U.S. patent application number 15/843380 was filed with the patent office on 2018-07-05 for solvent extraction for correction of color and aromatics distribution of heavy neutral base stocks.
The applicant listed for this patent is ExxonMobil Research and Engineering Company. Invention is credited to Michael B. Carroll, Kendall S. Fruchey, Camden N. Henderson, Timothy L. Hilbert, Tracie L. Owens, Lisa I-Ching Yeh.
Application Number | 20180187105 15/843380 |
Document ID | / |
Family ID | 60991545 |
Filed Date | 2018-07-05 |
United States Patent
Application |
20180187105 |
Kind Code |
A1 |
Owens; Tracie L. ; et
al. |
July 5, 2018 |
SOLVENT EXTRACTION FOR CORRECTION OF COLOR AND AROMATICS
DISTRIBUTION OF HEAVY NEUTRAL BASE STOCKS
Abstract
Systems and methods are provided for performing solvent
extraction on heavy neutral base stocks. The aromatic extraction
can reduce aromatics content while have a reduced or minimized
impact on lubricant properties. This can allow, for example, for
correction of color and/or haze for heavy neutral base stocks, such
as heavy neutral base stocks formed from a deasphalted oil.
Inventors: |
Owens; Tracie L.; (Houston,
TX) ; Fruchey; Kendall S.; (Easton, PA) ;
Carroll; Michael B.; (Center Valley, PA) ; Henderson;
Camden N.; (Mullica Hill, NJ) ; Yeh; Lisa
I-Ching; (Marlton, NJ) ; Hilbert; Timothy L.;
(Middleburg, VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Research and Engineering Company |
Annandale |
NJ |
US |
|
|
Family ID: |
60991545 |
Appl. No.: |
15/843380 |
Filed: |
December 15, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62439937 |
Dec 29, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 67/02 20130101;
C10G 67/049 20130101; C10G 2400/10 20130101; C10M 2203/1006
20130101; C10G 21/003 20130101; C10G 2300/301 20130101; C10G
67/0463 20130101; C10N 2030/02 20130101; C10N 2020/02 20130101;
C10M 101/02 20130101; C10G 67/0454 20130101; C10G 2300/302
20130101 |
International
Class: |
C10G 67/04 20060101
C10G067/04; C10G 67/02 20060101 C10G067/02; C10M 101/02 20060101
C10M101/02 |
Claims
1. A method for making lubricant base stock, comprising:
hydroprocessing a deasphalted oil comprising a 370.degree. C.+
fraction under first effective hydroprocessing conditions to form a
hydroprocessed effluent, at least a portion of the deasphalted oil
having an aromatics content of at least about 50 wt %, the
hydroprocessed effluent comprising a sulfur content of 300 wppm or
less or a nitrogen content of 100 wppm or less, or a combination
thereof; separating the hydroprocessed effluent to form at least a
first fraction comprising a T5 distillation point of at least
370.degree. C. and a kinematic viscosity at 100.degree. C. of 6 cSt
to 20 cSt; hydroprocessing at least a portion of the first fraction
under second effective hydroprocessing conditions, the second
effective hydroprocessing conditions comprising catalytic dewaxing
conditions, to form a catalytically dewaxed effluent comprising a
370.degree. C.+ portion; and solvent extracting at least a portion
of the 370.degree. C.+ portion of the catalytically dewaxed
effluent to form a solvent processed effluent.
2. A method for making lubricant base stock, comprising: performing
solvent deasphalting, optionally using a C.sub.4+ solvent, under
effective solvent deasphalting conditions on a feedstock having a
T5 boiling point of at least about 370.degree. C. (or at least
about 400.degree. C., or at least about 450.degree. C., or at least
about 500.degree. C.), the effective solvent deasphalting
conditions producing a yield of deasphalted oil of at least about
50 wt % of the feedstock; hydroprocessing at least a portion of the
deasphalted oil under first effective hydroprocessing conditions to
form a hydroprocessed effluent, the at least a portion of the
deasphalted oil having an aromatics content of at least about 50 wt
%, the hydroprocessed effluent comprising a sulfur content of 300
wppm or less, a nitrogen content of 100 wppm or less, or a
combination thereof; separating the hydroprocessed effluent to form
at least a first fraction comprising a T5 distillation point of at
least 370.degree. C. and a kinematic viscosity at 100.degree. C. of
6 cSt to 20 cSt; hydroprocessing at least a portion of the first
fraction under second effective hydroprocessing conditions, the
second effective hydroprocessing conditions comprising catalytic
dewaxing conditions, to form a catalytically dewaxed effluent
comprising a 370.degree. C.+ portion; and solvent extracting at
least a portion of the 370.degree. C.+ portion of the catalytically
dewaxed effluent to form a solvent processed effluent.
3. A method for making lubricant base stock, comprising:
hydroprocessing a feedstock comprising a 370.degree. C.+ fraction
under first effective hydroprocessing conditions to form a
hydroprocessed effluent, the at least a portion of the deasphalted
oil having an aromatics content of at least about 50 wt %, the
hydroprocessed effluent comprising a sulfur content of 300 wppm or
less, a nitrogen content of 100 wppm or less, or a combination
thereof; separating the hydroprocessed effluent to form at least a
first fraction having a T5 distillation point of at least
370.degree. C.; hydroprocessing at least a portion of the first
fraction under second effective hydroprocessing conditions, the
second effective hydroprocessing conditions comprising catalytic
dewaxing conditions, to form a catalytically dewaxed effluent
comprising a 370.degree. C.+ portion, the 370.degree. C.+ portion
comprising a second fraction comprising a kinematic viscosity at
100.degree. C. of 6 cSt to 20 cSt; and solvent extracting at least
a portion of the second fraction to form a solvent processed
effluent.
4. A method for making lubricant base stock, comprising: performing
solvent deasphalting, optionally using a C.sub.4+ solvent, under
effective solvent deasphalting conditions on a feedstock having a
T5 boiling point of at least about 370.degree. C. (or at least
about 400.degree. C., or at least about 450.degree. C., or at least
about 500.degree. C.), the effective solvent deasphalting
conditions producing a yield of deasphalted oil of at least about
50 wt % of the feedstock; hydroprocessing at least a portion of the
deasphalted oil under first effective hydroprocessing conditions to
form a hydroprocessed effluent, the at least a portion of the
deasphalted oil having an aromatics content of at least about 50 wt
%, the hydroprocessed effluent comprising a sulfur content of 300
wppm or less, a nitrogen content of 100 wppm or less, or a
combination thereof; separating the hydroprocessed effluent to form
at least a first fraction comprising a T5 distillation point of at
least 370.degree. C.; hydroprocessing at least a portion of the
first fraction under second effective hydroprocessing conditions,
the second effective hydroprocessing conditions comprising
catalytic dewaxing conditions, to form a catalytically dewaxed
effluent comprising a 370.degree. C.+ portion, the 370.degree. C.+
portion comprising a second fraction comprising a kinematic
viscosity at 100.degree. C. of 6 cSt to 20 cSt; and solvent
extracting at least a portion of the second fraction to form a
solvent processed effluent.
5. The method of claim 3, further comprising separating at least a
portion of the catalytically dewaxed effluent to form the second
fraction or separating at least a portion of the 370.degree. C.+
portion of the catalytically dewaxed effluent to form the second
fraction.
6. The method of claim 4, wherein the solvent processed effluent
comprises a VI of at least 80 and a kinematic viscosity at
100.degree. C. of 6 cSt to 20 cSt.
7. The method of claim 1, wherein the solvent processed effluent
comprises a pour point of -6.degree. C. or less, a cloud point of
-2.degree. C. or a combination thereof.
8. The method of claims 1-4, wherein the solvent extracting
comprises solvent extracting with N-methylpyrrolidone, furfural,
phenol, or a combination thereof.
9. The method of claim 2, wherein the yield of deasphalted oil is
at least 55 wt %, wherein the deasphalted oil has an aromatics
content of at least 55 wt %, based on a weight of the deasphalted
oil, or a combination thereof.
10. The method of claim 2, wherein the C.sub.4+ solvent comprises a
C.sub.5+ solvent, a mixture of two or more C.sub.5 isomers, or a
combination thereof.
11. The method of claim 2, wherein the solvent processed effluent
comprises a viscosity index of 80 to 160.
12. The method of claim 2, wherein prior to the solvent extracting,
the 370.degree. C.+ portion of the catalytically dewaxed effluent
or the second fraction comprises an absorptivity at 226 nm of at
least 0.020 and the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 226 nm of less than 0.020.
13. The method of claim 2, wherein prior to the solvent extracting,
the 370.degree. C.+ portion of the catalytically dewaxed effluent
or the second fraction comprises an absorptivity at 254 nm of at
least 0.010, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 254 nm of less than 0.010.
14. The method of claim 2, wherein prior to the solvent extracting,
the 370.degree. C.+ portion of the catalytically dewaxed effluent
or the second fraction comprises an absorptivity at 275 nm of at
least 0.010, and the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 275 nm of less than 0.010.
15. The method of claim 1, wherein prior to the solvent extracting,
the 370.degree. C.+ portion of the catalytically dewaxed effluent
or the second fraction comprises an absorptivity at 302 nm of at
least 0.020, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 302 nm of less than 0.010.
16. The method of claim 2, wherein prior to the solvent extracting,
the 370.degree. C.+ portion of the catalytically dewaxed effluent
or the second fraction comprises an absorptivity at 310 nm of at
least 0.030, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 310 nm of less than 0.010.
17. The method of claim 3, wherein prior to the solvent extracting,
the 370.degree. C.+ portion of the catalytically dewaxed effluent
or the second fraction comprises an absorptivity at 325 nm of at
least 0.010, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 310 nm of less than 0.010.
18. A solvent processed effluent produced according to claim 1.
19. A formulated lubricant formed from the solvent processed
effluent of claim 18 with the formulated lubricant optionally
comprising an additive.
20. The formulated lubricant of claim 19, wherein the additive is
selected from the group consisting of detergents, dispersants,
antioxidants, viscosity modifiers, pour point depressants, antiwear
agents, corrosion inhibitors, rust inhibitors, metal deactivators,
extreme pressure additives, anti-seizure agents, wax modifiers,
viscosity index improvers, viscosity modifiers, fluid-loss
additives, seal compatibility agents, friction modifiers, lubricity
agents, anti-staining agents, chromophoric agents, defoamants,
demulsifiers, emulsifiers, densifiers, wetting agents, gelling
agents, tackiness agents, colorants, and combinations thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 62/439,937 filed Dec. 29, 2016, which is
herein incorporated by reference in its entirety.
FIELD
[0002] Systems and methods are provided for production of heavy
neutral lubricant oil base stocks, such as heavy neutral base
stocks derived from deasphalted oils produced by low severity
deasphalting of resid fractions.
BACKGROUND
[0003] Lubricant base stocks are one of the higher value products
that can be generated from a crude oil or crude oil fraction. The
ability to generate lubricant base stocks of a desired quality is
often constrained by the availability of a suitable feedstock. For
example, most conventional processes for lubricant base stock
production involve starting with a crude fraction that has not been
previously processed under severe conditions, such as a virgin gas
oil fraction from a crude with moderate to low levels of initial
sulfur content.
[0004] In some situations, a deasphalted oil formed by propane
desaphalting of a vacuum resid can be used for additional lubricant
base stock production. Deasphalted oils can potentially be suitable
for production of heavier base stocks, such as bright stocks.
However, the severity of propane deasphalting required in order to
make a suitable feed for lubricant base stock production typically
results in a yield of only about 30 wt % deasphalted oil relative
to the vacuum resid feed.
[0005] U.S. Pat. No. 3,414,506 describes methods for making
lubricating oils by hydrotreating pentane-alcohol-deasphalted short
residue. The methods include performing deasphalting on a vacuum
resid fraction with a deasphalting solvent comprising a mixture of
an alkane, such as pentane, and one or more short chain alcohols,
such as methanol and isopropyl alcohol. The deasphalted oil is then
hydrotreated, followed by solvent extraction to perform sufficient
VI uplift to form lubricating oils.
[0006] U.S. Pat. No. 7,776,206 describes methods for catalytically
processing resids and/or deasphalted oils to form bright stock. A
resid-derived stream, such as a deasphalted oil, is hydroprocessed
to reduce the sulfur content to less than 1 wt % and reduce the
nitrogen content to less than 0.5 wt %. The hydroprocessed stream
is then fractionated to form a heavier fraction and a lighter
fraction at a cut point between 1150.degree. F.-1300.degree. F.
(620.degree. C.-705.degree. C.). The lighter fraction is then
catalytically processed in various manners to form a bright
stock.
SUMMARY
[0007] In various aspects, systems and methods are provided for
performing solvent extraction on heavy neutral base stocks. The
aromatic extraction can reduce aromatics content while have a
reduced or minimized impact on lubricant properties. This can
allow, for example, for correction of color and/or haze for heavy
neutral base stocks, such as heavy neutral base stocks formed from
a deasphalted oil.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 schematically shows an example of a configuration for
processing a deasphalted oil to form a lubricant base stock.
[0009] FIG. 2 schematically shows another example of a
configuration for processing a deasphalted oil to form a lubricant
base stock.
[0010] FIG. 3 schematically shows another example of a
configuration for processing a deasphalted oil to form a lubricant
base stock.
[0011] FIG. 4 shows results from processing a pentane deasphalted
oil at various levels of hydroprocessing severity.
[0012] FIG. 5 shows results from processing deasphalted oil in
configurations with various combinations of sour hydrocracking and
sweet hydrocracking.
[0013] FIG. 6 schematically shows an example of a configuration for
catalytic processing of deasphalted oil to form lubricant base
stocks.
[0014] FIG. 7 schematically shows an example of a configuration for
block catalytic processing of deasphalted oil to form lubricant
base stocks.
[0015] FIG. 8 schematically shows an example of a configuration for
block catalytic processing of deasphalted oil to form lubricant
base stocks.
[0016] FIG. 9 schematically shows an example of a configuration for
block catalytic processing of deasphalted oil to form lubricant
base stocks.
[0017] FIG. 10 shows UV absorption spectra from a heavy neutral
base stocks with and without aromatic extraction.
DETAILED DESCRIPTION
[0018] All numerical values within the detailed description and the
claims herein are modified by "about" or "approximately" the
indicated value, and take into account experimental error and
variations that would be expected by a person having ordinary skill
in the art.
Aromatic Extraction of Heavy Neutral Base Stocks
[0019] Some of the difficulties in producing lubricant base stocks,
such as heavy neutral base stocks, can be related to formation of
haze. Without being bound by any particular theory, it is believed
that a variety of factors can result in haze formation in a
lubricant base stock, either during processing, immediately after
processing, or subsequent to processing (such as after sitting for
a period of time). One of the factors that can contribute to haze
formation is the presence of aromatics within a heavy neutral
sample. For example, if a heavy neutral base stock contains an
excess of heavy aromatic compounds, the heavy aromatic compounds
may not stay completely in solution after formation of the heavy
neutral base stock, which could result in the base stock having a
hazy appearance over time.
[0020] One example of a lubricant production process that can
result in production of heavy neutral base stocks with a high
content of aromatic compounds is production of base stocks from
deasphalted oils. In particular, deasphalted oils formed using a
solvent deasphalting process with a high yield of deasphalted oil
(i.e., 50 wt % or greater), can have an increased likelihood of
containing high contents of aromatics. It has been discovered that
heavy neutral base stock samples, such as heavy neutral base stocks
formed derived (at least in part) from a deasphalted oil feed, can
be corrected to have a reduced or minimized likelihood of haze
formation by performing an aromatic (solvent) extraction process on
the heavy neutral base stock. Additionally or alternately, such an
aromatic extraction process can be beneficial for removing color
from a heavy neutral base stock sample. Without being bound by any
particular theory, it is believed that the aromatic extraction can
remove unstable molecules, such as high molecular weight
polynuclear aromatics and/or multi-core naphthenic molecules. The
aromatic extraction can be performed after formation of the heavy
neutral base stock, or alternatively the aromatic extraction can be
performed at an earlier stage in the formation of the heavy neutral
base stock.
[0021] The aromatic extraction can be performed using aromatic
extraction solvents that are commonly used for solvent extraction
during solvent processing to form Group I lubricant base stocks.
Examples of suitable solvents can include, but are not limited to,
N-methyl-pyrrolidone, furfural, and/or phenol. Any convenient type
of solvent contactor can be suitable. The heavy neutral base stock
can correspond to a base stock with a kinematic viscosity at
100.degree. C. of 6 cSt to 20 cSt, or 6 cSt to 16 cSt, or 6 cSt to
14 cSt, or 6 cSt to 12 cSt, or 8 cSt to 20 cSt, or 8 cSt to 16 cSt,
or 8 cSt to 14 cSt, or 8 cSt to 12 cSt, or 10 cSt to 20 cSt, or 10
cSt to 16 cSt, or 10 cSt to 14 cSt. The viscosity index of the
heavy neutral base stock can be at least 80, or at least 90, or at
least 100, or at least 110, or at least 120. Additionally or
alternately, the viscosity index of the heavy neutral base stock
can be 80 to 160, or 80 to 140, or 80 to 120, or 90 to 160, or 90
to 140, or 90 to 120, or 100 to 160, or 100 to 140, or 120 to 160,
or 120 to 140.
