U.S. patent application number 11/497932 was filed with the patent office on 2007-02-08 for dewaxing process using zeolites mtt and gon.
This patent application is currently assigned to Chevron U.S.A. Inc. .. Invention is credited to Edith Beerdsen, Theodorus Ludovicus Michael Maesen, Berend Smit.
Application Number | 20070029229 11/497932 |
Document ID | / |
Family ID | 37727863 |
Filed Date | 2007-02-08 |
United States Patent
Application |
20070029229 |
Kind Code |
A1 |
Maesen; Theodorus Ludovicus Michael
; et al. |
February 8, 2007 |
Dewaxing process using zeolites MTT and GON
Abstract
The present invention relates to the use of a combination of
zeolites having the MTT and GON framework topologies defined by the
connectivity of their tetrahedral atoms as a catalyst in a process
for dewaxing hydrocarbon feedstocks.
Inventors: |
Maesen; Theodorus Ludovicus
Michael; (Point Richmond, CA) ; Smit; Berend;
(Bloemendaal, NL) ; Beerdsen; Edith; (Amsterdam,
NL) |
Correspondence
Address: |
CHEVRON TEXACO CORPORATION
P.O. BOX 6006
SAN RAMON
CA
94583-0806
US
|
Assignee: |
Chevron U.S.A. Inc. .
|
Family ID: |
37727863 |
Appl. No.: |
11/497932 |
Filed: |
August 1, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60706134 |
Aug 4, 2005 |
|
|
|
Current U.S.
Class: |
208/134 |
Current CPC
Class: |
C10G 45/64 20130101;
B01J 29/74 20130101; C10G 2300/301 20130101; C10G 2300/1022
20130101; B01J 29/70 20130101; B01J 29/80 20130101; C10G 2300/304
20130101; C10G 2400/10 20130101 |
Class at
Publication: |
208/134 |
International
Class: |
C10G 35/04 20060101
C10G035/04 |
Claims
1. A dewaxing process comprising contacting a hydrocarbon feedstock
under dewaxing conditions with a catalyst comprising a combination
of zeolites having the MTT and GON framework topologies defined by
the connectivity of their tetrahedral atoms.
2. The process of claim 1 wherein the zeolites are predominantly in
the hydrogen form.
3. The process of claim 1 wherein the catalyst further comprises at
least one Group VIII metal.
4. The process of claim 1 wherein the feedstock is bright
stock.
5. The process of claim 1 wherein the feedstock is derived from a
Fischer Tropsch process.
6. The process of claim 1 wherein the MTT and GON zeolites have a
crystal size less than 0.1 micron.
7. A process for improving the viscosity index of a dewaxed product
of waxy hydrocarbon feeds comprising contacting a waxy hydrocarbon
feed under isomerization dewaxing conditions with a catalyst
comprising a combination of zeolites having the MTT and GON
framework topologies defined by the connectivity of their
tetrahedral atoms.
8. The process of claim 7 wherein the zeolites are predominantly in
the hydrogen form.
9. The process of claim 7 wherein the catalyst further comprises at
least one Group VIII metal.
10. A process for producing a C.sub.20+ lube oil from a C.sub.20+
olefin feed comprising isomerizing said olefin feed under
isomerization conditions over a catalyst comprising a combination
of zeolites having the MTT and GON framework topologies defined by
the connectivity of their tetrahedral atoms.
11. The process of claim 10 wherein the zeolites are predominantly
in the hydrogen form.
12. The process of claim 10 wherein the catalyst further comprises
at least one Group VIII metal.
13. A process for catalytically dewaxing a hydrocarbon oil
feedstock boiling above about 350.degree. F. (177.degree. C.) 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
15-3000 psi under dewaxing conditions with a catalyst comprising a
combination of zeolites having the MTT and GON framework topologies
defined by the connectivity of their tetrahedral atoms.
14. The process of claim 13 wherein the zeolites are predominantly
in the hydrogen form.
15. The process of claim 13 wherein the catalyst further comprises
at least one Group VIII metal.
16. A process for isomerization dewaxing a raffinate comprising
contacting said raffinate in the presence of added hydrogen under
isomerization dewaxing conditions with a catalyst comprising a
combination of zeolites having the MTT and GON framework topologies
defined by the connectivity of their tetrahedral atoms.
17. The process of claim 16 wherein the zeolites are predominantly
in the hydrogen form.
18. The process of claim 16 wherein the catalyst further comprises
at least one Group VIII metal.
19. The process of claim 16 wherein the raffinate is bright
stock.
