U.S. patent application number 10/943756 was filed with the patent office on 2006-03-23 for high activity hydrodesulfurization catalyst, a method of making a high activity hydrodesulfurization catalyst, and a process for manufacturing an ultra-low sulfur distillate product.
Invention is credited to Opinder Kishan Bhan.
Application Number | 20060060510 10/943756 |
Document ID | / |
Family ID | 35431248 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060060510 |
Kind Code |
A1 |
Bhan; Opinder Kishan |
March 23, 2006 |
High activity hydrodesulfurization catalyst, a method of making a
high activity hydrodesulfurization catalyst, and a process for
manufacturing an ultra-low sulfur distillate product
Abstract
A method of making a high activity catalyst composition suitable
for use in the hydrodesulfurization of a middle distillate feed,
such as diesel fuel, having a high concentration of sulfur, to
thereby provide a low sulfur middle distillate product. The method
comprises heat treating aluminum hydroxide under controlled
temperature conditions thereby converting said aluminum hydroxide
to gamma-alumina to give a converted aluminum hydroxide, and
controlling the fraction of said converted aluminum hydroxide that
is gamma-alumina by controlling said controlled temperature
conditions to within a calcination temperature range of from
850.degree. F. (454.degree. C.) to 950.degree. C. (510.degree. C.)
so that essentially all of said aluminum hydroxide is converted to
a transition alumina but less than a material amount of the
converted aluminum hydroxide is converted to a transition alumina
other than gamma-alumina. A catalytic component is incorporated
into said converted aluminum hydroxide to provide an intermediate,
which is heat treated to provide said high activity catalyst
composition. The high activity catalyst composition can, thus,
comprises gamma-alumina and a catalytic component, but having a
material absence of aluminum hydroxide and a phase of a transition
alumina other than gamma-alumina. Another embodiment of the high
activity catalyst composition comprises a support material
consisting essentially of gamma-alumina and a catalytic component.
The high activity catalyst composition can suitably be used in the
hydrodesulfurization of a middle distillate feed containing a high
sulfur concentration.
Inventors: |
Bhan; Opinder Kishan; (Katy,
TX) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
35431248 |
Appl. No.: |
10/943756 |
Filed: |
September 17, 2004 |
Current U.S.
Class: |
208/213 ;
208/216R; 208/217; 502/314 |
Current CPC
Class: |
B01J 35/1042 20130101;
B01J 27/19 20130101; B01J 23/75 20130101; C10G 2300/202 20130101;
B01J 23/755 20130101; C10G 45/08 20130101; B01J 21/04 20130101;
B01J 35/10 20130101; B01J 23/28 20130101; C10G 2300/1055 20130101;
B01J 23/882 20130101; B01J 35/1019 20130101; B01J 35/1047 20130101;
B01J 35/108 20130101; B01J 37/08 20130101; C10G 2400/04 20130101;
B01J 23/88 20130101; B01J 35/1061 20130101; B01J 37/0009
20130101 |
Class at
Publication: |
208/213 ;
502/314; 208/216.00R; 208/217 |
International
Class: |
C10G 45/04 20060101
C10G045/04; B01J 23/00 20060101 B01J023/00 |
Claims
1. A method of making a catalyst composition suitable for use in
the manufacture of ultra low sulfur diesel, said method comprises:
forming a shaped particle comprising at least 90 weight percent,
exclusive of water, boehmite; heat treating said shaped particle
under a controlled temperature condition to convert said boehmite
of said shaped particle to gamma-alumina; controlling said
controlled temperature condition to within a calcination
temperature range of from about 850.degree. F. and 950.degree. F.
so as to convert said boehmite to a crystalline transitional phase
of alumina thereby providing a heat treated shaped particle;
incorporating a hydrogenation catalytic component into said heat
treated shaped particle to thereby provide an impregnated heat
treated shaped particle; and heat treating said impregnated heat
treated shaped particle to thereby provide said catalyst
composition.
2. A method as recited in claim 1, wherein said controlled
temperature condition provides for the conversion of essentially
all but a non-material amount of said boehmite of said shaped
particle to be converted to a transitional crystalline phase of
alumina.
3. A method as recited in claim 2, wherein said controlled
temperature condition further provides for said transitional
crystalline phase that comprises gamma alumina and further wherein
said transitional crystalline phase includes a material absence of
said transitional crystalline phase of alumina other than gamma
alumina.
4. A method as recited in claim 3, wherein said heat treated shaped
particle contains less than 5 weight percent boehmite with the
weight percent being based on the total weight of said heat treated
shaped particle.
