BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to new crystalline zeolite
SSZ-60 and a method for preparing SSZ-60 using a N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium
cation or N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation templating
agent.
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.
WO0109037
relates to crystalline zeolite SSZ-52 prepared using a quaternary ammonium
cation templating agent comprising an anion which is not detrimental to the formation
of the SSZ-52. SSZ-52 is useful in catalysts for hydrocarbon conversion reactions.
WO0144109
relates to crystalline zeolite SSZ-50 prepared using a quaternary ammonium
cation templating agent comprising an anion which is not detrimental to the formation
of the SSZ-50. SSZ-50 is useful in catalysts for hydrocarbon conversion reactions.
US6049018
relates to a synthetic porous crystalline material, designated MCM-68,
a method and novel polycyclic organic cation for its preparation and its use in
catalytic conversion of organic compounds. The crystalline material exhibits a distinctive
X-ray diffraction pattern and has a unique crystal structure which contains at least
one channel system, in which each channel is defined by a 12-membered ring of tetrahedrally
coordinated atoms, and at least two further, independent channel systems, in each
of which each channel is defined by a 10-membered ring of tetrahedrally coordinated
atoms, wherein the number of unique 10-membered ring channels is twice the number
of 12-membered ring channels.
SUMMARY OF INVENTION
The present invention is directed to a family of crystalline
molecular sieves with unique properties, referred to herein as "zeolite SSZ-60"
or simply "SSZ-60". Preferably, SSZ-60 is obtained in its silicate, aluminosilicate,
titanosilicate, vanadosilicate or borosilicate form. The term "silicate" refers
to a zeolite having a high mole ratio of silicon oxide relative to aluminum oxide,
preferably a mole ratio greater than 100, including zeolites comprised entirely
of silicon oxide. As used herein, the term "aluminosilicate" refers to a zeolite
containing both alumina and silica and the term "borosilicate" refers to a zeolite
containing oxides of both boron and silicon.
In accordance with the broadest aspect of this invention,
there is provided a zeolite having a mole ratio greater than about 20 of an oxide
of a first tetravalent element to an oxide of a second tetravalent element different
from said first tetravalent element, trivalent element, pentavalent element or mixture
thereof and having, after calcination, the X-ray diffraction lines of Table II.
Further, in accordance with the broadest aspect of the
invention, there is provided a zeolite having a mole ratio greater than about 20
of an oxide selected from silicon oxide, germanium oxide and mixtures thereof to
an oxide selected from aluminum oxide, gallium oxide, iron oxide, boron oxide, titanium
oxide, indium oxide, vanadium oxide and mixtures thereof.
In an embodiment of the present invention there is further
provided a zeolite having a composition, as synthesized and in the anhydrous state,
in terms of mole ratios as follows:
YO2/WcOd
20 - 180
M2/n/YO2
0.01 - 0.03
Q/YO2
0.02 - 0:05
wherein Y is silicon, germanium or a mixture thereof, W is aluminum, gallium; iron,
boron, titanium, indium, vanadium or mixtures thereof; c is 1 or 2; d is 2 when
c is 1 (i.e., W is tetravalent) or d is 3 or 5 when c is 2 (i.e., d is 3 when W
is trivalent or 5 when W is pentavalent); 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-ethyl-N-(3,3,5-trimethylcyclohexyl)-pyrrolidinium cation or N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium
cation.
The zeolite of the present invention may be prepared by
thermally treating a zeolite having a mole ratio of an oxide selected from silicon
oxide, germanium oxide and mixtures thereof to an oxide selected from aluminum oxide,
gallium oxide, iron oxide, boron oxide, titanium oxide, indium oxide, vanadium oxide
and mixtures thereof greater than about 20 at a temperature of from about 200°C
to about 800°C. The present invention also includes this thus-prepared zeolite
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.
Also provided in accordance with the present invention
is a method of preparing the zeolite described above, said method comprising contacting
under crystallization conditions sources of said oxides and a templating agent comprising
a N-ethyl-N-(3,3,5-trimethylcyclohexyl)-pyrrolidinium cation or N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium
cation.
In accordance with the present invention there is provided
a process for converting hydrocarbons comprising contacting a hydrocarbonaceous
feed at hydrocarbon converting conditions with a catalyst comprising the zeolite
of this invention. The zeolite may be predominantly in the hydrogen form. It may
also be.substantially free of acidity.
Further provided by the present invention is a hydrocracking
process comprising contacting a hydrocarbon feedstock under hydrocracking conditions
with a catalyst comprising the zeolite of this invention, preferably predominantly
in the hydrogen form.
This invention also includes a dewaxing process comprising
contacting a hydrocarbon feedstock under dewaxing conditions with a catalyst comprising
the zeolite of this invention, preferably predominantly in the hydrogen form.
The present invention also includes a process for improving
the viscosity index of a dewaxed product of waxy hydrocarbon feeds comprising contacting
the waxy hydrocarbon feed under isomerization dewaxing conditions with a catalyst
comprising the zeolite of this invention, preferably predominantly in the hydrogen
form.
The present invention further includes a process for producing
a C20+ lube oil from a C20+ olefin feed comprising isomerizing
said olefin feed under isomerization conditions over a catalyst comprising at least
one Group VIII metal and the zeolite of this invention. The zeolite may be predominantly
in the hydrogen form.
In accordance with this invention, there is also provided
a process for catalytically dewaxing a hydrocarbon oil feedstock boiling above about
177°C (350°F) and containing straight chain and slightly branched chain
hydrocarbons comprising contacting said hydrocarbon oil feedstock in the presence
of added hydrogen gas at a hydrogen pressure of about 0.103-20.7 MPa (15-3000 psi)
with a catalyst comprising at least one Group VIII metal and the zeolite of this
invention, preferably predominantly in the hydrogen form. The catalyst may be a
layered catalyst comprising a first layer comprising at least one Group VIII metal
and the zeolite of this invention, and a second layer comprising an aluminosilicate
zeolite which is more shape selective than the zeolite of said first layer.
Also included in the present invention is a process for
preparing a lubricating oil which comprises hydrocracking in a hydrocracking zone
a hydrocarbonaceous feedstock to obtain an effluent comprising a hydrocracked oil,
and catalytically dewaxing said effluent comprising hydrocracked oil at a temperature
of at least about 204°C (400°F) and at a pressure of from about 0.103
MPa gauge (15 psig) to about 20.7 MPa gauge (3000 psig) in the presence of added
hydrogen gas with a catalyst comprising at least one Group VIII metal and the zeolite
of this invention. The zeolite may be predominantly in the hydrogen form.
Further included in this invention is a process for isomerization
dewaxing a raffinate comprising contacting said raffinate in the presence of added
hydrogen with a catalyst comprising at least one Group VIII metal and the zeolite
of this invention. The raffinate may be bright stock, and the zeolite may be predominantly
in the hydrogen form.
Also included in this invention is a process for increasing
the octane of a hydrocarbon feedstock to produce a product having an increased aromatics
content comprising contacting a hydrocarbonaceous feedstock which comprises normal
and slightly branched hydrocarbons having a boiling range above about 40°C
and less than about 200°C, under aromatic conversion conditions with a catalyst
comprising the zeolite of this invention made substantially free of acidity by neutralizing
said zeolite with a basic metal. Also provided in this invention is such a process
wherein the zeolite contains a Group VIII metal component.
Also provided by the present invention is a catalytic cracking
process comprising contacting a hydrocarbon feedstock in a reaction zone under catalytic
cracking conditions in the absence of added hydrogen with a catalyst comprising
the zeolite of this invention, preferably predominantly in the hydrogen form. Also
included in this invention is such a catalytic cracking process wherein the catalyst
additionally comprises a large pore crystalline cracking component
This invention further provides an isomerization process
for isomerizing C4 to C7 hydrocarbons, comprising contacting
a feed having normal and slightly branched C4 to C7 hydrocarbons
under isomerizing conditions with a catalyst comprising the zeolite of this invention,
preferably predominantly in the hydrogen form. The zeolite may be impregnated with
at least one Group VIII metal, preferably platinum. The catalyst may be calcined
in a steam/air mixture at an elevated temperature after impregnation of the Group
VIII metal.
