U.S. patent application number 10/949483 was filed with the patent office on 2005-05-26 for process for making lube oil basestocks.
Invention is credited to Riley, Kenneth L., Schleicher, Gary P., Smiley, Randolph J..
Application Number | 20050109679 10/949483 |
Document ID | / |
Family ID | 34594917 |
Filed Date | 2005-05-26 |
United States Patent
Application |
20050109679 |
Kind Code |
A1 |
Schleicher, Gary P. ; et
al. |
May 26, 2005 |
Process for making lube oil basestocks
Abstract
A process for producing lube oil basestocks involving contacting
a wax containing feedstock with a stacked bed catalyst system
thereby producing a lube oil boiling range basestock.
Inventors: |
Schleicher, Gary P.; (Baton
Rouge, LA) ; Riley, Kenneth L.; (Baton Rouge, LA)
; Smiley, Randolph J.; (Baton Rouge, LA) |
Correspondence
Address: |
EXXONMOBIL RESEARCH AND ENGINEERING COMPANY
P.O. BOX 900
1545 ROUTE 22 EAST
ANNANDALE
NJ
08801-0900
US
|
Family ID: |
34594917 |
Appl. No.: |
10/949483 |
Filed: |
September 24, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60518739 |
Nov 10, 2003 |
|
|
|
60608447 |
Sep 9, 2004 |
|
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Current U.S.
Class: |
208/210 ;
208/212; 208/216PP; 208/217 |
Current CPC
Class: |
C10G 45/08 20130101;
C10G 65/04 20130101; C10G 65/08 20130101; B01J 35/0006 20130101;
C10G 2400/10 20130101; C10G 2300/1022 20130101; B01J 23/85
20130101; B01J 35/1061 20130101 |
Class at
Publication: |
208/210 ;
208/216.0PP; 208/217; 208/212 |
International
Class: |
C10G 065/04; C10G
045/04 |
Claims
1. A process to prepare lubricating oil basestocks from a lube oil
boiling range feedstock comprising: a) contacting a lube oil
boiling range feedstock with a stacked bed hydrotreating catalyst
system in a reaction stage operated under effective hydrotreating
conditions thereby producing a hydrotreated effluent comprising at
least a gaseous product and a hydrotreated lubricating oil boiling
range feedstock; and b) stripping the hydrotreated effluent to
remove at least a portion of the gaseous product from the
hydrotreated effluent thereby producing at least a lubricating oil
basestock.
2. The process according to claim 1 wherein said lubricating oil
feedstock has a 10% distillation point greater than 650.degree. F.
(343.degree. C.) and an endpoint of greater than 800.degree. F.
(426.degree. C.), measured by ASTM D 86 or ASTM 2887, and are
derived from mineral sources, synthetic sources, or a mixture of
the two.
3. The process according to claim 2 wherein said lubricating oil
feedstock is selected from those derived from sources such as oils
derived from solvent refining processes such as raffinates,
partially solvent dewaxed oils, deasphalted oils, distillates,
vacuum gas oils, coker gas oils, slack waxes, foots oils and the
like, dewaxed oils, automatic transmission fluid feedstocks, and
Fischer-Tropsch waxes.
4. The process according to claim 2 wherein said lubricating oil
feedstock contains up to 0.2 wt. % of nitrogen, based on the
lubricating oil feedstock, and up to 3.0 wt. % of sulfur, based on
the lubricating oil feedstock.
5. The process according to claim 1 wherein said catalyst system
comprises at least a first and second hydrotreating catalyst.
6. The process according to claim 5 wherein said first
hydrotreating catalyst is selected from supported hydrotreating
catalysts comprising about 2 to 20 wt. % of at least one Group VIII
metal, and about 5 to 50 wt. % of at least one Group VI metal on a
high surface area support material having an average pore diameter
of greater than 10 nm.
7. The process according to claim 6 wherein said Group VIII metal
is selected from Co Ni, and mixtures thereof, said Group VI metal
is selected from Mo, W, and mixtures thereof, and said high surface
area support material is selected from silica, alumina, and
mixtures thereof.