5. A method as recited in claim 4, wherein less than 5 weight
percent of said alumina of said heat treated shaped particle is
said transitional crystalline phase of alumina other than gamma
alumina.
6. A method as recited in claim 5, wherein the median pore diameter
of said heat treated shaped particle is in the range of from about
70 angstroms to about 120 angstroms, wherein the total pore volume
of said heat treated shaped particle is in the range of from about
0.5 cc/gram to about 1.1 cc/gram, and wherein more than 70 percent
of the total pore volume of said heat treated shaped particle is
contained in the pores having a pore diameter of from 70 angstroms
to 350 angstroms.
7. A method as recited in claim 6, wherein said hydrogenation
catalytic component is selected from the group of consisting of
molybdenum compounds, cobalt compounds, nickel compounds,
phosphorous compounds, and any combination of one or more of such
compounds.
8. A method as recited in claim 7, wherein said heat treating of
said impregnated heat treated shaped particle is conducted so that
the at least 90 weight percent of the alumina of said catalyst
composition is in the crystalline transitional phase of gamma
alumina and less than 5 weight percent of the alumina of said
catalyst composition is in the crystalline transitional phase other
than gamma alumina.
9. A method as recited in claim 8, wherein said catalyst
composition is characterized as having a median pore diameter in
the range of from about 80 angstroms to about 110 angstroms, a
total pore volume in the range of from about 0.6 cc/gram to about
1.1 cc/gram, and more than 70 percent of said total pore volume
that is contained in the pores having a pore diameter of from 80
angstroms to 350 angstroms.
10. A method as recited in claim 9, wherein said catalyst
composition further comprises a molybdenum compound in the range of
from about 3 to about 30 weight percent, calculated as molybdenum
trioxide, a cobalt compound in the range of from about 0.01 to
about 10 weight percent, calculated as cobalt oxide, and a
phosphorous compound in the range of from about 0.01 weight percent
to about 5 weight percent, calculated as phosphorous.
11. A method of making a catalyst composition suitable for use in
the manufacture of ultra low sulfur diesel, said method comprises:
forming a shaped particle comprising at least 90 weight percent,
exclusive of water, boehmite; calcining said shaped particle under
a controlled temperature condition to convert said boehmite of said
shaped particle to gamma-alumina; controlling said controlled
temperature condition to within a calcination temperature range of
from about 850.degree. F. and 950.degree. F. so that a substantial
portion of said boehmite of said shaped particle is converted to a
crystalline transitional phase of alumina but less than a material
amount of said boehmite of said shaped particle is converted to a
crystalline transitional phase other than gamma-alumina to thereby
provide a calcined shaped particle; impregnating said calcined
shaped particle with a hydrogenation catalytic component to thereby
provide an impregnated calcined shaped particle; and calcining said
impregnated calcined shaped particle to thereby provide said
catalyst composition.
12. A method as recited in claim 11, wherein said calcined shaped
particle has a material absence of both boehmite and a crystalline
transitional phase of alumina other than gamma-alumina.
13. A method as recited in claim 12, wherein said calcined shaped
particle contains less than 5 weight percent boehmite with the
weight percent being based on the total weight of said calcined
shaped particle.
14. A method as recited in claim 13, wherein less than 5 weight
percent of said alumina of said calcined shaped particle is said
transitional crystalline phase of alumina other than gamma
alumina.
15. A method as recited in claim 14, wherein the median pore
diameter of said calcined shaped particle is in the range of from
about 80 angstroms to about 110 angstroms, wherein the total pore
volume of said calcined shaped particle is in the range of from
about 0.6 cc/gram to about 1.1 cc/gram, and wherein more than 70
percent of the total pore volume of said calcined shaped particle
is contained in the pores having a pore diameter of from 80
angstroms to 350 angstroms.
16. A method as recited in claim 15, wherein said hydrogenation
catalytic component is selected from the group of consisting of
molybdenum compounds, cobalt compounds, nickel compounds,
phosphorous compounds, and any combination of one or more of such
compounds.
17. A method as recited in claim 16, wherein said calcining of said
impregnated calcined shaped particle is conducted so that the at
least 90 weight percent of the alumina of the resulting said
catalyst composition is in the crystalline transitional phase of
gamma alumina and less than 5 weight percent of the alumina of said
catalyst composition is in the crystalline transitional phase other
than gamma alumina.
18. A method as recited in claim 17, wherein said catalyst
composition is characterized as having a median pore diameter in
the range of from about 80 angstroms to about 110 angstroms, a
total pore volume in the range of from about 0.6 cc/gram to about
1.1 cc/gram, and more than 70 percent of said total pore volume
that is contained in the pores having a pore diameter of from 80
angstroms to 350 angstroms.