20. A process for reducing the cloud point of a hydrocarbon feed
comprising contacting a hydrocarbon oil feedstock which has a major
portion boiling over 1000.degree. F. (538.degree. C.) with a
catalyst system comprising a combination of a zeolite having MTT
topology and a zeolite having GON topology, wherein at least a
portion of said feedstock is converted.
21. The process of claim 20 wherein the catalyst system further
comprises a hydrogenation component.
22. The process of claim 20 wherein the cloud point of the
feedstock is reduced to not more than 10.degree. C.
23. The process of claim 21 wherein the hydrogenation component
comprises a Group VIII metal.
24. The process of claim 23 wherein the Group VIII metal is
selected from platinum, palladium and mixtures thereof.
25. The process of claim 20 wherein the process is a dewaxing
process and wherein the contacting is conducted under dewaxing
conditions.
26. The process of claim 20 wherein the hydrocarbon oil is bright
stock.
27. The process of claim 20 wherein the hydrocarbon oil is derived
from a Fischer-Tropsch wax.
28. The process of claim 20 wherein the process is conducted in the
presence of added hydrogen gas.
29. The process of claim 20 wherein the MTT and GON zeolites are
aluminosilicates.
30. The process of claim 20 wherein the MTT and GON zeolites have a
crystal size less than about 0.1 micron.
Description
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 60/706,134 filed Aug. 4, 20005.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to processes for dewaxing
hydrocarbon feedstocks employing a combination of zeolites MTT and
GON as a catalyst.
[0004] 2. State of the Art
[0005] 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, including dewaxing of hydrocarbon feedstocks. Zeolites
may also be used for reducing the haze point in feedstocks such as
bright stock. (See, for example, U.S. Pat. No. 6,051,129, issued
Apr. 18, 2000 to Harris et al., in which zeolite EU-1 in
combination with ZSM-48 and/or SSZ-32 is used to reduce haze in
bright stock. This patent is incorporated by reference herein in
its entirety.) Although many different crystalline molecular sieves
have been disclosed, there is a continuing need for new zeolites
with desirable properties for hydrocarbon and chemical conversions,
and other applications.
SUMMARY OF THE INVENTION
[0006] In accordance with the present invention, there is provided
a dewaxing process comprising contacting a hydrocarbon feedstock
under dewaxing conditions with a catalyst comprising a combination
of zeolites having the MTT and GON framework topologies defined by
the connectivity of their tetrahedral atoms (referred to herein
simply as MTT and GON). The MTT and GON zeolites are preferably
predominantly in the hydrogen form.
[0007] 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 a combination of
zeolites MTT and GON, preferably predominantly in the hydrogen
form.
[0008] The present invention further includes a process for
producing a C.sub.20+ lube oil from a C.sub.20+ olefin feed
comprising isomerizing said olefin feed under isomerization
conditions over a catalyst comprising at least one Group VIII metal
and a combination of zeolites MTT and GON. The zeolites may be
predominantly in the hydrogen form.
[0009] In accordance with this invention, there is also provided a
process for catalytically dewaxing a hydrocarbon oil feedstock
boiling above about 350.degree. 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 15-3000 psi with a catalyst comprising
at least one Group VIII metal and a combination of zeolites MTT and
GON, preferably predominantly in the hydrogen form.
[0010] 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 a combination of
zeolites MTT and GON. The raffinate may be bright stock, and the
zeolites may be predominantly in the hydrogen form.
[0011] The present invention also provides a process for reducing
the cloud point of a hydrocarbon feed comprising contacting a
hydrocarbon oil feedstock which has a major portion boiling over
100.degree. F. (538.degree. C.) with a catalyst system comprising a
combination of a zeolite having MTT topology and a zeolite having
GON topology, wherein at least a portion of said feedstock is
converted.
DETAILED DESCRIPTION OF THE INVENTION
[0012] In hydrodewaxing, one target is to hydroconvert the longest
hydrocarbons in the feed. If these are left unconverted, they can
cause haze in the product. The haze is quantified by cloud
point.
[0013] The Gibbs free energy of adsorption for n-alkanes quantifies
the ability of a particular zeolite structure for selectively
absorbing and converting n-alkanes. In order to reduce the cloud
point, it is advantageous to employ zeolites that impose a
significantly lower Gibbs free energy of adsorption on a long as
opposed to short n-alkane.