[0022] As an example, a Group II heavy neutral (HN) base stock was
made from a hydroprocessed blend of C.sub.5 deasphalted oil and
vacuum gas oil. The C.sub.5 deasphalted oil was made from a pentane
deasphalting process with a deasphalted oil yield of 75 wt %. The
"as made" HN base stock sample had an unusual UV aromatics
distribution, and also had more color than desired, with the color
corresponding to a yellow hue. The HN sample was solvent extracted
with N-methyl-pyrrolidone at conditions corresponding to a 200 vol
% solvent treat rate, 1 wt % water content, and a temperature of
100.degree. C. Table A summarizes the properties of the HN sample
prior to and after the solvent extraction process.
TABLE-US-00001 TABLE A Heavy Neutral Properties Before and After
Solvent Extraction Refractive Index 1.4566 1.4553 Total Aromatics
~2 wt % 0.5-1 wt % 2+ Ring Aromatics >0.25 wt % <0.1 wt %
Viscosity Index 95 96 Mutagenicity Index (MI) 0.65 0 Yield, wt %
100 ~79
[0023] As shown in Table A, performing the solvent extraction
reduced the yield and the aromatics content of the heavy neutral
sample, but the properties of the heavy neutral sample were
otherwise similar before and after the solvent extraction.
Additionally, the solvent extraction removed the color of the
sample, so that post-extraction the heavy neutral sample was
water-white. It is noted that although 2+ ring aromatics were
removed effectively, a meaningful portion of total aromatics remain
in the HN sample after extraction, which is believed to show the
selective nature of the extraction process for removing multi-ring
structures.
[0024] FIG. 10 provides a UV absorptivity profile for the HN sample
prior to and after the solvent extraction. FIG. 10 shows a
reduction in UV absorptivity at various wavelengths. More
generally, prior to an aromatics extraction, a heavy neutral sample
can have an absorptivity at 226 nm of at least 0.020, or at least
0.025, or at least 0.030. After extraction, the heavy neutral
sample can have an absorptivity at 226 nm of less than 0.020, or
less than 0.018, or less than 0.016. Additionally or alternately,
prior to an aromatics extraction, a heavy neutral sample can have
an absorptivity at 254 nm of at least 0.010, or at least 0.012, or
at least 0.014. After extraction, the heavy neutral sample can have
an absorptivity at 254 nm of less than 0.010, or less than 0.008,
or less than 0.006, or less than 0.004. Additionally or
alternately, prior to an aromatics extraction, a heavy neutral
sample can have an absorptivity at 275 nm of at least 0.010, or at
least 0.012, or at least 0.014. After extraction, the heavy neutral
sample can have an absorptivity at 275 nm of less than 0.010, or
less than 0.008, or less than 0.006, or less than 0.004.
Additionally or alternately, prior to an aromatics extraction, a
heavy neutral sample can have an absorptivity at 302 nm of at least
0.020, or at least 0.025, or at least 0.030. After extraction, the
heavy neutral sample can have an absorptivity at 302 nm of less
than 0.010, or less than 0.008, or less than 0.006, or less than
0.004. Additionally or alternately, prior to an aromatics
extraction, a heavy neutral sample can have an absorptivity at 310
nm of at least 0.030, or at least 0.035, or at least 0.040. After
extraction, the heavy neutral sample can have an absorptivity at
310 nm of less than 0.010, or less than 0.008, or less than 0.006,
or less than 0.004. Additionally or alternately, prior to an
aromatics extraction, a heavy neutral sample can have an
absorptivity at 325 nm of at least 0.010, or at least 0.012, or at
least 0.014. After extraction, the heavy neutral sample can have an
absorptivity at 310 nm of less than 0.010, or less than 0.008, or
less than 0.006, or less than 0.004.
Overview of Lubricant Base Stock Production from Deasphalted
Oil
[0025] In various aspects, methods are provided for producing Group
I and Group II lubricant base stocks, including Group I and Group
II bright stock, from deasphalted oils generated by low severity
C.sub.4+ deasphalting. Low severity deasphalting as used herein
refers to deasphalting under conditions that result in a high yield
of deasphalted oil (and/or a reduced amount of rejected asphalt or
rock), such as a deasphalted oil yield of at least 50 wt % relative
to the feed to deasphalting, or at least 55 wt %, or at least 60 wt
%, or at least 65 wt %, or at least 70 wt %, or at least 75 wt %.
The Group I base stocks (including bright stock) can be formed
without performing a solvent extraction on the deasphalted oil. The
Group II base stocks (including bright stock) can be formed using a
combination of catalytic and solvent processing. In contrast with
conventional bright stock produced from deasphalted oil formed at
low severity conditions, the Group I and Group II bright stock
described herein can be substantially free from haze after storage
for extended periods of time. This haze free Group II bright stock
can correspond to a bright stock with an unexpected
composition.
[0026] In various additional aspects, methods are provided for
catalytic processing of C.sub.3 deasphalted oils to form Group II
bright stock. Forming Group II bright stock by catalytic processing
can provide a bright stock with unexpected compositional
properties.
[0027] Conventionally, crude oils are often described as being
composed of a variety of boiling ranges. Lower boiling range
compounds in a crude oil correspond to naphtha or kerosene fuels.
Intermediate boiling range distillate compounds can be used as
diesel fuel or as lubricant base stocks. If any higher boiling
range compounds are present in a crude oil, such compounds are
considered as residual or "resid" compounds, corresponding to the
portion of a crude oil that is left over after performing
atmospheric and/or vacuum distillation on the crude oil.
[0028] In some conventional processing schemes, a resid fraction
can be deasphalted, with the deasphalted oil used as part of a feed
for forming lubricant base stocks. In conventional processing
schemes a deasphalted oil used as feed for forming lubricant base
stocks is produced using propane deasphalting. This propane
deasphalting corresponds to a "high severity" deasphalting, as
indicated by a typical yield of deasphalted oil of about 40 wt % or
less, often 30 wt % or less, relative to the initial resid
fraction. In a typical lubricant base stock production process, the
deasphalted oil can then be solvent extracted to reduce the
aromatics content, followed by solvent dewaxing to form a base
stock. The low yield of deasphalted oil is based in part on the
inability of conventional methods to produce lubricant base stocks
from lower severity deasphalting that do not form haze over
time.
[0029] In some aspects, it has been discovered that using a mixture
of catalytic processing, such as hydrotreatment, and solvent
processing, such as solvent dewaxing, can be used to produce
lubricant base stocks from deasphalted oil while also producing
base stocks that have little or no tendency to form haze over
extended periods of time. The deasphalted oil can be produced by
deasphalting process that uses a C.sub.4 solvent, a C.sub.5
solvent, a C.sub.6+ solvent, a mixture of two or more C.sub.4+
solvents, or a mixture of two or more C.sub.5+ solvents. The
deasphalting process can further correspond to a process with a
yield of deasphalted oil of at least 50 wt % for a vacuum resid
feed having a T10 distillation point (or optionally a T5
distillation point) of at least 510.degree. C., or a yield of at
least 60 wt %, or at least 65 wt %, or at least 70 wt %. It is
believed that the reduced haze formation is due in part to the
reduced or minimized differential between the pour point and the
cloud point for the base stocks and/or due in part to forming a
bright stock with a cloud point of -5.degree. C. or less.
[0030] For production of Group I base stocks, a deasphalted oil can
be hydroprocessed (hydrotreated and/or hydrocracked) under
conditions sufficient to achieve a desired viscosity index increase
for resulting base stock products. The hydroprocessed effluent can
be fractionated to separate lower boiling portions from a lubricant
base stock boiling range portion. The lubricant base stock boiling
range portion can then be solvent dewaxed to produce a dewaxed
effluent. The dewaxed effluent can be separated to form a plurality
of base stocks with a reduced tendency (such as no tendency) to
form haze over time.
[0031] For production of Group II base stocks, in some aspects a
deasphalted oil can be hydroprocessed (hydrotreated and/or
hydrocracked), so that .about.700.degree. F.+(370.degree. C.+)
conversion is 10 wt % to 40 wt %. The hydroprocessed effluent can
be fractionated to separate lower boiling portions from a lubricant
base stock boiling range portion. The lubricant boiling range
portion can then be hydrocracked, dewaxed, and hydrofinished to
produce a catalytically dewaxed effluent. Optionally but
preferably, the lubricant boiling range portion can be
underdewaxed, so that the wax content of the catalytically dewaxed
heavier portion or potential bright stock portion of the effluent
is at least 6 wt %, or at least 8 wt %, or at least 10 wt %. This
underdewaxing can also be suitable for forming light or medium or
heavy neutral lubricant base stocks that do not require further
solvent upgrading to form haze free base stocks. In this
discussion, the heavier portion/potential bright stock portion can
roughly correspond to a 538.degree. C.+ portion of the dewaxed
effluent. The catalytically dewaxed heavier portion of the effluent
can then be solvent dewaxed to form a solvent dewaxed effluent. The
solvent dewaxed effluent can be separated to form a plurality of
base stocks with a reduced tendency (such as no tendency) to form
haze over time, including at least a portion of a Group II bright
stock product.
[0032] For production of Group II base stocks, in other aspects a
deasphalted oil can be hydroprocessed (hydrotreated and/or
hydrocracked), so that 370.degree. C.+ conversion is at least 40 wt
%, or at least 50 wt %. The hydroprocessed effluent can be
fractionated to separate lower boiling portions from a lubricant
base stock boiling range portion. The lubricant base stock boiling
range portion can then be hydrocracked, dewaxed, and hydrofinished
to produce a catalytically dewaxed effluent. The catalytically
dewaxed effluent can then be solvent extracted to form a raffinate.
The raffinate can be separated to form a plurality of base stocks
with a reduced tendency (such as no tendency) to form haze over
time, including at least a portion of a Group II bright stock
product.
[0033] In other aspects, it has been discovered that catalytic
processing can be used to produce Group II bright stock with
unexpected compositional properties from C.sub.3, C.sub.4, C.sub.5,
and/or C.sub.5+ deasphalted oil. The deasphalted oil can be
hydrotreated to reduce the content of heteroatoms (such as sulfur
and nitrogen), followed by catalytic dewaxing under sweet
conditions. Optionally, hydrocracking can be included as part of
the sour hydrotreatment stage and/or as part of the sweet dewaxing
stage.
[0034] Optionally, the systems and methods described herein can be
used in "block" operation to allow for additional improvements in
yield and/or product quality. During "block" operation, a
deasphalted oil and/or the hydroprocessed effluent from the sour
processing stage can be split into a plurality of fractions. The
fractions can correspond, for example, to feed fractions suitable
for forming a light neutral fraction, a heavy neutral fraction, and
a bright stock fraction, or the plurality of fractions can
correspond to any other convenient split into separate fractions.
The plurality of separate fractions can then be processed
separately in the process train (or in the sweet portion of the
process train) for forming lubricant base stocks. For example, the
light neutral portion of the feed can be processed for a period of
time, followed by processing of the heavy neutral portion, followed
by processing of a bright stock portion. During the time period
when one type of fraction is being processed, storage tanks can be
used to hold the remaining fractions.
[0035] Block operation can allow the processing conditions in the
process train to be tailored to each type of lubricant fraction.
For example, the amount of sweet processing stage conversion of the
heavy neutral fraction can be lower than the amount of sweet
processing stage conversion for the light neutral fraction. This
can reflect the fact that heavy neutral lubricant base stocks may
not need as high a viscosity index as light neutral base
stocks.
[0036] Another option for modifying the production of base stocks
can be to recycle a portion of at least one lubricant base stock
product for further processing in the process train. This can
correspond to recycling a portion of a base stock product for
further processing in the sour stage and/or recycling a portion of
a base stock product for further processing in the corresponding
sweet stage. Optionally, a base stock product can be recycled for
further processing in a different phase of block operation, such as
recycling light neutral base stock product formed during block
processing of the heavy neutral fraction for further processing
during block processing of the light neutral fraction. The amount
of base stock product recycled can correspond to any convenient
amount of a base stock product effluent from the fractionator, such
as 1 wt % to 50 wt % of a base stock product effluent, or 1 wt % to
20 wt %.
[0037] Recycling a portion of a base stock product effluent can
optionally be used while operating a lube processing system at
higher than typical levels of fuels conversion. When using a
conventional feed for lubricant production, conversion of feed
relative to 370.degree. C. can be limited to 65 wt % or less.
Conversion of more than 65 wt % of a feed relative to 370.degree.
C. is typically not favored due to loss of viscosity index with
additional conversion. At elevated levels of conversion, the loss
of VI with additional conversion is believed to be due to cracking
and/or conversion of isoparaffins within a feed. For feeds derived
from deasphalted oil, however, the amount of isoparaffins within a
feed is lower than a conventional feed. As a result, additional
conversion can be performed without loss of VI. In some aspects,
converting at least 70 wt % of a feed, or at least 75 wt %, or at
least 80 wt % can allow for production of lubricant base stocks
with substantially improved cold flow properties while still
maintaining the viscosity index of the products at a similar value
to the viscosity index at a conventional conversion of 60 wt %.
[0038] In various aspects, a variety of combinations of catalytic
and/or solvent processing can be used to form lubricant base
stocks, including Group II bright stock, from deasphalted oils.
These combinations include, but are not limited to:
[0039] a) Hydroprocessing of a deasphalted oil under sour
conditions (i.e., sulfur content of at least 500 wppm); separation
of the hydroprocessed effluent to form at least a lubricant boiling
range fraction; and solvent dewaxing of the lubricant boiling range
fraction. In some aspects, the hydroprocessing of the deasphalted
oil can correspond to hydrotreatment, hydrocracking, or a
combination thereof.
[0040] b) Hydroprocessing of a deasphalted oil under sour
conditions (i.e., sulfur content of at least 500 wppm); separation
of the hydroprocessed effluent to form at least a lubricant boiling
range fraction; and catalytic dewaxing of the lubricant boiling
range fraction under sweet conditions (i.e., 500 wppm or less
sulfur). The catalytic dewaxing can optionally correspond to
catalytic dewaxing using a dewaxing catalyst with a pore size
greater than 8.4 Angstroms. Optionally, the sweet processing
conditions can further include hydrocracking, noble metal
hydrotreatment, and/or hydrofinishing. The optional hydrocracking,
noble metal hydrotreatment, and/or hydrofinishing can occur prior
to and/or after or after catalytic dewaxing. For example, the order
of catalytic processing under sweet processing conditions can be
noble metal hydrotreating followed by hydrocracking followed by
catalytic dewaxing.
[0041] c) The process of b) above, followed by performing an
additional separation on at least a portion of the catalytically
dewaxed effluent. The additional separation can correspond to
solvent dewaxing, solvent extraction (such as solvent extraction
with furfural or n-methylpyrollidone), a physical separation such
as ultracentrifugation, or a combination thereof.
[0042] d) The process of a) above, followed by catalytic dewaxing
(sweet conditions) of at least a portion of the solvent dewaxed
product. Optionally, the sweet processing conditions can further
include hydrotreating (such as noble metal hydrotreating),
hydrocracking and/or hydrofinishing. The additional sweet
hydroprocessing can be performed prior to and/or after the
catalytic dewaxing.
[0043] Group I base stocks or base oils are defined as base stocks
with less than 90 wt % saturated molecules and/or at least 0.03 wt
% sulfur content. Group I base stocks also have a viscosity index
(VI) of at least 80 but less than 120. Group II base stocks or base
oils contain at least 90 wt % saturated molecules and less than
0.03 wt % sulfur. Group II base stocks also have a viscosity index
of at least 80 but less than 120. Group III base stocks or base
oils contain at least 90 wt % saturated molecules and less than
0.03 wt % sulfur, with a viscosity index of at least 120.
[0044] In some aspects, a Group III base stock as described herein
may correspond to a Group III+ base stock. Although a generally
accepted definition is not available, a Group III+ base stock can
generally correspond to a base stock that satisfies the
requirements for a Group III base stock while also having at least
one property that is enhanced relative to a Group III
specification. The enhanced property can correspond to, for
example, having a viscosity index that is substantially greater
than the required specification of 120, such as a Group III base
stock having a VI of at least 130, or at least 135, or at least
140. Similarly, in some aspects, a Group II base stock as described
herein may correspond to a Group II+ base stock. Although a
generally accepted definition is not available, a Group II+ base
stock can generally correspond to a base stock that satisfies the
requirements for a Group II base stock while also having at least
one property that is enhanced relative to a Group II specification.
The enhanced property can correspond to, for example, having a
viscosity index that is substantially greater than the required
specification of 80, such as a Group II base stock having a VI of
at least 103, or at least 108, or at least 113.
[0045] In the discussion below, a stage can correspond to a single
reactor or a plurality of reactors. Optionally, multiple parallel
reactors can be used to perform one or more of the processes, or
multiple parallel reactors can be used for all processes in a
stage. Each stage and/or reactor can include one or more catalyst
beds containing hydroprocessing catalyst. Note that a "bed" of
catalyst in the discussion below can refer to a partial physical
catalyst bed. For example, a catalyst bed within a reactor could be
filled partially with a hydrocracking catalyst and partially with a
dewaxing catalyst. For convenience in description, even though the
two catalysts may be stacked together in a single catalyst bed, the
hydrocracking catalyst and dewaxing catalyst can each be referred
to conceptually as separate catalyst beds.