8. The process according to claim 5 wherein said second catalyst is
a bulk metal hydrotreating catalyst comprising about 30 to about
100 wt. % of at least one Group VIII non-noble metal and at least
one Group VIB metal, based on the total weight of the bulk catalyst
particles, calculated as metal oxides and wherein the bulk catalyst
particles have a surface area of at least 10 m.sup.2/g.
9. The process according to claim 8 wherein said bulk metal
hydrotreating catalyst comprises one Group VIII non-noble metal and
two Group VIB metals wherein the molar ratio of Group VIB to Group
VIII non-noble metals ranges from 10:1-1:10.
10. The process according to claim 8 wherein the at least one Group
VIII non-noble metal and at least one Group VIB metals are present
as oxidic compounds of the corresponding metals, or if the catalyst
composition has been sulfided, sulfidic compounds of the
corresponding metals
11. The process according to claim 10 wherein the bulk metal
hydrotreating catalysts have a surface area of at least 50
m.sup.2/g, a pore size volume of about 0.05 to about 5 ml/g, and a
median diameter of at least 50 nm.
12. The process according to claim 1 wherein said effective
hydrotreating conditions include temperatures of from 150 to
400.degree. C., a hydrogen partial pressure of from 1480 to 20786
kPa (200 to 3000 psig), a space velocity of from 0.1 to 10 liquid
hourly space velocity (LHSV), and a hydrogen to feed ratio of from
89 to 1780 m.sup.3/m.sup.3 (500 to 10000 scf/B).
13. The process according to claim 5 wherein the catalyst system of
the present invention comprises about 5-95 vol. % of the first
hydrotreating catalyst with the second hydrotreating catalyst
comprising the remainder.
14. The process according to claim 6 wherein said first
hydrotreating catalyst has an average pore diameter of greater than
11 nm.
15. The process according to claim 6 wherein said first
hydrotreating catalyst has an average pore diameter of greater than
12 nm.
16. The process according to claim 5 wherein the catalyst system of
the present invention comprises about 40-60 vol. % of the first
catalyst with the second hydrotreating catalyst comprising the
remainder.
17. The process according to claim 5 wherein the catalyst system of
the present invention comprises about 5-50 vol. % of the first
catalyst with the second hydrotreating catalyst comprising the
remainder.
18. A process to prepare lubricating oil basestocks from a lube oil
boiling range feedstock comprising: a) contacting a lube oil
boiling range feedstock with a stacked bed hydrotreating catalyst
system comprising at least a first and second hydrotreating
catalyst in a reaction stage operated under effective hydrotreating
conditions thereby producing a hydrotreated effluent comprising at
least a gaseous product and a hydrotreated lubricating oil boiling
range feedstock; and b) stripping the hydrotreated effluent to
remove at least a portion of the gaseous product from the
hydrotreated effluent thereby producing at least a lubricating oil
basestock; wherein said first hydrotreating catalyst is selected
from supported hydrotreating catalysts comprising about 2 to 20 wt.
% of at least one Group VIII metal, and about 5 to 50 wt. % of at
least one Group VI metal on a high surface area support material
having an average pore diameter of greater than 10 nm and said
second hydrotreating catalyst is selected from bulk metal
hydrotreating catalyst comprising about 30 to about 100 wt. % of at
least one Group VIII non-noble metal and at least one Group VIB
metal, based on the total weight of the bulk catalyst particles,
calculated as metal oxides and wherein the bulk catalyst particles
have a surface area of at least 10 m.sup.2/g.
19. The process according to claim 18 wherein said lubricating oil
feedstock has a 10% distillation point greater than 650.degree. F.
(343.degree. C.) and an endpoint of greater than 800.degree. F.
(426.degree. C.), measured by ASTM D 86 or ASTM 2887, and are
derived from mineral sources, synthetic sources, or a mixture of
the two.