[0014] Gibbs free energies of adsorption can be determined with
consistency and accuracy. Examples of these determinations are
presented in "Journal of Physical Chemistry B" (2004), 108(33),
12301-12313. These determinations indicate that the difference
between absorbing and converting a long n-alkane and a short
n-alkane is only minimally different for MTT-type zeolites. The
GON-type zeolites exhibit the maximum difference in Gibbs free
energy of adsorption between long and short n-alkanes. It is
surprising the Gibbs free energies of adsorption of these zeolites
demonstrate such a markedly different response to the variation in
n-alkane chain length. By employing GON-type zeolites in addition
to MTT-type zeolites, the conversion of heavy wax (long n-alkanes)
can be significantly increased, thereby lowering the cloud point of
the product.
[0015] Zeolites having the MTT framework topology are known. For
example, the zeolite designated "SSZ-32" and methods for making it
are disclosed in U.S. Pat. No. 5,053,373, issued Oct. 1, 1991 to
Zones. This patent discloses the preparation of zeolite SSZ-32
using an N-lower alkyl-N'-isopropylimidazolium cation as an organic
structure directing agent (SDA), sometimes called a templating
agent. U.S. Pat. No. 4,076,842, issued Feb. 28, 1978 to Plank et
al., discloses the preparation of the zeolite designated "ZSM-23",
a zeolite with a structure similar to SSZ-32, using a cation
derived from pyrrolidine as the SDA. Zeolites SSZ-32 and ZSM-23 are
commonly referred to as having the MTT framework topology. Both of
the aforementioned patents are incorporated herein by reference in
their entirety. In addition, R. Szostak, Handbook of Molecular
Sieves, 1992 lists zeolites designated ISI-4 and KZ-1 as having the
MTT topology. The zeolite designated EU-13 is described in C.
Baerlocher et al., Atlas of Zeolite Framework Types, 5.sup.th
Revised Edition, 2001, International Zeolite Association as having
the MTT topology.
[0016] Dewaxing processes using MTT zeolites are known. For
example, U.S. Pat. No. 4,222,855, issued Sept. 16, 1980 to Pelrine
et al., discloses a dewaxing process using ZSM-23 or ZSM-35.
Likewise, U.S. Pat. No. 5,376,260, issued Dec. 27, 1994 to Santilli
et al., discloses a dewaxing process using a catalyst containing
SSZ-32. U.S. Pat. No. 6,663,768, issued Dec. 16, 2003 to Miller,
also discloses a dewaxing process which uses ZSM-23 or SSZ-32 in
the catalyst. U.S. Pat. No. 4,601,993, issued Jul. 22, 1986 to Chu
et al., discloses a dewaxing process using a combination of ZSM-23
and zeolite Beta.
[0017] Zeolites having the GON topology are also known. For
example, the zeolite designated "GUS-1" and a method of making it
is disclosed in Plevert et al., "GUS-1: a mordenite-like molecular
sieve with the 12-ring channel of ZSM-12", Chem. Commun., 2000, pp.
2363-2364 which in incorporated herein by reference in its
entirety. GON-type zeolites are 12 ring/8 ring zeolites with
uni-dimensional channels.
[0018] The MTT and GON zeolites are used in the present invention
in combination. As used herein, the term "combination" includes
mixtures of the zeolites, layers of the zeolites, or any other
configuration in which the feed comes in contact with both
zeolites. For example, the combination may be a graduated mixture
in which the feed initially contacts a portion of the mixture which
comprises essentially all one of the zeolites. The concentration of
the second zeolite can be gradually increased, and the
concentration of the first zeolite gradually decreased, in
successive portions of the mixture until the mixture becomes
essentially all second zeolite. Depending on the feed, reaction
conditions, and desired product, the combination may be such that
the feed initially contacts the MTT zeolite first or the GON
zeolite first.
[0019] The combination of MTT and GON zeolites may also be used in
layers. The use of catalyst layers is disclosed in U.S. Pat. No.
5,149,421, issued Sept. 22, 1992 to Miller, which is incorporated
by reference herein its entirety. The order of the layers may be
MTT in a first layer and GON in a subsequent layer, or vice
versa.
[0020] Depending upon the nature of the feed and the desired
products, the MTT and GON zeolites can be employed over a wide
range of concentrations. The catalyst combination may comprise 1-99
weight percent MTT zeolite and 99-1 weight percent GON zeolite.
Preferably, the crystal size of the zeolites is less than 0.1
micron, i.e., the longest dimension of the crystal is less than 0.1
micron.
[0021] The crystalline MTT and GON 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.
[0022] 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.
[0023] 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. Pat. No. 3,140,249
issued Jul. 7, 1964 to Plank et al.; U.S. Pat. No. 3,140,251 issued
Jul. 7, 1964 to Plank et al.; and U.S. Pat. No. 3,140,253 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.
