Molecular sieve abstract
The present invention relates to new molecular sieve SSZ-71 prepared
using a N-benzyl-14-diazabicyclo[2.2.2]octane cation as a structure-directing
agent, methods for synthesizing SSZ-71 and processes employing SSZ-71
in a catalyst.
Molecular sieve claims
What is claimed is:
1. A molecular sieve having a composition, as synthesized and in
the anhydrous state, in terms of mole ratios as follows: TABLE-US-00018
YO.sub.2/WO.sub.d 15 .infin. M.sub.2/n/YO.sub.2 0 0.03 Q/YO.sub.2
0.02 0.05
wherein Y is silicon, germanium or a mixture thereof; W is zinc,
titanium or mixtures thereof; d is 1 or 2; M is an alkali metal
cation, alkaline earth metal cation or mixtures thereof; n is the
valence of M; and Q is a N-benzyl-14-diazabicyclo[2.2.2]octane
cation, the as-synthesized molecular sieve having the X-ray diffraction
lines of Table I.
2. A molecular sieve according to claim 1 wherein Y is silicon.
3. A molecular sieve according to claim 1 wherein W is titanium
and Y is silicon.
4. A molecular sieve according to claim 1 wherein W is zinc and
Y is silicon.
5. A molecular sieve produced by the method comprising: (1) preparing
an as-synthesized molecular sieve having a composition, as synthesized
and in the anhydrous state, in terms of mole ratios as follows:
TABLE-US-00019 YO.sub.2/WO.sub.d 15 .infin. M.sub.2/n/YO.sub.2 0
0.03 Q/YO.sub.2 0.02 0.05
wherein Y is silicon, germanium or a mixture thereof; W is zinc,
titanium or mixtures thereof; d is 1 or 2 (i.e., d is 1 when W is
divalent or 2 when W is tetravalent); M is an alkali metal cation,
alkaline earth metal cation or mixtures thereof; n is the valence
of M (i.e., 1 or 2); and Q is a N-benzyl-14-diazabicyclo[2.2.2]octane
cation, the as-synthesized molecular sieve having the X-ray diffraction
lines of Table I; (2) thermally treating the as-synthesized molecular
sieve at a temperature and for a time sufficient to remove the N-benzyl-14-diazabicyclo[2.2.2]octane
cation from the molecular sieve; and (3) optionally, replacing at
least part of the zinc and/or titanium with a metal selected from
the group consisting of aluminum, gallium, iron, boron, indium,
vanadium and mixtures thereof.
6. A molecular sieve according to claim 5 wherein Y is silicon.
7. A molecular sieve according to claim 5 wherein Y is silicon
and W is zinc.
8. A molecular sieve according to claim 5 wherein Y is silicon
and W is titanium.
9. A molecular sieve according to claim 5 wherein Y is silicon
and the zinc and/or titanium is replaced with boron.
10. A molecular sieve according to claim 5 wherein Y is silicon
and the zinc and/or titanium is replaced with aluminum.
11. A molecular sieve according to claim 5 wherein said molecular
sieve is predominantly in the hydrogen form.
12. A molecular sieve according to claim 5 wherein said molecular
sieve is substantially free of acidity.
13. A method of preparing a molecular sieve comprising (1) a first
oxide comprising silicon oxide, germanium oxide or a mixture thereof
and (2) a second oxide comprising zinc oxide, titanium oxide or
a mixture thereof and having mole ratio of the first oxide to the
second oxide of greater than 15 and having, in its as-synthesized,
anhydrous state, the X-ray diffraction lines of Table I, said method
comprising contacting under crystallization conditions sources of
said oxides and a structure directing agent comprising a N-benzyl-14-diazabicyclo[2.2.2]octane
cation.
14. The method according to claim 13 wherein the first oxide is
silicon oxide.
15. The method according to claim 13 wherein the second oxide is
zinc oxide.
16. The method according to claim 13 wherein the second oxide is
titanium oxide.
17. The method according to claim 13 wherein the molecular sieve
is prepared from a reaction mixture comprising, in term of mole
ratios: TABLE-US-00020 YO.sub.2/WO.sub.d >15 OH--/YO.sub.2 0.10
0.50 Q/YO.sub.2 0.05 0.50 M.sub.2/n/YO.sub.2 0 0.40 H.sub.2O/YO.sub.2
10 80
wherein Y is silicon, germanium or a mixture thereof; W is zinc,
titanium or mixtures thereof; d is 1 or 2; M is an alkali metal
cation, alkaline earth metal cation or mixtures thereof; n is the
valence of M; and Q is a N-benzyl-14-diazabicyclo[2.2.2]octane
cation.