[0046] In this discussion, conditions may be provided for various
types of hydroprocessing of feeds or effluents. Examples of
hydroprocessing can include, but are not limited to, one or more of
hydrotreating, hydrocracking, catalytic dewaxing, and
hydrofinishing/aromatic saturation. Such hydroprocessing conditions
can be controlled to have desired values for the conditions (e.g.,
temperature, pressure, LHSV, treat gas rate) by using at least one
controller, such as a plurality of controllers, to control one or
more of the hydroprocessing conditions. In some aspects, for a
given type of hydroprocessing, at least one controller can be
associated with each type of hydroprocessing condition. In some
aspects, one or more of the hydroprocessing conditions can be
controlled by an associated controller. Examples of structures that
can be controlled by a controller can include, but are not limited
to, valves that control a flow rate, a pressure, or a combination
thereof; heat exchangers and/or heaters that control a temperature;
and one or more flow meters and one or more associated valves that
control relative flow rates of at least two flows. Such controllers
can optionally include a controller feedback loop including at
least a processor, a detector for detecting a value of a control
variable (e.g., temperature, pressure, flow rate, and a processor
output for controlling the value of a manipulated variable (e.g.,
changing the position of a valve, increasing or decreasing the duty
cycle and/or temperature for a heater). Optionally, at least one
hydroprocessing condition for a given type of hydroprocessing may
not have an associated controller.
[0047] In this discussion, unless otherwise specified a lubricant
boiling range fraction corresponds to a fraction having an initial
boiling point or alternatively a T5 boiling point of at least about
370.degree. C. (.about.700.degree. F.). A distillate fuel boiling
range fraction, such as a diesel product fraction, corresponds to a
fraction having a boiling range from about 193.degree. C.
(375.degree. F.) to about 370.degree. C. (.about.700.degree. F.).
Thus, distillate fuel boiling range fractions (such as distillate
fuel product fractions) can have initial boiling points (or
alternatively T5 boiling points) of at least about 193.degree. C.
and final boiling points (or alternatively T95 boiling points) of
about 370.degree. C. or less. A naphtha boiling range fraction
corresponds to a fraction having a boiling range from about
36.degree. C. (122.degree. F.) to about 193.degree. C. (375.degree.
F.) to about 370.degree. C. (.about.700.degree. F.). Thus, naphtha
fuel product fractions can have initial boiling points (or
alternatively T5 boiling points) of at least about 36.degree. C.
and final boiling points (or alternatively T95 boiling points) of
about 193.degree. C. or less. It is noted that 36.degree. C.
roughly corresponds to a boiling point for the various isomers of a
C5 alkane. A fuels boiling range fraction can correspond to a
distillate fuel boiling range fraction, a naphtha boiling range
fraction, or a fraction that includes both distillate fuel boiling
range and naphtha boiling range components. Light ends are defined
as products with boiling points below about 36.degree. C., which
include various C1-C4 compounds. When determining a boiling point
or a boiling range for a feed or product fraction, an appropriate
ASTM test method can be used, such as the procedures described in
ASTM D2887, D2892, and/or D86. Preferably, ASTM D2887 should be
used unless a sample is not appropriate for characterization based
on ASTM D2887. For example, for samples that will not completely
elute from a chromatographic column, ASTM D7169 can be used.
Feedstocks
[0048] In various aspects, at least a portion of a feedstock for
processing as described herein can correspond to a vacuum resid
fraction or another type 950.degree. F.+(510.degree. C.+) or
1000.degree. F.+(538.degree. C.+) fraction. Another example of a
method for forming a 950.degree. F.+(510.degree. C.+) or
1000.degree. F.+(538.degree. C.+) fraction is to perform a high
temperature flash separation. The 950.degree. F.+(510.degree. C.+)
or 1000.degree. F.+(538.degree. C.+) fraction formed from the high
temperature flash can be processed in a manner similar to a vacuum
resid.
[0049] A vacuum resid fraction or a 950.degree. F.+(510.degree.
C.+) fraction formed by another process (such as a flash
fractionation bottoms or a bitumen fraction) can be deasphalted at
low severity to form a deasphalted oil. Optionally, the feedstock
can also include a portion of a conventional feed for lubricant
base stock production, such as a vacuum gas oil.
[0050] A vacuum resid (or other 510.degree. C.+) fraction can
correspond to a fraction with a T5 distillation point (ASTM D2892,
or ASTM D7169 if the fraction will not completely elute from a
chromatographic system) of at least about 900.degree. F.
(482.degree. C.), or at least 950.degree. F. (510.degree. C.), or
at least 1000.degree. F. (538.degree. C.). Alternatively, a vacuum
resid fraction can be characterized based on a T10 distillation
point (ASTM D2892/D7169) of at least about 900.degree. F.
(482.degree. C.), or at least 950.degree. F. (510.degree. C.), or
at least 1000.degree. F. (538.degree. C.).
[0051] Resid (or other 510.degree. C.+) fractions can be high in
metals. For example, a resid fraction can be high in total nickel,
vanadium and iron contents. In an aspect, a resid fraction can
contain at least 0.00005 grams of Ni/V/Fe (50 wppm) or at least
0.0002 grams of Ni/V/Fe (200 wppm) per gram of resid, on a total
elemental basis of nickel, vanadium and iron. In other aspects, the
heavy oil can contain at least 500 wppm of nickel, vanadium, and
iron, such as up to 1000 wppm or more.
[0052] Contaminants such as nitrogen and sulfur are typically found
in resid (or other 510.degree. C.+) fractions, often in
organically-bound form. Nitrogen content can range from about 50
wppm to about 10,000 wppm elemental nitrogen or more, based on
total weight of the resid fraction. Sulfur content can range from
500 wppm to 100,000 wppm elemental sulfur or more, based on total
weight of the resid fraction, or from 1000 wppm to 50,000 wppm, or
from 1000 wppm to 30,000 wppm.
[0053] Still another method for characterizing a resid (or other
510.degree. C.+) fraction is based on the Conradson carbon residue
(CCR) of the feedstock. The Conradson carbon residue of a resid
fraction can be at least about 5 wt %, such as at least about 10 wt
% or at least about 20 wt %. Additionally or alternately, the
Conradson carbon residue of a resid fraction can be about 50 wt %
or less, such as about 40 wt % or less or about 30 wt % or
less.
[0054] In some aspects, a vacuum gas oil fraction can be
co-processed with a deasphalted oil. The vacuum gas oil can be
combined with the deasphalted oil in various amounts ranging from
20 parts (by weight) deasphalted oil to 1 part vacuum gas oil
(i.e., 20:1) to 1 part deasphalted oil to 1 part vacuum gas oil. In
some aspects, the ratio of deasphalted oil to vacuum gas oil can be
at least 1:1 by weight, or at least 1.5:1, or at least 2:1. Typical
(vacuum) gas oil fractions can include, for example, fractions with
a T5 distillation point to T95 distillation point of 650.degree. F.
(343.degree. C.)-1050.degree. F. (566.degree. C.) or 650.degree. F.
(343.degree. C.)-1000.degree. F. (538.degree. C.) or 650.degree. F.
(343.degree. C.)-950.degree. F. (510.degree. C.) or 650.degree. F.
(343.degree. C.)-900.degree. F. (482.degree. C.) or
.about.700.degree. F. (370.degree. C.)-1050.degree. F. (566.degree.
C.) or .about.700.degree. F. (370.degree. C.)-1000.degree. F.
(538.degree. C.) or .about.700.degree. F. (370.degree.
C.)-950.degree. F. (510.degree. C.) or .about.700.degree. F.
(370.degree. C.)-900.degree. F. (482.degree. C.), or 750.degree. F.
(399.degree. C.)-1050.degree. F. (566.degree. C.), or 750.degree.
F. (399.degree. C.)-1000.degree. F. (538.degree. C.), or
750.degree. F. (399.degree. C.)-950.degree. F. (510.degree. C.), or
750.degree. F. (399.degree. C.)-900.degree. F. (482.degree. C.).
For example a suitable vacuum gas oil fraction can have a T5
distillation point of at least 343.degree. C. and a T95
distillation point of 566.degree. C. or less; or a T10 distillation
point of at least 343.degree. C. and a T90 distillation point of
566.degree. C. or less; or a T5 distillation point of at least
370.degree. C. and a T95 distillation point of 566.degree. C. or
less; or a T5 distillation point of at least 343.degree. C. and a
T95 distillation point of 538.degree. C. or less.
Solvent Deasphalting
[0055] Solvent deasphalting is a solvent extraction process. In
some aspects, suitable solvents for methods as described herein
include alkanes or other hydrocarbons (such as alkenes) containing
4 to 7 carbons per molecule. Examples of suitable solvents include
n-butane, isobutane, n-pentane, C.sub.4+ alkanes, C.sub.5+ alkanes,
C.sub.4+ hydrocarbons, and C.sub.5+ hydrocarbons. In other aspects,
suitable solvents can include C.sub.3 hydrocarbons, such as
propane. In such other aspects, examples of suitable solvents
include propane, n-butane, isobutane, n-pentane, C.sub.3+ alkanes,
C.sub.4+ alkanes, C.sub.5+ alkanes, C.sub.3+ hydrocarbons, C.sub.4+
hydrocarbons, and C.sub.5+ hydrocarbons.
[0056] In this discussion, a solvent comprising C.sub.n
(hydrocarbons) is defined as a solvent composed of at least 80 wt %
of alkanes (hydrocarbons) having n carbon atoms, or at least 85 wt
%, or at least 90 wt %, or at least 95 wt %, or at least 98 wt %.
Similarly, a solvent comprising C.sub.n+ (hydrocarbons) is defined
as a solvent composed of at least 80 wt % of alkanes (hydrocarbons)
having n or more carbon atoms, or at least 85 wt %, or at least 90
wt %, or at least 95 wt %, or at least 98 wt %.
[0057] In this discussion, a solvent comprising C.sub.n alkanes
(hydrocarbons) is defined to include the situation where the
solvent corresponds to a single alkane (hydrocarbon) containing n
carbon atoms (for example, n=3, 4, 5, 6, 7) as well as the
situations where the solvent is composed of a mixture of alkanes
(hydrocarbons) containing n carbon atoms. Similarly, a solvent
comprising C.sub.n+ alkanes (hydrocarbons) is defined to include
the situation where the solvent corresponds to a single alkane
(hydrocarbon) containing n or more carbon atoms (for example, n=3,
4, 5, 6, 7) as well as the situations where the solvent corresponds
to a mixture of alkanes (hydrocarbons) containing n or more carbon
atoms. Thus, a solvent comprising C.sub.4+ alkanes can correspond
to a solvent including n-butane; a solvent include n-butane and
isobutane; a solvent corresponding to a mixture of one or more
butane isomers and one or more pentane isomers; or any other
convenient combination of alkanes containing 4 or more carbon
atoms. Similarly, a solvent comprising C.sub.5+ alkanes
(hydrocarbons) is defined to include a solvent corresponding to a
single alkane (hydrocarbon) or a solvent corresponding to a mixture
of alkanes (hydrocarbons) that contain 5 or more carbon atoms.
Alternatively, other types of solvents may also be suitable, such
as supercritical fluids. In various aspects, the solvent for
solvent deasphalting can consist essentially of hydrocarbons, so
that at least 98 wt % or at least 99 wt % of the solvent
corresponds to compounds containing only carbon and hydrogen. In
aspects where the deasphalting solvent corresponds to a C.sub.4+
deasphalting solvent, the C.sub.4+ deasphalting solvent can include
less than 15 wt % propane and/or other C.sub.3 hydrocarbons, or
less than 10 wt %, or less than 5 wt %, or the C.sub.4+
deasphalting solvent can be substantially free of propane and/or
other C.sub.3 hydrocarbons (less than 1 wt %). In aspects where the
deasphalting solvent corresponds to a C.sub.5+ deasphalting
solvent, the C.sub.5+ deasphalting solvent can include less than 15
wt % propane, butane and/or other C.sub.3-C.sub.4 hydrocarbons, or
less than 10 wt %, or less than 5 wt %, or the C.sub.5+
deasphalting solvent can be substantially free of propane, butane,
and/or other C.sub.3-C.sub.4 hydrocarbons (less than 1 wt %). In
aspects where the deasphalting solvent corresponds to a C.sub.3+
deasphalting solvent, the C.sub.3+ deasphalting solvent can include
less than 10 wt % ethane and/or other C.sub.2 hydrocarbons, or less
than 5 wt %, or the C.sub.3+ deasphalting solvent can be
substantially free of ethane and/or other C.sub.2 hydrocarbons
(less than 1 wt %).
[0058] Deasphalting of heavy hydrocarbons, such as vacuum resids,
is known in the art and practiced commercially. A deasphalting
process typically corresponds to contacting a heavy hydrocarbon
with an alkane solvent (propane, butane, pentane, hexane, heptane
etc and their isomers), either in pure form or as mixtures, to
produce two types of product streams. One type of product stream
can be a deasphalted oil extracted by the alkane, which is further
separated to produce deasphalted oil stream. A second type of
product stream can be a residual portion of the feed not soluble in
the solvent, often referred to as rock or asphaltene fraction. The
deasphalted oil fraction can be further processed into make fuels
or lubricants. The rock fraction can be further used as blend
component to produce asphalt, fuel oil, and/or other products. The
rock fraction can also be used as feed to gasification processes
such as partial oxidation, fluid bed combustion or coking
processes. The rock can be delivered to these processes as a liquid
(with or without additional components) or solid (either as pellets
or lumps).
[0059] During solvent deasphalting, a resid boiling range feed
(optionally also including a portion of a vacuum gas oil feed) can
be mixed with a solvent. Portions of the feed that are soluble in
the solvent are then extracted, leaving behind a residue with
little or no solubility in the solvent. The portion of the
deasphalted feedstock that is extracted with the solvent is often
referred to as deasphalted oil. Typical solvent deasphalting
conditions include mixing a feedstock fraction with a solvent in a
weight ratio of from about 1:2 to about 1:10, such as about 1:8 or
less. Typical solvent deasphalting temperatures range from
40.degree. C. to 200.degree. C., or 40.degree. C. to 150.degree.
C., depending on the nature of the feed and the solvent. The
pressure during solvent deasphalting can be from about 50 psig (345
kPag) to about 500 psig (3447 kPag).
[0060] It is noted that the above solvent deasphalting conditions
represent a general range, and the conditions will vary depending
on the feed. For example, under typical deasphalting conditions,
increasing the temperature can tend to reduce the yield while
increasing the quality of the resulting deasphalted oil. Under
typical deasphalting conditions, increasing the molecular weight of
the solvent can tend to increase the yield while reducing the
quality of the resulting deasphalted oil, as additional compounds
within a resid fraction may be soluble in a solvent composed of
higher molecular weight hydrocarbons. Under typical deasphalting
conditions, increasing the amount of solvent can tend to increase
the yield of the resulting deasphalted oil. As understood by those
of skill in the art, the conditions for a particular feed can be
selected based on the resulting yield of deasphalted oil from
solvent deasphalting. In aspects where a C.sub.3 deasphalting
solvent is used, the yield from solvent deasphalting can be 40 wt %
or less. In some aspects, C.sub.4 deasphalting can be performed
with a yield of deasphalted oil of 50 wt % or less, or 40 wt % or
less. In various aspects, the yield of deasphalted oil from solvent
deasphalting with a C.sub.4+ solvent can be at least 50 wt %
relative to the weight of the feed to deasphalting, or at least 55
wt %, or at least 60 wt % or at least 65 wt %, or at least 70 wt %.
In aspects where the feed to deasphalting includes a vacuum gas oil
portion, the yield from solvent deasphalting can be characterized
based on a yield by weight of a 950.degree. F.+(510.degree. C.)
portion of the deasphalted oil relative to the weight of a
510.degree. C.+ portion of the feed. In such aspects where a
C.sub.4+ solvent is used, the yield of 510.degree. C.+ deasphalted
oil from solvent deasphalting can be at least 40 wt % relative to
the weight of the 510.degree. C.+ portion of the feed to
deasphalting, or at least 50 wt %, or at least 55 wt %, or at least
60 wt % or at least 65 wt %, or at least 70 wt %. In such aspects
where a C.sub.4- solvent is used, the yield of 510.degree. C.+
deasphalted oil from solvent deasphalting can be 50 wt % or less
relative to the weight of the 510.degree. C.+ portion of the feed
to deasphalting, or 40 wt % or less, or 35 wt % or less.
Hydrotreating and Hydrocracking
[0061] After deasphalting, the deasphalted oil (and any additional
fractions combined with the deasphalted oil) can undergo further
processing to form lubricant base stocks. This can include
hydrotreatment and/or hydrocracking to remove heteroatoms to
desired levels, reduce Conradson Carbon content, and/or provide
viscosity index (VI) uplift. Depending on the aspect, a deasphalted
oil can be hydroprocessed by hydrotreating, hydrocracking, or
hydrotreating and hydrocracking. Optionally, one or more catalyst
beds and/or stages of demetallization catalyst can be included
prior to the initial bed of hydrotreating and/or hydrocracking
catalyst. Optionally, the hydroprocessing can further include
exposing the deasphalted oil to a base metal aromatic saturation
catalyst. It is noted that a base metal aromatic saturation
catalyst can sometimes be similar to a lower activity hydrotreating
catalyst.
