPO molecular sieve.
This invention also relates to catalysts comprising the molecular
sieves of this invention.
[0054] Materials which can be blended with the molecular sieve
can be various inert or catalytically active materials, or various
binder materials. These materials include compositions such as kaolin
and other clays, various forms of rare earth metals, other non-zeolite
catalyst components, zeolite catalyst components, alumina or alumina
sol, titania, zirconia, quartz, silica or silica sol, and mixtures
thereof. These components are also effective in reducing overall
catalyst cost, acting as a thermal sink to assist in heat shielding
the catalyst during regeneration, densifying the catalyst and increasing
catalyst strength. When blended with non-silicoaluminophosphate
molecular sieve materials, the amount of molecular sieve which is
contained in the final catalyst product ranges from 10 to 90 weight
percent of the total catalyst, preferably 20 to 70 weight percent
of the total catalyst.
[0055] The molecular sieves synthesized in accordance with the
present method can be used to dry gases and liquids; for selective
molecular separation based on size and polar properties; as ion-exchangers;
as catalysts in cracking, hydrocracking, disproportionation, alkylation,
isomerization, oxidation; as chemical carriers; in gas chromatography;
and in the petroleum industry to remove normal paraffins from distillates.
[0056] The silicoaluminophosphates of the present invention are
particularly suited for the catalytic conversion of oxygenates to
hydrocarbons. Accordingly, the present invention also relates to
a method for making an olefin product from an oxygenate feedstock
wherein said oxygenate feedstock is contacted with the catalyst
of this invention comprising the molecular sieve of this invention
under conditions effective to convert the oxygenate feedstock to
olefin products. When compared to other silicoaluminophosphates
under the same operating conditions, the silicoaluminophosphates
of the present invention exhibit higher selectivity to light olefins,
and produce fewer by-products.
[0057] In this process a feedstock containing an oxygenate contacts
a catalyst comprising the molecular sieve in a reaction zone of
a reactor at conditions effective to produce light olefins, particularly
ethylene and propylene. Typically, the oxygenate feedstock is contacted
with the catalyst containing the molecular sieve when the oxygenate
is in vapor phase. Alternately, the process may be carried out in
a liquid or a mixed vapor/liquid phase. When the process is carried
out in a liquid phase or a mixed vaporaiquid phase, different conversions
and selectivities of feed-to-product may result depending upon the
catalyst and reaction conditions.
[0058] In this oxygenate conversion process, olefins can generally
be produced at a wide range of temperatures. An effective operating
temperature range can be from about 200.degree. C. to 700.degree.
C. At the lower end of the temperature range, the formation of the
desired olefin products may become markedly slow. At the upper end
of the temperature range, the process may not form an optimum amount
of product. An operating temperature of at least 300.degree. C.,
and up to 525.degree. C. is preferred.
[0059] In a preferred embodiment, it is highly desirable to operate
at a temperature of at least 300.degree. C. and a Temperature Corrected
Normalized Methane Sensitivity (TCNMS) of less than about 0.016
preferably less than about 0.012 more preferably less than about
0.01. It is particularly preferred that the reaction conditions
for making olefin from oxygenate comprise a WHSV of at least about
20 hr.sup.-1 producing olefins and a TCNMS of less than about 0.016.
[0060] As used herein, TCNMS is defined as the Normalized Methane
Selectivity (NMS) when the temperature is less than 400.degree.
C. The NMS is defined as the methane product yield divided by the
ethylene product yield wherein each yield is measured on, or is
converted to, a weight % basis. When the temperature is 400.degree.
C. or greater, the TCNMS is defined by the following equation, in
which T is the average temperature within the reactor in .degree.
C.: 1 TCNMS = NMS 1 + ( ( ( T - 400 ) / 400 ) .times. 14.84 )
[0061] The pressure also may vary over a wide range, including
autogenous pressures. Preferred pressures are in the range of about
5 kPa to about 5 MPa, with the most preferred range being of from
about 50 kPa to about 0.5 MPa. The foregoing pressures are exclusive
of any oxygen depleted diluent, and thus, refer to the partial pressure
of the oxygenate compounds and/or mixtures thereof with feedstock.
[0062] The process can be carried out in a dynamic bed system or
any system using a variety of transport beds, although a fixed bed
system could be used. It is particularly desirable to operate the
reaction process at high space velocities.
[0063] The process may be carried out in a batch, semi-continuous
or continuous fashion. The process can be conducted in a single
reaction zone or a number of reaction zones arranged in series or
in parallel.
[0064] The conversion of oxygenates to produce olefins is preferably
carried out in a large scale continuous catalytic reactor. This
type of reactor includes fluid bed reactors and concurrent riser
reactors as described in "Free Fall Reactor," Fluidization
Engineering, D. Kunii and O. Levenspiel, Robert E. Krieger Publishing
Co. NY, 1977 incorporated in its entirety herein by reference.