Molecular sieve description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to new molecular sieve SSZ-71 a
method for preparing SSZ-71 using a N-benzyl-14-diazabicyclo[2.2.2]octane
cation as a structure directing agent and the use of SSZ-71 in catalysts
for, e.g., hydrocarbon conversion reactions.
2. State of the Art
Because of their unique sieving characteristics, as well as their
catalytic properties, crystalline molecular sieves and zeolites
are especially useful in applications such as hydrocarbon conversion,
gas drying and separation. Although many different crystalline molecular
sieves have been disclosed, there is a continuing need for new zeolites
with desirable properties for gas separation and drying, hydrocarbon
and chemical conversions, and other applications. New zeolites may
contain novel internal pore architectures, providing enhanced selectivities
in these processes.
Crystalline aluminosilicates are usually prepared from aqueous
reaction mixtures containing alkali or alkaline earth metal oxides,
silica, and alumina. Crystalline borosilicates are usually prepared
under similar reaction conditions except that boron is used in place
of aluminum. By varying the synthesis conditions and the composition
of the reaction mixture, different zeolites can often be formed.
SUMMARY OF THE INVENTION
The present invention is directed to a family of molecular sieves
with unique properties, referred to herein as "molecular sieve
SSZ-71" or simply "SSZ-71". Preferably, SSZ-71 is
in its silicate, zincosilicate, aluminosilicate, titanosilicate,
germanosilicate, vanadosilicate, ferrosilicate or borosilicate form.
The term "silicate" refers to a molecular sieve having
a high mole ratio of silicon oxide relative to aluminum oxide, preferably
a mole ratio greater than 100 including molecular sieves comprised
entirely of silicon oxide. As used herein, the term "zincosilicate"
refers to a molecular sieve containing both zinc oxide and silicon
oxide. The term "aluminosilicate" refers to a molecular
sieve containing both aluminum oxide and silicon oxide and the term
"borosilicate" refers to a molecular sieve containing
oxides of both boron and silicon.
The present invention provides such a molecular sieve having a
composition, as synthesized and in the anhydrous state, in terms
of mole ratios as follows:
TABLE-US-00001 YO.sub.2/WO.sub.d 15 .infin. M.sub.2/n/YO.sub.2
0 0.03 Q/YO.sub.2 0.02 0.05
wherein Y is silicon, germanium or a mixture thereof; W is zinc,
titanium or mixtures thereof; d is 1 or 2 (i.e., d is 1 when W is
divalent or 2 when W is tetravalent); M is an alkali metal cation,
alkaline earth metal cation or mixtures thereof; n is the valence
of M (i.e., 1 or 2); and Q is a N-benzyl-14-diazabicyclo[2.2.2]octane
cation, the as-synthesized molecular sieve having the X-ray diffraction
lines of Table I.
In accordance with this invention, there is also provided a molecular
sieve produced by the method comprising: (1) preparing an as-synthesized
molecular sieve having a composition, as synthesized and in the
anhydrous state, in terms of mole ratios as follows:
TABLE-US-00002 YO.sub.2/WO.sub.d 15 .infin. M.sub.2/n/YO.sub.2
0 0.03 Q/YO.sub.2 0.02 0.05
wherein Y is silicon, germanium or a mixture thereof; W is zinc,
titanium or mixtures thereof; d is 1 or 2 (i.e., d is 1 when W is
divalent or 2 when W is tetravalent); M is an alkali metal cation,
alkaline earth metal cation or mixtures thereof; n is the valence
of M (i.e., 1 or 2); and Q is a N-benzyl-14-diazabicyclo[2.2.2]octane
cation, the as-synthesized molecular sieve having the X-ray diffraction
lines of Table I; (2) thermally treating the as-synthesized molecular
sieve at a temperature (e.g., about 200.degree. C. to about 800.degree.
C.) and for a time sufficient to remove the N-benzyl-14-diazabicyclo[2.2.2]octane
cation from the molecular sieve; and (3) optionally, replacing at
least part of the zinc and/or titanium with a metal selected from
the group consisting of aluminum, gallium, iron, boron, indium,
vanadium and mixtures thereof.