Also provided by the present invention is a process for
alkylating an aromatic hydrocarbon which comprises contacting under alkylation conditions
at least a molar excess of an aromatic hydrocarbon with a C2 to C20
olefin under at least partial liquid phase conditions and in the presence of a catalyst
comprising the zeolite of this invention, preferably predominantly in the hydrogen
form. The olefin may be a C2 to C4 olefin, and the aromatic
hydrocarbon and olefin may be present in a molar ratio of about 4:1 to about 20:1,
respectively. The aromatic hydrocarbon may be selected from the group consisting
of benzene, toluene, ethylbenzene, xylene, naphthalene, naphthalene derivatives,
dimethylnaphthalene or mixtures thereof.
Further provided in accordance with this invention is a
process for transalkylating an aromatic hydrocarbon which comprises contacting under
transalkylating conditions an aromatic hydrocarbon with a polyalkyl aromatic hydrocarbon
under at least partial liquid phase conditions and in the presence of a catalyst
comprising the zeolite of this invention, preferably predominantly in the hydrogen
form. The aromatic hydrocarbon and the polyalkyl aromatic hydrocarbon may be present
in a molar ratio of from about 1:1 to about 25:1, respectively.
The aromatic hydrocarbon may be selected from the group
consisting of benzene, toluene, ethylbenzene, xylene, or mixtures thereof, and the
polyalkyl aromatic hydrocarbon may be a dialkylbenzene.
Further provided by this invention is a process to convert
paraffins to aromatics which comprises contacting paraffins under conditions which
cause paraffins to convert to aromatics with a catalyst comprising the zeolite of
this invention, said catalyst comprising gallium, zinc, or a compound of gallium
or zinc.
In accordance with this invention there is also provided
a process for isomerizing olefins comprising contacting said olefin under conditions
which cause isomerization of the olefin with a catalyst comprising the zeolite of
this invention.
Further provided in accordance with this invention is a
process for isomerizing an isomerization feed comprising an aromatic C8
stream of xylene isomers or mixtures of xylene isomers and ethylbenzene, wherein
a more nearly equilibrium ratio of ortho-, meta- and para-xylenes is obtained, said
process comprising contacting said feed under isomerization conditions with a catalyst
comprising the zeolite of this invention.
The present invention further provides a process for oligomerizing
olefins comprising contacting an olefin feed under oligomerization conditions with
a catalyst comprising the zeolite of this invention.
This invention also provides a process for converting lower
alcohols and other oxygenated hydrocarbons comprising contacting said lower alcohol
or other oxygenated hydrocarbon with a catalyst comprising the zeolite of this invention
under conditions to produce liquid products.
Further provided in accordance with the present invention
is a process for the production of higher molecular weight hydrocarbons from lower
molecular weight hydrocarbons comprising the steps of:
- (a) introducing into a reaction zone a lower molecular weight hydrocarbon-containing
gas and contacting said gas in said zone under C2+ hydrocarbon synthesis
conditions with the catalyst and a metal or metal compound capable of converting
the lower molecular weight hydrocarbon to a higher molecular weight hydrocarbon;
and
- (b) withdrawing from said reaction zone a higher molecular weight hydrocarbon-containing
stream.
In accordance with this invention, there is provided a
process for the reduction of oxides of nitrogen contained in a gas stream in the
presence of oxygen wherein said process comprises contacting the gas stream with
the zeolite of this invention. The zeolite may contain a metal or metal ions (such
as cobalt, copper or mixtures thereof) capable of catalyzing the reduction of the
oxides of nitrogen, and may be conducted in the presence of a stoichiometric excess
of oxygen. In a preferred embodiment, the gas stream is the exhaust stream of an
internal combustion engine.
DETAILED DESCRIPTION OF THE INVENTION
The present invention comprises a family of crystalline,
large pore zeolites designated herein "zeolite SSZ-60" or simply "SSZ-60". As used
herein, the term "large pore" means having an average pore size diameter greater
than about 6.0 Angstroms (6.0 × 10-10 m), preferably from about
6.5 Angstroms (6.5 × 10-10 m) to about 7.5 Angstroms (7.5 ×
10-10 m).
In preparing SSZ-60 zeolites, a N-ethyl-N-(3,3,5-trimethylcyclohexyl)-pyrrohdinium
cation or N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation is used as
a crystallization template. In general, SSZ-60 is prepared by contacting an active
source of one or more oxides selected from the group consisting of monovalent element
oxides, divalent element oxides, trivalent element oxides, and tetravalent element
oxides with the N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cation or N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium
cation templating agent.
SSZ-60 is prepared from a reaction mixture having the composition
shown in Table A below.
TABLE A
Reaction Mixture
Typical
Preferred
YO2/WaOb
> 20
30 - 70
OH-/YO2
0.10 - 0.50
0.20 - 0.30
Q/YO2
0.05 - 0.50
0.10 - 0.20
M2/n/YO2
0.02 - 0.40
0.10 - 0.25
H2O/YO2
30 - 80
35 - 45
where Y, W, Q, M and n are as defined above, and a is 1 or 2, and b is 2 when a
is 1 (i.e., W is tetravalent) and b is 3 when a is 2 (i.e., W is trivalent).
In practice, SSZ-60 is prepared by a process comprising:
- (a) preparing an aqueous solution containing sources of at least one oxide capable
of forming a crystalline molecular sieve and a N-ethyl-N-(3,3,5-trimethylcyclohexyl)-pyrrolidinium
cation or N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation having an anionic
counterion which is not detrimental to the formation of SSZ-60;
- (b) maintaining the aqueous solution under conditions sufficient to form crystals
of SSZ-60; and
- (c) recovering the crystals of SSZ-60.
Accordingly, SSZ-60 may comprise the crystalline material
and the templating agent 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 a first tetravalent element(s), and one or a combination
of a second tetravalent element(s) different from the first tetravalent element(s),
trivalent element(s), pentavalent 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 second tetravalent element (which is different from the first tetravalent element),
trivalent element and pentavalent element is preferably selected from the group
consisting of aluminum, gallium, iron, boron, titanium, indium, vanadium and combinations
thereof. More preferably, the second trivalent or tetravalent element is aluminum
or boron.
Typical sources of aluminum oxide for the reaction mixture
include aluminates, alumina, aluminum colloids, aluminum oxide coated on silica
sol, hydrated alumina gels such as Al(OH)3 and aluminum compounds such
as AlCl3 and Al2(SO4)3. Typical sources
of silicon oxide include silicates, silica hydrogel, silicic acid, fumed silica,
colloidal silica, tetra-alkyl orthosilicates, and silica hydroxides. Boron, as well
as gallium, germanium, titanium, indium, vanadium and iron, can be added in forms
corresponding to their aluminum and silicon counterparts.
A source zeolite reagent may provide a source of aluminum
or boron. In most cases, the source zeolite also provides a source of silica. The
source zeolite in its dealuminated or deboronated form 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 as a source of alumina for the present
process is more completely described in
U.S. Patent No. 5,225,179, issued July 6, 1993 to Nakagawa
entitled "Method of Making Molecular Sieves".
Typically, an alkali metal hydroxide and/or an alkaline
earth metal hydroxide, such as the hydroxide of sodium, potassium, lithium, cesium,
rubidium, calcium, and magnesium, is used in the reaction mixture; however, this
component can be omitted so long as the equivalent basicity is maintained. The templating
agent may be used to provide hydroxide ion. Thus, it may be beneficial to ion exchange,
for example, the halide for 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 crystalline oxide material, in order to balance
valence electron charges therein.