Additionally, countercurrent free fall reactors may be used in the
conversion process. See, for example, U.S. Pat. No. 4068136 and
"Riser Reactor", Fluidization and Fluid-Particle Systems,
pages 48-59 F. A. Zenz and D. F. Othmo, Reinhold Publishing Corp.,
NY 1960 the descriptions of which are expressly incorporated herein
by reference.
[0065] Any standard commercial scale reactor system can be used,
for example fixed bed or moving bed systems. The commercial scale
reactor systems can be operated at a weight hourly space velocity
(WHSV) of from 1 hr.sup.-1 to 1000 hr.sup.-1. In the case of commercial
scale reactors, WHSV is defined as the weight of hydrocarbon in
the feedstock per hour per weight of silicoaluminophosphate molecular
sieve content of the catalyst. The hydrocarbon content is the oxygenate
content and the content of any hydrocarbon which may be present
with the oxygenate. The silicoaluminophosphate molecular sieve content
means only the silicoaluminophosphate molecular sieve portion that
is contained within the catalyst. This excludes components such
as binders, diluents, inerts, rare earth components, etc.
[0066] One or more inert diluents may be present in the feedstock,
for example, in an amount of from 1 to 95 molar percent, based on
the total number of moles of all feed and diluent components fed
to the reaction zone. Typical diluents include, but are not necessarily
limited to helium, argon, nitrogen, carbon monoxide, carbon dioxide,
hydrogen, water, paraffins, alkanes (especially methane, ethane,
and propane), alkylenes, aromatic compounds, and mixtures thereof.
The preferred diluents are water and nitrogen. Water can be injected
in either liquid or vapor form.
[0067] The level of conversion of the oxygenates is maintained
to reduce the level of unwanted by-products. Conversion is also
maintained sufficiently high to avoid the need for commercially
undesirable levels of recycling of unreacted feeds. A reduction
in unwanted by-products is seen when conversion moves from 100 mol
% to about 98 mol % or less. Recycling up to as much as about 50
mol % of the feed is preferred. Therefore, conversions levels which
achieve both goals are from about 50 mol % to about 98 mol % and,
desirably, from about 85 mol % to about 98 mol %. However, it is
also acceptable to achieve conversion between 98 mol % and 100 mol
% in order to simplify the recycling process. Oxygenate conversion
is maintained using a number of methods familiar to persons of ordinary
skill in the art. Examples include, but are not necessarily limited
to, adjusting one or more of the following: the reaction temperature;
pressure; flow rate (i.e., WHSV); level and degree of catalyst regeneration;
amount of catalyst re-circulation; the specific reactor configuration;
the feed composition; and other parameters which affect the conversion.
[0068] If regeneration is used, the molecular sieve catalyst can
be continuously introduced as a moving bed to a regeneration zone
where it is be regenerated, such as for example by removing carbonaceous
materials or by oxidation in an oxygen-containing atmosphere. In
a preferred embodiment, the catalyst is subject to a regeneration
step by burning off carbonaceous deposits accumulated during the
conversion reactions.
[0069] The oxygenate feedstock comprises at least one organic compound
which contains at least one oxygen atom, such as aliphatic alcohols,
ethers, carbonyl compounds (aldehydes, ketones, carboxylic acids,
carbonates, esters and the like). When the oxygenate is an alcohol,
the alcohol can include an aliphatic moiety having from 1 to 10
carbon atoms, more preferably from 1 to 4 carbon atoms. Representative
alcohols include but are not necessarily limited to lower straight
and branched chain aliphatic alcohols and their unsaturated counterparts.
Examples of suitable oxygenate compounds include, but are not limited
to: methanol; ethanol; n-propanol; isopropanol; C.sub.4-C.sub.20
alcohols; methyl ethyl ether; dimethyl ether; diethyl ether; di-isopropyl
ether; formaldehyde; dimethyl carbonate; dimethyl ketone; acetic
acid; and mixtures thereof. Preferred oxygenate compounds are methanol,
dimethyl ether, or a mixture thereof The most preferred oxygenate
compound is methanol.
[0070] The process for making an olefin product from an oxygenate
feedstock by contacting the oxygenate feedstock with a catalyst
comprising a silicoaluminophosphate of the present invention has
good catalytic performances, which is reflected by a selectivity
to ethylene and propylene equal to or greater than 75.0%, and/or
an ethylene to propylene ratio equal to or greater than 0.75 and/or
a selectivity to propane equal to or lower than 1.0%.
