U.S. patent application number 10/464566 was filed with the patent office on 2004-12-23 for fuels and lubricants using layered bed catalysts in hydrotreating waxy feeds, including fischer-tropsch wax.
Invention is credited to Mayer, Jerome F., Miller, Stephen J., O'Rear, Dennis J., Rosenbaum, John M., Simmons, Christopher A..
Application Number | 20040256286 10/464566 |
Document ID | / |
Family ID | 33517317 |
Filed Date | 2004-12-23 |
United States Patent
Application |
20040256286 |
Kind Code |
A1 |
Miller, Stephen J. ; et
al. |
December 23, 2004 |
Fuels and lubricants using layered bed catalysts in hydrotreating
waxy feeds, including Fischer-Tropsch wax
Abstract
Waxy hydrocarbon feedstocks are contacted with a hydrocracking
catalyst and the effluent then contacted with an intermediate pore
size molecular sieve hydroisomerization catalyst. The effluent from
the hydroisomerization is fractionated to provide a heavy fraction
and a middle distillate fuel. A high quality lubricant base oil
with a high viscosity index and a low pour point is isolated from
the heavy fraction.
Inventors: |
Miller, Stephen J.; (San
Francisco, CA) ; O'Rear, Dennis J.; (Petaluma,
CA) ; Rosenbaum, John M.; (Richmond, CA) ;
Mayer, Jerome F.; (Novato, CA) ; Simmons, Christopher
A.; (El Cerrito, CA) |
Correspondence
Address: |
Burns, Doane, Swecker & Mathis, L.L.P.
P.O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
33517317 |
Appl. No.: |
10/464566 |
Filed: |
June 19, 2003 |
Current U.S.
Class: |
208/58 ; 208/108;
208/27 |
Current CPC
Class: |
C10G 2400/10 20130101;
C10G 65/12 20130101 |
Class at
Publication: |
208/058 ;
208/027; 208/108 |
International
Class: |
C10G 065/12 |
Claims
What is claimed is:
1. A process for treating a waxy hydrocarbon feedstock comprising
the steps of: a) contacting the feedstock with a hydrocracking
catalyst in a hydrocracking zone, producing a hydrocracking
effluent; b) contacting the hydrocracking effluent with an
intermediate pore size molecular sieve hydroisomerization catalyst
in a hydroisomerization zone, producing a hydroisomerization
effluent; c) fractionating the hydroisomerization effluent,
providing a heavy fraction and a middle distillate fuel; and d)
isolating from the heavy fraction a lubricant base oil fraction
having a viscosity index of greater than 130, a pour point of less
than -15.degree. C., and a viscosity of greater than 3 cSt at
100.degree. C.
2. A process according to claim 1, wherein the lubricant base oil
has a viscosity index of greater than 140, a pour point of less
than -15.degree. C., and a viscosity of greater than 4 cSt at
100.degree. C.
3. A process according to claim 1, wherein the lubricant base oil
has a viscosity index of greater than 150, a pour point of less
than -15.degree. C., and a viscosity of greater than 5 cSt at
100.degree. C.
4. A process according to claim 1, wherein the total hydrocracking
effluent is contacted with the hydroisomerization catalyst in a
hydroisomerization zone.
5. A process according to claim 1, wherein the hydrocracking
catalyst and the hydroisomerization catalyst are layered in a
single reaction zone in a single reactor.
6. A process according to claim 1, wherein the hydrocracking
catalyst and the hydroisomerization catalyst are layered in a
single reaction zone in close-coupled series reactors with no
product withdrawal or feed inlet between reactors.
7. A process according to claim 1, further comprising recycling a
heavy bottoms fraction to the hydrocracking zone.
8. A process according to claim 1, wherein the waxy hydrocarbon
feedstock comprises a Fischer Tropsch derived 650.degree. F.+
feed.
9. A process according to claim 1, wherein the waxy hydrocarbon
feedstock comprises greater than 20 weight % 900.degree. F.+
components.
10. A process according to claim 1, wherein the waxy hydrocarbon
feedstock comprises greater than 85 wt % 650.degree. F.+ components
and wherein less than 60 weight % of the 650.degree. F.+ components
are converted to 650.degree. F.- products.
11. A process for treating a 650.degree. F.+ waxy hydrocarbon
feedstock comprising the steps of: a) contacting the feedstock with
a hydrocracking catalyst in a hydrocracking zone, producing a
hydrocracking effluent; b) contacting the hydrocracking effluent
with an intermediate pore size molecular sieve hydroisomerization
catalyst in a hydroisomerization zone, producing a
hydroisomerization effluent; c) fractionating the
hydroisomerization effluent, providing a heavy fraction and a
middle distillate fuel; and d) isolating a lubricant base oil
fraction from the heavy fraction, said lubricant base oil fraction
having a viscosity index of greater than 130, a pour point of less
than -15.degree. C., and a viscosity of greater than 3 cSt at
100.degree. C., and wherein less than 60 weight % of the
650.degree. F.+ components are converted to 650.degree. F.-
products.
12. A process according to claim 11, wherein the lubricant base oil
has a viscosity index of greater than 140, a pour point of less
than -15.degree. C., and a viscosity of greater than 4 cSt at
100.degree. C.
13. A process according to claim 11, wherein the lubricant base oil
has a viscosity index of greater than 150, a pour point of less
than -15.degree. C., and a viscosity of greater than 5 cSt at
100.degree. C.
14. A process according to claim 11, wherein the hydrocracking
catalyst and the hydroisomerization catalyst are layered in a
single reaction zone in a single reactor.
15. A process according to claim 11, wherein the 650.degree. F.+
waxy hydrocarbon feedstock is derived from a Fischer Tropsch
process.
16. A process according to claim 15, wherein the 650.degree. F.+
waxy hydrocarbon feedstock is not hydrotreated prior to
hydrocracking.
17. A process according to claim 11, wherein the 650.degree. F.+
waxy hydrocarbon feedstock comprises greater than 20 weight %
900.degree. F.+ components.
18. A process according to claim 11, wherein the 650.degree. F.+
waxy hydrocarbon feedstock comprises greater than 85 wt %
650.degree. F.+ components.
19. A process according to claim 11, wherein the hydrocracking
catalyst and the hydroisomerization catalyst are layered in a
single reaction zone in close-coupled series reactors with no
product withdrawal, or feed inlet between reactors.
20. A process according to claim II further comprising recycling a
heavy bottoms fraction to the hydrocracking zone.
21. A process for treating a 650.degree. F.+ waxy hydrocarbon
feedstock comprising the steps of: a) contacting the feedstock with
a hydrocracking catalyst in a hydrocracking zone, producing a
hydrocracking effluent; b) contacting the hydrocracking effluent
with an intermediate pore size molecular sieve hydroisomerization
catalyst in a hydroisomerization zone, producing a
hydroisomerization effluent; c) fractionating the
hydroisomerization effluent, providing a heavy fraction and a
middle distillate fuel; and d) isolating from the heavy fraction a
lubricant base oil fraction having a viscosity index of greater
than 130, a pour point of less than -15.degree. C., and a viscosity
of greater than 4 cSt at 100.degree. C., and wherein the
650.degree. F.+ waxy hydrocarbon feedstock comprises greater than
20 weight % 900.degree. F.+ components.