The present invention also includes this thus-prepared molecular
sieve which is predominantly in the hydrogen form, which hydrogen
form is prepared by ion exchanging with an acid or with a solution
of an ammonium salt followed by a second calcination. If the molecular
sieve is synthesized with a high enough ratio of SDA cation to sodium
ion, calcination alone may be sufficient. For high catalytic activity,
the SSZ-71 molecular sieve should be predominantly in its hydrogen
ion form. As used herein, "predominantly in the hydrogen form"
means that, after calcination, at least 80% of the cation sites
are occupied by hydrogen ions and/or rare earth ions. It should
be noted that the mole ratio of the first oxide or mixture of first
oxides to the second oxide can be infinity, i.e., there is no second
oxide in the molecular sieve. In these cases, the molecular sieve
is an all-silica molecular sieve or a germanosilicate.
Also provided in accordance with the present invention is a method
of preparing a molecular sieve comprising (1) a first oxide comprising
silicon oxide, germanium oxide or a mixture thereof and (2) a second
oxide comprising zinc oxide, titanium oxide or a mixture thereof
and having a mole ratio of the first oxide to the second oxide of
greater than about 15 and having, in its as-synthesized, anhydrous
state, the X-ray diffraction lines of Table I, said method comprising
contacting under crystallization conditions sources of said oxides
and a structure directing agent comprising a N-benzyl-14-diazabicyclo[2.2.2]octane
cation.
DETAILED DESCRIPTION OF THE INVENTION
The present invention comprises a family of molecular sieves designated
herein "molecular sieve SSZ-71" or simply "SSZ-71".
In preparing SSZ-71 a N-benzyl-14-diazabicyclo[2.2.2]octane cation
(referred to herein as "benzyl DABCO") is used as a structure
directing agent ("SDA"), also known as a crystallization
template. The SDA useful for making SSZ-71 has the following structure:
##STR00001##
The SDA cation is associated with an anion (X.sup.-) which may
be any anion that is not detrimental to the formation of the molecular
sieve. Representative anions include halogen, e.g., fluoride, chloride,
bromide and iodide, hydroxide, acetate, sulfate, tetrafluoroborate,
carboxylate, and the like. Hydroxide is the most preferred anion.
Benzyl DABCO and a method for making it are disclosed in U.S. Pat.
No. 5653956 issued Aug. 5 1997 to Zones.
SSZ-71 is prepared from a reaction mixture having the composition
shown in Table A below.
TABLE-US-00003 TABLE A Reaction Mixture Typical Preferred YO.sub.2/WO.sub.d
>15 >30 OH--/YO.sub.2 0.10 0.50 0.20 0.30 Q/YO.sub.2 0.05
0.50 0.10 0.20 M.sub.2/n/YO.sub.2 0 0.40 0.10 0.25 H.sub.2O/YO.sub.2
10 80 15 45
where Y is silicon, germanium or a mixture thereof; W is zinc,
titanium or mixtures thereof; d is 1 or 2 (i.e., d is 1 when W is
divalent or 2 when W is tetravalent); M is an alkali metal cation,
alkaline earth metal cation or mixtures thereof; n is the valence
of M (i.e., 1 or 2); and Q is a N-benzyl-14-diazabicyclo[2.2.2]octane
cation.
In practice, SSZ-71 is prepared by a process comprising:
(a) preparing an aqueous solution containing sources of at least
one oxide capable of forming a molecular sieve and a benzyl DABCO
cation having an anionic counterion which is not detrimental to
the formation of SSZ-71;
(b) maintaining the aqueous solution under conditions sufficient
to form SSZ-71; and
(c) recovering the SSZ-71.
SSZ-71 can be prepared as a zincosilicate or titanosilicate. However,
once the SSZ-71 is made, the zinc and/or titanium can be replaced
with other metals by techniques well known in the art. Accordingly,
SSZ-71 may comprise the molecular sieve and the SDA in combination
with metallic and non-metallic oxides bonded in tetrahedral coordination
through shared oxygen atoms to form a cross-linked three dimensional
crystal structure. The metallic and non-metallic oxides comprise
one or a combination of oxides of (1) a first tetravalent element(s),
and (2) one or a combination of a divalent element(s), trivalent
element(s), pentavalent element(s), second tetravalent element(s)
different from the first tetravalent element(s) or mixture thereof.
The first tetravalent element(s) is preferably selected from the
group consisting of silicon, germanium and combinations thereof.