19. A method as recited in claim 18, wherein said catalyst
composition further comprises a molybdenum compound in the range of
from about 2 to about 10 weight percent, calculated as molybdenum
trioxide, a cobalt compound in the range of from about 0.01 to
about 10 weight percent, calculated as cobalt oxide, and a
phosphorous compound in the range of from about 0.01 weight percent
to about 5 weight percent, calculated as phosphorous.
20. A method, comprising: providing a shaped support, having a
material absence of aluminum hydroxide and a material absence of a
crystalline transitional phase of alumina other than gamma-alumina;
incorporating a catalytic component into said shaped support to
thereby provide an intermediate; and calcining said intermediate to
thereby provide a catalyst composition comprising said catalytic
component and alumina wherein less than 5 weight percent of said
alumina is a crystalline transitional alumina phase other than
gamma alumina.
21. A method as recited in claim 20, wherein said material absence
of aluminum hydroxide in said shaped support is less than 5 weight
percent of the total weight of said shaped support that is aluminum
hydroxide and wherein said material absence of said crystalline
transitional phase of alumina other than gamma alumina in said
shaped support is less than 5 weight percent of the total weight of
said shaped support that is said crystalline transitional phase of
alumina other than gamma alumina.
22. A method as recited in claim 21, wherein less than 2 weight
percent of said alumina is a crystalline transitional alumina phase
other than gamma alumina.
23. A method as recited in claim 22, wherein less than 1 weight
percent of said alumina is a crystalline transitional alumina phase
other than gamma alumina.
24. A method as recited in claim 23, wherein said catalytic
component incorporated into said shaped support is such as to
provide said catalyst composition that further comprises a
molybdenum compound in the range of from about 2 to about 10 weight
percent, calculated as molybdenum trioxide, a cobalt compound in
the range of from about 0.01 to about 10 weight percent, calculated
as cobalt oxide, and a phosphorous compound in the range of from
about 0.01 weight percent to about 5 weight percent, calculated as
phosphorous.
25. A catalyst composition, comprising: a calcined impregnated
shaped support, wherein said shaped support of said impregnated
shaped support has a material absence of aluminum hydroxide and a
material absence of crystalline transitional phase of alumina other
than gamma-alumina prior to the impregnation thereof with a
hydrogenation catalytic component to thereby provide said
impregnated shaped support thereafter calcined.
26. A catalyst composition as recited in claim 25, wherein said
material absence of aluminum hydroxide in said shaped support is
less than 5 weight percent of the total weight of said shaped
support and wherein said material absence of said crystalline
transitional phase of alumina other than gamma alumina in said
shaped support is less than 5 weight percent of the total weight of
said shaped support.
27. A catalyst composition as recited in claim 26, wherein said
material absence of said crystalline transitional phase of alumina
other than gamma alumina is less than 2 weight percent of the total
weight of said shaped support.
28. A catalyst composition as recited in claim 27, wherein said
material absence of said crystalline transitional phase of alumina
other than gamma alumina is less than 1 weight percent of the total
weight of said shaped support.
29. A catalyst as recited in claim 28, wherein said hydrogenation
catalytic component in said catalyst composition includes a
molybdenum compound in the range of from about 3 to about 30 weight
percent, calculated as molybdenum trioxide, a cobalt compound in
the range of from about 0.01 to about 10 weight percent, calculated
as cobalt oxide, and a phosphorous compound in the range of from
about 0.01 weight percent to about 5 weight percent, calculated as
phosphorous, wherein the weight percents are based on the total
weight of said catalyst composition.
30. A catalyst as recited in claim 29, wherein said catalyst
composition is characterized as having a median pore diameter in
the range of from about 80 angstroms to about 110 angstroms, a
total pore volume in the range of from about 0.6 cc/gram to about
1.1 cc/gram, and more than 70 percent of said total pore volume
that is contained in the pores having a pore diameter of from 80
angstroms to 350 angstroms.
31. A catalyst composition suitable for use in the
hydrodesufurization of a middle distillate feedstock having a
concentration of sulfur to yield a ultra low sulfur middle
distillate product, said catalyst composition comprises: a calcined
impregnated shaped support, wherein said shaped support of said
impregnated shaped support comprises, prior to its impregnation and
calcination, at least 90 weight percent alumina that is in the
crystalline transitional phase of gamma-alumina, less than 5 weight
percent alumina that is in the crystalline transitional phase of
delta-alumina, and less than 5 weight percent alumina that is in
the crystalline transitional phase other than gamma-alumina and
delta-alumina, and wherein said shaped support has incorporated
therein a hydrogenation catalytic component thereby providing said
impregnated shaped support, and wherein said impregnated shaped
support is calcined.