The reaction mixture is maintained at an elevated temperature
until the crystals of the SSZ-60 zeolite are formed. The hydrothermal crystallization
is usually conducted under autogenous pressure, at a temperature between 100°C
and 200°C, preferably between 135°C and 160°C. The crystallization
period is typically greater than 1 day and preferably from about 3 days to about
20 days.
Preferably, the zeolite is prepared using mild stirring
or agitation.
During the hydrothermal crystallization step, the SSZ-60
crystals can be allowed to nucleate spontaneously from the reaction mixture. The
use of SSZ-60 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-60 over any undesired phases. When used as seeds, SSZ-60 crystals are added
in an amount between 0.1 and 10% of the weight of silica used in the reaction mixture.
Once the zeolite 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°C
to 150°C for from 8 to 24 hours, to obtain the as-synthesized SSZ-60 zeolite
crystals. The drying step can be performed at atmospheric pressure or under vacuum.
SSZ-60 as prepared has a mole ratio of an oxide selected
from silicon oxide, germanium oxide and mixtures thereof to an oxide selected from
aluminum oxide, gallium oxide, iron oxide, boron oxide, titanium oxide, indium oxide,
vanadium oxide and mixtures thereof greater than about 20; and has, after calcination,
the X-ray diffraction lines of Table II below. SSZ-60 further has a composition,
as synthesized (i.e., prior to removal of the templating agent from the zeolite)
and in the anhydrous state, in terms of mole ratios, shown in Table B below.
TABLE B
As-Synthesized SSZ-60
YO2/WcOd
> 20
M2/n/YO2
0.01 - 0.03
Q/YO2
0.02 - 0.05
where Y, W, c, d, M and Q are as defined above.
SSZ-60 can be made essentially aluminum free, i.e., having
a silica to alumina mole ratio of ∞. A method of increasing the mole ratio
of silica to alumina is by using standard acid leaching or chelating treatments.
However, essentially aluminum-free SSZ-60 can be synthesized directly using essentially
aluminum-free silicon sources as the main tetrahedral metal oxide component, if
boron is also present. SSZ-60 can also be prepared directly as either an aluminosilicate
or a borosilicate.
Lower silica to alumina ratios may also be obtained by
using methods which insert aluminum into the crystalline framework. For example,
aluminum insertion may occur by thermal treatment of the zeolite in combination
with an alumina binder or dissolved source of alumina. Such procedures are described
in
U.S. Patent No. 4,559,315, issued on December 17,1985 to Chang et al.
It is believed that SSZ-60 is comprised of a new framework
structure or topology which is characterized by its X-ray diffraction pattern. SSZ-60
zeolites, as-synthesized, have a crystalline structure whose X-ray powder diffraction
pattern exhibit the characteristic lines shown in Table I and is thereby distinguished
from other zeolites.
TABLE I
As-Synthesized SSZ-60
Two Theta(deg.)(a)
d-spacing (Å / × 10-10 m)
Relative Intensity(b)
6.4
13.8
M
7.6
11.6
M
8.0
11.0
S
10.3
8.56
M
15.2
5.82
W
17.4
5.09
M
19.3
4.60
M
20.5
4.33
S
22.4
3.97
VS
24.2
3.69
M
27.2
3.28
M
28.1
3.17
W
35.9
2.50
M
(a)±0.2
(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 SSZ-60 including actual relative intensities.
TABLE IA
Two Theta(a)
d-spacing (Å / × 10-10 m)
Intensity I/Io x 100.
6.39
13.83
38
7.64
Sh 11.56
24
7.98
11.07
49
10.29
8.588
19
13.40
6.604
6
15.19
5.828
12
17.44
5.080
36
19.30
4.596
36
20.53
4.322
57
21.49
4.132
13
22.36
3.973
100
23.39
3.801
16
24.12
Sh 3.687
18
24.23
3.670
25
25.22
3.528
13
25.95
3.431
15
26.78
Sh 3.327
12
27.16
3.281
27
28.08
3.176
19
29.05
3.071
6
30.72
2.908
6
31.34
2.852
5
32.65
2.740
6
33.63
2.663
5
35.87
2.594
31
37.47
2.502
4
39.58
2.398
4
(a)± 0.2
After calcination, the SSZ-60 zeolites have a crystalline
structure whose X-ray powder diffraction pattern include the characteristic lines
shown in Table II:
TABLE II
Calcined SSZ-60
Two Theta (deg.)(a)
d-spacing (Å / × 10-10 m)
Relative Intensity
6.4
13.8
VS
7.6
11.6
S
8.0
11.0
VS
10.25
8.62
S
15.1
5.86
W
17.5
5.06
W
19.2
4.62
M
20.4
4.35
M
22.3
3.98
S
24.2
3.67
W
27.1
3.29
W
28.0
3.18
W
35.7
2.51
W
(a) ±0.2
Table IIA below shows the X-ray powder diffraction lines
for calcined SSZ-60 including actual relative intensities.
TABLE IIA
Two Theta (deg.)(a)
d-spacing (Å / × 10-10 m)
Intensity I/Io x 100
6.36
13.88
100
7.63
Sh 11.58
44
7.98
11.07
76
10.25
8.625
48
15.11
5.860
5
16.12
5.495
4
17.47
5.073
10
18.07
4.904
2
19.20
4.620
40
19.70
4.503
2
20.44
4.342
39
22.28
3.987
64
23.32
3.811
15
24.19
3.676
14
25.17
3.536
9
25.86
3.442
12
26.59
3.349
10
27.11
3.286
13
28.00
3.185
6
29.03
3.074
4
30.56
2.923
3
31.32
2.854
5
32.57
2.747
4
33.53
2.671
4
35.70
2.513
18
(a) ±0.2
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&thgr; where &thgr; 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 ± 0.20 degrees.
The X-ray diffraction pattern of Table I is representative
of "as-synthesized" or "as-made" SSZ-60 zeolites. Minor variations in the diffraction
pattern can result from variations in the silica-to-alumina or silica-to-boron 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.
Representative peaks from the X-ray diffraction pattern
of calcined SSZ-60 are shown in Table II. Calcination can also result in changes
in the intensities of the peaks as compared to patterns of the "as-made" material,
as well as minor shifts in the diffraction pattern. The zeolite produced by exchanging
the metal or other cations present in the zeolite with various other cations (such
as H+ or NH4
+) 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.
Crystalline SSZ-60 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 zeolite can be leached with chelating agents, e.g., EDTA or dilute
acid solutions, to increase the silica to alumina mole ratio. The zeolite can also
be steamed; steaming helps stabilize the crystalline lattice to attack from acids.
The zeolite 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 zeolite by replacing
some of the cations in the zeolite with metal cations via standard ion exchange
techniques (see, for example,
U.S. Patent Nos. 3,140,249 issued July 7, 1964 to Plank et al.
;
3,140,251 issued July 7, 1964 to Plank et al.
; and
3,140,253 issued July 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-60. The zeolite can also be impregnated with the metals, or, the metals
can be physically and intimately admixed with the zeolite using standard methods
known to the art.
Typical ion-exchange techniques involve contacting the
synthetic zeolite 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 zeolite
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. Patent Nos. 3,140,249 issued on July 7, 1964 to Plank et al.
;
3,140,251 issued on July 7, 1964 to Plank et al.
; and
3,140,253 issued on July 7, 1964 to Plank et al.
Following contact with the salt solution of the desired
replacing cation, the zeolite is typically washed with water and dried at temperatures
ranging from 65°C to about 200°C. After washing, the zeolite can be calcined
in air or inert gas at temperatures ranging from about 200°C to about 800°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-60, the spatial arrangement of the atoms which form the basic crystal lattice
of the zeolite remains essentially unchanged.