More preferably, the first tetravalent element is silicon. The divalent
element, trivalent element, pentavalent element and second tetravalent
element (which is different from the first tetravalent element)
is preferably selected from the group consisting of zinc, aluminum,
gallium, iron, boron, titanium, indium, vanadium and combinations
thereof. More preferably, the divalent or trivalent element or second
tetravalent element is zinc, aluminum, titanium or boron.
Silicon can be added as silicon oxide or Si(OC.sub.2H.sub.5).sub.4.
Zinc can be added as a zinc salt such as zinc acetate. Titanium
can be added as Ti(OC.sub.2H.sub.5).sub.4.
A source zeolite reagent may provide a source of metals. In most
cases, the source zeolite also provides a source of silica. The
source zeolite may also be used as a source of silica, with additional
silicon added using, for example, the conventional sources listed
above. Use of a source zeolite reagent is described in U.S. Pat.
No. 5225179 issued Jul. 6 1993 to Nakagawa entitled "Method
of Making Molecular Sieves", the disclosure of which is incorporated
herein by reference.
Typically, an alkali metal hydroxide and/or an alkaline earth metal
hydroxide, such as the hydroxide of sodium, potassium, lithium,
cesium, rubidium, calcium, strontium, barium and magnesium, is used
in the reaction mixture; however, this component can be omitted
so long as the equivalent basicity is maintained. The SDA may be
used to provide hydroxide ion. Thus, it may be beneficial to ion
exchange, for example, the halide to hydroxide ion, thereby reducing
or eliminating the alkali metal hydroxide quantity required. The
alkali metal cation or alkaline earth cation may be part of the
as-synthesized material, in order to balance valence electron charges
therein.
The reaction mixture is maintained at an elevated temperature until
the crystals of the SSZ-71 are formed. The hydrothermal crystallization
is usually conducted under autogenous pressure, at a temperature
between 100.degree. C. and 200.degree. C., preferably between 135.degree.
C. and 160.degree. C. The crystallization period is typically greater
than 1 day and preferably from about 3 days to about 20 days.
Optionally, the molecular sieve is prepared using mild stirring
or agitation.
During the hydrothermal crystallization step, the SSZ-71 crystals
can be allowed to nucleate spontaneously from the reaction mixture.
The use of SSZ-71 or SSZ-42 (disclosed in U.S. Pat. No. 5653956
issued Aug. 5 1997 to Zones) crystals 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
SSZ-71 over any undesired phases. When used as seeds, as-synthesized
SSZ-71 or SSZ-42 crystals (containing the SDA) are added in an amount
between 0.1 and 10% of the weight of first tetravalent element oxide,
e.g. silica, used in the reaction mixture.
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, e.g., at 90.degree. C. to 150.degree. C. for from 8
to 24 hours, to obtain the as-synthesized SSZ-71 crystals. The drying
step can be performed at atmospheric pressure or under vacuum.
SSZ-71 as prepared has a mole ratio of an oxide selected from silicon
oxide, germanium oxide and mixtures thereof to an oxide selected
from zinc oxide, titanium oxide and mixtures thereof greater than
about 15. SSZ-71 further has a composition, as synthesized (i.e.,
prior to calcination of the SSZ-71) and in the anhydrous state,
in terms of mole ratios, shown in Table B below.
TABLE-US-00004 TABLE B As-Synthesized SSZ-71 YO.sub.2/WO.sub.d
>15 M.sub.2/n/YO.sub.2 0 0.03 Q/YO.sub.2 0.02 0.05
where Y, W, d, M, n and Q are as defined above.
SSZ-71 can be made with a mole ratio of YO.sub.2/WO.sub.d of .infin.,
i.e., there is essentially no WO.sub.d present in the SSZ-71. In
this case, the SSZ-71 would be an all-silica material or a germanosilicate.
If SSZ-71 is prepared as a zincosilicate, the zinc can be removed
and replaced with metal atoms by techniques known in the art. See,
for example, U.S. Pat. No. 6117411 issued Sep. 12 2000 to Takewaki
et al. Metals such as aluminum, gallium, iron, boron, titanium,
indium, vanadium and mixtures thereof may be added in this manner.
It is believed that SSZ-71 is comprised of a new framework structure
or topology which is characterized by its X-ray diffraction pattern.