[0071] The method of making the olefin products from an oxygenate
feedstock can include the additional step of making the oxygenate
feedstock from hydrocarbons such as oil, coal, tar sand, shale,
biomass and natural gas. Methods for making oxygenate feedstocks
are known in the art. These methods include fermentation to alcohol
or ether, making synthesis gas, then converting the synthesis gas
to alcohol or ether. Synthesis gas can be produced by known processes
such as steam reforming, autothermal reforming and partial oxidization.
[0072] One skilled in the art will also appreciate that the olefin
products made by the oxygenate-to-olefin conversion reaction using
the molecular sieve of the present invention can be polymerized
to form polyolefins, particularly polyethylenes and polypropylenes.
Processes for forming polyolefins from olefins are known in the
art. Catalytic processes are preferred. Particularly preferred are
metallocene, Ziegler/Natta and acid catalytic systems. See, for
example, U.S. Pat. Nos. 3258455; 3305538; 3364190; 5892079;
4659685; 4076698; 3645992; 4302565; and 4243691 the catalyst
and process descriptions of each being expressly incorporated herein
by reference. In general, these methods involve contacting the olefin
product with a polyolefin-forming catalyst at a pressure and temperature
effective to form the polyolefin product.
[0073] A preferred polyolefin-forming catalyst is a metallocene
catalyst as described in U.S. Pat. No. 5324800. The preferred
temperature range of operation is between 50 and 240.degree. C.
and the reaction can be carried out at low, medium or high pressure,
being anywhere within the range of about 1 to 200 bars. For processes
carried out in solution, an inert diluent can be used, and the preferred
operating pressure range is between 10 and 150 bars, with a preferred
temperature range of between 120 and 230.degree. C. For gas phase
processes, it is preferred that the temperature generally be within
a range of 60 to 1600C, and that the operating pressure be between
5 and 50 bars.
[0074] In addition to polyolefins, numerous other olefin derivatives
may be formed from the olefins recovered from this invention. These
include, but are not limited to, aldehydes, alcohols, acetic acid,
linear alpha olefins, vinyl acetate, ethylene dichloride and vinyl
chloride, ethylbenzene, ethylene oxide, cumene, isopropyl alcohol,
acrolein, allyl chloride, propylene oxide, acrylic acid, ethylene-propylene
rubbers, and acrylonitrile, and trimers and dimers of ethylene,
propylene or butylenes. The methods of manufacturing these derivatives
are well known in the art, and therefore, are not discussed herein.
EXAMPLES
[0075] The following examples illustrate specific embodiments within
the overall scope of the invention as claimed.
[0076] In these examples, the XRD diffraction patterns were recorded
on a SCINTAG X2 X-Ray Powder Diffractometer (Scintag Inc. USA),
using copper K.alpha. radiation. The molecular sieve samples were
calcined after preparation and kept moisture-free according to the
following procedure:
[0077] About 2 grams of molecular sieve were heated-up from room
temperature to 200.degree. C. under a flow of nitrogen at a rate
of 2.degree. C. per minute. The temperature was held at 200.degree.
C. for 30 minutes. Then the sample was heated-up from 200.degree.
C. to 650.degree. C. under nitrogen at a rate of 2.degree. C. per
minute. The sample was held at 650.degree. C. under nitrogen for
5 hours. Nitrogen was then replaced by air and the sample was kept
at 650.degree. C. under air for 3 hours. The sample was then cooled
to 200.degree. C. and kept at 200.degree. C. to prevent hydration.
The hot sample was then transferred into the XRD sample cup and
was covered by Mylar foil to prevent hydration. XRD diffraction
patterns were recorded in the 2.theta. range of 12 to 24 degrees.
[0078] DIFFaX analysis was used to determine the AEI/CHA ratio
of the molecular sieves. Powder XRD diffraction patterns for varying
ratios of AEI/CHA were generated using the DIFFaX program available
from the International Zeolite Association (see also M. M. J. Tracey
et al., Proceedings of the Royal Chemical Society, London, A (1991),
Vol. 433 pp.499-520 "Collection of Simulated XRD Powder Patterns
for Zeolites" by M. M. J. Treacy and J. B. Higgins, 2001 Fourth
Edition, published on behalf of the Structure Commission of the
International Zeolite Association). Table 2 gives the DIFFaX input
file used to simulate the XRD diffraction patterns. For the purposes
of this analysis, calculations were based on a random distribution
of the layers. Such calcaulations are used for statistical purposes
only, and do not mean that the true nature of the material is necessarily
random. The simulation diffraction patterns were then compared with
the experimental powder XRD diffraction patterns.