22. A process according to claim 21, wherein the 650.degree. F.+
waxy hydrocarbon feedstock comprises greater than 40 weight %
900.degree. F.+ components.
23. A process according to claim 21, wherein the 650.degree. F.+
waxy hydrocarbon feedstock comprises greater than 60 weight %
900.degree. F.+ components.
24. A process according to claim 21, wherein the lubricant base oil
has a viscosity index of greater than 140, a pour point of less
than -15.degree. C., and a viscosity of greater than 4 cSt at
100.degree. C.
25. A process according to claim 21, wherein the lubricant base oil
has a viscosity index of greater than 150, a pour point of less
than -15.degree. C., and a viscosity of greater than 5 cSt at
100.degree. C.
26. A process according to claim 21, wherein the hydrocracking
catalyst and the hydroisomerization catalyst are layered in a
single reaction zone in a single reactor.
27. A process according to claim 21, wherein the 650.degree. F.+
waxy hydrocarbon feedstock is derived from a Fischer Tropsch
process.
28. A process according to claim 21, wherein the hydrocracking
catalyst and the hydroisomerization catalyst are layered in a
single reaction zone in close-coupled series reactors with no
product withdrawal or feed inlet between reactors.
29. A process according to claim 21, further comprising isolating a
bottoms fraction from the heavy fraction, and recycling the bottoms
fraction to the hydrocracking zone.
30. A process according to claim 23, wherein the lubricant base oil
has a viscosity index of greater than 140, a pour point of less
than -15.degree. C., and a viscosity of greater than 4 cSt at
100.degree. C.
31. A process according to claim 23, wherein the lubricant base oil
has a viscosity index of greater than 150, a pour point of less
than -15.degree. C., and a viscosity of greater than 5 cSt at
100.degree. C.
32. A process according to claim 21, wherein less than 60 weight %
of the 650.degree. F.+ components of the 650.degree. F.+ waxy
hydrocarbon feed are converted to 650.degree. F.- products.
Description
FIELD OF THE INVENTION
[0001] This invention relates to processes for converting waxy
hydrocarbon feedstocks into salable products. More particularly,
the invention relates to a process of converting a Fischer-Tropsch
derived waxy feedstock to middle distillate fuels and lubricant
base oils.
BACKGROUND OF THE INVENTION
[0002] A Fischer-Tropsch synthesis process may be used to convert a
gas composed primarily of CO and H.sub.2 (commonly referred to as
synthesis gas or syngas) under catalytic conditions to a wide
variety of gaseous, liquid and solid hydrocarbonaceous products.
Many of these liquid and solid products contain waxy materials
composed of high molecular weight paraffins. These paraffinic waxes
can crystallize upon cooling, and products comprising these
paraffinic waxes typically have unacceptably high pour points and
high cloud points. Pour point is the temperature at which a sample
will begin to flow under carefully controlled conditions and may be
measured according to ASTM D5950-96. Cloud point is the temperature
at which a sample begins to develop a haze under controlled
conditions and may be measured according to ASTM D5773-95.
[0003] It is known to catalytically convert waxy paraffins in
hydrocarbon feedstocks to lower boiling hydrocarbons within the
middle distillate product range. This conversion may be
accomplished by hydroprocessing techniques, such as hydrocracking
and hydroisomerization. Hydrocracking converts larger molecules
into smaller ones and introduces some amount of branching into the
cracked products. Hydroisomerization primarily introduces branching
into the paraffinic molecules, thus improving properties, such as
pour and cloud points. Unreacted components of the hydrocarbon
feed, which have not been hydrocracked and/or hydroisomerized, may
be recycled for further treatment to provide additional products in
the desired boiling range.
[0004] The combination of treating paraffinic hydrocarbon feeds by
hydrocracking and hydroisomerization to produce middle distillate
hydrocarbons is taught in EP 0544766 B1. EP 0544766 B1 teaches a
process for preparing low pour point middle distillate hydrocarbons
by contacting a hydrocarbonaceous feedstock with a large pore
hydrocracking catalyst and a catalyst comprising an intermediate
pore size silicoaluminophosphate molecular sieve and a
hydrogenation component.
[0005] U.S. Pat. No. 5,935,414 relates to a process for reducing
the wax content of wax-containing hydrocarbon feedstocks to produce
middle distillate products, which include a low freeze point jet
fuel and/or a low pour point and low cloud point diesel fuel and
heating oil. In the process, the feedstock is contacted with a
hydrocracking catalyst containing a carrier, at least one
hydrogenation metal component of Group VIB and Group VIII metals,
and a large pore zeolite such as a Y type zeolite, in a
hydrocracking zone in the presence of hydrogen at elevated
temperature and pressure. The entire effluent from the
hydrocracking zone is contacted with a dewaxing catalyst containing
a crystalline, intermediate pore size molecular sieve selected from
metallosilicates and silicoaluminophosphates in a hydrodewaxing
zone in the presence of hydrogen at elevated temperature and
pressure.
[0006] U.S. Pat. No. 5,139,647 relates to a process for making
middle distillates from a hydrocarbonaceous feedstock by a
hydrocracking and isomerization. In the process the feedstock is
contacted with a catalyst containing an intermediate pore size
silicoaluminophosphate molecular sieve and a hydrogenation
component.
[0007] U.S. Pat. No. 4,859,312 relates to a process for making
middle distillates. The process uses a catalyst comprising a
silicoaluminophosphate molecular sieve such as SAPO-11 and SAPO-41,
and platinum or palladium, a hydrogenation component, to
simultaneously subject heavy oils to hydrocracking and
isomerization reactions. The process selectively produces middle
distillates in high yields having good low temperature fluid
characteristics, especially reduced pour point and viscosity.
[0008] EP 0323092 A2 and U.S. Pat. No. 4,943,672 relate to a
process for converting Fischer Tropsch wax into a lubricating oil
having a high viscosity index and a low pour point. In the process
as disclosed first the wax is hydrotreated under relatively severe
conditions and thereafter the hydrotreated wax is hydroisomerized
in the presence of hydrogen on a specified type of fluorided Group
VIII metal-on-alumina catalyst. The hydroisomerate is then dewaxed
to produce a premium lubricating oil base stock.
[0009] U.S. Pat. No. 4,080,397 discloses a method for upgrading a
350.degree. F.+ product of Fischer-Tropsch synthesis. In the method
as disclosed, the Fischer-Tropsch synthesis product is hydrotreated
and the hydrotreated material boiling above about 600.degree. F. is
selectively cracked.
[0010] EP 0583836 A1 discloses a process for preparing of
hydrocarbon fuels. In the process as disclosed a substantially
paraffinic hydrocarbon product is prepared, and the hydrocarbon
product is contacted with hydrogen in the presence of a
hydroconversion catalyst under conditions such that substantially
no isomerization or hydrocracking of the hydrocarbon product
occurs. At least a portion of the hydrocarbon product from this
process is contacted with hydrogen in the presence of a
hydroconversion catalyst under conditions such that hydrocracking
and isomerization of the hydrocarbon feed occurs to yield a
substantially paraffinic hydrocarbon fuel.