SSZ-60 can be formed into a wide variety of physical shapes.
Generally speaking, the zeolite 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 aluminosilicate
can be extruded before drying, or, dried or partially dried and then extruded.
SSZ-60 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. Patent No. 4,910,006, issued May 20,1990 to Zones et al.
, and
U.S. Patent No. 5,316,753, issued May 31, 1994 to Nakagawa
.
Hydrocarbon Conversion Processes
SSZ-60 zeolites are useful in hydrocarbon conversion reactions.
Hydrocarbon conversion reactions are chemical and catalytic processes in which carbon
containing compounds are changed to different carbon containing compounds. Examples
of hydrocarbon conversion reactions in which SSZ-60 are expected to be useful include
hydrocracking, dewaxing, catalytic cracking and olefin and aromatics formation reactions.
The catalysts are also expected to be useful in other petroleum refining and hydrocarbon
conversion reactions such as isomerizing n-paraffins and naphthenes, polymerizing
and oligomerizing olefinic or acetylenic compounds such as isobutylene and butene-1,
reforming, isomerizing polyalkyl substituted aromatics (e.g., in-xylene), and disproportionating
aromatics (e.g., toluene) to provide mixtures of benzene, xylenes and higher methylbenzenes
and oxidation reactions. Also included are rearrangement reactions to make various
naphthalene derivatives, and forming higher molecular weight hydrocarbons from lower
molecular weight hydrocarbons (e.g., methane upgrading). The SSZ-60 catalysts may
have high selectivity, and under hydrocarbon conversion conditions can provide a
high percentage of desired products relative to total products.
SSZ-60 zeolites can be used in processing hydrocarbonaceous
feedstocks. Hydrocarbonaceous feedstocks contain carbon compounds and can be from
many different sources, such as virgin petroleum fractions, recycle petroleum fractions,
shale oil, liquefied coal, tar sand oil, synthetic paraffins from NAO, recycled
plastic feedstocks and, in general, can be any carbon containing feedstock susceptible
to zeolitic catalytic reactions. Depending on the type of processing the hydrocarbonaceous
feed is to undergo, the feed can contain metal or be free of metals, it can also
have high or low nitrogen or sulfur impurities. It can be appreciated, however,
that in general processing will be more efficient (and the catalyst more active)
the lower the metal, nitrogen, and sulfur content of the feedstock.
The conversion of hydrocarbonaceous feeds can take place
in any convenient mode, for example, in fluidized bed, moving bed, or fixed bed
reactors depending on the types of process desired. The formulation of the catalyst
particles will vary depending on the conversion process and method of operation.
Other reactions which can be performed using the catalyst
of this invention containing a metal, e.g., a Group VIII metal such platinum, include
hydrogenation-dehydrogenation reactions, denitrogenation and desulfurization reactions.
The following table indicates typical reaction conditions
which may be employed when using catalysts comprising SSZ-60 in the hydrocarbon.conversion
reactions of this invention. Preferred conditions are indicated in parentheses.
Process
Temp.,°C
Pressure
LHSV
Hydrocracking
175-485
0.5-350 bar
0.1-30
Dewaxing
200-475
15-3000 psig,
0.1-20
(250-450)
0.103-20.7 MPa
(0.2-10)
gauge
(200-3000, 1.38-
20.7 MPa gauge)
Aromatics formation
400-600 (480-550)
atm.-10 bar
0.1-15
Cat. Cracking
127-885
subatm.-1
0.5-50
(atm.-5 atm.)
Oligomerization
232-6492
0.1-50 atm.2,3
0.2-502
10-2324
-
0.05-205
(27-204)4
-
(0.1-10)5
Paraffins to
100-700
0-1000 psig, 0-
0.5-405
aromatics
6.89 MPa gauge
Condensation of
260-538
0.5-1000 psig,
0.5-505
alcohols
0.00345-6.89 MPa
gauge
Isomerization
93-538
50-1000 psig,
1-10
(204-315)
0.345-6.89 MPa
(1-4)
gauge
Xylene
260-5932
0.5-50 atm.2
0.1-1005
isomerization
(315-566)2
(1-5 atm)2
(0.5-50)5
38-3714
1-200 atm.4
0.5-50
1 Several hundred atmospheres (1 atm = 101 kPa)
2 Gas phase reaction
3 Hydrocarbon partial pressure
4 Liquid phase reaction
5 WHSV
Other reaction conditions and parameters are provided below.
Hydrocracking
Using a catalyst which comprises SSZ-60, preferably predominantly
in the hydrogen form, and a hydrogenation promoter, heavy petroleum residual feedstocks,
cyclic stocks and other hydrocrackate charge stocks can be hydrocracked using the
process conditions and catalyst components disclosed in the aforementioned
U.S. Patent No. 4,910,006
and
U.S. Patent No. 5,316,753
.
The hydrocracking catalysts contain an effective amount
of at least one hydrogenation component of the type commonly employed in hydrocracking
catalysts. The hydrogenation component is generally selected from the group of hydrogenation
catalysts consisting of one or more metals of Group VIB and Group VIII, including
the salts, complexes and solutions containing such. The hydrogenation catalyst is
preferably selected from the group of metals, salts and complexes thereof of the
group consisting of at least one of platinum, palladium, rhodium, iridium, ruthenium
and mixtures thereof or the group consisting of at least one of nickel, molybdenum,
cobalt, tungsten, titanium, chromium and mixtures thereof. Reference to the catalytically
active metal or metals is intended to encompass such metal or metals in the elemental
state or in some form such as an oxide, sulfide, halide, carboxylate and the like.
The hydrogenation catalyst is present in an effective amount to provide the hydrogenation
function of the hydrocracking catalyst, and preferably in the range of from 0.05
to 25% by weight.
Dewaxing
SSZ-60, preferably predominantly in the hydrogen form,
can be used to dewax hydrocarbonaceous feeds by selectively removing straight chain
paraffins. Typically, the viscosity index of the dewaxed product is improved (compared
to the waxy feed) when the waxy feed is contacted with SSZ-60 under isomerization
dewaxing conditions.
The catalytic dewaxing conditions are dependent in large
measure on the feed used and upon the desired pour point. Hydrogen is preferably
present in the reaction zone during the catalytic dewaxing process. The hydrogen
to feed ratio is typically between about 0.089 to 5.34 SCM (standard cubic metres)/liter
(500 and about 30,000 SCF/bbl (standard cubic feet per barrel) preferably about
0.178 to 3.56 SCM/liter (1000 to about 20,000 SCF/bbl). Generally, hydrogen will
be separated from the product and recycled to the reaction zone. Typical feedstocks
include light gas oil, heavy gas oils and reduced crudes boiling above about 177°C
(350°F).
A typical dewaxing process is the catalytic dewaxing of
a hydrocarbon oil feedstock boiling above about 177°C (350°F) and containing
straight chain and slightly branched chain hydrocarbons by contacting the hydrocarbon
oil fe tock in the presence of added hydrogen gas at a hydrogen pressure of about
0.103-20.7 MPa (15-3000 psi) with a catalyst comprising SSZ-60 and at least one
Group VIII metal.
The SSZ-60 hydrodewaxing catalyst may optionally contain
a hydrogenation component of the type commonly employed in dewaxing catalysts. See
the aforementioned
U.S. Patent No. 4,910,006
and
U.S. Patent No. 5,316,753
for examples of these hydrogenation components.
The hydrogenation component is present in an effective
amount to provide an effective hydrodewaxing and hydroisomerization catalyst preferably
in the range of from about 0.05 to 5% by weight. The catalyst may be run in such
a mode to increase isodewaxing at the expense of cracking reactions.
The feed may be hydrocracked, followed by dewaxing. This
type of two stage process and typical hydrocracking conditions are described in
U.S. Patent No. 4,921,594, issued May 1, 1990 to Miller
.