[0024] The hydrogen, ammonium and metal components can be
ion-exchanged into the zeolites. The zeolites can also be
impregnated with the metals, or the metals can be physically and
intimately admixed with the zeolites using standard methods known
to the art.
[0025] Typical ion-exchange techniques involve contacting the
zeolites 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 zeolites are usually
calcined prior to the ion-exchange procedure to remove the organic
matter 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.
3,140,249 issued Jul. 7, 1964 to Plank et al.; U.S. Pat. No.
3,140,251 issued Jul. 7, 1964 to Plank et al. and U.S. Pat. No.
3,140,253 issued on Jul. 7, 1964 to Plank et al.
[0026] Following contact with the salt solution of the desired
replacing cation, the zeolites are typically washed with water and
dried at temperatures ranging from 65.degree. C. to about
200.degree. C. After washing, the zeolites 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.
[0027] The zeolites 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 zeolite can be extruded before drying, or dried or partially
dried and then extruded.
[0028] The zeolites 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. 4,910,006, issued
May 20, 1990 to Zones et al. and U.S. Pat. No. 5,316,753, issued
May 31, 1994 to Nakagawa, both of which are incorporated by
reference herein in their entirety.
[0029] The MTT and GON zeolites are used in dewaxing
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, bright stock, Fischer-Tropsch waxes
(i.e., synthetic waxes derived from a Fischer Tropsch process,
preferably an oxygenate-containing Fischer Tropsch process, boiling
below about 700.degree. F. (371.degree. C.)) and, in general, can
be any carbon containing feedstock susceptible to zeolitic
catalytic dewaxing 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. Preferably, after treating the feedstock in accordance
with the present invention, the cloud point of the feedstock
(depending on its original composition) is reduced to not more than
10.degree. C.
[0030] The dewaxing 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.
[0031] Typical dewaxing reaction conditions which may be employed
when using catalysts comprising a combination of zeolites MTT and
GON in the dewaxing reactions of this invention include a
temperature of about 200-475.degree. C., preferably about
250-450.degree. C., a pressure of about 15-3000 psig, preferably
about 200-3000 psig, and a LHSV of about 0.1-20, preferably
0.2-10.
[0032] The MTT and GON combination, 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 a combination of
zeolites MTT and GON under isomerization dewaxing conditions.
[0033] 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 500 and about 30,000 SCF/bbl (standard cubic feet per
barrel), preferably about 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 350.degree. F.
(177.degree. C.).
[0034] A typical dewaxing process is the catalytic dewaxing of a
hydrocarbon oil feedstock boiling above about 350.degree. F.
(177.degree. C.) and containing straight chain and slightly
branched chain hydrocarbons by contacting the hydrocarbon oil
feedstock in the presence of added hydrogen gas at a hydrogen
pressure of about 15-3000 psi with a catalyst comprising a
combination of zeolites MTT and GON and at least one Group VIII
metal.
[0035] The hydrodewaxing catalyst may optionally contain a
hydrogenation component of the type commonly employed in dewaxing
catalysts. See the aforementioned U.S. Pat. No. 4,910,006 and U.S.
Pat. No. 5,316,753 for examples of these hydrogenation
components.
[0036] 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.
[0037] The feed may be hydrocracked, followed by dewaxing. This
type of two stage process and typical hydrocracking conditions are
described in U.S. Pat. No. 4,921,594, issued May 1, 1990 to Miller,
which is incorporated herein by reference in its entirety.
[0038] The combination of MTT and GON may also be used to dewax
raffinates, including bright stock, under conditions such as those
disclosed in U.S. Pat. No. 4,181,598, issued Jan. 1, 1980 to
Gillespie et al., which is incorporated by reference herein in its
entirety.
[0039] 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.degree.
C. to about 340.degree. C. at pressures from about 400 psig to
about 3000 psig at space velocities (LHSV) between about 0.1 and 20
and a hydrogen recycle rate of about 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. Pat. No. 4,921,594,
issued May 1, 1990 to Miller, which is incorporated by reference
herein in its entirety. 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.
[0040] Lube oil may be prepared using a combination of zeolites MTT
and GON. For example, a C.sub.20+ lube oil may be made by
isomerizing a C.sub.20+ olefin feed over a catalyst comprising a
combination of zeolites MTT and GON, preferably predominantly 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 400.degree. F.
(204.degree. C.) and at a pressure of from about 15 psig to about
3000 psig in the presence of added hydrogen gas with a catalyst
comprising a combination of zeolites MTT and GON, preferably
predominantly in the hydrogen form, and at least one Group VIII
metal.
* * * * *