[0011] EP 0147873 A1 discloses a process for preparing middle
distillates. Middle distillates are prepared from syngas by a two
stage series-flow process. The process comprises a Fischer Tropsch
synthesis over a special Zr, Ti, or Cr promoted Co-catalyst
followed by hydroconverting the total synthesized product of a
Fischer-Tropsch synthesis over a supported noble metal
catalyst.
[0012] There remains a need for an efficient and economical process
for converting waxy paraffinic feeds to both middle distillate
fuels and lubricant base oils in high yields without compromising
the desirable properties of the paraffins in the original feed. It
is desired that the primary product of the process be lubricant
base oil having good low temperature properties (i.e., cloud point,
pour point, cold filter plugging point, etc. and high
viscosities).
SUMMARY OF THE INVENTION
[0013] The present invention relates to a process for treating a
waxy hydrocarbon feedstock. The process comprises contacting the
feedstock with a hydrocracking catalyst in a hydrocracking zone,
producing a hydrocracking effluent and contacting the hydrocracking
effluent with a molecular sieve hydroisomerization catalyst in a
hydroisomerization zone, producing a hydroisomerization effluent.
The hydroisomerization effluent is fractionated, providing a heavy
fraction and a middle distillate fuel. A lubricant base oil
fraction is isolated from the heavy fraction and this lubricant
base oil has a viscosity index of greater than 130, a pour point of
less than -15.degree. C., and a viscosity of greater than 3 cSt at
100.degree. C.
[0014] The present invention further relates to a process for
treating a 650.degree. F.+ waxy hydrocarbon feedstock. The process
comprises contacting the feedstock with a hydrocracking catalyst in
a hydrocracking zone, producing a hydrocracking effluent, and
contacting the hydrocracking effluent with a molecular sieve
hydroisomerization catalyst in a hydroisomerization zone, producing
a hydroisomerization effluent. The hydroisomerization effluent is
fractionated, providing a heavy fraction and a middle distillate
fuel; and a lubricant base oil fraction is isolated from the heavy
fraction. The lubricant base oil has a viscosity index of greater
than 130, a pour point of less than -15.degree. C., and a viscosity
of greater than 3 cSt at 100.degree. C. Preferably, less than 60
weight % of the 650.degree. F.+ components in the feed are
converted to 650.degree. F.- products.
[0015] In a further embodiment, the present invention relates to a
process for treating a 650.degree. F.+ waxy hydrocarbon feedstock.
In the process the feedstock is contacted with a hydrocracking
catalyst in a hydrocracking zone, producing a hydrocracking
effluent; and the hydrocracking effluent is contacted with a
molecular sieve hydroisomerization catalyst in a hydroisomerization
zone, producing a hydroisomerization effluent. The
hydroisomerization effluent is fractionated, providing a heavy
fraction and a middle distillate fuel; and a lubricant base oil
fraction is isolated from the heavy fraction. The lubricant base
oil produced from this process has a viscosity index of greater
than 130, a pour point of less than -15.degree. C., and a viscosity
of greater than 3 cSt at 100.degree. C., and the 650.degree. F.+
waxy hydrocarbon feedstock comprises greater than 20 weight %
900.degree. F.+ components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIGURE illustrates a schematic representation of one
embodiment of the process of the present invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0017] The present invention relates to a process for producing
high yields of high quality lubricant base oils from waxy
hydrocarbon feedstocks. It has been discovered that one can readily
and economically convert waxy hydrocarbon feeds having high initial
boiling points and containing high levels of paraffinic waxes, such
as Fischer Tropsch waxes, into high quality middle distillate fuels
and high quality lubricant base oils, with the lubricant base oils
being the primary product. In the processes of the present
invention these waxy hydrocarbon feeds are contacted with a
hydrocracking catalyst followed by a hydroisomerization catalyst,
separated into a middle distillate product and a heavy fraction.
From the heavy fraction a lubricant base oil is isolated. This
process converts high boiling waxy hydrocarbon feeds into high
quality middle distillate fuels with low pour and cloud points and
high quality lubricant base oils with high viscosity indexes, and
low pour and cloud points. The process of the present invention
results in less cracking of the high boiling end of the high
boiling waxy feed (i.e., less conversion of the high boiling end of
the feed to lighter products). Accordingly, high quality lubricant
base oils with high viscosity indexes, and low pour and cloud
points.
[0018] Definitions
[0019] The following terms will be used throughout the
specification and will have the following meanings unless otherwise
indicated.
[0020] "Heavy fraction" is the heavier fraction separated after
hydrocracking and hydroisomerization of a waxy hydrocarbon
feedstock. The heavy fraction has an initial boiling point in the
range of 600 to 750.degree. F., an end boiling point in the range
of 950 to greater than 1200.degree. F. The heavy fraction comprises
lubricant base oil and wax. The heavy fraction may have a wax
content between 0.1 and 5 weight percent. A heavy fraction may also
be fractionated such that a bottoms fraction is obtained.
[0021] "Bottoms fraction" is a non-vaporized (i.e. residuum)
fraction contained as a part of the heavy fraction.
[0022] "Derived from a Fischer-Tropsch synthesis" means that the
fuel or product in question originates from or is produced at some
stage by a Fischer-Tropsch process.
[0023] "Waxy hydrocarbon feedstock" useful in the processes
disclosed herein may be synthetic waxy feedstocks, such as Fischer
Tropsch waxy hydrocarbons, or may be derived from natural sources,
such as petroleum waxes. The waxy hydrocarbon feedstock contains
greater than 50% wax, more preferably greater than about 80% wax,
most preferably greater than about 90% wax. As used herein, wax
content is determined by a solvent dewaxing process. The solvent
dewaxing process is a standard method, and well known in the art.
In the process, 300 grams of a waxy product is diluted 50/50 by
volume with a 4:1 mixture of methyl ethyl ketone and toluene which
had been cooled to -20.degree. C. The mixture is cooled at a
uniform slow rate in the range of about 0.5.degree. to 4.5.degree.
C./min) to -15.degree. C., and then filtered through a Coors funnel
at -15.degree. C. using Whatman No. 3 filter paper. The wax is
removed from the filter and placed in a tarred 2 liter flask.
Solvent remaining in the wax is removed on a hot plate and the wax
weighed.
[0024] "650.degree. F.+ waxy hydrocarbon feedstock" has an initial
boiling point of 650.degree. F. wherein at least 70 wt %,
preferably at least 85 wt %, of the feedstock boils above
650.degree. F.
[0025] "Middle distillate fuel" or "middle distillate fuel
fraction" is the lighter fraction separated after hydrocracking and
hydroisomerization of a waxy hydrocarbon feedstock. It is a
material containing hydrocarbons with boiling points between
approximately 300.degree. F. to 650.degree. F. The term
"distillate" means that traditional fuels of this type could be
generated from vapor overhead streams from distilling petroleum
crude. Within the broad category of distillate fuels are specific
fuels that include naphtha, jet fuel, diesel fuel, kerosene,
aviation gas, fuel oil, and blends thereof.
[0026] "Lubricant base oil" means a fraction meeting specifications
for a lubricant base oil. Lubricant base oil fractions are isolated
from the heavy fractions according to the process of the present
invention. Properties of the lubricant base oils provided according
to the present invention include initial boiling points in the
range of 600 to 750.degree. F., end boiling points in the range of
900 to greater than 1200.degree. F., viscosities in the range of 3
to 15 cSt at 100.degree. C., viscosity indices in the range of 115
to 160, preferably in the range of 130 to 180, and more preferably
in the range of 140 to 180, pour points less then -9.degree. C.,
preferably in the range of -10 to -24.degree. C., and cloud points
in the range of 0 to -20.degree. C.