SSZ-60 may also be utilized as a dewaxing catalyst in the
form of a layered catalyst. That is, the catalyst comprises a first layer comprising
zeolite SSZ-60 and at least one Group VIII metal, and a second layer comprising
an aluminosilicate zeolite which is more shape selective than zeolite SSZ-60. The
use of layered catalysts is disclosed in
U.S. Patent No. 5,149,421, issued September 22, 1992 to Miller
.
The layering may also include a bed of SSZ-60 layered with
a non-zeolitic component designed for either hydrocracking or hydrofinishing.
SSZ-60 may also be used to dewax raffinates, including
bright stock, under conditions such as those disclosed in U. S.Patent No. 4,181,598,
issued January 1,1980 to Gillespie et al.
It is often desirable to use mild hydrogenation (sometimes
referred to as hydrofinishing) to produce more stable dewaxed products. The hydrofinishing
step can be performed either before or after the dewaxing step, and preferably after.
Hydrofinishing is typically conducted at temperatures ranging from about 190°C
to about 340°C at pressures from about 2.76 MPa gauge (400 psig) to about 20.7
MPa gauge (3000 psig) at space velocities (LHSV) between about 0.1 and 20 and a
hydrogen recycle rate of about 0.071 to 0.27 SCM/ liter (400 to 1500 SCF/bbl). The
hydrogenation catalyst employed must be active enough not only to hydrogenate the
olefins, diolefins and color bodies which may be present, but also to reduce the
aromatic content. Suitable hydrogenation catalyst are disclosed in U. S. Patent
No.
4,921,594, issued May 1, 1990 to Miller
. The hydrofinishing step is beneficial in preparing an acceptably stable
product (e.g., a lubricating oil) since dewaxed products prepared from hydrocracked
stocks tend to be unstable to air and light and tend to form sludges spontaneously
and quickly.
Lube oil may be prepared using SSZ-60. For example, a C20+
lube oil may be made by isomerizing a C20+ olefin feed over a catalyst
comprising SSZ-60 in the hydrogen form and at least one Group VIII metal. Alternatively,
the lubricating oil may be made by hydrocracking in a hydrocracking zone a hydrocarbonaceous
feedstock to obtain an effluent comprising a hydrocracked oil, and catalytically
dewaxing the effluent at a temperature of at least about 204°C (400°F)
and at a pressure of from about 0.103 MPa gauge (15 psig) to about 20.7 MPa gauge
(3000 psig) in the presence of added hydrogen gas with a catalyst comprising SSZ-60
in the hydrogen form and at least one Group VIII metal.
Aromatics Formation
SSZ-60 can be used to convert light straight run naphthas
and similar mixtures to highly aromatic mixtures. Thus, normal and slightly branched
chained hydrocarbons, preferably having a boiling range above about 40°C and
less than about 200°C, can be converted to products having a substantial higher
octane aromatics content by contacting the hydrocarbon feed with a catalyst comprising
SSZ-60. It is also possible to convert heavier feeds into BTX or naphthalene derivatives
of value using a catalyst comprising SSZ-60.
The conversion catalyst preferably contains a Group VIII
metal compound to have sufficient activity for commercial use. By Group VIII metal
compound as used herein is meant the metal itself or a compound thereof. The Group
VIII noble metals and their compounds, platinum, palladium, and iridium, or combinations
thereof can be used. Rhenium or tin or a mixture thereof may also be used in conjunction
with the Group VIII metal compound and preferably a noble metal compound. The most
preferred metal is platinum. The amount of Group VIII metal present in the conversion
catalyst should be within the normal range of use in reforming catalysts, from about
0.05 to 2.0 weight percent, preferably 0.2 to 0.8 weight percent.
It is critical to the selective production of aromatics
in useful quantities that the conversion catalyst be substantially free of acidity,
for example, by neutralizing the zeolite with a basic metal, e.g., alkali metal,
compound. Methods for rendering the catalyst free of acidity are known in the art.
See the aforementioned
U.S. Patent No. 4,910,006
and
U.S. Patent No. 5,316,753
for a description of such methods.
The preferred alkali metals are sodium, potassium, rubidium
and cesium. The zeolite itself can be substantially free of acidity only at very
high silica:alumina mole ratios.
Catalytic Cracking
Hydrocarbon cracking stocks can be catalytically cracked
in the absence of hydrogen using SSZ-60, preferably predominantly in the hydrogen
form.
When SSZ-60 is used as a catalytic cracking catalyst in
the absence of hydrogen, the catalyst may be employed in conjunction with traditional
cracking catalysts, e.g., any aluminosilicate heretofore employed as a component
in cracking catalysts. Typically, these are large pore, crystalline aluminosilicates.
Examples of these traditional cracking catalysts are disclosed in the aforementioned
U.S. Patent No. 4,910,006
and
U.S. Patent No 5,316,753
. When a traditional cracking catalyst (TC) component is employed, the
relative weight ratio of the TC to the SSZ-60 is generally between about 1:10 and
about 500:1, desirably between about 1:10 and about 200:1, preferably between about
1:2 and about 50:1, and most preferably is between about 1:1 and about 20:1. The
novel zeolite and/or the traditional cracking component may be further ion exchanged
with rare earth ions to modify selectivity.
The cracking catalysts are typically employed with an inorganic
oxide matrix component. See the aforementioned
U.S. Patent No. 4,910,006
and
U.S. Patent No. 5,316,753
for examples of such matrix components.
Isomerization
The present catalyst is highly active and highly selective
for isomerizing C4 to C7 hydrocarbons. The activity means
that the catalyst can operate at relatively low temperature which thermodynamically
favors highly branched paraffins. Consequently, the catalyst can produce a high
octane product. The high selectivity means that a relatively high liquid yield can
be achieved when the catalyst is run at a high octane.
The present process comprises contacting the isomerization
catalyst, i.e., a catalyst comprising SSZ-60 in the hydrogen form, with a hydrocarbon
feed under isomerization conditions. The feed is preferably a light straight run
fraction, boiling within the range of -1°C to 121°C (30°F to 250°F)
and preferably from 16°C to 93°C (60°F to 200°F). Preferably,
the hydrocarbon feed for the process comprises a substantial amount of C4
to C7 normal and slightly branched low octane hydrocarbons, more preferably
C5 and C6 hydrocarbons.
It is preferable to carry out the isomerization reaction
in the presence of hydrogen. Preferably, hydrogen is added to give a hydrogen to
hydrocarbon ratio (H2/HC) of between 0.5 and 10 H2/HC, more
preferably between 1 and 8 H2/HC. See the aforementioned
U.S. Patent No. 4,910,006
and
U.S. Patent No. 5,316,753
for a further discussion of isomerization process conditions.
A low sulfur feed is especially preferred in the present
process. The feed preferably contains less than 10 ppm, more preferably less than
1 ppm, and most preferably less than 0.1 ppm sulfur. In the case of a feed which
is not already low in sulfur, acceptable levels can be reached by hydrogenating
the feed in a presaturation zone with a hydrogenating catalyst which is resistant
to sulfur poisoning. See the aforementioned
U.S. Patent No. 4,910,006
and
U.S. Patent No. 5,316,753
for a further discussion of this hydrodesulfurization process.
It is preferable to limit the nitrogen level and the water
content of the feed. Catalysts and processes which are suitable for these purposes
are known to those skilled in the art.
After a period of operation, the catalyst can become deactivated
by sulfur or coke. See-the aforementioned
U.S. Patent No. 4,910,006
and
U.S. Patent No. 5,316,753
for a further discussion of methods of removing this sulfur and coke,
and of regenerating the catalyst.