2TABLE 2 Input file used to simulate XRD diffraction patterns with
DIFFaX. {data File for Random AEI-CHA Intergrowths - Starting from
an AEI Unit Cell} {This file is for a 75% probability of a transition
generating CHA-type cages} { and a 25% probability of a transition
generating AEI-type cages} INSTRUMENTAL {Header for instrumental
section} X-RAY {Simulate X-ray diffraction} 1.5418 {X-ray wavelength}
PSEUDO-VOIGT 0.1 -0.036 0.009 0.6 {Instrumental broadening (much
slower)} STRUCTURAL {Header for structural section} 13.711 12.731
18.57 90. {unit cell coordinates a, b, c, and gamma} UNKNOWN {P1
- all coordinates given} 2 {Layer 1 & Layer 2} infinite {Layers
are very wide in the a-b plane} LAYER 1 NONE Al 11 0.885410 0.951850
0.168520 1.5 1.0 Al 12 0.385410 0.451850 0.168520 1.5 1.0 Al 13
0.114590 0.048150 -.168520 1.5 1.0 Al 14 0.614590 0.548150 -.168520
1.5 1.0 Al 21 0.881620 0.230480 -.059470 1.5 1.0 Al 22 0.381620
0.730480 -.059470 1.5 1.0 Al 23 0.118380 0.769520 0.059470 1.5 1.0
Al 24 0.618380 0.269520 0.059470 1.5 1.0 Al 31 0.220800 0.094820
0.051200 1.5 1.0 Al 32 0.720800 0.594820 0.051200 1.5 1.0 Al 33
0.779200 0.905180 -.051200 1.5 1.0 Al 34 0.279200 0.405180 -.051200
1.5 1.0 P 41 0.779200 0.101060 0.055650 1.5 1.0 P 42 0.279200 0.601060
0.055650 1.5 1.0 P 43 0.220800 0.898940 -.055650 1.5 1.0 P 44 0.720800
0.398940 -.055650 1.5 1.0 P 51 0.113750 0.236960 -.062850 1.5 1.0
P 52 0.613750 0.736960 -.062850 1.5 1.0 P 53 0.886250 0.763040 0.062850
1.5 1.0 P 54 0.386250 0.263040 0.062850 1.5 1.0 P 61 0.119660 0.962530
0.166920 1.5 1.0 P 62 0.619660 0.462530 0.166920 1.5 1.0 P 63 0.880340
0.037470 -.166920 1.5 1.0 P 64 0.380340 0.537470 -.166920 1.5 1.0
O 71 0.168130 0.057460 0.132520 3.0 1.0 O 72 0.668130 0.557460 0.132520
3.0 1.0 O 73 0.831870 0.942540 -.132520 3.0 1.0 O 74 0.331870 0.442540
-.132520 3.0 1.0 O 81 0.141650 0.178130 0.005340 3.0 1.0 O 82 0.641650
0.678130 0.005340 3.0 1.0 O 83 0.858350 0.821870 -.005340 3.0 1.0
O 84 0.358350 0.321870 -.005340 3.0 1.0 O 91 0.005220 0.261180 -.061110
3.0 1.0 O 92 0.505220 0.761180 -.061110 3.0 1.0 O 93 0.994780 0.738820
0.061110 3.0 1.0 O 94 0.494780 0.238820 0.061110 3.0 1.0 O 101 0.850040
0.181060 0.024720 3.0 1.0 O 102 0.350040 0.681060 0.024720 3.0 1.0
O 103 0.149960 0.818940 -.024720 3.0 1.0 O 104 0.649960 0.318940
-.024720 3.0 1.0 O 111 0.824370 0.050450 0.121850 3.0 1.0 O 112
0.324370 0.550450 0.121850 3.0 1.0 O 113 0.175630 0.949550 -.121850
3.0 1.0 O 114 0.675630 0.449550 -.121850 3.0 1.0 O 121 0.009850
0.978500 0.168460 3.0 1.0 O 122 0.509850 0.478500 0.168460 3.0 1.0
O 123 0.990150 0.021500 -.168460 3.0 1.0 O 124 0.490150 0.521500
-.168460 3.0 1.0 O 131 0.144120 0.863920 0.124490 3.0 1.0 O 132
0.644120 0.363920 0.124490 3.0 1.0 O 133 0.855880 0.136080 -.124490
3.0 1.0 O 134 0.355880 0.636080 -.124490 3.0 1.0 O 141 0.329790
0.160550 0.067710 3.0 1.0 O 142 0.829790 0.660550 0.067710 3.0 1.0
O 143 0.670210 0.839450 -.067710 3.0 1.0 O 144 0.170210 0.339450
-.067710 3.0 1.0 O 161 0.814580 0.343580 -.077240 3.0 1.0 O 162
0.314580 0.843580 -.077240 3.0 1.0 O 163 0.185420 0.656420 0.077240
3.0 1.0 O 164 0.685420 0.156420 0.077240 3.0 1.0 O 171 0.136560
0.169180 -.128110 3.0 1.0 O 172 0.636560 0.669180 -.128110 3.0 1.0
O 173 0.863440 0.830820 0.128110 3.0 1.0 O 174 0.363440 0.330820
0.128110 3.0 1.0 O 181 0.243600 0.983110 -.000100 3.0 1.0 O 182