[0062] The deasphalted oil can be hydrotreated and/or hydrocracked
with little or no solvent extraction being performed prior to
and/or after the deasphalting. As a result, the deasphalted oil
feed for hydrotreatment and/or hydrocracking can have a substantial
aromatics content. In various aspects, the aromatics content of the
deasphalted oil feed can be at least 50 wt %, or at least 55 wt %,
or at least 60 wt %, or at least 65 wt %, or at least 70 wt %, or
at least 75 wt %, such as up to 90 wt % or more. Additionally or
alternately, the saturates content of the deasphalted oil feed can
be 50 wt % or less, or 45 wt % or less, or 40 wt % or less, or 35
wt % or less, or 30 wt % or less, or 25 wt % or less, such as down
to 10 wt % or less. In this discussion and the claims below, the
aromatics content and/or the saturates content of a fraction can be
determined based on ASTM D7419.
[0063] The reaction conditions during demetallization and/or
hydrotreatment and/or hydrocracking of the deasphalted oil (and
optional vacuum gas oil co-feed) can be selected to generate a
desired level of conversion of a feed. Any convenient type of
reactor, such as fixed bed (for example trickle bed) reactors can
be used. Conversion of the feed can be defined in terms of
conversion of molecules that boil above a temperature threshold to
molecules below that threshold. The conversion temperature can be
any convenient temperature, such as .about.700.degree. F.
(370.degree. C.) or 1050.degree. F. (566.degree. C.). The amount of
conversion can correspond to the total conversion of molecules
within the combined hydrotreatment and hydrocracking stages for the
deasphalted oil. Suitable amounts of conversion of molecules
boiling above 1050.degree. F. (566.degree. C.) to molecules boiling
below 566.degree. C. include 30 wt % to 90 wt % conversion relative
to 566.degree. C., or 30 wt % to 80 wt %, or 30 wt % to 70 wt %, or
40 wt % to 90 wt %, or 40 wt % to 80 wt %, or 40 wt % to 70 wt %,
or 50 wt % to 90 wt %, or 50 wt % to 80 wt %, or 50 wt % to 70 wt
%. In particular, the amount of conversion relative to 566.degree.
C. can be 30 wt % to 90 wt %, or 30 wt % to 70 wt %, or 50 wt % to
90 wt %. Additionally or alternately, suitable amounts of
conversion of molecules boiling above .about.700.degree. F.
(370.degree. C.) to molecules boiling below 370.degree. C. include
10 wt % to 70 wt % conversion relative to 370.degree. C., or 10 wt
% to 60 wt %, or 10 wt % to 50 wt %, or 20 wt % to 70 wt %, or 20
wt % to 60 wt %, or 20 wt % to 50 wt %, or 30 wt % to 70 wt %, or
30 wt % to 60 wt %, or 30 wt % to 50 wt %. In particular, the
amount of conversion relative to 370.degree. C. can be 10 wt % to
70 wt %, or 20 wt % to 50 wt %, or 30 wt % to 60 wt %.
[0064] The hydroprocessed deasphalted oil can also be characterized
based on the product quality. After hydroprocessing (hydrotreating
and/or hydrocracking), the hydroprocessed deasphalted oil can have
a sulfur content of 200 wppm or less, or 100 wppm or less, or 50
wppm or less (such as down to .about.0 wppm). Additionally or
alternately, the hydroprocessed deasphalted oil can have a nitrogen
content of 200 wppm or less, or 100 wppm or less, or 50 wppm or
less (such as down to .about.0 wppm). Additionally or alternately,
the hydroprocessed deasphalted oil can have a Conradson Carbon
residue content of 1.5 wt % or less, or 1.0 wt % or less, or 0.7 wt
% or less, or 0.1 wt % or less, or 0.02 wt % or less (such as down
to .about.0 wt %). Conradson Carbon residue content can be
determined according to ASTM D4530.
[0065] In various aspects, a feed can initially be exposed to a
demetallization catalyst prior to exposing the feed to a
hydrotreating catalyst. Deasphalted oils can have metals
concentrations (Ni+V+Fe) on the order of 10-100 wppm. Exposing a
conventional hydrotreating catalyst to a feed having a metals
content of 10 wppm or more can lead to catalyst deactivation at a
faster rate than may desirable in a commercial setting. Exposing a
metal containing feed to a demetallization catalyst prior to the
hydrotreating catalyst can allow at least a portion of the metals
to be removed by the demetallization catalyst, which can reduce or
minimize the deactivation of the hydrotreating catalyst and/or
other subsequent catalysts in the process flow. Commercially
available demetallization catalysts can be suitable, such as large
pore amorphous oxide catalysts that may optionally include Group VI
and/or Group VIII non-noble metals to provide some hydrogenation
activity.
[0066] In various aspects, the deasphalted oil can be exposed to a
hydrotreating catalyst under effective hydrotreating conditions.
The catalysts used can include conventional hydroprocessing
catalysts, such as those comprising at least one Group VIII
non-noble metal (Columns 8-10 of IUPAC periodic table), preferably
Fe, Co, and/or Ni, such as Co and/or Ni; and at least one Group VI
metal (Column 6 of IUPAC periodic table), preferably Mo and/or W.
Such hydroprocessing catalysts optionally include transition metal
sulfides that are impregnated or dispersed on a refractory support
or carrier such as alumina and/or silica. The support or carrier
itself typically has no significant/measurable catalytic activity.
Substantially carrier- or support-free catalysts, commonly referred
to as bulk catalysts, generally have higher volumetric activities
than their supported counterparts.
[0067] The catalysts can either be in bulk form or in supported
form. In addition to alumina and/or silica, other suitable
support/carrier materials can include, but are not limited to,
zeolites, titania, silica-titania, and titania-alumina. Suitable
aluminas are porous aluminas such as gamma or eta having average
pore sizes from 50 to 200 .ANG., or 75 to 150 .ANG.; a surface area
from 100 to 300 m.sup.2/g, or 150 to 250 m.sup.2/g; and a pore
volume of from 0.25 to 1.0 cm.sup.3/g, or 0.35 to 0.8 cm.sup.3/g.
More generally, any convenient size, shape, and/or pore size
distribution for a catalyst suitable for hydrotreatment of a
distillate (including lubricant base stock) boiling range feed in a
conventional manner may be used. Preferably, the support or carrier
material is an amorphous support, such as a refractory oxide.
Preferably, the support or carrier material can be free or
substantially free of the presence of molecular sieve, where
substantially free of molecular sieve is defined as having a
content of molecular sieve of less than about 0.01 wt %.
[0068] The at least one Group VIII non-noble metal, in oxide form,
can typically be present in an amount ranging from about 2 wt % to
about 40 wt %, preferably from about 4 wt % to about 15 wt %. The
at least one Group VI metal, in oxide form, can typically be
present in an amount ranging from about 2 wt % to about 70 wt %,
preferably for supported catalysts from about 6 wt % to about 40 wt
% or from about 10 wt % to about 30 wt %. These weight percents are
based on the total weight of the catalyst. Suitable metal catalysts
include cobalt/molybdenum (1-10% Co as oxide, 10-40% Mo as oxide),
nickel/molybdenum (1-10% Ni as oxide, 10-40% Co as oxide), or
nickel/tungsten (1-10% Ni as oxide, 10-40% W as oxide) on alumina,
silica, silica-alumina, or titania.
[0069] The hydrotreatment is carried out in the presence of
hydrogen. A hydrogen stream is, therefore, fed or injected into a
vessel or reaction zone or hydroprocessing zone in which the
hydroprocessing catalyst is located. Hydrogen, which is contained
in a hydrogen "treat gas," is provided to the reaction zone. Treat
gas, as referred to in this invention, can be either pure hydrogen
or a hydrogen-containing gas, which is a gas stream containing
hydrogen in an amount that is sufficient for the intended
reaction(s), optionally including one or more other gasses (e.g.,
nitrogen and light hydrocarbons such as methane). The treat gas
stream introduced into a reaction stage will preferably contain at
least about 50 vol. % and more preferably at least about 75 vol. %
hydrogen. Optionally, the hydrogen treat gas can be substantially
free (less than 1 vol %) of impurities such as H.sub.2S and
NH.sub.3 and/or such impurities can be substantially removed from a
treat gas prior to use.
[0070] Hydrogen can be supplied at a rate of from about 100 SCF/B
(standard cubic feet of hydrogen per barrel of feed) (17
Nm.sup.3/m.sup.3) to about 10000 SCF/B (1700 Nm.sup.3/m.sup.3).
Preferably, the hydrogen is provided in a range of from about 200
SCF/B (34 Nm.sup.3/m.sup.3) to about 2500 SCF/B (420
Nm.sup.3/m.sup.3). Hydrogen can be supplied co-currently with the
input feed to the hydrotreatment reactor and/or reaction zone or
separately via a separate gas conduit to the hydrotreatment
zone.
[0071] Hydrotreating conditions can include temperatures of
200.degree. C. to 450.degree. C., or 315.degree. C. to 425.degree.
C.; pressures of 250 psig (1.8 MPag) to 5000 psig (34.6 MPag) or
300 psig (2.1 MPag) to 3000 psig (20.8 MPag); liquid hourly space
velocities (LHSV) of 0.1 hr.sup.-1 to 10 hr.sup.-1; and hydrogen
treat rates of 200 scf/B (35.6 m.sup.3/m.sup.3) to 10,000 scf/B
(1781 m.sup.3/m.sup.3), or 500 (89 m.sup.3/m.sup.3) to 10,000 scf/B
(1781 m.sup.3/m.sup.3).
[0072] In various aspects, the deasphalted oil can be exposed to a
hydrocracking catalyst under effective hydrocracking conditions.
Hydrocracking catalysts typically contain sulfided base metals on
acidic supports, such as amorphous silica alumina, cracking
zeolites such as USY, or acidified alumina. Often these acidic
supports are mixed or bound with other metal oxides such as
alumina, titania or silica. Examples of suitable acidic supports
include acidic molecular sieves, such as zeolites or
silicoaluminophophates. One example of suitable zeolite is USY,
such as a USY zeolite with cell size of 24.30 Angstroms or less.
Additionally or alternately, the catalyst can be a low acidity
molecular sieve, such as a USY zeolite with a Si to Al ratio of at
least about 20, and preferably at least about 40 or 50. ZSM-48,
such as ZSM-48 with a SiO.sub.2 to Al.sub.2O.sub.3 ratio of about
110 or less, such as about 90 or less, is another example of a
potentially suitable hydrocracking catalyst. Still another option
is to use a combination of USY and ZSM-48. Still other options
include using one or more of zeolite Beta, ZSM-5, ZSM-35, or
ZSM-23, either alone or in combination with a USY catalyst.
Non-limiting examples of metals for hydrocracking catalysts include
metals or combinations of metals that include at least one Group
VIII metal, such as nickel, nickel-cobalt-molybdenum,
cobalt-molybdenum, nickel-tungsten, nickel-molybdenum, and/or
nickel-molybdenum-tungsten. Additionally or alternately,
hydrocracking catalysts with noble metals can also be used.
Non-limiting examples of noble metal catalysts include those based
on platinum and/or palladium. Support materials which may be used
for both the noble and non-noble metal catalysts can comprise a
refractory oxide material such as alumina, silica, alumina-silica,
kieselguhr, diatomaceous earth, magnesia, zirconia, or combinations
thereof, with alumina, silica, alumina-silica being the most common
(and preferred, in one embodiment).
[0073] When only one hydrogenation metal is present on a
hydrocracking catalyst, the amount of that hydrogenation metal can
be at least about 0.1 wt % based on the total weight of the
catalyst, for example at least about 0.5 wt % or at least about 0.6
wt %. Additionally or alternately when only one hydrogenation metal
is present, the amount of that hydrogenation metal can be about 5.0
wt % or less based on the total weight of the catalyst, for example
about 3.5 wt % or less, about 2.5 wt % or less, about 1.5 wt % or
less, about 1.0 wt % or less, about 0.9 wt % or less, about 0.75 wt
% or less, or about 0.6 wt % or less. Further additionally or
alternately when more than one hydrogenation metal is present, the
collective amount of hydrogenation metals can be at least about 0.1
wt % based on the total weight of the catalyst, for example at
least about 0.25 wt %, at least about 0.5 wt %, at least about 0.6
wt %, at least about 0.75 wt %, or at least about 1 wt %. Still
further additionally or alternately when more than one
hydrogenation metal is present, the collective amount of
hydrogenation metals can be about 35 wt % or less based on the
total weight of the catalyst, for example about 30 wt % or less,
about 25 wt % or less, about 20 wt % or less, about 15 wt % or
less, about 10 wt % or less, or about 5 wt % or less. In
embodiments wherein the supported metal comprises a noble metal,
the amount of noble metal(s) is typically less than about 2 wt %,
for example less than about 1 wt %, about 0.9 wt % or less, about
0.75 wt % or less, or about 0.6 wt % or less. It is noted that
hydrocracking under sour conditions is typically performed using a
base metal (or metals) as the hydrogenation metal.
[0074] In various aspects, the conditions selected for
hydrocracking for lubricant base stock production can depend on the
desired level of conversion, the level of contaminants in the input
feed to the hydrocracking stage, and potentially other factors. For
example, hydrocracking conditions in a single stage, or in the
first stage and/or the second stage of a multi-stage system, can be
selected to achieve a desired level of conversion in the reaction
system. Hydrocracking conditions can be referred to as sour
conditions or sweet conditions, depending on the level of sulfur
and/or nitrogen present within a feed. For example, a feed with 100
wppm or less of sulfur and 50 wppm or less of nitrogen, preferably
less than 25 wppm sulfur and/or less than 10 wppm of nitrogen,
represent a feed for hydrocracking under sweet conditions. In
various aspects, hydrocracking can be performed on a thermally
cracked resid, such as a deasphalted oil derived from a thermally
cracked resid. In some aspects, such as aspects where an optional
hydrotreating step is used prior to hydrocracking, the thermally
cracked resid may correspond to a sweet feed. In other aspects, the
thermally cracked resid may represent a feed for hydrocracking
under sour conditions.
[0075] A hydrocracking process under sour conditions can be carried
out at temperatures of about 550.degree. F. (288.degree. C.) to
about 840.degree. F. (449.degree. C.), hydrogen partial pressures
of from about 1500 psig to about 5000 psig (10.3 MPag to 34.6
MPag), liquid hourly space velocities of from 0.05 h.sup.-1 to 10
h.sup.-1, and hydrogen treat gas rates of from 35.6 m.sup.3/m.sup.3
to 1781 m.sup.3/m.sup.3 (200 SCF/B to 10,000 SCF/B). In other
embodiments, the conditions can include temperatures in the range
of about 600.degree. F. (343.degree. C.) to about 815.degree. F.
(435.degree. C.), hydrogen partial pressures of from about 1500
psig to about 3000 psig (10.3 MPag-20.9 MPag), and hydrogen treat
gas rates of from about 213 m.sup.3/m.sup.3 to about 1068
m.sup.3/m.sup.3 (1200 SCF/B to 6000 SCF/B). The LHSV can be from
about 0.25 h.sup.-1 to about 50 h.sup.-1, or from about 0.5
h.sup.-1 to about 20 h.sup.-1, preferably from about 1.0 h.sup.-1
to about 4.0 h.sup.-1.
[0076] In some aspects, a portion of the hydrocracking catalyst can
be contained in a second reactor stage. In such aspects, a first
reaction stage of the hydroprocessing reaction system can include
one or more hydrotreating and/or hydrocracking catalysts. The
conditions in the first reaction stage can be suitable for reducing
the sulfur and/or nitrogen content of the feedstock. A separator
can then be used in between the first and second stages of the
reaction system to remove gas phase sulfur and nitrogen
contaminants. One option for the separator is to simply perform a
gas-liquid separation to remove contaminant. Another option is to
use a separator such as a flash separator that can perform a
separation at a higher temperature. Such a high temperature
separator can be used, for example, to separate the feed into a
portion boiling below a temperature cut point, such as about
350.degree. F. (177.degree. C.) or about 400.degree. F.
(204.degree. C.), and a portion boiling above the temperature cut
point. In this type of separation, the naphtha boiling range
portion of the effluent from the first reaction stage can also be
removed, thus reducing the volume of effluent that is processed in
the second or other subsequent stages. Of course, any low boiling
contaminants in the effluent from the first stage would also be
separated into the portion boiling below the temperature cut point.
If sufficient contaminant removal is performed in the first stage,
the second stage can be operated as a "sweet" or low contaminant
stage.
[0077] Still another option can be to use a separator between the
first and second stages of the hydroprocessing reaction system that
can also perform at least a partial fractionation of the effluent
from the first stage. In this type of aspect, the effluent from the
first hydroprocessing stage can be separated into at least a
portion boiling below the distillate (such as diesel) fuel range, a
portion boiling in the distillate fuel range, and a portion boiling
above the distillate fuel range. The distillate fuel range can be
defined based on a conventional diesel boiling range, such as
having a lower end cut point temperature of at least about
350.degree. F. (177.degree. C.) or at least about 400.degree. F.
(204.degree. C.) to having an upper end cut point temperature of
about 700.degree. F. (371.degree. C.) or less or 650.degree. F.
(343.degree. C.) or less. Optionally, the distillate fuel range can
be extended to include additional kerosene, such as by selecting a
lower end cut point temperature of at least about 300.degree. F.
(149.degree. C.).
[0078] In aspects where the inter-stage separator is also used to
produce a distillate fuel fraction, the portion boiling below the
distillate fuel fraction includes, naphtha boiling range molecules,
light ends, and contaminants such as H.sub.2S. These different
products can be separated from each other in any convenient manner.