[0027] "Hydrocarbon or hydrocarbonaceous" means a compound or
substance that contains hydrogen and carbon atoms, which may also
include heteroatoms such as oxygen, sulfur or nitrogen.
[0028] In the processes according to the present invention, a waxy
hydrocarbon feedstock is converted to a middle distillate fuel
product and a lubricant base oil product by contacting the
feedstock with a hydrocracking catalyst and then a
hydroisomerization catalyst. The process according to the present
invention provides a lubricant base oil product having a high
viscosity index and low pour and cloud points. The process of the
present invention results in less cracking of the high boiling end
of the high boiling waxy feed (i.e., less conversion of the high
boiling end of the feed to lighter products). Accordingly, high
quality lubricant base oils with high viscosity indexes and low
pour and cloud points are produced.
[0029] The processes as described herein are able to convert this
heavy waxy feed to high quality middle distillate products and high
quality lubricant base oil products. The waxy hydrocarbon feedstock
has an initial boiling point of less than 700.degree. F.+. The waxy
hydrocarbon feedstock has an end boiling point in the range of 1000
to greater than 1200.degree. F. Preferably the waxy hydrocarbon
feedstock to the processes as described herein comprises greater
than 70 weight percent 650.degree. F.+ material, and even more
preferably greater than 85 weight percent 650.degree. F.+ material.
The feed preferably comprises greater than 20 weight percent
900.degree. F.+ material.
[0030] The waxy feeds to the process of the present invention are
comprised of greater than 80 weight % wax, preferably greater than
95 weight % wax. As used herein, wax content is determined by a
solvent dewaxing process. The solvent dewaxing process is a
standard method, and well known in the art. In the process, 300
grams of a waxy product is diluted 50/50 by volume with a 4:1
mixture of methyl ethyl ketone and toluene which had been cooled to
-20.degree. C. The mixture is cooled at a uniform slow rate in the
range of about 0.5.degree. to 4.5.degree. C./min to -15.degree. C.,
and then filtered through a Coors funnel at -15.degree. C. using
Whatman No. 3 filter paper. The wax is removed from the filter and
placed in a tarred 2 liter flask. Solvent remaining in the wax is
removed on a hot plate and the wax weighed.
[0031] The waxy hydrocarbon feedstocks useful in the processes
disclosed herein may be synthetic waxy feedstocks, such as Fischer
Tropsch waxy hydrocarbons, or may be derived from natural sources,
such as petroleum waxes. Accordingly, the waxy feedstocks to the
processes may comprise Fischer Tropsch derived waxy feeds,
petroleum waxes, waxy distillate stocks such as gas oils,
lubricating oil stocks, high pour point polyalphaolefins, foots
oils, normal alpha olefin waxes, slack waxes, deoiled waxes, and
microcrystalline waxes, and mixtures thereof. Preferably, the waxy
feedstocks are derived from Fischer Tropsch waxy feeds.
[0032] The waxy hydrocarbon feedstock may be hydrotreated prior to
the process as described herein if desired. However, for Fischer
Tropsch derived waxy feeds hydrotreating is typically not
necessary.
[0033] A preferred waxy feed of the present invention is a
Fischer-Tropsch derived waxy feed. In Fischer-Tropsch chemistry,
syngas is converted to liquid hydrocarbons by contact with a
Fischer-Tropsch catalyst under reactive conditions. Typically,
methane and optionally heavier hydrocarbons (ethane and heavier)
can be sent through a conventional syngas generator to provide
synthesis gas. Generally, synthesis gas contains hydrogen and
carbon monoxide, and may include minor amounts of carbon dioxide
and/or water. The presence of sulfur, nitrogen, halogen, selenium,
phosphorus and arsenic contaminants in the syngas is undesirable.
For this reason and depending on the quality of the syngas, it is
preferred to remove sulfur and other contaminants from the feed
before performing the Fischer-Tropsch chemistry. Means for removing
these contaminants are well known to those of skill in the art. For
example, ZnO guardbeds are preferred for removing sulfur
impurities. Means for removing other contaminants are well known to
those of skill in the art. It also may be desirable to purify the
syngas prior to the Fischer-Tropsch reactor to remove carbon
dioxide produced during the syngas reaction and any additional
sulfur compounds not already removed. This can be accomplished, for
example, by contacting the syngas with a mildly alkaline solution
(e.g., aqueous potassium carbonate) in a packed column.
[0034] In the Fischer-Tropsch process, contacting a synthesis gas
comprising a mixture of H.sub.2 and CO with a Fischer-Tropsch
catalyst under suitable temperature and pressure reactive
conditions forms liquid and gaseous hydrocarbons. The
Fischer-Tropsch reaction is typically conducted at temperatures of
about 300-700.degree. F. (149-371.degree. C.), preferably about
400-550.degree. F. (204-228.degree. C.); pressures of about 10-600
psia, (0.7-41 bars), preferably about 30-300 psia, (2-21 bars); and
catalyst space velocities of about 100-10,000 cc/g/hr, preferably
about 300-3,000 cc/g/hr. Examples of conditions for performing
Fischer-Tropsch type reactions are well known to those of skill in
the art.
[0035] The products of the Fischer-Tropsch synthesis process may
range from C, to C.sub.200+ with a majority in the C.sub.5 to
C.sub.100+ range. The reaction can be conducted in a variety of
reactor types, such as fixed bed reactors containing one or more
catalyst beds, slurry reactors, fluidized bed reactors, or a
combination of different type reactors. Such reaction processes and
reactors are well known and documented in the literature.
[0036] In general, Fischer-Tropsch catalysts contain a Group VIII
transition metal on a metal oxide support. The catalysts may also
contain a noble metal promoter(s) and/or crystalline molecular
sieves. Certain catalysts are known to provide chain growth
probabilities that are relatively low to moderate, and the reaction
products include a relatively high proportion of low molecular
(C.sub.2-8) weight olefins and a relatively low proportion of high
molecular weight (C.sub.30+) waxes. Certain other catalysts are
known to provide relatively high chain growth probabilities, and
the reaction products include a relatively low proportion of low
molecular (C.sub.2-8) weight olefins and a relatively high
proportion of high molecular weight (C.sub.30+) waxes. Such
catalysts are well known to those of skill in the art and can be
readily obtained and/or prepared.
[0037] The product from a Fischer-Tropsch process contains
predominantly paraffins; however, it may also contain C.sub.2+
olefins, oxygenates, and heteroatom impurities. The most abundant
oxygenates in Fischer-Tropsch products are alcohols, and mostly
primary linear alcohols. Less abundant types of oxygenates in
Fischer-Tropsch products include other alcohol types such as
secondary alcohols, acids, esters, aldehydes, and ketones. The
products from Fischer-Tropsch reactions generally include a light
reaction product and a waxy reaction product. The light reaction
product (i.e., the condensate fraction) includes hydrocarbons
boiling below about 700.degree. F. (e.g., tail gases through middle
distillate fuels), largely in the C.sub.5-C.sub.20 range, with
decreasing amounts up to about C.sub.30. The waxy reaction product
(i.e., the wax fraction) includes hydrocarbons boiling above about
600.degree. F. (e.g., vacuum gas oil through heavy paraffins),
largely in the C.sub.20+ range, with decreasing amounts down to
C.sub.10.