0.743600 0.483110 -.000100 3.0 1.0 O 183 0.756400 0.016890 0.000100
3.0 1.0 O 184 0.256400 0.516890 0.000100 3.0 1.0 O 151 0.842490
0.949350 0.256680 3.0 1.0 O 152 0.342490 0.449350 0.256680 3.0 1.0
O 155 0.157510 0.949350 0.243320 3.0 1.0 O 156 0.657510 0.449350
0.243320 3.0 1.0 LAYER 2 NONE Al 15 0.114590 0.951850 -.168520 1.5
1.0 Al 16 0.614590 0.451850 -.168520 1.5 1.0 Al 15 0.885410 0.048150
0.168520 1.5 1.0 Al 18 0.385410 0.548150 0.168520 1.5 1.0 Al 25
0.118380 0.230480 0.059470 1.5 1.0 Al 26 0.618380 0.730480 0.059470
1.5 1.0 Al 27 0.881620 0.769520 -.059470 1.5 1.0 Al 28 0.381620
0.269520 -.059470 1.5 1.0 Al 35 0.779200 0.094820 -.051200 1.5 1.0
Al 36 0.279200 0.594820 -.051200 1.5 1.0 Al 37 0.220800 0.905180
0.051200 1.5 1.0 Al 38 0.720800 0.405180 0.051200 1.5 1.0 P 45 0.220800
0.101060 -.055650 1.5 1.0 P 46 0.720800 0.601060 -.055650 1.5 1.0
P 47 0.779200 0.898940 0.055650 1.5 1.0 P 48 0.279200 0.398940 0.055650
1.5 1.0 P 55 0.886250 0.236960 0.062850 1.5 1.0 P 56 0.386250 0.736960
0.062850 1.5 1.0 P 57 0.113750 0.763040 -.062850 1.5 1.0 P 58 0.613750
0.263040 -.062850 1.5 1.0 P 65 0.880340 0.962530 -.166920 1.5 1.0
P 66 0.380340 0.462530 -.166920 1.5 1.0 P 67 0.119660 0.037470 0.166920
1.5 1.0 P 68 0.619660 0.537470 0.166920 1.5 1.0 O 75 0.831870 0.057460
-.132520 3.0 1.0 O 76 0.331870 0.557460 -.132520 3.0 1.0 O 77 0.168130
0.942540 0.132520 3.0 1.0 O 78 0.668130 0.442540 0.132520 3.0 1.0
O 85 0.858350 0.178130 -.005340 3.0 1.0 O 86 0.358350 0.678130 -.005340
3.0 1.0 O 87 0.141650 0.821870 0.005340 3.0 1.0 O 88 0.641650 0.321870
0.005340 3.0 1.0 O 95 0.994780 0.261180 0.061110 3.0 1.0 O 96 0.494780
0.761180 0.061110 3.0 1.0 O 97 0.005220 0.738820 -.061110 3.0 1.0
O 98 0.505220 0.238820 -.061110 3.0 1.0 O 105 0.149960 0.181060
-.024720 3.0 1.0 O 106 0.649960 0.681060 -.024720 3.0 1.0 O 107
0.850040 0.818940 0.024720 3.0 1.0 O 108 0.350040 0.318940 0.024720
3.0 1.0 O 115 0.175630 0.050450 -.121850 3.0 1.0 O 116 0.675630
0.550450 -.121850 3.0 1.0 O 117 0.824370 0.949550 0.121850 3.0 1.0
O 118 0.324370 0.449550 0.121850 3.0 1.0 O 125 0.990150 0.978500
-.168460 3.0 1.0 O 126 0.490150 0.478500 -.168460 3.0 1.0 O 127
0.009850 0.021500 0.168460 3.0 1.0 O 128 0.509850 0.521500 0.168460
3.0 1.0 O 135 0.855880 0.863920 -.124490 3.0 1.0 O 136 0.355880
0.363920 -.124490 3.0 1.0 O 137 0.144120 0.136080 0.124490 3.0 1.0
O 138 0.644120 0.636080 0.124490 3.0 1.0 O 145 0.670210 0.160550
-.067710 3.0 1.0 O 146 0.170210 0.660550 -.067710 3.0 1.0 O 147
0.329790 0.839450 0.067710 3.0 1.0 O 148 0.829790 0.339450 0.067710
3.0 1.0 O 165 0.185420 0.343580 0.077240 3.0 1.0 O 166 0.685420
0.843580 0.077240 3.0 1.0 O 167 0.814580 0.656420 -.077240 3.0 1.0
O 168 0.314580 0.156420 -.077240 3.0 1.0 O 175 0.863440 0.169180
0.128110 3.0 1.0 O 176 0.363440 0.669180 0.128110 3.0 1.0 O 177
0.136560 0.830820 -.128110 3.0 1.0 O 178 0.636560 0.330820 -.128110
3.0 1.0 O 185 0.756400 0.983110 0.000100 3.0 1.0 O 186 0.256400
0.483110 0.000100 3.0 1.0 O 187 0.243600 0.016890 -.000100 3.0 1.0
O 188 0.743600 0.516890 -.000100 3.0 1.0 O 1511 0.157510 0.050650
0.243320 3.0 1.0 O 1512 0.657510 0.550650 0.243320 3.0 1.0 O 1515
0.842490 0.050650 0.256680 3.0 1.0 O 1516 0.342490 0.550650 0.256680
3.0 1.0 STACKING {Header for stacking description} recursive {Statistical
ensemble} infinite {Infinite number of layers} TRANSITIONS {Header