SSZ-71 as-synthesized, has a structure whose X-ray powder diffraction
pattern exhibit the characteristic lines shown in Table I and Table
II and is thereby distinguished from other molecular sieves. The
XRD data shown in Table I and IA was obtained from a sample of SSZ-71
prepared in the presence of sodium hydroxide. The XRD data shown
in Table II and IIA was obtained from a sample of SSZ-71 prepared
in the presence of strontium hydroxide.
TABLE-US-00005 TABLE I As-Synthesized Zn-SSZ-71 Prepared with NaOH
2 Theta.sup.(a) d-spacing (Angstroms) Relative Intensity.sup.(b)
5.64 15.7 S 8.65 10.2 S 13.65 6.49 M 17.06 5.20 M 20.32 4.37 M 20.64
4.30 VS 23.12 3.85 M 24.08 3.70 VS 26.15 3.41 M 26.57 3.35 M .sup.(a).+-.0.15
.sup.(b)The X-ray patterns provided are based on a relative intensity
scale in which the strongest line in the X-ray pattern is assigned
a value of 100: W (weak) is less than 20; M (medium) is between
20 and 40; S (strong) is between 40 and 60; VS (very strong) is
greater than 60.
Table IA below shows the X-ray powder diffraction lines for as-synthesized
Zn-SSZ-71 prepared with NaOH including actual relative intensities.
TABLE-US-00006 TABLE IA 2 Theta.sup.(a) d-spacing (Angstroms) Relative
Intensity (%) 5.64 15.7 60 8.65 10.2 57 11.40 7.8 5 11.95 7.4 7
13.11 6.75 7 13.65 6.49 21 14.34 6.18 5 17.06 5.20 29 17.84 4.97
4 18.23 4.87 10 18.84 4.71 12 19.49 4.55 18 20.32 4.37 37 20.64
4.30 100 21.55 4.12 16 22.03 4.03 16 23.12 3.85 34 24.08 3.70 62
25.29 3.52 20 25.52 3.49 20 26.15 3.41 29 26.57 3.35 33 27.15 3.28
9 28.55 3.13 18 30.00 2.98 8 30.80 2.90 5 31.68 2.82 10 32.45 2.76
5 33.16 2.70 7 34.92 2.57 11 35.61 2.52 14 36.90 2.44 12 38.82 2.32
14 40.26 2.24 12 .sup.(a).+-.0.15
TABLE-US-00007 TABLE II As-Synthesized Zn-SSZ-71 prepared with
Sr(OH).sub.2 2 Theta.sup.(a) d-spacing (Angstroms) Relative Intensity.sup.(b)
5.65 15.6 VS 8.69 10.2 VS 16.99 5.22 S 19.52 4.55 M 20.60 4.31 VS
23.13 3.85 M 24.01 3.71 S 24.23 3.67 M 26.14 3.41 M 26.52 3.36 M
.sup.(a).+-.0.15 .sup.(b)The X-ray patterns provided are based on
a relative intensity scale in which the strongest line in the X-ray
pattern is assigned a value of 100: W (weak) is less than 20; M
(medium) is between 20 and 40; S (strong) is between 40 and 60;
VS (very strong) is greater than 60.
Table IIA below shows the X-ray powder diffraction lines for as-synthesized
SSZ-71 (Zn-SSZ-71 prepared with Sr(OH).sub.2) including actual relative
intensities.
TABLE-US-00008 TABLE IIA 2 Theta.sup.(a) d-spacing (Angstroms)
Relative Intensity (%) 5.65 15.6 84 8.69 10.2 67 11.36 7.8 5 11.94
7.4 5 13.17 6.7 7 13.68 6.5 20 14.34 6.18 6 15.31 5.79 2 16.99 5.22
42 18.24 4.86 8 18.79 4.72 17 19.52 4.55 26 20.34 4.37 23 20.60
4.31 100 21.59 4.12 13 22.06 4.03 16 23.13 3.85 37 24.01 3.71 41
24.23 3.67 25 25.25 3.53 20 25.52 3.49 23 26.14 3.41 36 26.52 3.36
30 27.10 3.29 12 28.52 3.13 22 29.85 2.99 6 30.24 2.96 2 30.84 2.90
3 31.64 2.83 11 32.44 2.76 5 33.11 2.71 5 34.86 2.57 6 35.63 2.52
14 36.10 2.49 6 .sup.(a).+-.0.15
The X-ray powder diffraction patterns were determined by standard
techniques. The radiation was the K-alpha/doublet of copper. 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, and d, the interplanar spacing in Angstroms corresponding
to the recorded lines, can be calculated.