[0038] Both the light reaction product and the waxy product are
substantially paraffinic. The waxy product generally comprises
greater than 70 weight % normal paraffins, and often greater than
80 weight % normal paraffins. The light reaction product comprises
paraffinic products with a significant proportion of alcohols and
olefins. In some cases, the light reaction product may comprise as
much as 50 weight %, and even higher, alcohols and olefins. It is
the waxy reaction product (i.e., the wax fraction) that may be used
as a feedstock for the processes of the present invention.
[0039] According to the present invention, the waxy hydrocarbon
feedstock is contacted with a hydrocracking catalyst in a
hydrocracking zone, producing a hydrocracking effluent and the
hydrocracking effluent is contacted with a molecular sieve
hydroisomerization catalyst in a hydroisomerization zone, producing
a hydroisomerization effluent. The hydrocracking catalyst and
hydroisomerization catalyst may be arranged in a variety of design
options so long as the entire effluent from the hydrocracking zone
is passed to the hydroisomerization zone. Accordingly, the
hydrocracking and hydroisomerization catalysts may be layered in a
single reaction zone in a single reactor, or the hydrocracking and
hydroisomerization catalysts may be layered in close-coupled series
reactors with no heating, product withdrawal or feed inlet between
reactors. The preferred catalyst system is a layered catalyst
system, with the hydrocracking catalyst layered above the
hydroisomerization catalyst, preferably in a ratio of about 1:1 to
15:1.
[0040] The hydrocracking zone of the process includes a
hydrocracking catalyst. During hydrocracking, the high molecular
weight wax molecules are cracked into a desirable boiling range.
During cracking, at least some of the cracked molecules may also be
isomerized. The resulting cracked product largely comprises a
mixture of paraffins and isoparaffins, which boil in the desired
fuel or lubricant oil product range According to the present
process, it is desired to minimize the cracking of the feedstock so
that a smaller amount of light products will be produced.
[0041] Hydrocracking catalysts are well known to those of skill in
the art. Conventional hydrocracking catalysts generally comprise a
cracking component, a hydrogenation component and a binder or
matrix. Such catalysts are well known in the art.
[0042] The matrix component can be of many types including some
that have acidic catalytic activity. Ones that have acidic activity
include amorphous silica-alumina. The catalyst may also contain a
large pore zeolitic or non-zeolitic crystalline molecular sieve,
where large pore is defined as having a pore diameter of greater
than 7.1 .ANG.. Examples of suitable molecular sieves include
zeolite Y, zeolite X and the so called ultra stable zeolite Y and
high structural silica:alumina ratio zeolite Y such as that
described in U.S. Pat. Nos. 4,401,556, 4,820,402 and 5,059,567.
Small crystal size zeolite Y, such as that described in U.S. Pat.
No. 5,073,530, can also be used. Non-zeolitic molecular sieves
which can be used include, for example, silicoaluminophosphates
(SAPO), ferroaluminophosphate, titanium aluminophosphate and the
various ELAPO molecular sieves described in U.S. Pat. No. 4,913,799
and the references cited therein. Details regarding the preparation
of various non-zeolite molecular sieves can be found in U.S. Pat.
No. 5,114,563 (SAPO); U.S. Pat. No. 4,913,799 and the various
references cited in U.S. Pat. No. 4,913,799. Mesoporous molecular
sieves can also be used, for example the M41S family of materials
(J. Am. Chem. Soc., 114:10834-10843(1992)), MCM-41 (U.S. Pat. Nos.
5,246,689; 5,198,203; 5,334,368), and MCM-48 (Kresge et al., Nature
359:710 (1992)). The contents of each of the patents and
publications referred to above are hereby incorporated by reference
in their entirety. Perferably, the molecular sieve content of the
hydrocracking catalyst is less than 2 wt %.
[0043] Suitable matrix materials may also include synthetic or
natural substances as well as inorganic materials such as clay,
silica and/or metal oxides such as silica-alumina, silica-magnesia,
silica-zirconia, silica-thoria, silica-berylia, silica-titania as
well as ternary compositions, such as silica-alumina-thoria,
silica-alumina-zirconia, silica-alumina-magnesia, and
silica-magnesia zirconia. The latter may be either naturally
occurring or in the form of gelatinous precipitates or gels
including mixtures of silica and metal oxides. Naturally occurring
clays which can be composited with the catalyst include those of
the montmorillonite and kaolin families. These clays can be used in
the raw state as originally mined or initially subjected to
calumniation, acid treatment or chemical modification.
[0044] The hydrogenation component will be a Group VI, Group VII,
or Group VIII metal or oxide or sulfide thereof, preferably one or
more of molybdenum, tungsten, cobalt, or nickel, or the sulfides or
oxides thereof. If present in the catalyst, these hydrogenation
components generally make up from about 5 weight % to about 40
weight % of the catalyst. Alternatively, platinum group metals,
especially platinum and/or palladium, may be present as the
hydrogenation component, either alone or in combination with the
base metal hydrogenation components such as molybdenum, tungsten,
cobalt, or nickel. If present, the platinum group metals will
generally make up from about 0.1 weight % to about 2 weight % of
the catalyst. The hydrogenation component can be added to the
catalyst by methods such as co-mulling, impregnation, or
ion-exchange.
[0045] Typical hydrocracking conditions include: reaction
temperature of from about 400 to 950.degree. F. (204 to 510.degree.
C.), preferably 600 to 750.degree. F. (316 to 399.degree. C.);
reaction pressure of from about 300 to 5000 psig (2.1 to 34.5 MPa),
preferably 500-2000 psig (5.2-13.8 MPa); liquid hourly space
velocity (LHSV) of from about 0.1 to 15 hr.sup.-1, preferably 0.25
to 2.5 hr.sup.-1; and hydrogen recycle rate of from about 500 to
5000 standard cubic feet (SCF) per barrel of liquid hydrocarbon
feed (89.1 to 890 m.sup.3H.sub.2/m.sup.3 feed).
[0046] The effluent from the hydrocracking zone is then contacted
with an intermediate pore size molecular sieve hydroisomerization
catalyst in a hydroisomerization zone.
[0047] The phrase "intermediate pore size," as used herein means an
effective pore aperture in the range of from about 4.8 to about 7.1
.ANG. when the porous inorganic oxide is in the calcined form.
[0048] Hydroisomerization dewaxing is intended to improve the cold
flow properties of a lubricating base oil by the selective addition
of branching into the molecular structure. Hydroisomerization
dewaxing ideally will achieve high conversion levels of waxy feed
to non-waxy iso-paraffins while at the same time minimizing the
conversion by cracking.