Similarly, one or more distillate fuel fractions can be formed, if
desired, from the distillate boiling range fraction. The portion
boiling above the distillate fuel range represents the potential
lubricant base stocks. In such aspects, the portion boiling above
the distillate fuel range is subjected to further hydroprocessing
in a second hydroprocessing stage.
[0079] A hydrocracking process under sweet conditions can be
performed under conditions similar to those used for a sour
hydrocracking process, or the conditions can be different. In an
embodiment, the conditions in a sweet hydrocracking stage can have
less severe conditions than a hydrocracking process in a sour
stage. Suitable hydrocracking conditions for a non-sour stage can
include, but are not limited to, conditions similar to a first or
sour stage. Suitable hydrocracking conditions can include
temperatures of about 500.degree. F. (260.degree. C.) to about
840.degree. F. (449.degree. C.), hydrogen partial pressures of from
about 1500 psig to about 5000 psig (10.3 MPag to 34.6 MPag), liquid
hourly space velocities of from 0.05 h.sup.-1 to 10 h.sup.-1, and
hydrogen treat gas rates of from 35.6 m.sup.3/m.sup.3 to 1781
m.sup.3/m.sup.3 (200 SCF/B to 10,000 SCF/B). In other embodiments,
the conditions can include temperatures in the range of about
600.degree. F. (343.degree. C.) to about 815.degree. F.
(435.degree. C.), hydrogen partial pressures of from about 1500
psig to about 3000 psig (10.3 MPag-20.9 MPag), and hydrogen treat
gas rates of from about 213 m.sup.3/m.sup.3 to about 1068
m.sup.3/m.sup.3 (1200 SCF/B to 6000 SCF/B). The LHSV can be from
about 0.25 to about 50 h.sup.-1, or from about 0.5 h.sup.-1 to
about 20 h.sup.-1, preferably from about 1.0 to about 4.0
h.sup.-1.
[0080] In still another aspect, the same conditions can be used for
hydrotreating and hydrocracking beds or stages, such as using
hydrotreating conditions for both or using hydrocracking conditions
for both. In yet another embodiment, the pressure for the
hydrotreating and hydrocracking beds or stages can be the same.
[0081] In yet another aspect, a hydroprocessing reaction system may
include more than one hydrocracking stage. If multiple
hydrocracking stages are present, at least one hydrocracking stage
can have effective hydrocracking conditions as described above,
including a hydrogen partial pressure of at least about 1500 psig
(10.3 MPag). In such an aspect, other hydrocracking processes can
be performed under conditions that may include lower hydrogen
partial pressures. Suitable hydrocracking conditions for an
additional hydrocracking stage can include, but are not limited to,
temperatures of about 500.degree. F. (260.degree. C.) to about
840.degree. F. (449.degree. C.), hydrogen partial pressures of from
about 250 psig to about 5000 psig (1.8 MPag to 34.6 MPag), liquid
hourly space velocities of from 0.05 to 10 h.sup.-1, and hydrogen
treat gas rates of from 35.6 m.sup.3/m.sup.3 to 1781
m.sup.3/m.sup.3 (200 SCF/B to 10,000 SCF/B). In other embodiments,
the conditions for an additional hydrocracking stage can include
temperatures in the range of about 600.degree. F. (343.degree. C.)
to about 815.degree. F. (435.degree. C.), hydrogen partial
pressures of from about 500 psig to about 3000 psig (3.5 MPag-20.9
MPag), and hydrogen treat gas rates of from about 213
m.sup.3/m.sup.3 to about 1068 m.sup.3/m.sup.3 (1200 SCF/B to 6000
SCF/B). The LHSV can be from about 0.25 to about 50 h.sup.-1, or
from about 0.5 h.sup.-1 to about 20 h.sup.-1, and preferably from
about 1.0 h.sup.-1 to about 4.0 h.sup.-1.
Hydroprocessed Effluent--Solvent Dewaxing to Form Group I Bright
Stock
[0082] The hydroprocessed deasphalted oil (optionally including
hydroprocessed vacuum gas oil) can be separated to form one or more
fuel boiling range fractions (such as naphtha or distillate fuel
boiling range fractions) and at least one lubricant base stock
boiling range fraction. The lubricant base stock boiling range
fraction(s) can then be solvent dewaxed to produce a lubricant base
stock product with a reduced (or eliminated) tendency to form haze.
Lubricant base stocks (including bright stock) formed by
hydroprocessing a deasphalted oil and then solvent dewaxing the
hydroprocessed effluent can tend to be Group I base stocks due to
having an aromatics content of at least 10 wt %.
[0083] Solvent dewaxing typically involves mixing a feed with
chilled dewaxing solvent to form an oil-solvent solution.
Precipitated wax is thereafter separated by, for example,
filtration. The temperature and solvent are selected so that the
oil is dissolved by the chilled solvent while the wax is
precipitated.
[0084] An example of a suitable solvent dewaxing process involves
the use of a cooling tower where solvent is prechilled and added
incrementally at several points along the height of the cooling
tower. The oil-solvent mixture is agitated during the chilling step
to permit substantially instantaneous mixing of the prechilled
solvent with the oil. The prechilled solvent is added incrementally
along the length of the cooling tower so as to maintain an average
chilling rate at or below 10.degree. F. per minute, usually between
about 1 to about 5.degree. F. per minute. The final temperature of
the oil-solvent/precipitated wax mixture in the cooling tower will
usually be between 0 and 50.degree. F. (-17.8 to 10.degree. C.).
The mixture may then be sent to a scraped surface chiller to
separate precipitated wax from the mixture.
[0085] Representative dewaxing solvents are aliphatic ketones
having 3-6 carbon atoms such as methyl ethyl ketone and methyl
isobutyl ketone, low molecular weight hydrocarbons such as propane
and butane, and mixtures thereof. The solvents may be mixed with
other solvents such as benzene, toluene or xylene.
[0086] In general, the amount of solvent added will be sufficient
to provide a liquid/solid weight ratio between the range of 5/1 and
20/1 at the dewaxing temperature and a solvent/oil volume ratio
between 1.5/1 to 5/1. The solvent dewaxed oil can be dewaxed to a
pour point of -6.degree. C. or less, or -10.degree. C. or less, or
-15.degree. C. or less, depending on the nature of the target
lubricant base stock product. Additionally or alternately, the
solvent dewaxed oil can be dewaxed to a cloud point of -2.degree.
C. or less, or -5.degree. C. or less, or -10.degree. C. or less,
depending on the nature of the target lubricant base stock product.
The resulting solvent dewaxed oil can be suitable for use in
forming one or more types of Group I base stocks. Preferably, a
bright stock formed from the solvent dewaxed oil can have a cloud
point below -5.degree. C. The resulting solvent dewaxed oil can
have a viscosity index of at least 90, or at least 95, or at least
100. Preferably, at least 10 wt % of the resulting solvent dewaxed
oil (or at least 20 wt %, or at least 30 wt %) can correspond to a
Group I bright stock having a kinematic viscosity at 100.degree. C.
of at least 15 cSt, or at least 20 cSt, or at least 25 cSt, such as
up to 50 cSt or more.
[0087] In some aspects, the reduced or eliminated tendency to form
haze for the lubricant base stocks formed from the solvent dewaxed
oil can be demonstrated by a reduced or minimized difference
between the cloud point temperature and pour point temperature for
the lubricant base stocks. In various aspects, the difference
between the cloud point and pour point for the resulting solvent
dewaxed oil and/or for one or more lubricant base stocks, including
one or more bright stocks, formed from the solvent dewaxed oil, can
be 22.degree. C. or less, or 20.degree. C. or less, or 15.degree.
C. or less, or 10.degree. C. or less, or 8.degree. C. or less, or
5.degree. C. or less. Additionally or alternately, a reduced or
minimized tendency for a bright stock to form haze over time can
correspond to a bright stock having a cloud point of -10.degree. C.
or less, or -8.degree. C. or less, or -5.degree. C. or less, or
-2.degree. C. or less.
Additional Hydroprocessing--Catalytic Dewaxing, Hydrofinishing, and
Optional Hydrocracking
[0088] In some alternative aspects, at least a lubricant boiling
range portion of the hydroprocessed deasphalted oil can be exposed
to further hydroprocessing (including catalytic dewaxing) to form
either Group I and/or Group II base stocks, including Group I
and/or Group II bright stock. In some aspects, a first lubricant
boiling range portion of the hydroprocessed deasphalted oil can be
solvent dewaxed as described above while a second lubricant boiling
range portion can be exposed to further hydroprocessing. In other
aspects, only solvent dewaxing or only further hydroprocessing can
be used to treat a lubricant boiling range portion of the
hydroprocessed deasphalted oil.
[0089] Optionally, the further hydroprocessing of the lubricant
boiling range portion of the hydroprocessed deasphalted oil can
also include exposure to hydrocracking conditions before and/or
after the exposure to the catalytic dewaxing conditions. At this
point in the process, the hydrocracking can be considered "sweet"
hydrocracking, as the hydroprocessed deasphalted oil can have a
sulfur content of 200 wppm or less.
[0090] Suitable hydrocracking conditions can include exposing the
feed to a hydrocracking catalyst as previously described above.
Optionally, it can be preferable to use a USY zeolite with a silica
to alumina ratio of at least 30 and a unit cell size of less than
24.32 Angstroms as the zeolite for the hydrocracking catalyst, in
order to improve the VI uplift from hydrocracking and/or to improve
the ratio of distillate fuel yield to naphtha fuel yield in the
fuels boiling range product.
[0091] Suitable hydrocracking conditions can also include
temperatures of about 500.degree. F. (260.degree. C.) to about
840.degree. F. (449.degree. C.), hydrogen partial pressures of from
about 1500 psig to about 5000 psig (10.3 MPag to 34.6 MPag), liquid
hourly space velocities of from 0.05 h.sup.-1 to 10 h.sup.-1, and
hydrogen treat gas rates of from 35.6 m.sup.3/m.sup.3 to 1781
m.sup.3/m.sup.3 (200 SCF/B to 10,000 SCF/B). In other embodiments,
the conditions can include temperatures in the range of about
600.degree. F. (343.degree. C.) to about 815.degree. F.
(435.degree. C.), hydrogen partial pressures of from about 1500
psig to about 3000 psig (10.3 MPag-20.9 MPag), and hydrogen treat
gas rates of from about 213 m.sup.3/m.sup.3 to about 1068
m.sup.3/m.sup.3 (1200 SCF/B to 6000 SCF/B). The LHSV can be from
about 0.25 h.sup.-1 to about 50 h.sup.1, or from about 0.5 h.sup.-1
to about 20 and preferably from about 1.0 to about 4.0
h.sup.-1.
[0092] For catalytic dewaxing, suitable dewaxing catalysts can
include molecular sieves such as crystalline aluminosilicates
(zeolites). In an embodiment, the molecular sieve can comprise,
consist essentially of, or be ZSM-22, ZSM-23, ZSM-48. Optionally
but preferably, molecular sieves that are selective for dewaxing by
isomerization as opposed to cracking can be used, such as ZSM-48,
ZSM-23, or a combination thereof. Additionally or alternately, the
molecular sieve can comprise, consist essentially of, or be a
10-member ring 1-D molecular sieve, such as EU-2, EU-11, ZBM-30,
ZSM-48, or ZSM-23. ZSM-48 is most preferred. Note that a zeolite
having the ZSM-23 structure with a silica to alumina ratio of from
about 20:1 to about 40:1 can sometimes be referred to as SSZ-32.
Optionally but preferably, the dewaxing catalyst can include a
binder for the molecular sieve, such as alumina, titania, silica,
silica-alumina, zirconia, or a combination thereof, for example
alumina and/or titania or silica and/or zirconia and/or
titania.
[0093] Preferably, the dewaxing catalysts used in processes
according to the invention are catalysts with a low ratio of silica
to alumina. For example, for ZSM-48, the ratio of silica to alumina
in the zeolite can be about 100:1 or less, such as about 90:1 or
less, or about 75:1 or less, or about 70:1 or less. Additionally or
alternately, the ratio of silica to alumina in the ZSM-48 can be at
least about 50:1, such as at least about 60:1, or at least about
65:1.
[0094] In various embodiments, the catalysts according to the
invention further include a metal hydrogenation component. The
metal hydrogenation component is typically a Group VI and/or a
Group VIII metal. Preferably, the metal hydrogenation component can
be a combination of a non-noble Group VIII metal with a Group VI
metal. Suitable combinations can include Ni, Co, or Fe with Mo or
W, preferably Ni with Mo or W.
[0095] The metal hydrogenation component may be added to the
catalyst in any convenient manner. One technique for adding the
metal hydrogenation component is by incipient wetness. For example,
after combining a zeolite and a binder, the combined zeolite and
binder can be extruded into catalyst particles. These catalyst
particles can then be exposed to a solution containing a suitable
metal precursor. Alternatively, metal can be added to the catalyst
by ion exchange, where a metal precursor is added to a mixture of
zeolite (or zeolite and binder) prior to extrusion.
[0096] The amount of metal in the catalyst can be at least 0.1 wt %
based on catalyst, or at least 0.5 wt %, or at least 1.0 wt %, or
at least 2.5 wt %, or at least 5.0 wt %, based on catalyst. The
amount of metal in the catalyst can be 20 wt % or less based on
catalyst, or 10 wt % or less, or 5 wt % or less, or 2.5 wt % or
less, or 1 wt % or less. For embodiments where the metal is a
combination of a non-noble Group VIII metal with a Group VI metal,
the combined amount of metal can be from 0.5 wt % to 20 wt %, or 1
wt % to 15 wt %, or 2.5 wt % to 10 wt %.
[0097] The dewaxing catalysts useful in processes according to the
invention can also include a binder. In some embodiments, the
dewaxing catalysts used in process according to the invention are
formulated using a low surface area binder, a low surface area
binder represents a binder with a surface area of 100 m.sup.2/g or
less, or 80 m.sup.2/g or less, or 70 m.sup.2/g or less.
Additionally or alternately, the binder can have a surface area of
at least about 25 m.sup.2/g. The amount of zeolite in a catalyst
formulated using a binder can be from about 30 wt % zeolite to 90
wt % zeolite relative to the combined weight of binder and zeolite.
Preferably, the amount of zeolite is at least about 50 wt % of the
combined weight of zeolite and binder, such as at least about 60 wt
% or from about 65 wt % to about 80 wt %.
[0098] Without being bound by any particular theory, it is believed
that use of a low surface area binder reduces the amount of binder
surface area available for the hydrogenation metals supported on
the catalyst. This leads to an increase in the amount of
hydrogenation metals that are supported within the pores of the
molecular sieve in the catalyst.
[0099] A zeolite can be combined with binder in any convenient
manner. For example, a bound catalyst can be produced by starting
with powders of both the zeolite and binder, combining and mulling
the powders with added water to form a mixture, and then extruding
the mixture to produce a bound catalyst of a desired size.
Extrusion aids can also be used to modify the extrusion flow
properties of the zeolite and binder mixture. The amount of
framework alumina in the catalyst may range from 0.1 to 3.33 wt %,
or 0.1 to 2.7 wt %, or 0.2 to 2 wt %, or 0.3 to 1 wt %.
[0100] Effective conditions for catalytic dewaxing of a feedstock
in the presence of a dewaxing catalyst can include a temperature of
from 280.degree. C. to 450.degree. C., preferably 343.degree. C. to
435.degree. C., a hydrogen partial pressure of from 3.5 MPag to
34.6 MPag (500 psig to 5000 psig), preferably 4.8 MPag to 20.8
MPag, and a hydrogen circulation rate of from 178 m.sup.3/m.sup.3
(1000 SCF/B) to 1781 m.sup.3/m.sup.3 (10,000 scf/B), preferably 213
m.sup.3/m.sup.3 (1200 SCF/B) to 1068 m.sup.3/m.sup.3 (6000 SCF/B).
The LHSV can be from about 0.2 h.sup.-1 to about 10 h.sup.-1, such
as from about 0.5 h.sup.-1 to about 5 and/or from about 1 to about
4 h.sup.-1.
[0101] Before and/or after catalytic dewaxing, the hydroprocessed
deasphalted oil (i.e., at least a lubricant boiling range portion
thereof) can optionally be exposed to an aromatic saturation
catalyst, which can alternatively be referred to as a
hydrofinishing catalyst. Exposure to the aromatic saturation
catalyst can occur either before or after fractionation. If
aromatic saturation occurs after fractionation, the aromatic
saturation can be performed on one or more portions of the
fractionated product. Alternatively, the entire effluent from the
last hydrocracking or dewaxing process can be hydrofinished and/or
undergo aromatic saturation.
[0102] Hydrofinishing and/or aromatic saturation catalysts can
include catalysts containing Group VI metals, Group VIII metals,
and mixtures thereof. In an embodiment, preferred metals include at
least one metal sulfide having a strong hydrogenation function. In
another embodiment, the hydrofinishing catalyst can include a Group
VIII noble metal, such as Pt, Pd, or a combination thereof. The
mixture of metals may also be present as bulk metal catalysts
wherein the amount of metal is about 30 wt. % or greater based on
catalyst. For supported hydrotreating catalysts, suitable metal
oxide supports include low acidic oxides such as silica, alumina,
silica-aluminas or titania, preferably alumina. The preferred
hydrofinishing catalysts for aromatic saturation will comprise at
least one metal having relatively strong hydrogenation function on
a porous support. Typical support materials include amorphous or
crystalline oxide materials such as alumina, silica, and
silica-alumina. The support materials may also be modified, such as
by halogenation, or in particular fluorination. The metal content
of the catalyst is often as high as about 20 weight percent for
non-noble metals. In an embodiment, a preferred hydrofinishing
catalyst can include a crystalline material belonging to the M41S
class or family of catalysts. The M41S family of catalysts are
mesoporous materials having high silica content. Examples include
MCM-41, MCM-48 and MCM-50. A preferred member of this class is
MCM-41.