20. The process according to claim 19 wherein said lubricating oil
feedstock is selected from those derived from sources such as oils
derived from solvent refining processes such as raffinates,
partially solvent dewaxed oils, deasphalted oils, distillates,
vacuum gas oils, coker gas oils, slack waxes, foots oils and the
like, dewaxed oils, automatic transmission fluid feedstocks, and
Fischer-Tropsch waxes.
21. The process according to claim 19 wherein said lubricating oil
feedstock contains up to 0.2 wt. % of nitrogen, based on the
lubricating oil feedstock, and up to 3.0 wt. % of sulfur, based on
the lubricating oil feedstock.
22. The process according to claim 18 wherein said Group VIII metal
of said first hydrotreating catalyst is selected from Co Ni, and
mixtures thereof, said Group VI metal of said first hydrotreating
catalyst is selected from Mo, W, and mixtures thereof, and high
surface area support material is selected from silica, alumina, and
mixtures thereof.
23. The process according to claim 18 wherein said bulk metal
hydrotreating catalyst comprises one Group VIII non-noble metal and
two Group VIB metals wherein the molar ratio of Group VIB to Group
VIII non-noble metals ranges from 10:1-1:10.
24. The process according to claim 23 wherein the at least one
Group VIII non-noble metal and at least one Group VIB metals are
present as oxidic compounds of the corresponding metals, or if the
catalyst composition has been sulfided, sulfidic compounds of the
corresponding metals.
25. The process according to claim 18 wherein the bulk metal
hydrotreating catalysts have a surface area of at least 50
m.sup.2/g, a pore size volume of about 0.05 to about 5 ml/g, and a
median diameter of at least 50 nm.
26. The process according to claim 18 wherein said effective
hydrotreating conditions include temperatures of from 150 to
400.degree. C., a hydrogen partial pressure of from 1480 to 20786
kPa (200 to 3000 psig), a space velocity of from 0.1 to 10 liquid
hourly space velocity (LHSV), and a hydrogen to feed ratio of from
89 to 1780 m.sup.3/m.sup.3 (500 to 10000 scf/B).
27. The process according to claim 18 wherein the catalyst system
of the present invention comprises about 5-95 vol. % of the first
hydrotreating catalyst with the second hydrotreating catalyst
comprising the remainder.
28. The process according to claim 18 wherein said first
hydrotreating catalyst has an average pore diameter of greater than
11 nm.
29. The process according to claim 18 wherein said first
hydrotreating catalyst has an average pore diameter of greater than
12 nm.
30. The process according to claim 27 wherein the catalyst system
of the present invention comprises about 40-60 vol. % of the first
hydrotreating catalyst with the second hydrotreating catalyst
comprising the remainder.
31. The process according to claim 18 wherein the catalyst system
of the present invention comprises about 5-50 vol. % of the first
hydrotreating catalyst with the second hydrotreating catalyst
comprising the remainder.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional Patent
Application Ser. No. 60/518,739 filed Nov. 10, 2003 and Ser. No.
60/608,447 filed Sep. 9, 2004.
FIELD OF THE INVENTION
[0002] This invention relates to a process for preparing
lubricating oil basestocks from lube oil boiling range feedstreams.
More particularly, the present invention is directed at a process
wherein a wax containing feedstock is hydrotreated over a stacked
bed catalyst system thereby producing a lube oil boiling range
basestock.
BACKGROUND OF THE INVENTION
[0003] It has long been recognized that one of the most valuable
products generated through the refining of crude mineral oils is
lubricating oils. It is common practice to recover lubricating oil
basestocks by solvent extracting, with a selective solvent,
undesirable components such as sulfur compounds, oxygenated
compounds, and aromatics from straight distillates. However, with
the decline in the availability of paraffinic base crudes, and a
corresponding increase in the proportion of naphthenic and
asphaltic base crudes, it is becoming increasingly difficult to
meet the demand for lubricating oil basestocks, or base oils. For
example, American Petroleum Institute (API) requirements for Group
II basestocks include a saturates content of at least 90%, a sulfur
content of 0.03 wt. % or less and a viscosity index (VI) between 80
and 120. Thus, there is a trend in the lube oil market to use Group
II basestocks instead of Group I basestocks in order to meet the
demand for higher quality basestocks that provide for increased
fuel economy, reduced emissions, etc.