for stacking transition data} {Transitions from layer 1} 0.75 0.0
-0.084 0.5 {layer 1 to layer 1: CHA-type cages} 0.25 0.0 0.0 0.5
{layer 1 to layer 2: AEI-type cages} {Transitions from layer 2}
0.25 0.0 0.0 0.5 {layer 2 to layer 1: AEI-type cages} 0.75 0.0 0.0857
0.5 {layer 2 to layer 2: CHA-type cages}
Example 1
[0079] A solution of 33.55 gr of phosphoric acid (85% in water),
32.13 gr of de-mineralized water, and 61.4 gr of a TEAOH solution
(35% in water) was prepared in a glass beaker. To this solution
were added 3.32 gr of Ludox AS 40 (40% silica). 19.85 gr of alumina
(Condea Pural SB) were added and a slurry was obtained with the
following composition expressed as molar ratios:
0.15 SiO.sub.2/P.sub.2O.sub.5/Al.sub.2O.sub.3/TEAOH/35 H.sub.2O
[0080] This slurry was mixed until homogeneous and transferred
to a 150 ml stainless steel autoclave. This autoclave was mounted
on a rotating axis in an oven. The axis was rotated at 60 rpm and
the oven was heated in 8 hours to 175.degree. C. The autoclave was
kept at this temperature for 48 hours. After cooling to room temperature,
a sample was taken and washed and dried. An X-ray diffraction pattern
was obtained. According to DIFFaX analysis, the AEI/CHA ratio was
15/85 (AEI/CHA=0.18). The silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3)
was 0.15. The sample is hereinafter identified as Sample A.
Example 2
[0081] 67.51 gr of phosphoric acid (85% in water, available from
Aldrich) were diluted with 67.29 gr of demineralized water. To this
solution were added 123.33 gr of a tetraethylammonium hydroxide
solution (35% in water, available from Eastern). Then 2.23 gr of
Ludox AS 40 (40% silica from Dupont) were added to this solution.
Finally 39.84 gr of alumina (Condea Pural SB) were added and a slurry
was obtained. The compositon of the mixture can be expressed with
the following molar ratios:
0.05SiO.sub.2/P.sub.2O.sub.5/Al.sub.2O.sub.3/TEAOH/35 H.sub.2O.
[0082] This slurry was mixed until homogeneous and transferred
to a 150 ml stainless steel autoclave. This autoclave was mounted
on a rotating axis in an oven. The axis was rotated at 60 rpm and
the oven was heated in 8 hours to 175 C. The autoclave was kept
at this temperature for 48 hours. After cooling to room temperature,
a sample was taken and washed and dried and an X-ray diffraction
pattern was taken. According to DIFFaX analysis the AEI/CHA ratio
was 25/75 (AEI/CHA=0.33). The silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3)
was 0.06. The sample is hereinafter identified as Sample B.
[0083] Another sample was prepared using the same procedure, except
the autoclave was rotated at 30 rpm instead of 60 rpm. Mixing or
tumbling was thus more moderate than in for the preparation of Sample
B, which was mixed more vigorously. According to DIFFaX analysis
the AEI/CHA ratio was 90/10 (AEI/CHA=0.9). The sample is hereinafter
identified as Comparative 1.
[0084] FIGS. 3 and 5 show the X-ray diffraction pattern of Sample
B. For comparison purposes, they also show the X-ray diffraction
pattern of MTO-RUW-356 described in example 1 and FIG. 1 of WO 98/15496
and of MTO-RUW-335T described in example 3 and FIG. 1 of WO 98/15496.
The diffraction patterns of MTO-RUW-356 and MTO-RUW-335T were digitized
and re-normalized. DIFFaX analysis of MTO-RUW-356 and MTO-RUW-335T
gives AEI/CHA ratios of 2.3 and 4.0 respectively.