[0103] Hydrofinishing conditions can include temperatures from
about 125.degree. C. to about 425.degree. C., preferably about
180.degree. C. to about 280.degree. C., a hydrogen partial pressure
from about 500 psig (3.4 MPa) to about 3000 psig (20.7 MPa),
preferably about 1500 psig (10.3 MPa) to about 2500 psig (17.2
MPa), and liquid hourly space velocity from about 0.1 hr.sup.-1 to
about 5 hr.sup.-1 LHSV, preferably about 0.5 hr.sup.-1 to about 1.5
hr.sup.-1. Additionally, a hydrogen treat gas rate of from 35.6
m.sup.3/m.sup.3 to 1781 m.sup.3/m.sup.3 (200 SCF/B to 10,000 SCF/B)
can be used.
Solvent Processing of Catalytically Dewaxed Effluent or Input Flow
to Catalytic Dewaxing
[0104] For deasphalted oils derived from propane deasphalting, the
further hydroprocessing (including catalytic dewaxing) can be
sufficient to form lubricant base stocks with low haze formation
and unexpected compositional properties. For deasphalted oils
derived from C.sub.4+ deasphalting, after the further
hydroprocessing (including catalytic dewaxing), the resulting
catalytically dewaxed effluent can be solvent processed to form one
or more lubricant base stock products with a reduced or eliminated
tendency to form haze. The type of solvent processing can be
dependent on the nature of the initial hydroprocessing
(hydrotreatment and/or hydrocracking) and the nature of the further
hydroprocessing (including dewaxing).
[0105] In aspects where the initial hydroprocessing is less severe,
corresponding to 10 wt % to 40 wt % conversion relative to
.about.700.degree. F. (370.degree. C.), the subsequent solvent
processing can correspond to solvent dewaxing. The solvent dewaxing
can be performed in a manner similar to the solvent dewaxing
described above. However, this solvent dewaxing can be used to
produce a Group II lubricant base stock. In some aspects, when the
initial hydroprocessing corresponds to 10 wt % to 40 wt %
conversion relative to 370.degree. C., the catalytic dewaxing
during further hydroprocessing can also be performed at lower
severity, so that at least 6 wt % wax remains in the catalytically
dewaxed effluent, or at least 8 wt %, or at least 10 wt %, or at
least 12 wt %, or at least 15 wt %, such as up to 20 wt %. The
solvent dewaxing can then be used to reduce the wax content in the
catalytically dewaxed effluent by 2 wt % to 10 wt %. This can
produce a solvent dewaxed oil product having a wax content of 0.1
wt % to 12 wt %, or 0.1 wt % to 10 wt %, or 0.1 wt % to 8 wt %, or
0.1 wt % to 6 wt %, or 1 wt % to 12 wt %, or 1 wt % to 10 wt %, or
1 wt % to 8 wt %, or 4 wt % to 12 wt %, or 4 wt % to 10 wt %, or 4
wt % to 8 wt %, or 6 wt % to 12 wt %, or 6 wt % to 10 wt %. In
particular, the solvent dewaxed oil can have a wax content of 0.1
wt % to 12 wt %, or 0.1 wt % to 6 wt %, or 1 wt % to 10 wt %, or 4
wt % to 12 wt %.
[0106] In other aspects, the subsequent solvent processing can
correspond to solvent extraction. Solvent extraction can be used to
reduce the aromatics content and/or the amount of polar molecules.
The solvent extraction process selectively dissolves aromatic
components to form an aromatics-rich extract phase while leaving
the more paraffinic components in an aromatics-poor raffinate
phase. Naphthenes are distributed between the extract and raffinate
phases. Typical solvents for solvent extraction include phenol,
furfural and N-methyl pyrrolidone. By controlling the solvent to
oil ratio, extraction temperature and method of contacting
distillate to be extracted with solvent, one can control the degree
of separation between the extract and raffinate phases. Any
convenient type of liquid-liquid extractor can be used, such as a
counter-current liquid-liquid extractor. Depending on the initial
concentration of aromatics in the deasphalted oil, the raffinate
phase can have an aromatics content of 5 wt % to 25 wt %. For
typical feeds, the aromatics contents can be at least 10 wt %.
[0107] Optionally, the raffinate from the solvent extraction can be
under-extracted. In such aspects, the extraction is carried out
under conditions such that the raffinate yield is maximized while
still removing most of the lowest quality molecules from the feed.
Raffinate yield may be maximized by controlling extraction
conditions, for example, by lowering the solvent to oil treat ratio
and/or decreasing the extraction temperature. In various aspects,
the raffinate yield from solvent extraction can be at least 40 wt
%, or at least 50 wt %, or at least 60 wt %, or at least 70 wt
%.
[0108] The solvent processed oil (solvent dewaxed or solvent
extracted) can have a pour point of -6.degree. C. or less, or
-10.degree. C. or less, or -15.degree. C. or less, or -20.degree.
C. or less, depending on the nature of the target lubricant base
stock product. Additionally or alternately, the solvent processed
oil (solvent dewaxed or solvent extracted) can have a cloud point
of -2.degree. C. or less, or -5.degree. C. or less, or -10.degree.
C. or less, depending on the nature of the target lubricant base
stock product. Pour points and cloud points can be determined
according to ASTM D97 and ASTM D2500, respectively. The resulting
solvent processed oil can be suitable for use in forming one or
more types of Group II base stocks. The resulting solvent dewaxed
oil can have a viscosity index of at least 80, or at least 90, or
at least 95, or at least 100, or at least 110, or at least 120.
Viscosity index can be determined according to ASTM D2270.
Preferably, at least 10 wt % of the resulting solvent processed oil
(or at least 20 wt %, or at least 30 wt %) can correspond to a
Group II base stock having a kinematic viscosity at 100.degree. C.
of 6 cSt to 20 cSt, or 6 cSt to 16 cSt, or 6 cSt to 14 cSt, or 6
cSt to 12 cSt, or 8 cSt to 20 cSt, or 8 cSt to 16 cSt, or 8 cSt to
14 cSt, or 8 cSt to 12 cSt, or 10 cSt to 20 cSt, or 10 cSt to 16
cSt, or 10 cSt to 14 cSt Kinematic viscosity can be determined
according to ASTM D445. Additionally or alternately, the resulting
base stock can have a turbidity of at least 1.5 (in combination
with a cloud point of less than 0.degree. C.), or can have a
turbidity of at least 2.0, and/or can have a turbidity of 4.0 or
less, or 3.5 or less, or 3.0 or less. In particular, the turbidity
can be 1.5 to 4.0, or 1.5 to 3.0, or 2.0 to 4.0, or 2.0 to 3.5.
Group II Base Stock Products
[0109] For deasphalted oils derived from propane, butane, pentane,
hexane and higher or mixtures thereof, the further hydroprocessing
(including catalytic dewaxing) and potentially solvent processing
can be sufficient to form lubricant base stocks with low haze
formation (or no haze formation) and novel compositional
properties. Traditional products manufactured today with kinematic
viscosity of about 32 cSt at 100.degree. C. contain aromatics that
are >10% and/or sulfur that is >0.03% of the base oil.
[0110] In various aspects, base stocks produced according to
methods described herein can have a kinematic viscosity of at least
14 cSt, or at least 20 cSt, or at least 25 cSt, or at least 30 cSt,
or at least 32 cSt at 100.degree. C. and can contain less than 10
wt % aromatics/greater than 90 wt % saturates and less than 0.03%
sulfur. Optionally, the saturates content can be still higher, such
as greater than 95 wt %, or greater than 97 wt %. In addition,
detailed characterization of the branchiness (branching) of the
molecules by C-NMR reveals a high degree of branch points as
described further below in the examples. This can be quantified by
examining the absolute number of methyl branches, or ethyl
branches, or propyl branches individually or as combinations
thereof. This can also be quantified by looking at the ratio of
branch points (methyl, ethyl, or propyl) compared to the number of
internal carbons, labeled as epsilon carbons by C-NMR. This
quantification of branching can be used to determine whether a base
stock will be stable against haze formation over time. For
.sup.13C-NMR results reported herein, samples were prepared to be
25-30 wt % in CDCl.sub.3 with 7% Chromium (III)-acetylacetonate
added as a relaxation agent. .sup.13C NMR experiments were
performed on a JEOL ECS NMR spectrometer for which the proton
resonance frequency is 400 MHz. Quantitative .sup.13C NMR
experiments were performed at 27.degree. C. using an inverse gated
decoupling experiment with a 45.degree. flip angle, 6.6 seconds
between pulses, 64 K data points and 2400 scans. All spectra were
referenced to TMS at 0 ppm. Spectra were processed with 0.2-1 Hz of
line broadening and baseline correction was applied prior to manual
integration. The entire spectrum was integrated to determine the
mole % of the different integrated areas as follows: 170-190 PPM
(aromatic C); 30-29.5 PPM (epsilon carbons); 15-14.5 PPM (terminal
and pendant propyl groups) 14.5-14 PPM--Methyl at the end of a long
chain (alpha); 12-10 PPM (pendant and terminal ethyl groups). Total
methyl content was obtained from proton NMR. The methyl signal at
0-1.1 PPM was integrated. The entire spectrum was integrated to
determine the mole % of methyls. Average carbon numbers obtained
from gas chromatography were used to convert mole % methyls to
total methyls.
[0111] Also unexpected in the composition is the discovery using
Fourier Transform Ion Cyclotron Resonance--Mass Spectrometry
(FTICR-MS) and/or Field Desorption Mass Spectrometry (FDMS) that
the prevalence of smaller naphthenic ring structures below 6 or
below 7 or below 8 naphthene rings can be similar but the residual
numbers of larger naphthenic rings structures with 7 or more rings
or 8+ rings or 9+ rings or 10+ rings is diminished in base stocks
that are stable against haze formation.
[0112] For FTICR-MS results reported herein, the results were
generated according to the method described in U.S. Pat. No.
9,418,828. The method described in U.S. Pat. No. 9,418,828
generally involves using laser desorption with Ag ion complexation
(LDI-Ag) to ionize petroleum saturates molecules (including
538.degree. C.+ molecules) without fragmentation of the molecular
ion structure. Ultra-high resolution Fourier Transform Ion
Cyclotron Resonance Mass Spectrometry is applied to determine exact
elemental formula of the saturates-Ag cations and corresponding
abundances. The saturates fraction composition can be arranged by
homologous series and molecular weights. The portion of U.S. Pat.
No. 9,418,828 related to determining the content of saturate ring
structures in a sample is incorporated herein by reference.
[0113] For FDMS results reported herein, Field desorption (FD) is a
soft ionization method in which a high-potential electric field is
applied to an emitter (a filament from which tiny "whiskers" have
formed) that has been coated with a diluted sample resulting in the
ionization of gaseous molecules of the analyte. Mass spectra
produced by FD are dominated by molecular radical cations M.sup.+.
or in some cases protonated molecular ions [M+H].sup.+. Because
FDMS cannot distinguish between molecules with `n` naphthene rings
and molecules with `n+7` rings, the FDMS data was "corrected" by
using the FTICR-MS data from the most similar sample. The FDMS
correction was performed by applying the resolved ratio of "n" to
"n+7" rings from the FTICR-MS to the unresolved FDMS data for that
particular class of molecules. Hence, the FDMS data is shown as
"corrected" in the figures.
[0114] Base oils of the compositions described above have further
been found to provide the advantage of being haze free upon initial
production and remaining haze free for extended periods of time.
This is an advantage over the prior art of high saturates heavy
base stocks that was unexpected.
[0115] Additionally, it has been found that these base stocks can
be blended with additives to form formulated lubricants, such as
but not limited to marine oils, engine oils, greases, paper machine
oils, and gear oils. These additives may include, but are not
restricted to, detergents, dispersants, antioxidants, viscosity
modifiers, and pour point depressants. More generally, a formulated
lubricating including a base stock produced from a deasphalted oil
may additionally contain one or more of the other commonly used
lubricating oil performance additives including but not limited to
antiwear agents, dispersants, other detergents, corrosion
inhibitors, rust inhibitors, metal deactivators, extreme pressure
additives, anti-seizure agents, wax modifiers, viscosity index
improvers, viscosity modifiers, fluid-loss additives, seal
compatibility agents, friction modifiers, lubricity agents,
anti-staining agents, chromophoric agents, defoamants,
demulsifiers, emulsifiers, densifiers, wetting agents, gelling
agents, tackiness agents, colorants, and others. For a review of
many commonly used additives, see Klamann in Lubricants and Related
Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0.
These additives are commonly delivered with varying amounts of
diluent oil, that may range from 5 weight percent to 50 weight
percent.
[0116] When so blended, the performance as measured by standard low
temperature tests such as the Mini-Rotary Viscometer (MRV) and
Brookfield test has been shown to be superior to formulations
blended with traditional base oils.
[0117] It has also been found that the oxidation performance, when
blended into industrial oils using common additives such as, but
not restricted to, defoamants, pour point depressants,
antioxidants, rust inhibitors, has exemplified superior oxidation
performance in standard oxidation tests such as the US Steel
Oxidation test compared to traditional base stocks.
[0118] Other performance parameters such as interfacial properties,
deposit control, storage stability, and toxicity have also been
examined and are similar to or better than traditional base
oils.
[0119] In addition to being blended with additives, the base stocks
described herein can also be blended with other base stocks to make
a base oil. These other base stocks include solvent processed base
stocks, hydroprocessed base stocks, synthetic base stocks, base
stocks derived from Fisher-Tropsch processes, PAO, and naphthenic
base stocks. Additionally or alternately, the other base stocks can
include Group I base stocks, Group II base stocks, Group III base
stocks, Group IV base stocks, and/or Group V base stocks.
Additionally or alternately, still other types of base stocks for
blending can include hydrocarbyl aromatics, alkylated aromatics,
esters (including synthetic and/or renewable esters), and or other
non-conventional or unconventional base stocks. These base oil
blends of the inventive base stock and other base stocks can also
be combined with additives, such as those mentioned above, to make
formulated lubricants.
CONFIGURATION EXAMPLES
[0120] FIG. 1 schematically shows a first configuration for
processing of a deasphalted oil feed 110. Optionally, deasphalted
oil feed 110 can include a vacuum gas oil boiling range portion. In
FIG. 1, a deasphalted oil feed 110 is exposed to hydrotreating
and/or hydrocracking catalyst in a first hydroprocessing stage 120.
The hydroprocessed effluent from first hydroprocessing stage 120
can be separated into one or more fuels fractions 127 and a
370.degree. C.+ fraction 125. The 370.degree. C.+ fraction 125 can
be solvent dewaxed 130 to form one or more lubricant base stock
products, such as one or more light neutral or heavy neutral base
stock products 132 and a bright stock product 134.
[0121] FIG. 2 schematically shows a second configuration for
processing a deasphalted oil feed 110. In FIG. 2, solvent dewaxing
stage 130 is optional. The effluent from first hydroprocessing
stage 120 can be separated to form at least one or more fuels
fractions 127, a first 370.degree. C.+ portion 245, and a second
optional 370.degree. C.+ portion 225 that can be used as the input
for optional solvent dewaxing stage 130. The first 370.degree. C.+
portion 245 can be used as an input for a second hydroprocessing
stage 250. The second hydroprocessing stage can correspond to a
sweet hydroprocessing stage for performing catalytic dewaxing,
aromatic saturation, and optionally further performing
hydrocracking. In FIG. 2, at least a portion 253 of the
catalytically dewaxed output 255 from second hydroprocessing stage
250 can be solvent dewaxed 260 to form at least a solvent processed
lubricant boiling range product 265 that has a T10 boiling point of
at least 510.degree. C. and that corresponds to a Group II bright
stock.
[0122] FIG. 3 schematically shows another configuration for
producing a Group II bright stock. In FIG. 3, at least a portion
353 of the catalytically dewaxed output 355 from the second
hydroprocessing stage 250 is solvent extracted 370 to form at least
a processed lubricant boiling range product 375 that has a T10
boiling point of at least 510.degree. C. and that corresponds to a
Group II bright stock.
[0123] FIG. 6 schematically shows yet another configuration for
producing a Group II bright stock. In FIG. 6, a vacuum resid feed
675 and a deasphalting solvent 676 is passed into a deasphalting
unit 680. In some aspects, deasphalting unit 680 can perform
propane deasphalting, but in other aspects a C.sub.4+ solvent can
be used. Deasphalting unit 680 can produce a rock or asphalt
fraction 682 and a deasphalted oil 610. Optionally, deasphalted oil
610 can be combined with another vacuum gas oil boiling range feed
671 prior to being introduced into first (sour) hydroprocessing
stage 620. A lower boiling portion 627 of the effluent from
hydroprocessing stage 620 can be separated out for further use
and/or processing as one or more naphtha fractions and/or
distillate fractions. A higher boiling portion 625 of the
hydroprocessing effluent can be a) passed into a second (sweet)
hydroprocessing stage 650 and/or b) withdrawn 626 from the
processing system for use as a fuel, such as a fuel oil or fuel oil
blendstock. Second hydroprocessing stage 650 can produce an
effluent that can be separated to form one or more fuels fractions
657 and one or more lubricant base stock fractions 655, such as one
or more bright stock fractions.