[0049] A hydroisomerization dewaxing catalyst useful in the present
invention comprises a shape selective intermediate pore size
molecular sieve and optionally a catalytically active metal
hydrogenation component on a refractory oxide support. The shape
selective intermediate pore size molecular sieves used in the
practice of the present invention are generally l-D 10-, 11- or
12-ring molecular sieves. The preferred molecular sieves of the
invention are of the 1-D 10-ring variety, where 10- (or 11- or 12-)
ring molecular sieves have 10 (or 11 or 12)
tetrahedrally-coordinated atoms (T-atoms) joined by oxygens. In the
1-D molecular sieve, the 10-ring (or larger) pores are parallel
with each other, and do not interconnect. The classification of
intrazeolite channels as 1-D, 2-D and 3-D is set forth by R. M.
Barrer in Zeolites, Science and Technology, edited by F. R.
Rodrigues, L. D. Rollman and C. Naccache, NATO ASI Series, 1984
which classification is incorporated in its entirety by reference
(see particularly page 75).
[0050] Preferred shape selective intermediate pore size molecular
sieves used for hydroisomerization dewaxing are based upon aluminum
phosphates, such as SAPO-11, SAPO-31, and SAPO-41. SAPO-11 and
SAPO-31 are more preferred, with SAPO-11 being most preferred. SM-3
is a particularly preferred shape selective intermediate pore size
SAPO, which has a crystalline structure falling within that of the
SAPO-11 molecular sieves. The preparation of SM-3 and its unique
characteristics are described in U.S. Pat. Nos. 4,943,424 and
5,158,665. Also preferred shape selective intermediate pore size
molecular sieves used for hydroisomerization dewaxing are zeolites,
such as ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, SSZ-32, offretite,
and ferrierite. SSZ-32 and ZSM-23 are more preferred.
[0051] A particularly preferred intermediate pore size molecular
sieve, which is useful in the present process is described, for
example, in U.S. Pat. No. 5,135,638 and 5,282,958, the contents of
which are hereby incorporated by reference in their entirety. In
U.S. Pat. No. 5,282,958, such an intermediate pore size molecular
sieve has a crystallite size of no more than about 0.5 microns and
pores with a minimum diameter of at least about 4.8 .ANG. and with
a maximum diameter of about 7.1 .ANG.. The catalyst has sufficient
acidity so that 0.5 grams thereof when positioned in a tube reactor
converts at least 50% of hexadecane at 370.degree. C., a pressure
of 1200 psig, a hydrogen flow of 160 ml/min, and a feed rate of 1
ml/hr. The catalyst also exhibits isomerization selectivity of 40
or greater (isomerization selectivity is determined as follows:
100.times.(weight % branched C16 in product)/(weight % branched C16
in product+weight % C13-in product) when used under conditions
leading to 96% conversion of normal hexadecane (n-C16) to other
species.
[0052] Such a particularly preferred molecular sieve may further be
characterized by pores or channels having a crystallographic free
diameter in the range of from about 4.0 to about 7.1 .ANG., and
preferably in the range of 4.0 to 6.5 .ANG.., The crystallographic
free diameters of the channels of molecular sieves are published in
the "Atlas of Zeolite Framework Types", Fifth Revised Edition,
2001, by Ch. Baerlocher, W. M. Meier, and D. H. Olson, Elsevier, pp
10-15, which is incorporated herein by reference.
[0053] If the crystallographic free diameters of the channels of a
molecular sieve are unknown, the effective pore size of the
molecular sieve can be measured using standard adsorption
techniques and hydrocarbonaceous compounds of known minimum kinetic
diameters. See Breck, Zeolite Molecular Sieves, 1974 (especially
Chapter 8); Anderson et al. J. Catalysis 58, 114 (1979); and U.S.
Pat. No. 4,440,871, the pertinent portions of which are
incorporated herein by reference. In performing adsorption
measurements to determine pore size, standard techniques are used.
It is convenient to consider a particular molecule as excluded if
does not reach at least 95% of its equilibrium adsorption value on
the molecular sieve in less than about 10 minutes
(p/po=0.5;25.degree. C.). Intermediate pore size molecular sieves
will typically admit molecules having kinetic diameters of 5.3 to
6.5 Angstrom with little hindrance.
[0054] Hydroisomerization dewaxing catalysts useful in the present
invention optionally comprise a catalytically active hydrogenation
metal. The presence of a catalytically active hydrogenation metal
leads to product improvement, especially VI and stability. Typical
catalytically active hydrogenation metals include chromium,
molybdenum, nickel, vanadium, cobalt, tungsten, zinc, platinum, and
palladium. The metals platinum and palladium are especially
preferred, with platinum most especially preferred. If platinum
and/or palladium is used, the total amount of active hydrogenation
metal is typically in the range of 0.1 to 5 weight percent of the
total catalyst, usually from 0.1 to 2 weight percent, and not to
exceed 10 weight percent.
[0055] The refractory oxide support may be selected from those
oxide supports which are conventionally used for catalysts,
including silica, alumina, silica-alumina, magnesia, titania and
combinations thereof.
[0056] The intermediate pore molecular sieve hydroisomerization
catalyst is particularly suited for hydroisomerizing normal
paraffins to produce a low cloud point, low pour point product.
Thus, distillate fuel fractions recovered from the
hydroisomerization step have reduced cloud points. Furthermore, the
hydroisomerization step reduces the pour point of the heavy
fraction, and permits at least a portion of the heavy fraction to
be recovered for lubricant oils. While it is expected that some
cracking conversion will also occur over the hydroisomerization
catalyst, the conditions in the hydroisomerization step are
maintained such that the hydroisomerization reaction dominates.
[0057] With previous hydroisomerization processes, we have found
that the cloud point of the lubricant base oil can be high (above
0.degree. C.). While additional isomerization can reduce cloud
point, this results in a loss of base oil yield, viscosity index,
and viscosity due to cracking and excessive branching.
[0058] With this hydrocracking/hydroisomerization process, cracking
conversion is minimized while achieving low pour points in the
lubricant base oil and middle distillate fuel products. The process
of the present invention results in less cracking of the high
boiling end of the high boiling waxy feed (i.e., less conversion of
the high boiling end of the feed to lighter products). Accordingly,
high quality lubricant base oils with high viscosity indexes, low
pour points, and higher viscosities are produced. According to the
process of the present invention, preferably less than 60 weight
percent of the 650.degree. F.+ products is the feed is converted to
650.degree. F.- products. Therefore, with this process, cracking
conversion is minimized while achieving low pour points in the
products. In addition, since there is less cracking, high yields of
high quality lubricant base oil products are provided.
[0059] The product of this hydrocracking/hydroisomerization process
is fractionated by conventional methods to provide at least a
middle distillate fuel fraction and a heavy fraction. The
fractionation can be accomplished by conventional methods of
distillation with an appropriate cut point for isolating the middle
distillate fuel fraction and heavy fraction.
[0060] A lubricant base oil is isolated from heavy fraction. The
heavy fraction may be fractionated by convention methods, including
vacuum distillation, to provide the lubricant base oil fraction and
optionally, a bottoms fraction may also be isolated. The bottoms
fraction may be recycled to the hydrocracking reaction zone. When
recycling all or a portion of the bottoms fraction, the bottoms
fraction may be subjected to the hydrocracking step of the present
invention alone or may be combined with another waxy hydrocarbon
feedstock. Recycling all or a portion of the bottoms fraction
increases the yield of the process.