The conversion catalyst preferably contains a Group VIII
metal compound to have sufficient activity for commercial use. By Group VIII metal
compound as used herein is meant the metal itself or a compound thereof. The Group
VIII noble metals and their compounds, platinum, palladium, and iridium, or combinations
thereof can be used. Rhenium and tin may also be used in conjunction with the noble
metal. The most preferred metal is platinum. The amount of Group VIII metal present
in the conversion catalyst should be within the normal range of use in isomerizing
catalysts, from about 0.05 to 2.0 weight percent, preferably 0.2 to 0.8 weight percent.
Alkylation and Transalkylation
SSZ-60 can be used in a process for the alkylation or transalkylation
of an aromatic hydrocarbon. The process comprises contacting the aromatic hydrocarbon
with a C2 to C16 olefin alkylating agent or a polyalkyl aromatic
hydrocarbon transalkylating agent, under at least partial liquid phase conditions,
and in the presence of a catalyst comprising SSZ-60.
SSZ-60 can also be used for removing benzene from gasoline
by alkylating the benzene as described above and removing the alkylated product
from the gasoline.
For high catalytic activity, the SSZ-60 zeolite should
be predominantly in its hydrogen ion form. It is preferred that, after calcination,
at least 80% of the cation sites are occupied by hydrogen ions and/or rare earth
ions.
Examples of suitable aromatic hydrocarbon feedstocks which
may be alkylated or transalkylated by the process of the invention include aromatic
compounds such as benzene, toluene and xylene. The preferred aromatic hydrocarbon
is benzene. There may be occasions where naphthalene or naphthalene derivatives
such as dimethylnaphthalene may be desirable. Mixtures of aromatic hydrocarbons
may also be employed.
Suitable olefins for the alkylation of the aromatic hydrocarbon
are those containing 2 to 20, preferably 2 to 4, carbon atoms, such as ethylene,
propylene, butene-1, trans-butene-2 and cis-butene-2, or mixtures thereof. There
may be instances where pentenes are desirable. The preferred olefins are ethylene
and propylene. Longer chain alpha olefins may be used as well.
When transalkylation is desired, the transalkylating agent
is a polyalkyl aromatic hydrocarbon containing two or more alkyl groups that each
may have from 2 to about 4 carbon atoms. For example, suitable polyalkyl aromatic
hydrocarbons include di-, tri- and tetra-alkyl aromatic hydrocarbons, such as diethylbenzene,
triethylbenzene, diethylmethylbenzene (diethyltoluene), di-isopropylbenzene, di-isopropyltoluene,
dibutylbenzene, and the like. Preferred polyalkyl aromatic hydrocarbons are the
dialkyl benzenes. A particularly preferred polyalkyl aromatic hydrocarbon is di-isopropylbenzene.
When alkylation is the process conducted, reaction conditions
are as follows. The aromatic hydrocarbon feed should be present in stoichiometric
excess. It is preferred that molar ratio of aromatics to olefins be greater than
four-to-one to prevent rapid catalyst fouling. The reaction temperature may range
from 38°C (100°F) to 316°C (600°F), preferably 121°C (250°F)
to 232°C (450°F). The reaction pressure should be sufficient to maintain
at least a partial liquid phase in order to retard catalyst fouling. This is typically
0.345 MPa gauge (50 psig) to 6.89 MPa gauge (1000 psig) depending on the feedstock
and reaction temperature. Contact time may range from 10 seconds to 10 hours, but
is usually from 5 minutes to an hour. The weight hourly space velocity (WHSV), in
terms of grams (pounds) of aromatic hydrocarbon and olefin per gram (pound) of catalyst
per hour, is generally within the range of about 0.5 to 50.
When transalkylation is the process conducted, the molar
ratio of aromatic hydrocarbon will generally range from about 1:1 to 25:1, and preferably
from about 2:1 to 20:1. The reaction temperature may range from about 38°C
to 316°C (100°F to 600°F), but it is preferably about 121°C
to 232°C (250°F to 450°F). The reaction pressure should be sufficient
to maintain at least a partial liquid phase, typically in the range of about 0.345
MPa gauge (50 psig) to 6.89 MPa gauge (1000 psig) preferably 2.07 MPa gauge (300
psig) to 4.14 MPa gauge (600 psig). The weight hourly space velocity will range
from about 0.1 to 10.
U.S. Patent No. 5,082,990 issued on January 21, 1992 to Hsieh, et al.
describes such processes.
Conversion of Paraffins to Aromatics
SSZ-60 can be used to convert light gas C2-C6
paraffins to higher molecular weight hydrocarbons including aromatic compounds.
Preferably, the zeolite will contain a catalyst metal or metal oxide wherein said
metal is selected from the group consisting of Groups IB, IIB, VIII and IIIA of
the Periodic Table. Preferably, the metal is gallium, niobium, indium or zinc in
the range of from about 0.05 to 5% by weight
Xylene Isomerization
SSZ-60 may also be useful in a process for isomerizing
one or more xylene isomers in a C8 aromatic feed to obtain ortho-, meta-,
and para-xylene in a ratio approaching the equilibrium value. In particular, xylene
isomerization is used in conjunction with a separate process to manufacture para-xylene.
For example, a portion of the para-xylene in a mixed C8 aromatics stream
may be recovered by crystallization and centrifugation. The mother liquor from the
crystallizer is then reacted under xylene isomerization conditions to restore ortho-,
meta- and para-xylenes to a near equilibrium ratio. At the same time, part of the
ethylbenzene in the mother liquor is converted to xylenes or to products which are
easily separated by filtration. The isomerate is blended with fresh feed and the
combined stream is distilled to remove heavy and light byproducts. The resultant
C8 aromatics stream is then sent to the crystallizer to repeat the cycle.
Optionally, isomerization in the vapor phase is conducted
in the presence of 3.0 to 30.0 moles of hydrogen per mole of alkylbenzene (e.g.,
ethylbenzene). If hydrogen is used, the catalyst should comprise about 0.1 to 2.0
wt.% of a hydrogenation/dehydrogenation component selected from Group VIII (of the
Periodic Table) metal component, especially platinum or nickel. By Group VIII metal
component is meant the metals and their compounds such as oxides and sulfides.
Optionally, the isomerization feed may contain 10 to 90
wt. of a diluent such as toluene, trimethylbenzene, naphthenes or paraffins.
Oligomerization
It is expected that SSZ-60 can also be used to oligomerize
straight and branched chain olefins having from about 2 to 21 and preferably 2-5
carbon, atoms. The oligomers which are the products of the process are medium to
heavy olefins which are useful for both fuels, i.e., gasoline or a gasoline blending
stock and chemicals.
The oligomerization process comprises contacting the olefin
feedstock in the gaseous or liquid phase with a catalyst comprising SSZ-60.
The zeolite can have the original cations associated therewith
replaced by a wide variety of other cations according to techniques well known in
the.art. Typical cations would include hydrogen, ammonium and metal cations including
mixtures of the same-Of the replacing metallic cations, particular preference is
given to cations of metals such as rare earth metals, manganese, calcium, as well
as metals of Group II of the Periodic Table, e.g., zinc, and Group VIII of the Periodic
Table, e.g., nickel. One of the prime requisites is that the zeolite have a fairly
low aromatization activity, i.e., in which the amount of aromatics produced is not
more than about 20% by weight. This is accomplished by using a zeolite with controlled
acid activity [alpha value] of from about 0:1 to about 120, preferably from about
0.1 to about 100, as measured by its ability to crack n-hexane.
Alpha values are defined by a standard test known in the
art, e.g., as shown in
U.S. Patent No. 3,960,978 issued on June 1, 1976 to Givens et al.
If required, such zeolites may be obtained by steaming,
by use in a conversion process or by any other method which may occur to one skilled
in this art.
Condensation of Alcohols
SSZ-60 can be used to condense lower aliphatic alcohols
having 1 to 10 carbon atoms to a gasoline boiling point hydrocarbon product comprising
mixed aliphatic and aromatic hydrocarbon. The process disclosed in
U.S. Patent No. 3,894,107, issued July 8, 1975
to Butter et al., describes the process conditions used in this process.