The variation in the scattering angle (two theta) measurements,
due to instrument error and to differences between individual samples,
is estimated at .+-.0.15 degrees.
The X-ray diffraction pattern of Table I is representative of "as-synthesized"
or "as-made" SSZ-71 molecular sieves. Minor variations
in the diffraction pattern can result from variations in the silica-to-zinc
or silica-to-titanium mole ratio 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. The molecular sieve produced by exchanging the
metal or other cations present in the molecular sieve with various
other cations (such as H.sup.+ or NH.sub.4.sup.+) yields essentially
the same diffraction pattern, although again, there may be minor
shifts in the interplanar spacing and variations in the relative
intensities of the peaks. Notwithstanding these minor perturbations,
the basic crystal lattice remains unchanged by these treatments.
SSZ-71 can be used as-synthesized, but preferably will be thermally
treated (calcined). Usually, it is desirable to remove the alkali
metal cation by ion exchange and replace it with hydrogen, ammonium,
or any desired metal ion. The molecular sieve can also be steamed;
steaming helps stabilize the molecular sieve to attack from acids.
The molecular sieve can be used in intimate combination with hydrogenating
components, such as tungsten, vanadium, molybdenum, rhenium, nickel,
cobalt, chromium, manganese, or a noble metal, such as palladium
or platinum, for those applications in which a hydrogenation-dehydrogenation
function is desired.
Metals may also be introduced into the molecular sieve by replacing
some of the cations in the molecular sieve with metal cations via
standard ion exchange techniques (see, for example, U.S. Pat. No.
3140249 issued Jul. 7 1964 to Plank et al.; U.S. Pat. No. 3140251
issued Jul. 7 1964 to Plank et al.; and U.S. Pat. No. 3140253
issued Jul. 7 1964 to Plank et al.). Typical replacing cations
can include metal cations, e.g., rare earth, Group IA, Group IIA
and Group VIII metals, as well as their mixtures. Of the replacing
metallic cations, cations of metals such as rare earth, Mn, Ca,
Mg, Zn, Cd, Pt, Pd, Ni, Co, Ti, Al, Sn, and Fe are particularly
preferred.
The hydrogen, ammonium, and metal components can be ion-exchanged
into the SSZ-71. The SSZ-71 can also be impregnated with the metals,
or the metals can be physically and intimately admixed with the
SSZ-71 using standard methods known to the art.
Typical ion-exchange techniques involve contacting the synthetic
molecular sieve with a solution containing a salt of the desired
replacing cation or cations. Although a wide variety of salts can
be employed, chlorides and other halides, acetates, nitrates, and
sulfates are particularly preferred. The molecular sieve is usually
calcined prior to the ion-exchange procedure to remove the organic
matter present in the channels and on the surface, since this results
in a more effective ion exchange. Representative ion exchange techniques
are disclosed in a wide variety of patents including U.S. Pat. No.
3140249 issued on Jul. 7 1964 to Plank et al.; U.S. Pat. No.
3140251 issued on Jul. 7 1964 to Plank et al.; and U.S. Pat.
No. 3140253 issued on Jul. 7 1964 to Plank et al.
Following contact with the salt solution of the desired replacing
cation, the molecular sieve is typically washed with water and dried
at temperatures ranging from 65.degree. C. to about 200.degree.
C. After washing, the molecular sieve can be calcined in air or
inert gas at temperatures ranging from about 200.degree. C. to about
800.degree. C. for periods of time ranging from 1 to 48 hours, or
more, to produce a catalytically active product especially useful
in hydrocarbon conversion processes.
Regardless of the cations present in the synthesized form of SSZ-71
the spatial arrangement of the atoms which form the basic crystal
lattice of the molecular sieve remains essentially unchanged.
SSZ-71 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 SSZ-71 can be extruded
before drying, or, dried or partially dried and then extruded.
SSZ-71 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. No. 4910006 issued May 20 1990 to Zones et al.,
and U.S. Pat. No. 5316753 issued May 31 1994 to Nakagawa, both
of which are incorporated by reference herein in their entirety.
SSZ-71 is useful in catalysts for a variety of hydrocarbon conversion
reactions such as hydrocracking, dewaxing, olefin isomerization,
alkylation of aromatic compounds and the like. |