Example 3
[0085] A solution of 191.23 gr of phosphoric acid (85% in water
from Aldrich) and 214.25 gr of de-mineralized water was mixed in
a mixing bowl. To this solution 348.71 gr of a tetraethylammonium
hydroxide solution (35% in water, Sachem) were added with a burette.
After the mixture was homogeneous, 6.04 gr of Ludox AS 40 (40% silica
from Dupont) were added. Then 122.33 gr of alumina (Condea Pural
SB) were added and the mixture was stirred for 15 minutes. Then
163.46 gr of a tetraethylammonium hydroxide solution (35% in water)
were added and 10.13 gr of de-mineralized water. A slurry was obtained
with the following composition expressed as molar ratios:
0.045 SiO.sub.2/0.92 P.sub.2O.sub.5/Al.sub.2O.sub.3/1.35 TEAOH/41
H.sub.2O
[0086] This slurry was mixed until homogeneous and transferred
to a 1L PARR autoclave. stainless steel autoclave and the mixture
was stirred at 600 rpm during the whole hydrothermal treatment.
The autoclave was heated in 5 hours to 175.degree. C. The autoclave
was kept at this temperature for 72 hours. After cooling to room
temperature, the slurry was washed and dried and a X-ray diffraction
pattern was taken. According to DIFFaX analysis the AEI/CHA ratio
was 30/70 (AEI/CHA=0.43). The silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3)
was 0.09. The sample is hereinafter identified as Sample C.
Example 4
[0087] A solution of 437.92 gr of phosphoric acid (85% in water)
and 350.56 gr of de-mineralized water was mixed in a mixing bowl.
To this solution 28.49 gr of Ludox AS 40 (40% silica) were added
and a hazy solution was obtained. Then 799.09 gr of a tetraethylammonium
hydroxide solution (35% in water) were added with a burette and
when all TEAOH was added a clear solution was obtained. To this
solution 258.29 gr of alumina (Condea Pural SB) were carefully added
and also 42.45 gr of demineralized water. A slurry was obtained
with the following composition expressed as molar ratios:
0.1 SiO.sub.2/P.sub.2O.sub.5/Al.sub.2O.sub.3/TEAOH/34 H.sub.2O
[0088] This slurry was mixed until homogeneous and transferred
to a 2L PARR stainless steel autoclave (T316SS) with a jacket welded
to the outer wall. The reactor is heated by flowing heated oil from
an external heating bath through the double wall. The stainless
steel stirrer consists of a combination of a standard PARR anchor
stirrer and a standard turbine type impeller. The mixture was stirred
at 170 rpm during crystallization. The autoclave was heated in 8
hours to 175.degree. C. The autoclave was kept at this temperature
for 36 hours. After cooling to room temperature, the slurry was
washed and dried and an X-ray diffraction pattern was taken. According
to DIFFaX analysis the AEI/CHA ratio was 30/70 (AEI/CHA=0.43). The
silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3) was 0.14.
The sample is hereinafter identified as Sample D.
Example 5
[0089] A solution of 434.19 gr of phosphoric acid (85% in water)
and 347.58 gr of de-mineralized water was mixed in a mixing bowl.
To this solution 28.25 gr of Ludox AS 40 (40% silica) were added
and a hazy solution was obtained. Then 792.24 gr of a tetraethylammonium
hydroxide solution (35% in water) were added with a burette and
when all TEAOH was added a clear solution was obtained. To this
solution 256.08 gr of alumina (Condea Pural SB) were carefully added,
followed by the addition of a suspension of 0.761 gr of SAPO-34
powder in 10 gr of de-mineralized water (the seed suspension had
been put in an ultra-sonic bath for 10 minutes). Also 42.07 gr of
de-mineralized water were added to the mixture. A slurry was obtained
with the following composition expressed as molar ratios:
0.1 SiO.sub.2/P.sub.2O.sub.5/Al.sub.2O.sub.3/TEAOH/34 H.sub.2O
and 0.04 wt % SAPO-34 seeds
[0090] This slurry was mixed until homogeneous and transferred
to a 2L stainless steel PARR autoclave and the mixture was stirred
at 170 rpm during crystallization. The autoclave was heated in 8
hours to 175.degree. C. The autoclave was kept at this temperature
for 36 hours. After cooling the autoclave to room temperature, the
crystalline material was removed from the autoclave, washed and
dried at 120.degree. C. and an X-ray diffraction pattern was taken.
According to DIFFaX analysis, the AEI/CHA ratio was 30/70 (AEI/CHA=0.43).
The silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3) was
0.12. The sample is hereinafter identified as Sample E.
Example 6
[0091] A solution of 184.36 gr of phosphoric acid (85% in water)
and 176.29 gr of de-mineralized water was mixed in a mixing bowl.