[0004] Conventional techniques for preparing basestocks such as
hydrocracking or solvent extraction require severe operating
conditions such as high pressure and temperature or high
solvent:oil ratios and high extraction temperatures to reach these
higher basestock qualities. Either alternative involves expensive
operating conditions and low yields.
[0005] Hydrocracking has been combined with hydrotreating as a
preliminary step. However, this combination also results in
decreased yields of lubricating oils due to the conversion to
distillates that typically accompany the hydrocracking process.
[0006] Thus, as the demand for quality lube oil basestock continues
to increase, the search for new and different processes, catalysts,
and catalyst systems that exhibit improved activity, increased
yields, selectivity and/or longevity is a continuous, ongoing
exercise. Therefore, there is a need in the lube oil market to
provide processes that can produce lube oil basestocks that meet
the demand for increased fuel economy, reduced emissions, etc.
BRIEF DESCRIPTION OF THE FIGURE
[0007] The FIGURE is a plot of the relative volume activity of
various catalysts and catalyst systems versus the days the
respective catalysts and catalyst systems were on stream.
SUMMARY OF THE INVENTION
[0008] The present invention is directed at a process to prepare
lubricating oil basestocks from lube oil boiling range feedstocks.
The process comprises:
[0009] a) contacting a lube oil boiling range feedstock with a
stacked bed hydrotreating catalyst system in a reaction stage
operated under effective conditions thereby producing a
hydrotreated effluent comprising at least a gaseous product and a
hydrotreated lubricating oil boiling range feedstock; and
[0010] b) stripping the hydrotreated effluent to remove at least a
portion of the gaseous product from the hydrotreated effluent
thereby producing at least a lubricating oil basestock.
[0011] In one embodiment of the instant invention, the stacked bed
hydrotreating catalyst system comprises a first and second
catalyst, the first catalyst comprising a conventional
hydrotreating catalyst having an average pore diameter of greater
than about 10 nm and said second catalyst comprises a bulk metal
hydrotreating catalyst.
DETAILED DESCRIPTION OF THE INVENTION
[0012] It should be noted that the terms "feedstock" and
"feedstream" as used herein are synonymous.
[0013] The present process involves hydrotreating a lubricating oil
feedstock with a stacked bed hydrotreating catalyst system in a
reaction stage operated under effective hydrotreating conditions to
produce a hydrotreated effluent comprising at least a gaseous
product and a hydrotreated lubricating oil feedstock. The
hydrotreated effluent is stripped to remove at least a portion of
the gaseous product from the hydrotreated effluent thereby
producing at least a lubricating oil basestock. Lube oil basestocks
having a saturates content of at least 90%, a sulfur content of
0.03 wt. % or less, and a viscosity index (VI) between 80 and 120
can readily be produced through the use of the instant
invention.
[0014] Lubricating Oil Feedstocks
[0015] Feedstocks suitable for use in the present invention are
wax-containing feeds that boil in the lubricating oil range,
typically having a 10% distillation point greater than 650.degree.
F. (343.degree. C.) and an endpoint greater than 800.degree. F.
(426.degree. C.), measured by ASTM D 86 or ASTM 2887. These
feedstocks can be derived from mineral sources, synthetic sources,
or a mixture of the two. Non-limiting examples of suitable
lubricating oil feedstocks include those derived from sources such
as oils derived from solvent refining processes such as raffinates,
partially solvent dewaxed oils, deasphalted oils, distillates,
vacuum gas oils, coker gas oils, slack waxes, foots oils and the
like, dewaxed oils, automatic transmission fluid feedstocks, and
Fischer-Tropsch waxes. Automatic transmission fluid ("ATF")
feedstocks are lube oil feedstocks having an initial boiling point
between about 200.degree. C. and 275.degree. C., and a 10%
distillation point greater than about 300.degree. C. ATF feedstocks
are typically 75-110N feedstocks.