[0124] FIGS. 11 to 13 show examples of using blocked operation
and/or partial product recycle during lubricant production based on
a feed including deasphalted resid. In FIGS. 11 to 13, after
initial sour stage processing, the hydroprocessed effluent is
fractionated to form light neutral, heavy neutral, and brightstock
portions. FIG. 11 shows an example of the process flow during
processing to form light neutral base stock. FIG. 12 shows an
example of the process flow during processing to form heavy neutral
base stock. FIG. 13 shows an example of the process flow during
processing to form brightstock.
[0125] In FIG. 11, a feed 705 is introduced into a deasphalter 710.
The deasphalter 710 generates a deasphalted oil 715 and deasphalter
rock or residue 718. The deasphalted oil 715 is then processed in a
sour processing stage 720. Optionally, a portion 771 of recycled
light neutral base product 762 can be combined with deasphalted oil
715. Sour processing stage 720 can include one or more of a
deasphalting catalyst, a hydrotreating catalyst, a hydrocracking
catalyst, and/or an aromatic saturation catalyst. The conditions in
sour processing stage 720 can be selected to at least reduce the
sulfur content of the hydroprocessed effluent 725 to 20 wppm or
less. This can correspond to 15 wt % to 40 wt % conversion of the
feed relative to 370.degree. C. Optionally, the amount of
conversion in the sour processing stage 720 can be any convenient
higher amount so long as the combined conversion in sour processing
stage 720 and sweet processing stage 750 is 90 wt % or less.
[0126] The hydroprocessed effluent 725 can then be passed into
fractionation stage 730 for separation into a plurality of
fractions. In the example shown in FIG. 11, the hydroprocessed
effluent is separated into a light neutral portion 732, a heavy
neutral portion 734, and a brightstock portion 736. To allow for
blocked operation, the light neutral portion 732 can be sent to
corresponding light neutral storage 742, the heavy neutral portion
734 can be sent to corresponding heavy neutral storage 744, and the
brightstock portion 736 can be sent to corresponding brightstock
storage 746. A lower boiling range fraction 731 corresponding to
fuels and/or light ends can also be generated by fractionation
stage 730. Optionally, fractionation stage can generate a plurality
of lower boiling range fractions 731.
[0127] FIG. 11 shows an example of the processing system during a
light neutral processing block. In FIG. 11, the feed 752 to sweet
processing stage 750 corresponds to a feed derived from light
neutral storage 742. The sweet processing stage 750 can include at
least dewaxing catalyst, and optionally can further include one or
more of hydrocracking catalyst and aromatics saturation catalyst.
The dewaxed effluent 755 from sweet processing stage 750 can then
be passed into a fractionator 760 to form light neutral base stock
product 762. A lower boiling fraction 761 corresponding to fuels
and/or light ends can also be separated out by fractionator 760.
Optionally, a portion of light neutral base stock 762 can be
recycled. The recycled portion of light neutral base stock 762 can
be used as a recycled feed portion 771 and/or as a recycled portion
772 that is added to light neutral storage 742. Recycling a portion
771 for use as part of the feed can be beneficial for increasing
the lifetime of the catalysts in sour processing stage 720.
Recycling a portion 772 to light neutral storage 742 can be
beneficial for increasing conversion and/or VI.
[0128] FIG. 12 shows the same processing configuration during
processing of a heavy neutral block. In FIG. 12, the feed 754 to
sweet processing stage 750 is derived from heavy neutral storage
744. The dewaxed effluent 755 from sweet processing stage 750 can
be fractionated 760 to form lower boiling portion 761, heavy
neutral base stock product 764, and light neutral base stock
product 762. Because block operation to form a heavy neutral base
stock results in production of both a light neutral product 762 and
a heavy neutral product 764, various optional recycle streams can
also be used. In the example shown in FIG. 12, optional recycle
portions 771 and 772 can be used for recycle of the light neutral
product 762. Additionally, optional recycle portions 781 and 784
can be used for recycle of the heavy neutral product 764. Recycle
portions 781 and 784 can provide similar benefits to those for
recycle portions 771 and/or 772.
[0129] FIG. 13 shows the same processing configuration during
processing of a bright stock block. In FIG. 13, the feed 756 to
sweet processing stage 750 is derived from bright stock storage
746. The dewaxed effluent 755 from sweet processing stage 750 can
be fractionated 760 to form lower boiling portion 761, bottoms
product 766, heavy neutral base stock product 764, and light
neutral base stock product 762. Bottoms product 766 can then be
extracted 790 to form a bright stock product 768. The aromatic
extract 793 produced in extractor 790 can be recycled for use, for
example, as part of the feed to deasphalter 710.
[0130] Because block operation to form a bright stock results in
production of a bright stock product 768 as well as a light neutral
product 762 and a heavy neutral product 764, various optional
recycle streams can also be used. In the example shown in FIG. 9,
optional recycle portions 771 and 772 can be used for recycle of
the light neutral product 762, while optional recycle portions 781
and 784 can be used for recycle of the heavy neutral product 764.
Additionally, optional recycle portions 791 and 796 can be used for
recycle of the bottoms product 766. Recycle portions 791 and 796
can provide similar benefits to those for recycle portions 771,
772, 781, and/or 784.
Example 1
[0131] A deasphalted oil and vacuum gas oil mixture shown in Table
B was processed in a configuration similar to FIG. 3.
TABLE-US-00002 TABLE 1 Pentane deasphalted oil (65%) and vacuum gas
oil (35%) properties API Gravity 13.7 Sulfur (wt %) 3.6 Nitrogen
(wppm) 2099 Ni (wppm) 5.2 V (wppm) 14.0 CCR (wt %) 8.1 Wax (wt %)
4.2 GCD Distillation (wt %) (.degree. C.) 5% 422 10% 465 30% 541
50% 584 70% n/a 90% 652
[0132] The deasphalted oil in Table 1 was processed at 0.2
hr.sup.-1 LHSV, a treat gas rate of 8000 scf/b, and a pressure of
2250 psig over a catalyst fill of 50 vol % demetalization catalyst,
42.5 vol % hydrotreating catalyst, and 7.5% hydrocracking catalyst
by volume. The demetallization catalyst was a commercially
available large pore supported demetallization catalyst. The
hydrotreating catalyst was a stacked bed of commercially available
supported NiMo hydrotreating catalyst and commercially available
bulk NiMo catalyst. The hydrocracking catalyst was a standard
distillate selective catalyst used in industry. Such catalysts
typically include NiMo or NiW on a zeolite/alumina support. Such
catalysts typically have less than 40 wt % zeolite of a zeolite
with a unit cell size of less than 34.38 Angstroms. A preferred
zeolite content can be less than 25 wt % and/or a preferred unit
cell size can be less than 24.32 Angstroms. Activity for such
catalysts can be related to the unit cell size of the zeolite, so
the activity of the catalyst can be adjusted by selecting the
amount of zeolite. The feed was exposed to the demetallization
catalyst at 745.degree. F. (396.degree. C.) and exposed to the
combination of the hydrotreating and hydrocracking catalyst at
761.degree. F. (405.degree. C.) in an isothermal fashion.
[0133] The above processing conditions resulted in conversion
relative to 510.degree. C. of 73.9 wt % and conversion relative to
370.degree. C. of 50 wt %. The hydroprocessed effluent was
separated to remove fuels boiling range portions from a 370.degree.
C.+ portion. The resulting 370.degree. C.+ portion was then further
hydroprocessed. The further hydroprocessing included exposing the
370.degree. C.+ portion to a 0.6 wt % Pt on ZSM-48 dewaxing
catalyst (70:1 silica to alumina ratio, 65 wt % zeolite to 35 wt %
binder) followed by a 0.3 wt % Pt/0.9 wt % Pd on MCM-41 aromatic
saturation catalyst (65% zeolite to 35 wt % binder). The operating
conditions included a hydrogen pressure of 2400 psig, a treat gas
rate of 5000 scf/b, a dewaxing temperature of 658.degree. F.
(348.degree. C.), a dewaxing catalyst space velocity of 1.0
hr.sup.-1, an aromatic saturation temperature of 460.degree. F.
(238.degree. C.), and an aromatic saturation catalyst space
velocity of 1.0 hr.sup.-1. The properties of the 560.degree. C.+
portion of the catalytically dewaxed effluent are shown in Table 2.
Properties for a raffinate fraction and an extract fraction derived
from the catalytically dewaxed effluent are also shown.
TABLE-US-00003 TABLE 2 Catalytically dewaxed effluent 560.degree.
C.+ Raffinate Product Fraction CDW effluent (yield 92.2%) Extract
API 30.0 30.2 27.6 VI 104.2 105.2 89 KV @100.degree. C. 29.8 30.3
29.9 KV @40.degree. C. 401 405 412 Pour Pt (.degree. C.) -21 -30
Cloud Pt (.degree. C.) 7.8 -24
[0134] Although the catalytically dewaxed effluent product was
initially clear, haze developed within 2 days. Solvent dewaxing of
the catalytically dewaxed effluent product in Table 2 did not
reduce the cloud point significantly (cloud after solvent dewaxing
of 6.5.degree. C.) and removed only about 1 wt % of wax, due in
part to the severity of the prior catalytic dewaxing. However,
extracting the catalytically dewaxed product shown in Table 9 with
N-methyl pyrrolidone (NMP) at a solvent/water ratio of 1 and at a
temperature of 100.degree. C. resulted in a clear and bright
product with a cloud point of -24.degree. C. that appeared to be
stable against haze formation. The extraction also reduced the
aromatics content of the catalytically dewaxed product from about 2
wt % aromatics to about 1 wt % aromatics. This included reducing
the 3-ring aromatics content of the catalytically dewaxed effluent
(initially about 0.2 wt %) by about 80%. This result indicates a
potential relationship between waxy haze formation and the presence
of polynuclear aromatics in a bright stock.
Example 2
[0135] A feed similar to Example 1 was processed in a configuration
similar to FIG. 2, with various processing conditions were
modified. The initial hydroprocessing severity was reduced relative
to the conditions in Example 1 so that the initial hydroprocessing
conversion was 59 wt % relative to 510.degree. C. and 34.5 wt %
relative to 370.degree. C. These lower conversions were achieved by
operating the demetallization catalyst at 739.degree. F.
(393.degree. C.) and the hydrotreating/hydrocracking catalyst
combination at 756.degree. F. (402.degree. C.).
[0136] The hydroprocessed effluent was separated to separate fuels
boiling range fraction(s) from the 370.degree. C.+ portion of the
hydroprocessed effluent. The 370.degree. C.+ portion was then
treated in a second hydroprocessing stage over a hydrocracking
catalyst and a dewaxing catalyst. Additionally, a small amount of a
hydrotreating catalyst (hydrotreating catalyst LHSV of 10
hr.sup.-1) was included prior to the hydrocracking catalyst, and
the feed was exposed to the hydrotreating catalyst under
substantially the same conditions as the hydrocracking catalyst.
The reaction conditions included a hydrogen pressure of 2400 psig
and a treat gas rate of 5000 scf/b. In a first run, the second
hydroprocessing conditions were selected to under dewax the
hydroprocessed effluent. The under-dewaxing conditions corresponded
to a hydrocracking temperature of 675.degree. F. (357.degree. C.),
a hydrocracking catalyst LHSV of 1.2 hr.sup.-1, a dewaxing
temperature of 615.degree. F. (324.degree. C.), a dewaxing catalyst
LHSV of 1.2 hr.sup.-1, an aromatic saturation temperature of
460.degree. F. (238.degree. C.), and an aromatic saturation
catalyst LHSV of 1.2 hr.sup.-1. In a second run, the second
hydroprocessing conditions were selected to more severely dewax the
hydroprocessed effluent. The higher severity dewaxing conditions
corresponded to a hydrocracking temperature of 675.degree. F.
(357.degree. C.), a hydrocracking catalyst LHSV of 1.2 hr.sup.-1, a
dewaxing temperature of 645.degree. F. (340.degree. C.), a dewaxing
catalyst LHSV of 1.2 hr.sup.-1, an aromatic saturation temperature
of 460.degree. F. (238.degree. C.), and an aromatic saturation
catalyst LHSV of 1.2 hr.sup.-1. The 510.degree. C.+ portions of the
catalytically dewaxed effluent are shown in Table 3.
TABLE-US-00004 TABLE 3 Catalytically dewaxed effluents Product
Fraction Under-dewaxed Higher severity VI 106.6 106.4 KV
@100.degree. C. 37.6 30.5 KV @40.degree. C. 551 396 Pour Pt
(.degree. C.) -24 -24 Cloud Pt (.degree. C.) 8.6 4.9
[0137] Both samples in Table 3 were initially bright and clear, but
a haze developed in both samples within one week. Both samples were
solvent dewaxed. This reduced the wax content of the under-dewaxed
sample to 6.8 wt % and the wax content of the higher severity
dewaxing sample to 1.1 wt %. The higher severity dewaxing sample
still showed a slight haze. However, the under-dewaxed sample,
after solvent dewaxing, had a cloud point of -21.degree. C. and
appeared to be stable against haze formation.
Example 3--Viscosity and Viscosity Index Relationships
[0138] FIG. 4 shows an example of the relationship between
processing severity, kinematic viscosity, and viscosity index for
lubricant base stocks formed from a deasphalted oil. The data in
FIG. 4 corresponds to lubricant base stocks formed form a pentane
deasphalted oil at 75 wt % yield on resid feed. The deasphalted oil
had a solvent dewaxed VI of 75.8 and a solvent dewaxed kinematic
viscosity at 100.degree. C. of 333.65.
[0139] In FIG. 4, kinematic viscosities (right axis) and viscosity
indexes (left axis) are shown as a function of hydroprocessing
severity (510.degree. C.+ conversion) for a deasphalted oil
processed in a configuration similar to FIG. 1, with the catalysts
described in Example 1. As shown in FIG. 4, increasing the
hydroprocessing severity can provide VI uplift so that deasphalted
oil can be converted (after solvent dewaxing) to lubricant base
stocks. However, increasing severity also reduces the kinematic
viscosity of the 510.degree. C.+ portion of the base stock, which
can limit the yield of bright stock. The 370.degree. C.-510.degree.
C. portion of the solvent dewaxed product can be suitable for
forming light neutral and/or heavy neutral base stocks, while the
510.degree. C.+ portion can be suitable for forming bright stocks
and/or heavy neutral base stocks.
Example 4--Variations in Sweet and Sour Hydrocracking
[0140] In addition to providing a method for forming Group II base
stocks from a challenged feed, the methods described herein can
also be used to control the distribution of base stocks formed from
a feed by varying the amount of conversion performed in sour
conditions versus sweet conditions. This is illustrated by the
results shown in FIG. 5.
[0141] In FIG. 5, the upper two curves show the relationship
between the cut point used for forming a lubricant base stock of a
desired viscosity (bottom axis) and the viscosity index of the
resulting base stock (left axis). The curve corresponding to the
circle data points represents processing of a C.sub.5 deasphalted
oil using a configuration similar to FIG. 2, with all of the
hydrocracking occurring in the sour stage. The curve corresponding
to the square data points corresponds to performing roughly half of
the hydrocracking conversion in the sour stage and the remaining
hydrocracking conversion in the sweet stage (along with the
catalytic dewaxing). The individual data points in each of the
upper curves represent the yield of each of the different base
stocks relative to the amount of feed introduced into the sour
processing stage. It is noted that summing the data points within
each curve shows the same total yield of base stock, which reflects
the fact that the same total amount of hydrocracking conversion was
performed in both types of processing runs. Only the location of
the hydrocracking conversion (all sour, or split between sour and
sweet) was varied.
[0142] The lower pair of curves provides additional information
about the same pair of process runs. As for the upper pair of
curves, the circle data points in the lower pair of curves
represent all hydrocracking in the sour stage and the square data
points correspond to a split of hydrocracking between sour and
sweet stages. The lower pair of curves shows the relationship
between cut point (bottom axis) and the resulting kinematic
viscosity at 100.degree. C. (right axis). As shown by the lower
pair of curves, the three cut point represent formation of a light
neutral base stock (5 or 6 cSt), a heavy neutral base stock (10-12
cSt), and a bright stock (about 30 cSt). The individual data points
for the lower curves also indicate the pour point of the resulting
base stock.
[0143] As shown in FIG. 5, altering the conditions under which
hydrocracking is performed can alter the nature of the resulting
lubricant base stocks. Performing all of the hydrocracking
conversion during the first (sour) hydroprocessing stage can result
in higher viscosity index values for the heavy neutral base stock
and bright stock products, while also producing an increased yield
of heavy neutral base stock. Performing a portion of the
hydrocracking under sweet conditions increased the yield of light
neutral base stock and bright stock with a reduction in heavy
neutral base stock yield. Performing a portion of the hydrocracking
under sweet conditions also reduced the viscosity index values for
the heavy neutral base stock and bright stock products. This
demonstrates that the yield of base stocks and/or the resulting
quality of base stocks can be altered by varying the amount of
conversion performed under sour conditions versus sweet
conditions.
Example 5--Blocked Operation
[0144] A configuration similar to the configuration shown in FIGS.