The catalyst may be in the hydrogen form or may be base
exchanged or impregnated to contain ammonium or a metal cation complement, preferably
in the range of from about 0.05 to 5% by weight. The metal cations that may be present
include any of the metals of the Groups I through VIII of the Periodic Table. However,
in the case of Group IA metals, the cation content should in no case be so large
as to effectively inactivate the catalyst, nor should the exchange be such as to
eliminate all acidity. There may be other processes involving treatment of oxygenated
substrates where a basic catalyst is desired.
Methane Upgrading
Higher molecular weight hydrocarbons can be formed from
lower molecular weight hydrocarbons by contacting the lower molecular weight hydrocarbon
with a catalyst comprising SSZ-60 and a metal or metal compound capable of converting
the lower molecular weight hydrocarbon to a higher molecular weight hydrocarbon.
Examples of such reactions include the conversion of methane to C2+ hydrocarbons
such as ethylene or benzene or both. Examples of useful metals and metal compounds
include lanthanide and or actinide metals or metal compounds.
These reactions, the metals or metal compounds employed
and the conditions under which they can be run are disclosed in
U.S. Patents No. 4,734,537, issued March 29, 1988 to Devries et al.
;
4,939,311, issued July 3, 1990 to Washecheck et al.
;
4,962,261, issued October 9, 1990 to Abrevaya et al.
;
5,095,161, issued March 10, 1992 to Abrevaya et al.
;
5,105,044, issued April 14, 1992 to Han et al.
;
5,105,046, issued April 14, 1992 to Washecheck
;
5,238,898, issued August 24, 1993 to Han et al.
;
5,321,185, issued June 14, 1994 to van der Vaart
; and
5,336,825, issued August 9, 1994 to Choudhary et al.
SSZ-60 can also be used as an adsorbent with high selectivities
based on molecular sieve behavior and also based upon preferential hydrocarbon packing
within the pores.
SSZ-60 may be used for the catalytic reduction of the oxides
of nitrogen in a gas stream. Typically, the gas stream also contains oxygen, often
a stoichiometric excess thereof. Also, the SSZ-60 may contain a metal or metal ions
within or on it which are capable of catalyzing the reduction of the nitrogen oxides.
Examples of such metals or metal ions include copper, cobalt and mixtures thereof.
One example of such a process for the catalytic reduction
of oxides of nitrogen in the presence of a zeolite is disclosed in
U.S. Patent No. 4,297,328, issued October 27, 1981 to Ritscher et al.
There, the catalytic process is the combustion of carbon monoxide and
hydrocarbons and the catalytic reduction of the oxides of nitrogen contained in
a gas stream, such as the exhaust gas from an internal combustion engine. The zeolite
used is metal ion-exchanged, doped or loaded sufficiently so as to provide an effective
amount of catalytic copper metal or copper ions within or on the zeolite. In addition,
the process is conducted in an excess of oxidant, e.g., oxygen.
EXAMPLES
The following examples demonstrate but do not limit the
present invention. The templating agents indicated in Table C below are used in
these examples.
TABLE C
N-Ethyl-N-(3,3,5-trimethyleyclohexyl)pyrrolidinium cation
N-Ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation
The anion (X-) associated with the cation may
be any anion which is not detrimental to the formation of the zeolite. 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.
Example 1
Synthesis of N-Ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cation (Template
A)
Synthesis of N-(3,3,5-trimethylcyclohexyl)pyrrolidine
The structure-directing agent (SDA) was synthesized using
the reaction sequence described in the scheme bellow.
Synthesis of the parent amine N-(3,3,5-trimethylcyclohexyl)pyrrolidine
In a 3-liter three neck flask a 150 g (2.13 mole) of pyrrolidine,
100 g of 3,5,5-trimethylcyclohexanone (0.71 mole) were mixed in a and 1500 ml anhydrous
hexane. To the resulting solution, 150 g (1.25 mole) of anhydrous magnesium sulfate
were added and the mixture was mechanically stirred and heated at reflux (the reaction
was monitored by NMR analysis) for 132 hrs. The reaction mixture was filtered through
a fritted glass funnel. The filtrate was concentrated under reduced pressure on
a rotary evaporator to give 133 g of an isomeric mixture of the desired enamine
as was indicated by 1H-NMR and 13C-NMR analysis [(3,3,5-trimethylcyclohex-enyl)pyrrolidine
and (3,3,5-trimethylcyclohex-enyl)pyrrolidine]. Saturation of the enamine mixture,
to give N-(3,5,5-trimethylcyclohexyl)pyrrolidine, was accomplished in quantitative
yield by hydrogenation in ethanol at a 0.379 MPa (55 psi) pressure of hydrogen gas
in the presence of 10% Pd on activated carbon.
Ouaternization of N-(3,3,5-trimethylcyclohexyl)pyrrolidine (Synthesis of N-ethyl-N-(3,3,5-trimethycyclohexyl)pyrrolidinium
Iodide)
To a solution of 131 g (0.67 mole) of N-(3,3,5-trimethylcyclohexyl)pyrrolidine
in 1000 ml anhydrous methanol, 210 g (1.34 mole) of ethyl iodide were added. The
reaction was mechanically stirred for 3 days at room temperature. Then, an additional
equivalent of ethyl iodide and one equivalent (67.7 g; 0.0.67 mole) of potassium
bicarbonate were added and the reaction was stirred at refluxing temperature for
72 hrs. The reaction mixture was concentrated under reduced pressure on a rotary
evaporator to give an off-white-colored solid material. The solids were rinsed several
times with chloroform and filtered after each rinse. All the chloroform rinses were
combined and concentrated to give a white powder whose NMR data were acceptable
for the desired quaternary ammonium iodide salt. The reaction afforded 218g (93%
yield) of the product. The iodide salt was purified by re-crystallization in acetone
and ether. This was done by completely dissolving the iodide salt in acetone and,
then, the precipitation of the product was facilitated by addition of ethyl ether
to the acetone solution. Re-crystallization gave 211 g of the product as white powder
(pure by 1H and 13C-NMR NMR analysis).
Ion Exchange (Synthesis of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium
Hydroxide)
To a solution of N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium
iodide salt (100 g; 0.285 mole) in 350 ml water in a 1-liter plastic bottle, To
the solution, 340 g of Ion-Exchange Resin-OH (BIO RAD® AH1-X8) were
added and the mixture was gently stirred at room temperature overnight. The mixture
was filtered and the solids were rinsed with additional 75 ml of water. Titration
analysis with 0.1N HCl gave a total yield of 0.215 mole of hydroxide ions (0.215
mole N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide).
Example 2
Synthesis of N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation (Template
B)
N-ethyl-N-(2,4,4,-trimethylcyclopentyl)pyrrolidinium cation
was synthesized using the synthetic scheme described above starting from pyrrolidine
and 2,4,4-trimethylcyclopentanone.
Example 3
Typical Preparation of Borosilicate SSZ-60 Starting SiO
2
/B
2
O
3
=46
In a 23-in Teflon liner, 5.93 g of 0.50 M solution (aqueous)
of the templating agent N-ethyl-N-(3,3,5-trimethycyclohexyl)pyrrolidinium hydroxide
(3 mmol) were mixed with 1.2 g of 1.0N NaOH (1.2 mmol) and 4.9 g of de-ionized water.
To this mixture, 0.06 g of sodium borate decahydrate were added and stirred until
completely dissolved. To this mixture, 0.9 g of CABOSIL-M-5(SiO2) were
added. The mixture was thoroughly stirred and the resulting gel was capped off and
placed in steel Parr autoclave and heated in an oven at 160°C while tumbling
at 43 rpm. The progress of the reaction was monitored by Scanning Electron Microscopy
at intervals of 6 days. Once completed, the reaction mixture (a clear liquid and
fine solids settled to the bottom) was filtered through a fritted glass funnel.