[0016] These feedstocks may also have high contents of nitrogen-
and sulfur-contaminants. Feeds containing up to 0.2 wt. % of
nitrogen, based on feed and up to 3.0 wt. % of sulfur can be
processed in the present process. Feeds having a high wax content
typically have high viscosity indexes of up to 200 or more. Sulfur
and nitrogen contents may be measured by standard ASTM methods
D5453 and D4629, respectively.
[0017] Hydrotreating
[0018] It should be noted that the term "hydrotreating" as used
herein refers to processes wherein a hydrogen-containing treat gas
is used in the presence of a suitable catalyst that is primarily
active for the removal of heteroatoms, such as sulfur, and
nitrogen, and saturation of aromatics. In the practice of the
present invention, the lubricating oil feedstock is hydrotreated
with a stacked bed hydrotreating catalyst system in a reaction
stage operated under effective hydrotreating conditions to produce
a hydrotreated effluent comprising at least a gaseous product and a
hydrotreated lubricating oil feedstock.
[0019] The catalyst system used herein comprises at least a first
and second hydrotreating catalyst. By "stacked bed" it is meant
that the first catalyst appears in a separate catalyst bed,
reactor, or reaction zone, and the second hydrotreating catalyst
appears in a separate catalyst bed, reactor, or reaction zone
downstream, in relation to the flow of the lubricating oil
feedstock, from the first catalyst.
[0020] The first hydrotreating catalyst is a supported catalyst.
Suitable hydrotreating catalysts for use as the first catalyst of
the present catalyst system include any conventional hydrotreating
catalyst. Conventional hydrotreating catalyst as used herein is
meant to refer to those which are comprised of at least one Group
VIII metal, preferably Fe, Co and Ni, more preferably Co and/or Ni,
and most preferably Ni; and at least one Group VI metal, preferably
Mo and W, more preferably Mo, on a high surface area support
material, preferably alumina. The Group VIII metal is typically
present in an amount ranging from about 2 to 20 wt. %, preferably
from about 4 to 12%. The Group VI metal will typically be present
in an amount ranging from about 5 to 50 wt. %, preferably from
about 10 to 40 wt. %, and more preferably from about 20 to 30 wt.
%. All metals weight percents are on support. By "on support" we
mean that the percents are based on the weight of the support. For
example, if the support were to weigh 100 g. then 20 wt. % Group
VIII metal would mean that 20 g. of Group VIII metal was on the
support.
[0021] However, not all conventional hydrotreating catalysts
fitting the above-described criteria are suitable for use in the
present invention. The inventors hereof have unexpectedly found
that the average pore diameter of the first catalyst must have a
specific size to be suitable for use herein. Thus, in the practice
of the present invention, a conventional catalyst, as described
above, but having an average pore diameter greater than 10 nm, as
measured by water adsorption porosimetry, must be used as the first
catalyst of the present stacked bed catalyst system. It is
preferred that the average pore diameter of the first catalyst,
i.e. the conventional hydrotreating catalyst, of the present
stacked bed catalyst system be greater than 11 nm, more preferably
greater than 12 nm.
[0022] The second hydrotreating catalyst is a bulk metal catalyst.
By bulk metal, it is meant that the catalysts are unsupported
wherein the bulk catalyst particles comprise 30-100 wt. % of at
least one Group VIII non-noble metal and at least one Group VIB
metal, based on the total weight of the bulk catalyst particles,
calculated as metal oxides and wherein the bulk catalyst particles
have a surface area of at least 10 m.sup.2/g. It is furthermore
preferred that the bulk metal hydrotreating catalysts used herein
comprise about 50 to about 100 wt. %, and even more preferably
about 70 to about 100 wt. %, of at least one Group VIII non-noble
metal and at least one Group VIB metal, based on the total weight
of the particles, calculated as metal oxides. The amount of Group
VIB and Group VIII non-noble metals can easily be determined VIB
TEM-EDX.