7 to 9 was used to process a resid-type feed that substantially
included 510.degree. C.+ components. The configuration for this
example did not include recycle products as part of the feed for
the sour stage or for further sweet stage processing. The feed was
initially deasphalted using n-pentane to product 75 wt %
deasphalted oil and 25 wt % deasphalter rock or residue. The
resulting deasphalted oil had an API gravity of 12.3, a sulfur
content of 3.46 wt %, and a nitrogen content of 2760 wppm. The
deasphalted oil was then hydroprocessed in an initial sour
hydroprocessing stage that included four catalyst beds. The first
two catalyst beds corresponded to commercially available
demetallization catalysts. The third catalyst bed corresponded to
commercially available hydrotreating catalyst, including at least a
portion of a commercially available bulk metal hydrotreating
catalyst. The fourth catalyst bed included a commercially available
hydrocracking catalyst. The effluent from each catalyst bed was
cascaded to the next catalyst bed. The average reaction temperature
across each catalyst bed was 378.degree. C. for the first
demetallization catalyst bed, 388.degree. C. for the second
demetallization catalyst bed, 389.degree. C. for the hydrotreating
catalyst bed, and 399.degree. C. for the hydrocracking catalyst
bed. The flow rate of the feed relative to the total volume of
catalyst in the sour hydroprocessing stage was an LHSV of 0.16
hr.sup.-1. The hydrogen partial pressure was 2500 psia (17.2 MPa-a)
and the hydrogen treat gas flow rate was 8000 scf/b (.about.1420
Nm.sup.3/m.sup.3). Under these conditions, the hydroprocessing
consumed roughly 2300 scf/b (.about.400 Nm.sup.3/m.sup.3). The
conditions resulted in roughly 50 wt % conversion relative to
370.degree. C.
[0145] After processing in the initial sour stage, a fractionator
was used to separate the hydroprocessed effluent into various
fractions. The fractions included light ends, at least one fuels
fraction, a light neutral fraction, a heavy neutral fraction, and a
brightstock fraction. Table 4 shows additional details regarding
the hydroprocessed effluent from the initial sour stage.
TABLE-US-00005 TABLE 4 Hydroprocessed Effluent (Sour Stage) Wt %
(of total Nitrogen content Solvent Product effluent) (wppm) dewaxed
VI H.sub.2S 3.7 NH.sub.3 0.3 C.sub.1 0.4 C.sub.2 0.4 C.sub.3 0.7
C.sub.4 0.9 C.sub.5 1.3 C.sub.6 to 370.degree. C. (fuels 45.6
fraction) Light Neutral 13.9 1 102.8 Heavy Neutral 14.0 1 99.8
Brightstock 22.2 5-10 110.5
[0146] The light neutral, heavy neutral, and brightstock fractions
from the initial sour hydroprocessing stage were then further
hydroprocessed in the presence of a noble metal hydrocracking
catalyst (0.6 wt % Pt on alumina-bound USY) and a noble metal
dewaxing catalyst (0.6 wt % Pt on alumina bound ZSM-48. The sweet
stage conditions for each fraction were selected separately to
achieve desired VI values.
[0147] For the light neutral feed, the sweet stage conditions were
selected to achieve roughly 30 wt % conversion relative to
370.degree. C. This produced a light neutral lubricant base stock
in a 70.6 wt % yield relative to the light neutral feed. The
resulting light neutral base stock had a VI of 109.9 and a
kinematic viscosity at 100.degree. C. of 5.8 cSt. For the heavy
neutral feed, the sweet stage conditions were selected to achieve
roughly 6 wt % conversion relative to 370.degree. C. This produced
a heavy neutral lubricant base stock in a 93.7 wt % yield relative
to the heavy neutral feed. The resulting heavy neutral base stock
had a VI of 106.6 and a kinematic viscosity at 100.degree. C. of
11.7 cSt. For the brightstock feed, the sweet stage conditions were
selected to achieve roughly 30 wt % conversion relative to
370.degree. C. This produced a brightstock base stock in a 54.3 wt
% yield relative to the brightstock feed. The resulting brightstock
base stock had a VI of 103 and a kinematic viscosity at 100.degree.
C. of 32 cSt. Additionally, a yield of 16.1 wt % of a light neutral
lubricant boiling range product was generated with a kinematic
viscosity at 100.degree. C. of 6 cSt and a viscosity index of
roughly 100. This additional light neutral lubricant boiling range
product was optionally suitable for recycle to either the light
neutral or heavy neutral processing block. This could allow, for
example, the light neutral or heavy neutral processing block to be
operated at a reduced temperature (due to further reduced nitrogen
in the combined feed). Such reduced temperature can be favorable
for further reducing any additional aromatics that might be present
in the recycled product. Alternatively, the additional light
neutral product could be recycled to the initial sour stage for
further upgrading, although this could lead to additional
production of fuels as opposed to lubricant products.
Example 6--Production of Base Stocks (Including Bright Stock) at
High Conversion
[0148] Another series of processing runs were performed using a
C.sub.5 DAO (75 wt % yield) as a feed for lubricant production. The
configuration was similar to Example 5. Block processing was used
for the sweet processing stage. The light neutral, heavy neutral,
and brightstock portions were processed under conditions to produce
two levels of conversion relative to 370.degree. C. In a first set
of runs, the combined sour stage and sweet stage conversion was 60
wt %. In a second set of runs, the combined sour stage and sweet
stage conversion was 82 wt %. It is noted that at high rates of
conversion during a single pass, any portions of a lubricant
product that are recycled could potentially undergo conversion
amounts of greater than 70 wt %, or greater than 75 wt %, or
greater than 80 wt %, such as up to 90 wt % or more.
[0149] Conventionally, conversion of greater than roughly 70 wt %
of a feedstock during lubricant product is believed to lead to
large reductions in viscosity index for resulting lubricant
products. Without being bound by any particular theory, this is
believed to be due in part to conversion of isoparaffins with the
feed at elevated levels of conversion. It has been surprisingly
discovered that feeds derived from high yield deasphalted oils
(such as deasphalting yields of at least 50 wt %) can be undergo
greater than 70 wt % conversion without having substantial
reductions in VI. This is believed to be related to the unusually
high aromatic content of lubricant feeds derived from high yield
deasphalted oils.
[0150] Table 5 shows results from processing the C.sub.5 DAO feed
in this example at conversion amounts of 60 wt % and 82 wt %
(combined conversion across initial sour stage and second sweet
stage) for production during block operation of a light neutral
product, a heavy neutral product, and a brightsock product. As
shown in Table 5, increasing the combined conversion results in
products with comparable (or potentially higher) viscosity index
values, while also allowing generating products with substantially
reduced pour point values.
TABLE-US-00006 TABLE 5 Product properties at varying conversion 82
wt % 60 wt % combined conversion combined conversion (relative to
370.degree. C.) (relative to 370.degree. C.) Light Neutral VI 106
106 Pour Point (.degree. C.) -64 -34 KV @ 100.degree. C. (cSt) 4.9
4.3 Heavy Neutral VI 100.9 100.5 Pour Point (.degree. C.) -48 -34
KV @ 100.degree. C. (cSt) 11.9 12.6 Bright Stock VI 109 106.3 Pour
Point (.degree. C.) -32 -20 KV @ 100.degree. C. (cSt) 34.6 43.2
Additional Embodiments
Embodiment 1
[0151] A method for making lubricant base stock, comprising:
hydroprocessing a feedstock comprising a 370.degree. C.+ fraction
under first effective hydroprocessing conditions to form a
hydroprocessed effluent, the at least a portion of the deasphalted
oil having an aromatics content of at least about 50 wt %, the
hydroprocessed effluent comprising a sulfur content of 300 wppm or
less, a nitrogen content of 100 wppm or less, or a combination
thereof; separating the hydroprocessed effluent to form at least a
first fraction comprising a T5 distillation point of at least
370.degree. C. and a kinematic viscosity at 100.degree. C. of 6 cSt
to 20 cSt (or 8 cSt to 16 cSt, or 10 cSt to 14 cSt);
hydroprocessing at least a portion of the first fraction under
second effective hydroprocessing conditions, the second effective
hydroprocessing conditions comprising catalytic dewaxing
conditions, to form a catalytically dewaxed effluent comprising a
370.degree. C.+ portion; and solvent extracting at least a portion
of the 370.degree. C.+ portion of the catalytically dewaxed
effluent to form a solvent processed effluent.
Embodiment 2
[0152] A method for making lubricant base stock, comprising:
performing solvent deasphalting, optionally using a C.sub.4+
solvent, under effective solvent deasphalting conditions on a
feedstock having a T5 boiling point of at least about 370.degree.
C. (or at least about 400.degree. C., or at least about 450.degree.
C., or at least about 500.degree. C.), the effective solvent
deasphalting conditions producing a yield of deasphalted oil of at
least about 50 wt % of the feedstock; hydroprocessing at least a
portion of the deasphalted oil under first effective
hydroprocessing conditions to form a hydroprocessed effluent, the
at least a portion of the deasphalted oil having an aromatics
content of at least about 50 wt %, the hydroprocessed effluent
comprising a sulfur content of 300 wppm or less, a nitrogen content
of 100 wppm or less, or a combination thereof; separating the
hydroprocessed effluent to form at least a first fraction
comprising a T5 distillation point of at least 370.degree. C. and a
kinematic viscosity at 100.degree. C. of 6 cSt to 20 cSt (or 8 cSt
to 16 cSt, or 10 cSt to 14 cSt); hydroprocessing at least a portion
of the first fraction under second effective hydroprocessing
conditions, the second effective hydroprocessing conditions
comprising catalytic dewaxing conditions, to form a catalytically
dewaxed effluent comprising a 370.degree. C.+ portion; and solvent
extracting at least a portion of the 370.degree. C.+ portion of the
catalytically dewaxed effluent to form a solvent processed
effluent.
Embodiment 3
[0153] A method for making lubricant base stock, comprising:
hydroprocessing a feedstock comprising a 370.degree. C.+ fraction
under first effective hydroprocessing conditions to form a
hydroprocessed effluent, the at least a portion of the deasphalted
oil having an aromatics content of at least about 50 wt %, the
hydroprocessed effluent comprising a sulfur content of 300 wppm or
less, a nitrogen content of 100 wppm or less, or a combination
thereof; separating the hydroprocessed effluent to form at least a
first fraction having a T5 distillation point of at least
370.degree. C.; hydroprocessing at least a portion of the first
fraction under second effective hydroprocessing conditions, the
second effective hydroprocessing conditions comprising catalytic
dewaxing conditions, to form a catalytically dewaxed effluent
comprising a 370.degree. C.+ portion, the 370.degree. C.+ portion
comprising a second fraction comprising a kinematic viscosity at
100.degree. C. of 6 cSt to 20 cSt (or 8 cSt to 16 cSt, or 10 cSt to
14 cSt); and solvent extracting at least a portion of the second
fraction to form a solvent processed effluent.
Embodiment 4
[0154] A method for making lubricant base stock, comprising:
performing solvent deasphalting, optionally using a C.sub.4+
solvent, under effective solvent deasphalting conditions on a
feedstock having a T5 boiling point of at least about 370.degree.
C. (or at least about 400.degree. C., or at least about 450.degree.
C., or at least about 500.degree. C.), the effective solvent
deasphalting conditions producing a yield of deasphalted oil of at
least about 50 wt % of the feedstock; hydroprocessing at least a
portion of the deasphalted oil under first effective
hydroprocessing conditions to form a hydroprocessed effluent, the
at least a portion of the deasphalted oil having an aromatics
content of at least about 50 wt %, the hydroprocessed effluent
comprising a sulfur content of 300 wppm or less, a nitrogen content
of 100 wppm or less, or a combination thereof; separating the
hydroprocessed effluent to form at least a first fraction
comprising a T5 distillation point of at least 370.degree. C.;
hydroprocessing at least a portion of the first fraction under
second effective hydroprocessing conditions, the second effective
hydroprocessing conditions comprising catalytic dewaxing
conditions, to form a catalytically dewaxed effluent comprising a
370.degree. C.+ portion, the 370.degree. C.+ portion comprising a
second fraction comprising a kinematic viscosity at 100.degree. C.
of 6 cSt to 20 cSt (or 8 cSt to 16 cSt, or 10 cSt to 14 cSt); and
solvent extracting at least a portion of the second fraction to
form a solvent processed effluent.
Embodiment 5
[0155] The method of Embodiment 3 or 4, further comprising
separating at least a portion of the catalytically dewaxed effluent
to form the second fraction or separating at least a portion of the
370.degree. C.+ portion of the catalytically dewaxed effluent to
form the second fraction.
Embodiment 6
[0156] The method of any of the above embodiments, wherein the
solvent processed effluent comprises a VI of at least 80 and a
kinematic viscosity at 100.degree. C. of 6 cSt to 20 cSt.
Embodiment 7
[0157] The method of any of the above embodiments, wherein the
solvent processed effluent comprises a pour point of -6.degree. C.
or less (or -10.degree. C. or less, or -15.degree. C. or less, or
-20.degree. C. or less), a cloud point of -2.degree. C. or less (or
-5.degree. C. or less or -10.degree. C. or less, or -15.degree. C.
or less, or -20.degree. C. or less), or a combination thereof.
Embodiment 8
[0158] The method of any of the above embodiments, wherein the
solvent extracting comprises solvent extracting with
N-methylpyrrolidone, furfural, phenol, or a combination
thereof.
Embodiment 9
[0159] The method of any of Embodiments 2 or 4-8, wherein the yield
of deasphalted oil is at least 55 wt %, or at least 60 wt %, or at
least 65 wt %, or at least 70 wt %, or at least 75 wt %, or wherein
the deasphalted oil has an aromatics content of at least 55 wt %,
or at least 60 wt %, or at least 65 wt %, or at least 70 wt % based
on a weight of the deasphalted oil, or a combination thereof.
Embodiment 10
[0160] The method of any of Embodiments 2 or 4-9, wherein the
C.sub.4+ solvent comprises a C.sub.5+ solvent, a mixture of two or
more C.sub.5 isomers, or a combination thereof.
Embodiment 11
[0161] The method of any of the above embodiments, wherein the
solvent processed effluent comprises a viscosity index of 80 to
160, or 80 to 140, or 80 to 120, or 90 to 160, or 90 to 140, or 90
to 120, or 100 to 160, or 100 to 140, or 120 to 160, or 120 to
140.
Embodiment 12
[0162] The method of any of the above embodiments, wherein prior to
the solvent extracting, the 370.degree. C.+ portion of the
catalytically dewaxed effluent or the second fraction comprises an
absorptivity at 226 nm of at least 0.020, or at least 0.025, or at
least 0.030, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 226 nm of less than 0.020, or less than 0.018,
or less than 0.016.
Embodiment 13
[0163] The method of any of the above embodiments, wherein prior to
the solvent extracting, the 370.degree. C.+ portion of the
catalytically dewaxed effluent or the second fraction comprises an
absorptivity at 254 nm of at least 0.010, or at least 0.012, or at
least 0.014, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 254 nm of less than 0.010, or less than 0.008,
or less than 0.006, or less than 0.004.
Embodiment 14
[0164] The method of any of the above embodiments, wherein prior to
the solvent extracting, the 370.degree. C.+ portion of the
catalytically dewaxed effluent or the second fraction comprises an
absorptivity at 275 nm of at least 0.010, or at least 0.012, or at
least 0.014, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 275 nm of less than 0.010, or less than 0.008,
or less than 0.006, or less than 0.004.
Embodiment 15
[0165] The method of any of the above embodiments, wherein prior to
the solvent extracting, the 370.degree. C.+ portion of the
catalytically dewaxed effluent or the second fraction comprises an
absorptivity at 302 nm of at least 0.020, or at least 0.025, or at
least 0.030, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 302 nm of less than 0.010, or less than 0.008,
or less than 0.006, or less than 0.004.
Embodiment 16
[0166] The method of any of the above embodiments, wherein prior to
the solvent extracting, the 370.degree. C.+ portion of the
catalytically dewaxed effluent or the second fraction comprises an
absorptivity at 310 nm of at least 0.030, or at least 0.035, or at
least 0.040, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 310 nm of less than 0.010, or less than 0.008,
or less than 0.006, or less than 0.004.
Embodiment 17
[0167] The method of any of the above embodiments, wherein prior to
the solvent extracting, the 370.degree. C.+ portion of the
catalytically dewaxed effluent or the second fraction comprises an
absorptivity at 325 nm of at least 0.010, or at least 0.012, or at
least 0.014, the 370.degree. C.+ portion of the catalytically
dewaxed effluent or the second fraction after extraction comprising
an absorptivity at 310 nm of less than 0.010, or less than 0.008,
or less than 0.006, or less than 0.004.
Embodiment 18
[0168] A solvent processed effluent produced according to any of
Embodiments 1-17.
Embodiment 19
[0169] A formulated lubricant formed from the solvent processed
effluent of Embodiment 18, the formulated optionally comprising an
additive.
[0170] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated. While the illustrative embodiments of the invention
have been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those skilled in the art without departing from the spirit
and scope of the invention. Accordingly, it is not intended that
the scope of the claims appended hereto be limited to the examples
and descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present invention, including all features which
would be treated as equivalents thereof by those skilled in the art
to which the invention pertains.
[0171] The present invention has been described above with
reference to numerous embodiments and specific examples. Many
variations will suggest themselves to those skilled in this art in
light of the above detailed description. All such obvious
variations are within the full intended scope of the appended
claims.
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