The collected solid was rinsed with water (1 liter) and air-dried overnight. The
solids were further dried in an oven at 120°C for 2hrs. The reaction yielded
0.85 g of SSZ-60 as a white powder.
Analysis by XRD shows the product to be SSZ-60. The XRD
data appears in Table III below.
TABLE III
Two Theta
d-spacing (Å / × 10-10 m)
Intensity I/Io x 100
6.39
13.83
38
7.64
Sh 11.56
24
7.98
11.07
49
10.29
8.588
19
13.40
6.604
6
15.19
5.828
12
17.44
5.080
36
19.30
4.596
36
20.53
4.322
57
21.49
4.132
13
22.36
3.973
100
23.39
3.801
16
24.12
Sh 3.687
18
24.23
3.670
25
25.22
3.528
13
25.95
3.431
15
26.78
Sh 3.327
12
27.16
3.281
27
28.08
3.176
19
29.05
3.071
6
30.72
2.908
6
31.34
2.852
5
32.65
2.740
6
33.63
2.663
5
35.87
2.594
31
37.47
2.502
4
39.58
2.398
4
Example 4
Calcination of SSZ-60
The material from Example 3 is calcined in the following
manner. A thin bed of material is heated in a muffle furnace from room temperature
to 120°C at a rate of 1°C per minute and held at 120°C for three
hours. The temperature is then ramped up to 540°C at the same rate and held
at this temperature for 5 hours, after which it is increased to 594°C and held
there for another 5 hours. A 50/50 mixture of air and nitrogen is passed over the
zeolite at a rate of 566 l/min (20 standard cubic feet per minute) during heating.
The X-ray diffraction data for the product is provided in Table IV below.
TABLE IV
Two Theta (deg.)
d-spacing (Å /× 10-10 m)
Intensity I/Io x 100
6.36
13.88
100
7.63
Sh 11.58
44
7.98
11.07
76
10.25
8.625
48
15.11
5.860
5
16.12
. 5.495
4
17.47
5.073
10
18.07
4.904
2
19.20
4.620
40
19.70
4.503
2
20.44
4.342
39
22.28
3.987
64
23.32
3.811
15
24.19
3.676
14
25.17
3.536
9
25.86
3.442
12
26.59
3.349
10
27.11
3.286
13
28.00
3.185
6
29.03
3.074
4
30.56
2.923
3
31.32
2.854
5
32.57
2.747
4
33.53
2.671
4
35.70
2.513
18
Table V below shows the results of attempts at making borosilicate
SSZ-60 at varying SiO2B2O3 ratios. The results
in Table V were obtained using the synthesis of example 3 by varying the amount
of Na2B4O7.10H2O while keeping the amount
of all other reagent constant. Template A was used as structure directing agent.
Table V
SiO2/B2O3
XRD Results
0
SSZ-31
280
SSZ-31
140
SSZ-60
93.3
SSZ-60
70
SSZ-60
56
SSZ-60
46.7
SSZ-60
40
SSZ-60
35
SSZ-60
31
SSZ-60
28
SSZ-60
25.5
SSZ-60
23.5
SSZ-60
20
SSZ-60
18.7
SSZ-60 & Cristobalite
15.6
SSZ-60 & Cristobalite
14
SSZ-60 & Cristobalite
Example 5
Conversion of Boron-SSZ-60 to Aluminum-SSZ-60
Boron-SSZ-60 was converted to the more acidic Al-SSZ-60
by treatment with aluminum nitrate ((Al(NO3)3).9H2O)
to exchange the boron in the framework of the zeolite with aluminum. Boron-SSZ-60
(as prepared in example 3 and calcined as in example 4) was heated at reflux in
a 1.0 molar solution of boron was refluxed in a 1.0 molar solution of Al(NO3)3).9H2O
(40 ml/ 1gm zeolite) overnight. The mixture was then filtered and thoroughly rinsed
with water. The collected solids were rinsed with 0.05 N HCl and again with water
to remove any residual aluminum nitrate. The solids were air-dried overnight and
calcined at 540°C for 5 hrs to give the proton form of the aluminum version
of SSZ-60.
Example 6
NH
4
Exchange
Ion exchange of calcined SSZ-60 material (prepared in Example
3) is performed using NH4NO3 to convert the zeolite from its
Na+ form to the NH4
+ form, and, ultimately, the H+ form. Typically, the same
mass of NH4NO3 as zeolite is slurried in water at a ratio
of 25-50:1 water to zeolite. The exchange solution is heated at 95°C for 2
hours and then filtered. This procedure can be repeated up to three times. Following
the final exchange, the zeolite is washed several times with water and dried. This
NH4
+ form of SSZ-60 can then be converted to the H+ form by calcination
(as described in Example 9) to 540°C.
Example 7
Constraint Index Determination
The hydrogen form of the zeolite of Example 3 (after treatment
according to Examples 4 and 5) is pelletized at 13790-20684 kN/m2 (2-3
KPSI), crushed and meshed to 0.422-0.853 mm (20-40), and then > 0.50 gram is
calcined at about 540°C in air for four hours and cooled in a desiccator. 0.50
Gram is packed into a 9.5 mm (3/8 inch) stainless steel tube with alundurn on both
sides of the zeolite bed. A Lindburg furnace is used to heat the reactor tube. Helium
is introduced into the reactor tube at 10 m/min. and at atmospheric pressure. The
reactor is heated to about 315°C, and a 50/50 (w/w) feed of n-hexane and 3-methylpentane
is introduced into the reactor at a rate of 8 µl/min. Feed delivery is made
via a Brownlee pump. Direct sampling into a gas chromatograph begins after 10 minutes
of feed introduction. The Constraint Index value is calculated from the gas chromatographic
data using methods known in the art, and is found to be 0.7, which appears to be
constant with time. At 315°C and 10 minutes on-stream, feed conversion was
greater than 33%.
Example 8
Hydrocracking of n-Hexadecane
A sample of SSZ-60 as prepared in example 3 was treated
as in examples 4 and 5. Then a sample was slurried in water and the pH of the slurry
was adjusted to a pH of ~10 with dilute ammonium hydroxide. To the slurry was added
a solution of Pd(NH3)4(NO3)2 at a concentration
which would provide 0.5 wt. % Pd with respect to the dry weight of the zeolite sample.
This slurry was stirred for 48 hours at 100°C. After cooling, the slurry was
filtered through a glass frit, washed with de-ionized water, and dried at 100°C.
The catalyst was then calcined slowly up to 482°C (900°F) in air and held
there for three hours.
The calcined catalyst was pelletized in a Carver Press
and crushed to yield particles with a 20/40 mesh size range. Sized catalyst (0.5
g) was packed into a R" OD tubing reactor in a micro unit for n-hexadecane
hydroconversion. Table VI gives the run conditions and the products data for the
hydrocracking test on n-hexadecane. After the catalyst was tested with n-hexadecane,
it was titrated using a solution of butyl amine in hexane. The temperature was increased
and the conversion and product data evaluated again under titrated conditions. The
results shown in Table VI show that SSZ-60 is effective as a hydrocracking catalyst.
Table VI
Temperature
315°C (599°F)
WHSV
1.55
PSIG (1 PSI = 6.89 kPa)
1200
Titrated?
No
n-16, % Conversion
99.3
Hydrocracking Conversion, %
70.6
Isomerization Selectivity, %
28.9
C4
-, %
9.3
C5+C6%
20.7
C4 i/n
2.34
C5 i/n
2.67
C6 i/n
2.25
C7 i/n
2.51
C8 i/n
3.32
C9 i/n
3.77
C10 i/n
4.50
C 11 i/n
4.76
C12 i/n
5.65