[0023] Bulk catalyst compositions comprising one Group VIII
non-noble metal and two Group VIB metals are preferred. It has been
found that in this case, the bulk catalyst particles are
sintering-resistant. Thus the active surface area of the bulk
catalyst particles is maintained during use. The molar ratio of
Group VIB to Group VIII non-noble metals ranges generally from
10:1-1:10 and preferably from 3:1-1:3. In the case of a core-shell
structured particle, these ratios of course apply to the metals
contained in the shell. If more than one Group VIB metal is
contained in the bulk catalyst particles, the ratio of the
different Group VIB metals is generally not critical. The same
holds when more than one Group VIII non-noble metal is applied. In
the case where molybdenum and tungsten are present as Group VIB
metals, the molybenum:tungsten ratio preferably lies in the range
of 9:1-1:9. Preferably the Group VIII non-noble metal comprises
nickel and/or cobalt. It is further preferred that the Group VIB
metal comprises a combination of molybdenum and tungsten.
Preferably, combinations of nickel/molybdenum/tungsten and
cobalt/molybdenum/tungsten and nickel/cobalt/molybdenum/tungsten
are used. These types of precipitates appear to be
sinter-resistant. Thus, the active surface area of the precipitate
is remained during use. The metals are preferably present as oxidic
compounds of the corresponding metals, or if the catalyst
composition has been sulfided, sulfidic compounds of the
corresponding metals.
[0024] It is also preferred that the bulk metal hydrotreating
catalysts used herein have a surface area of at least 50 m.sup.2/g
and more preferably of at least 100 m.sup.2/g. It is also desired
that the pore size distribution of the bulk metal hydrotreating
catalysts be approximately the same as the one of conventional
hydrotreating catalysts. More in particular, these bulk metal
hydrotreating catalysts have preferably a pore volume of 0.05-5
ml/g, more preferably of 0.1-4 ml/g, still more preferably of 0.1-3
ml/g and most preferably 0.1-2 ml/g determined by nitrogen
adsorption. Preferably, pores smaller than 1 nm are not present.
Furthermore these bulk metal hydrotreating catalysts preferably
have a median diameter of at least 50 nm, more preferably at least
100 nm, and preferably not more than 5000 .mu.m and more preferably
not more than 3000 .mu.n. Even more preferably, the median particle
diameter lies in the range of 0.1-50 .mu.m and most preferably in
the range of 0.5-50 .mu.m.
[0025] The reaction stage containing the stacked bed hydrotreating
catalyst system used in the present invention can be comprised of
one or more fixed bed reactors or reaction zones each of which can
comprise one or more catalyst beds of the same or different
catalyst. Although other types of catalyst beds can be used, fixed
beds are preferred. Such other types of catalyst beds include
fluidized beds, ebullating beds, slurry beds, and moving beds.
Interstage cooling or heating between reactors, reaction zones, or
between catalyst beds in the same reactor, can be employed since
some olefin saturation can take place, and olefin saturation and
the desulfurization reaction are generally exothermic. A portion of
the heat generated during hydrotreating can be recovered. Where
this heat recovery option is not available, conventional cooling
may be performed through cooling utilities such as cooling water or
air, or through use of a hydrogen quench stream. In this manner,
optimum reaction temperatures can be more easily maintained.
[0026] The catalyst system of the present invention comprises about
5-95 vol. % of the first catalyst with the second catalyst
comprising the remainder, preferably about 40-60 vol. %, more
preferably about 5 to about 50 vol. %. Thus, if the catalyst system
comprises 50 vol. % of the first catalyst, the second catalyst will
comprise 50 vol. % also.
[0027] Effective hydrotreating conditions include temperatures of
from 150 to 400.degree. C., a hydrogen partial pressure of from
1480 to 20786 kPa (200 to 3000 psig), a space velocity of from 0.1
to 10 liquid hourly space velocity (LHSV), and a hydrogen to feed
ratio of from 89 to 1780 m.sup.3/m.sup.3 (500 to 10000 scf/B).