[0061] According to the present invention, a high quality lubricant
base oil is isolated from the heavy fraction without the need for
an additional dewaxing step. A high viscosity lubricant base oil is
provided by the processes of the present invention due to less
cracking of the high boiling end of the waxy feedstock. Preferably
less than 60 weight percent of the 650.degree. F.+ in the feed is
converted to 650.degree. F.- products. The lubricant base oil
recovered from the process of the present invention has a viscosity
index of greater than 130, preferably greater than 140, and more
preferably greater than 150. The lubricant base oil provided also
has a pour point of less than -15.degree. C. The lubricant base oil
has a viscosity of greater than 3 cSt at 100.degree. C., preferably
greater than 4 cSt at 100.degree. C., and more preferably greater
than 5 cSt at 100.degree. C.
[0062] The recovered lubricant oil may optionally be subjected to
hydrofinishing in a mild hydrogenation process to improve its
stability to heat and oxidation. The hydrofinishing can be
conventionally carried out in the presence of a metallic
hydrogenation catalyst such as, for example, platinum on alumina.
The hydrofinishing can be carried out at a temperature of from
about 190 to about 340.degree. C., a pressure of from about 300 to
about 3000 psig (2.76 to 20.7 Mpa), a LHSV between about 0.1 and
20, and hydrogen recycle rates of about 400 to about 1500
SCF/bbl.
[0063] The lubricant base oil recovered from the processes of the
present invention may be used as such as a lubricant, or it may be
blended with another refined lubricant stock having different
properties. Alternatively, the lubricant base oil, prior to use as
a lubricant, may be blended with one or more additives, for
example, as antioxidants, extreme pressure additives, viscosity
index improvers, and the like.
[0064] Illustrative Embodiment
[0065] The FIGURE illustrates a schematic representation of one
embodiment of the present invention. Referring to the FIGURE, a
waxy hydrocarbon feedstock (10) is fed into a single reactor (100)
containing a hydrocracking catalyst in a hydrocracking zone (110)
and a hydroisomerization catalyst in a hydroisomerization zone
(120), wherein the hydrocracking zone (110) is above the
hydroisomerization zone (120). The waxy hydrocarbon feedstock (10)
is first contacted with the hydrocracking catalyst in the
hydrocracking zone (110) and the effluent from the hydrocracking
zone (110) is next contacted with the hydroisomerization catalyst
in the hydroisomerization zone (120). The entire effluent (20) from
the hydroisomerization zone (120) is then fractioned in a
fractionator (200), providing a heavy fraction (30), a middle
distillate fuel (50) and a lighter product (70). From the heavy
fraction (30), a lubricant base oil (60) and optionally a bottoms
fraction (40) are obtained. The lubricant base oil has a viscosity
index of greater than 130, a pour point of less than -15.degree.
C., and a viscosity at 100.degree. C. of greater than 3 cSt.
Optionally, the bottoms fraction (40) may be recycled to the
hydrocracking zone (110) in the reactor (100). In addition to the
lubricant base oil (60), the fractionation also produces a middle
distillate product (50). Finally, the lubricant base oil (60) may
be optionally hydrofinished in a hydrofinishing unit (300) to
provide a hydrofinished lube oil (70).
[0066] The invention will now be illustrated by the following
examples which is intended to be merely exemplary and in no manner
limiting.
EXAMPLES
Example 1
[0067] A 450.degree. F.+ Arab Heavy VGO first stage product was
hydrocracked at 68% 700.degree. F.+ conversion at 1.2 hr.sup.-1
LHSV and 1800 psig over a nickel-tungsten/silica-alumina
hydrocracking catalyst (Catalyst A), the 700.degree. F.+ bottoms
had a +21.degree. C. pour point and 125 VI. By contrast, using a
layered bed of 2:1 Catalyst A/Pt SAPO-11 hydroisomerization
catalyst (Catalyst B) at the same conditions yielded a 725.degree.
F.+ product (4 cSt at 100.degree. C.) of-20.degree. C. pour point
and 127 VI. Cloud point in the diesel cut was decreased and cetane
index increased versus the case with Catalyst A alone. Total
mid-distillate was 56.9 weight %, versus 53.1 weight % with
Catalyst A alone, due in part to an extension of the diesel
endpoint from 700.degree. F. to 725.degree. F.
Example 2
[0068] A light Fischer-Tropsch wax (Table 1) was hydrocracked over
a sulfided nickel-tungsten/silica-alumina catalyst followed at 1
hr.sup.-1 LHSV, 1000 psig, 685.degree. F., and 6300 standard cubic
feet (SCF)/Bbl. At these conditions, conversion below 650.degree.
F. was 80.4 weight %. The liquid product was cut at about
350.degree. F. and about 675.degree. F. to give a diesel fraction.
Yields and properties of the diesel cut and 675.degree. F.+ bottoms
are given in Table II. The cloud point of the bottoms fraction
(+29.degree. C.) was too high to be preferred for lube use.
1 TABLE I Description Light Fischer-Tropsch Wax Gravity, API 42.5
Nitrogen, ppm 3.2 Sim. Dist., LV %, .degree. F. ST/5 728/771 10/30
789/811 50 839 70/90 858/885 95/EP 898/943
[0069]
2 TABLE II Conversion <650.degree. F., Weight % 80.4 Yield,
Weight % C.sub.1-C.sub.2 0.03 C.sub.3-C.sub.4 5.06
C.sub.5-180.degree. F. 17.77 180-350.degree. F. 20.85
350-650.degree. F. 37.51 650.degree. F.+ 19.71 C.sub.5+ 95.49
350-675.degree. F. Weight % of Feed 52.9 Gravity, API 50.7
Viscosity, 40.degree. C., cSt 2.631 Cloud Point, .degree. C. -26
Aromatics, (SFC), Weight % Total <0.5 PNA Not Detected Cetane
Index 75.9 Refractive Index 1.4342 Density, g/mL 0.7745 Molecular
Weight 253 P/N/A Carbon 100/0/0 Sim. Dist., LV %, .degree. F. ST/5
288/342 10/30 368/448 50 523 70/90 594/673 95/EP 697/743
675.degree. F.+ Weight % of Feed 14.1 Cloud Point, .degree. C. +29
Viscosity, 100.degree. C., cSt 3.364 Sim. Dist., LV %, .degree. F.
ST/5 700/722 10/30 732/777 50 808 70/90 829/857 95/EP 871/900
Example 3
[0070] The same feed as in Example 2 was hydrocracked over a
sulfided 3/1 layered bed of the same catalyst as in Example 2 and
then over a Pt/SAPO-11 catalyst bound with 15 weight % alumina.
Conditions were the same as in Example 2, that is 1.0 hr.sup.-1
overall LHSV, 1000 psig, 685.degree. F., and 6.3 MSCF/Bbl H2.
Conversion below 650.degree. F. was 74.6 weigh %. The product was
cut at about 350.degree. F. and about 650.degree. F. to give a
diesel cut. Yields and properties of the diesel cut and 650.degree.
F.+ bottoms are given in Table III. The diesel was high temperature
stable by ASTM test D6468. Aromatics in the diesel were less than
0.5 weight %. The cetane index was very high (73.8) and the cloud
point very low (-57.degree. C.). The 650.degree. F.+ stripper
bottoms were found to be a 3 cSt (at 100.degree. C.) oil with low
pour and cloud points and high VI.