To this solution 13.33 gr of Ludox AS 40 (40% silica) were added
and a hazy solution was obtained. Then 373.79 gr of a tetraethylammonium
hydroxide solution (35% in water) were added with a burette and
when all TEAOH was added a clear solution was obtained. To this
solution 120.82 gr of alumina (Condea Pural SB) were carefully added
and also 31.42 gr of de-mineralized water. A slurry was obtained
with the following composition expressed as molar ratios:
0.1 SiO.sub.2/0.9 P.sub.2O.sub.5/Al.sub.2O.sub.3/TEAOH/35 H.sub.2O
[0092] This slurry was mixed until homogeneous and transferred
to a 1L stainless steel PARR autoclave and the mixture was stirred
at 170 rpm during crystallization. The autoclave was heated in 8
hours to 175.degree. C. The autoclave was kept at this temperature
for 48 hours. After cooling to room temperature, the slurry was
washed and dried. X-ray diffraction data was obtained. According
to DIFFaX analysis, the AEI/CHA ratio was 20/80 (AEI/CHA=0.25).
The silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3) was
0.16. The sample is hereinafter identified as Sample F
Example 7
[0093] A solution of 411.23 gr of phosphoric acid (85% in water)
and 329.18 gr of de-mineralized water was mixed in a mixing bowl.
To this solution 26.75 gr of Ludox AS 40 (40% silica) were added
and a hazy solution was obtained. Then 750.35 gr of a tetraethylammonium
hydroxide solution (35% in water) were added with a burette and
when all TEAOH was added a clear solution was obtained. To this
solution 242.59 gr of alumina (Condea Pural SB) were carefully added
and also 39.86 gr of de-mineralized water. A slurry was obtained
with the following composition expressed as molar ratios:
0.1 SiO.sub.2/P.sub.2O.sub.5/Al.sub.2O.sub.3/TEAOH/34 H.sub.2O
[0094] This slurry was mixed until homogeneous and transferred
to a 2L stainless steel PARR autoclave and the mixture was stirred
at 170 rpm during crystallization. The autoclave was heated in 12
hours to 170.degree. C. The autoclave was kept at this temperature
for 24 hours. After cooling to room temperature, a sample was taken,
washed and dried and a x-ray diffraction pattern was taken. According
to DIFFaX analysis the AEI/CHA ratio was 40/60 (AEI/CHA=0.67). The
silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3) was 0.13.
The sample is hereinafter identified as Sample G.
Example 8-Comparative 2
[0095] This example is presented by way of comparison to illustrate
the catalytic performances of an intergrown phase of AEI and CHA
molecular sieves where the AEI/CHA ratio is outside the scope of
the present invention.
[0096] 90.74 gr of aluminum isopropoxide were placed in a mixing
bowl and 135.29 gr of de-mineralized water were added. This mixture
was left static for 10 minutes, after which it was mixed and a gel
was obtained. To this gel, 50.19 g of phosphoric acid (85% in water)
were added dropwise with a burette, followed by the addition of
3.26 gr of Ludox AS 40 (40% silica). Then 91.54 gr of tetraethylammonium
hydroxide solution (35% in water) were added with a burette and
also 5.23 gr of de-mineralized water were added. A slurry was obtained
with the following composition expressed as molar ratios:
0.1 SiO.sub.2/P.sub.2O.sub.5/Al.sub.2O.sub.3/TEAOH/56.9 H.sub.2O
[0097] This slurry was mixed until homogeneous and transferred
to a 300 ml steel autoclave. The autoclave was heated in 6 hours
to 150.degree. C. The autoclave was kept at this temperature for
133 hours. The crystallization was performed under static conditions.
After cooling to room temperature, a sample was taken and washed
and dried and an X-ray diffraction pattern was taken. According
to DIFFaX analysis, the AEI/CHA ratio was 80/20 (AEI/CHA=4.0). The
silica to alumina molar ratio (SiO.sub.2/Al.sub.2O.sub.3) was 0.10.
The sample is hereinafter identified as Comparative 2.
Example 9
[0098] The conversion of methanol to olefins was performed in a
tubular, fixed-bed reactor equipped with an on-line gas chromatograph
for product analysis. A portion of the tested sample was calcined
in nitrogen at 650.degree. C. for 5 hours, followed by heating in
air at 650.degree. C. for 3 hours. The calcined molecular sieve
was added to the reactor and contacted with a feedstock containing
methanol at a temperature of 450.degree. C., a weight hourly space
velocity (WHSV) of 25 hr.sup.-1 and a pressure of 25 psig. The combined
ethylene and propylene product selectivity and propane selectivity
are shown in Table 3. |