[0028] As stated above, the contacting of the lube oil boiling
range feedstock with the stacked bed hydrotreating catalyst system
produces a hydrotreated effluent comprising at least a gaseous
product and a hydrotreated lubricating oil feedstock. The
hydrotreated effluent is stripped to remove at least a portion of
the gaseous product from the hydrotreated effluent thereby
producing at least a lubricating oil basestock The means used
herein to strip the hydrotreated effluent is not critical to the
present invention. Thus, any stripping method, process, or means
known can be used. Non-limiting examples of suitable stripping
methods, means, and processes include flash drums, fractionators,
knock-out drums, steam stripping, etc.
[0029] The above description is directed to preferred embodiments
of the present invention. Those skilled in the art will recognize
that other embodiments that are equally effective could be devised
for carrying out the spirit of this invention.
[0030] The following examples will illustrate the improved
effectiveness of the present invention, but is not meant to limit
the present invention in any fashion.
EXAMPLES
Example 1
[0031] A medium vacuum gas oil having the properties outlined in
Table 1 was processed in an isothermal pilot plant over three
catalysts systems at 1200 psig hydrogen partial pressure. The
catalyst systems and operating conditions are given in Table 2.
Catalyst B is a conventional hydrotreating catalyst having about
4.5 wt. % Group VI metal, about 23 wt. % Group VIII metal on an
alumina support and has an average pore size of 14.0 nm. The bulk
metal hydrotreating catalyst was a commercial bulk metal
hydrotreating catalyst marketed under the name Nebula by
Akzo-Nobel.
[0032] In the Examples, all the catalyst systems were lined out at
about 50 days on stream. A first order kinetic model with an
activation energy of 31,000 cal/gmol was used to compare volume
activities between the catalysts.
1 TABLE 1 Medium Vacuum Gas Oil Density at 70.degree. C. (g/cc)
0.88 Nitrogen (wppm) 700 Sulfur (wt. %) 2.6 GCD 5 WT % Boiling
Point (.degree. C.) 334 GCD 50 WT % Boiling Point (.degree. C.) 441
GCD 95 WT % Boiling Point (.degree. C.) 531
[0033]
2TABLE 2 50 vol. % Catalyst B 100 vol. % 100 vol. % followed by
Catalyst System Catalyst B Nebula 1 50 vol. % Nebula 1 Average
Catalyst 370 380 370 Temperature (.degree. C.) Liquid Hourly 2 1 1
Space Velocity (hr.sup.-1) Stripped reactor 227 17 34 Effluent
Nitrogen Content (wppm) Nitrogen Removal 1 1.18 1.34 Relative
Volume Activity
[0034] The Nitrogen Removal Relative Volume Activity ("RVA") for
each catalyst system was calculated by simple first order kinetic
modeling. As shown in Table 2, the 50/50 vol. % stacked bed
catalyst system, with the large average pore size Catalyst B
upstream of the bulk metal catalyst, showed higher nitrogen removal
activity than either of the single catalyst systems demonstrated on
their own.
Example 2
[0035] The hydrotreating ability of different stacked beds of
Catalyst B and Nebula were analyzed by hydrotreating different
feedstreams over the stacked beds in the in two parallel reactor
trains of the same isothermal pilot plant unit used in Example 1
above. The feedstreams used were Medium Cycle Oils ("MCO") from an
FCC unit and blends of the MCO with a virgin feedstock were tested
in two parallel reactor trains. The feed properties are described
in Table 3, below.
[0036] In this Example, one reactor train consisted entirely of a
conventional NiMo on Alumina hydrotreating catalyst, Catalyst C,
with an average pore diameter of 7.5 nm. The other reactor train
contained a stacked bed system with 75-vol. % of Catalyst C
followed by 25-vol. % of Catalyst A, a bulk multimetallic sulfide
catalyst having an average pore diameter of 5.5 nm.
[0037] The separate reactors in both trains were immersed in a
fluidized sandbath for efficient heat transfer. Thus, the
temperature of the first 75-vol. % of Catalyst C was at the same
temperature whether it was in train 1 or 2. Likewise, the last
25-vol. % of Catalyst C in train 1 was at the same temperature as
the last 25-vol. % of Catalyst A in train 2. Therefore, In Example
2, each of the two reactor trains was divided into two separate
reactor vessels where the temperature of the first 75-volume %
containing 75 vol. % of the catalyst loading of that reactor could
be independently controlled from the last 25-volume % of
catalyst.