3 TABLE III Conversion <650.degree. F., Weight % 74.6 Yield,
Weight % C.sub.1-C.sub.2 0.08 C.sub.3-C.sub.4 5.16
C.sub.5-180.degree. F. 13.02 180-350.degree. F. 15.70
350-650.degree. F. 40.97 650.degree. F.+ 25.59 C.sub.5+ 95.36
350-650.degree. F. Weight % of Feed 43.1 Gravity, API 51.3
Viscosity, 40.degree. C., cSt 2.206 Cloud Point, .degree. C. -57
Olefins, Weight % (GC-MS) Not Detected Aromatics, (SFC), Weight %
Total <0.5 PNA Not Detected High Temperature Stability,
150.degree. C., % Reflectance, ASTM D6468 1.5 Hr 99.7 3.0 Hr 99.8
Cetane Index 73.8 Refractive Index 1.4318 Density, g/mL 0.7699
Molecular Weight 239 P/N/A Carbon 100/0/0 Sim. Dist., LV %,
.degree. F. ST/5 314/352 10/30 370/433 50 496 70/90 549/606 95/EP
629/676 650.degree. F.+ Weight % of Feed 29.7 Pour Point, .degree.
C. -39 Cloud Point, .degree. C. -26 Viscosity, 40.degree. C., cSt
10.69 100.degree. C., cSt 2.849 VI 114 Sim. Dist., LV %, .degree.
F. ST/5 602/627 10/30 641/690 50 736 70/90 798/837 95/EP
851/880
Example 4
[0071] The run of Example 3 was continued, but at a catalyst
temperature of 670.degree. F. At this temperature, conversion below
650.degree. F. was 40.1 weight %. Yields and properties of the
650.degree. F.+ stripper bottoms are given in Table IV. This is
found to be a 3.4 cSt (at 100.degree. C.) oil of high VI.
4 TABLE IV Conversion <650.degree. F., Weight % 40.1 Yield,
Weight % C.sub.1-C.sub.2 0.08 C.sub.3-C.sub.4 5.69
C.sub.5-180.degree. F. 7.36 180-350.degree. F. 6.60 350-650.degree.
F. 20.61 650.degree. F.+ 60.25 C.sub.5+ 94.83 650.degree. F.+
Weight % of Feed 64.4 Pour Point, .degree. C. -8 Cloud Point,
.degree. C. 0 Viscosity, 40.degree. C., cSt 13.33 100.degree. C.,
cSt 3.433 VI 138 Sim. Dist., LV %, .degree. F. ST/5 587/639 10/30
678/775 50 817 70/90 840/869 95/EP 881/911
Example 5
[0072] A 700-1000.degree. F. hydrotreated Fischer-Tropsch Wax
(Table V) was hydrocracked over the same layered bed catalyst
system of Example 3. Conditions included a 1.0 hr.sup.-1 overall
LHSV, reactor pressure of 300 psig, 680.degree. F. for the top
catalyst and 690.degree. F. for the bottom catalyst, and 6.3
MSCF/Bbl H.sub.2. Conversion below 650.degree. F. was 58.2 weight
%. The product was cut at about 300.degree. F. and about
650.degree. F. to give a diesel cut. Yields and properties of the
diesel cut and 650.degree. F.+ bottoms are given in Table VI. The
diesel was high temperature stable by ASTM test D6468. Aromatics in
the diesel were 6.1 weight %. The cetane index was high (67.6) and
the cloud point was -44.degree. C. The 650.degree. F.+ stripper
bottoms were found to be a 5 cSt (at 100.degree. C.) oil with low
pour and cloud points and very high VI.
5 TABLE V Description 700-1000.degree. F. Hydrotreated
Fischer-Tropsch Wax Gravity, API 42.3 Sim. Dist., LV %, .degree. F.
ST/5 691/804 10/30 824/884 50 919 70/90 940/974 95/EP 991/1031
[0073]
6 TABLE VI Conversion <650.degree. F., Weight % 58.2 Yield,
Weight % C.sub.1-C.sub.2 0 C.sub.3-C.sub.4 4.78 C.sub.5-180.degree.
F. 14.93 180-350.degree. F. 15.53 350-650.degree. F. 23.22
650.degree. F.+ 41.92 C.sub.5+ 95.7 350-650.degree. F. Weight % of
Feed 31.1 Gravity, API 50.1 Viscosity, 40.degree. C., cSt 2.027
Cloud Point, .degree. C. -44 Olefins, Weight % (GC-MS) Not Detected
Aromatics, (SFC), Weight % Total 6.1 PNA 0.5 High Temperature
Stability, 150.degree. C., % Reflectance, ASTM D6468 1.5 Hr 99.2
3.0 Hr 99.2 Cetane Index 67.6 Refractive Index 1.4348 Density, g/mL
0.7741 Molecular Weight 196 P/N/A Carbon 92.40/5.01/2.59 Sim.
Dist., LV %, .degree. F. ST/5 266/300 10/30 325/396 50 472 70/90
561/645 95/EP 667/698 650.degree. F.+ Weight % of Feed 41.0 Pour
Point, .degree. C. -26 Cloud Point, .degree. C. -5 Viscosity,
40.degree. C., cSt 22.04 100.degree. C., cSt 4.882 VI 151 Sim.
Dist., LV %, .degree. F. ST/5 681/710 10/30 732/803 50 856 70/90
896/937 95/EP 954/990
Example 6
[0074] A full boiling range hydrotreated Fischer-Tropsch Wax (Table
VII), from which the feed of Table V was prepared, was hydrocracked
over the same layered bed catalyst system of Example 3. Conditions
included a 1.0 hr.sup.-1 overall LHSV, reactor pressure of 1000
psig, 680.degree. F. for the top catalyst and 691.degree. F. for
the bottom catalyst, and 6.3 MSCF/Bbl H.sub.2. Conversion below
650.degree. F. was 45.9 weight %. Yields and properties of the
650.degree. F.+ stripper bottoms are given in Table VIII. This was
found to be a 5.5 cSt (at 100.degree. C.) oil with low pour point
and very high VI.
7 TABLE VII Description Full Boiling Range Hydrotreated
Fischer-Tropsch Wax Gravity, API 38.2 Nitrogen, ppm 1.9 Sim. Dist.,
LV %, .degree. F. ST/5 791/856 10/30 876/942 50 995 70/90 1031/1085
95/EP 1107/1133
[0075]
8 TABLE VIII Conversion <650.degree. F., Weight % 45.9 Yield,
Weight % C.sub.1-C.sub.2 0.06 C.sub.3-C.sub.4 3.99
C.sub.5-180.degree. F. 5.76 180-350.degree. F. 8.21 350-650.degree.
F. 27.91 650.degree. F.+ 54.34 C.sub.5+ 96.44 650.degree. F.+
Weight % of Feed 52.5 Pour Point, .degree. C. -18 Cloud Point,
.degree. C. +10 Viscosity, 40.degree. C., cSt 26.58 100.degree. C.,
cSt 5.529 VI 152 Sim. Dist., LV %, .degree. F. ST/5 666/706 10/30
739/847 50 909 70/90 966/1056 95/EP 1083/1138
[0076] Various modifications and alterations of this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention. Other objects and
advantages will become apparent to those skilled in the art from a
review of the preceding description.
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