[0038] The operating conditions for the two trains were 1350 psig
H.sub.2, liquid hourly space velocities ("LHSV") of 1.4
vol./hr/vol., and 5500-6300 SCF/B of hydrogen. The temperature
schedule for both trains is described in Table 4 below.
3 TABLE 3 FEED 50% 67% 100% 100% Normal Normal Normal Heavy FCC MCO
FCC MCO FCC MCO FCC MCO API Gravity 18.1 15.0 9.5 7.0 Hydrogen,
10.65 10.04 8.77 8.61 wt. % Sulfur, wt. % 3.23 3.53 4.28 4.40
Nitrogen, ppm 959 1153 1485 1573 Aromatics- -- -- 12.0 8.8 Mono,
wt. % Aromatics-Di, -- -- 43.9 41.7 wt. % Aromatics- -- -- 22.4
30.7 Poly, wt. % Distillation, D2887 GCD 10 498 493 485 493 50 627
625 618 642 90 703 705 706 749 95 726 721 724 777
[0039]
4TABLE 4 Days on Oil Feedstock 75%/25% Temperatures, .degree. F.
4-6 50% FCC MCO 585/650 7-15 67% FCC MCO 585/650 16-30 100% FCC MCO
585-610/650-675 31-50 100% Heavy FCC MCO 610-635/675-700
[0040] The relative HDN volume activity of the stacked bed Catalyst
C/Catalyst A compared to Catalyst A is shown in the FIGURE below.
Note that for the 50%, 67% and 100% FCC MCO feeds the stacked bed
system with only 25-volume % of catalyst A shows a stable activity
advantage of about 275%.
[0041] As shown in the FIGURE, when the 100% Heavy FCC MCO was used
as the feed note the activity advantage for the stacked bed
catalyst system containing begins to decrease from about 275% to
about 225% and then was subsequently reduced over about 20 days to
slightly less than 150%.
Example 3
[0042] In this Example, a stacked bed catalyst system containing 75
vol. % of Catalyst B and 25 vol. % Nebula, both as described above,
was used to hydrotreat a light cycle cat oil feed ("Feed A") and a
heavier medium cycle cat oil feed ("Feed B") as described in Table
5 below. Example 2 was conducted in the same two reactor train
pilot plant unit as described in Example 2 above. The operating
conditions for the two trains were 1200 psig H.sub.2, liquid hourly
space velocities of 2 vol./hr/vol., and 5000 SCF/B of hydrogen.
[0043] The reactor effluents were stripped with nitrogen in an oven
at 100.degree. C. to remove substantially all of the gaseous
reaction products. The nitrogen content of the liquid reactor
effluent was then analyzed by ASTM 4629. The temperature schedules
for both trains along with the results of this example are
described in Table 5 below.
5 TABLE 5 FEED Feed A Feed B API Gravity 0.973 0.9 Sulfur, wt. %
2.6 2.50 Nitrogen, ppm 713 742 Distillation, D2887 GCD 5 427 448 50
551 590 95 707 755 EP 764 823 Catalyst B Temperature 570 617 Nebula
Temperature 645 692 Stripped Reactor Effluent 2 7 Nitrogen Content
Nitrogen Removal Relative 1.75 1.75 Volume Activity
[0044] As can be seen in Table 5, when a conventional catalyst
having an average pore diameter of 14 nm was used in the first 75
vol. % of the reactor, the Nitrogen Removal Relative Volume
Activity ("RVA") for the catalyst system remained constant when the
heavier feed was used. In comparing the results of Example 3 to
those obtained in Example 2, one can see that when a catalyst
having a pore volume of 7.5 nm preceded the bulk metal catalyst,
the RVA of the catalyst system decreased. However, in Example 3,
the heavier feed did not negatively impact the RVA of the catalyst
system.
* * * * *