32. A catalyst composition as recited in claim 31, having less than
2 weight percent alumina that is in the crystalline transitional
phase other than gamma alumina.
33. A catalyst composition as recited in claim 32, having less than
1 weight percent alumina that is in the crystalline transitional
phase other than gamma alumina.
34. A catalyst as recited in claim 33, wherein said hydrogenation
catalytic component in said catalyst composition includes a
molybdenum compound in the range of from about 3 to about 30 weight
percent, calculated as molybdenum trioxide, a cobalt compound in
the range of from about 0.01 to about 10 weight percent, calculated
as cobalt oxide, and a phosphorous compound in the range of from
about 0.01 weight percent to about 5 weight percent, calculated as
phosphorous, wherein the weight percents are based on the total
weight of said catalyst composition.
35. A catalyst as recited in claim 34, wherein said catalyst
composition is characterized as having a median pore diameter in
the range of from about 80 angstroms to about 110 angstroms, a
total pore volume in the range of from about 0.6 cc/gram to about
1.1 cc/gram, and more than 70 percent of said total pore volume
that is contained in the pores having a pore diameter of from 80
angstroms to 350 angstroms.
36. A catalyst composition, comprising: a support material
comprising, exclusive of catalytic components, alumina comprising
more than 90 weight percent gamma alumina and less than 5 weight
percent crystalline transitional phase other than gamma alumina;
and catalytic components including a molybdenum compound in the
range of from about 2 to about 10 weight percent, calculated as
molybdenum trioxide, a cobalt compound in the range of from about
0.01 to about 10 weight percent, calculated as cobalt oxide, and a
phosphorous compound in the range of from about 0.01 weight percent
to about 5 weight percent, calculated as phosphorous, wherein the
weight percents are based on the total weight of said catalyst
composition; and wherein said catalyst composition is characterized
as having a median pore diameter in the range of from about 80
angstroms to about 110 angstroms, a total pore volume in the range
of from about 0.6 cc/gram to about 1.1 cc/gram, and more than 70
percent of said total pore volume that is contained in the pores
having a pore diameter of from 80 angstroms to 350 angstroms.
37. A catalyst made by the methods of claims 1 through 24.
38. A process for making an ultra low sulfur diesel product, said
process comprises: contacting, under hydrodesulfurization
conditions, a diesel feedstock, wherein said diesel feedstock
comprises a first sulfur concentration, with a catalyst composition
of any one of claims 25 through 36; and yielding said ultra low
sulfur diesel product having a second sulfur concentration.
39. A process, comprising: contacting under hydrodesulfurization
conditions a middle distillate feedstock having a high sulfur
concentration with a catalyst composition of any one of claims 25
through 36 and yielding an ultra low sulfur middle distillate
feedstock having a ultra low sulfur concentration.
Description
[0001] This invention relates to a catalyst and process for the
manufacture of a hydrocarbon product having a low sulfur
concentration. The invention further relates to a high activity
hydrodesulfurization catalyst, a method of making such high
activity hydrodesulfurization catalyst, and a process for
manufacturing diesel distillate product having a low sulfur
concentration using the high activity hydrodesulfurization
catalyst.
[0002] U.S. Environmental Protection Agency regulations are
currently targeting for the year 2006 a limitation on the maximum
sulfur concentration in on-road diesel of 15 parts per million
(ppm). The European Union will limit the sulfur concentration in
diesel fuel starting in the year 2005 to less than 50 ppm. Other
organizations are supporting even stricter requirements of as low
as 5 to 10 ppm sulfur in diesel. With the current
hydrodesulfurization technology, the ability to produce such a low
sulfur diesel product is a real challenge, and there are ongoing
efforts to develop improvements in the existing
hydrodesulfurization technology that will permit the economical
hydrodesulfurization of a sulfur-containing diesel feed stream to
yield an ultra-low sulfur diesel product.
[0003] A conventional hydrodesulfurization process employed to
reduce the concentration of organosulfur compounds contained in a
hydrocarbon feedstock is typically carried out by contacting the
hydrocarbon feedstock with a hydrotreating catalyst in the presence
of hydrogen and at an elevated temperature and pressure. A typical
hydrotreating catalyst contains a group 6 metal component, such as
molybdenum, and a group 9 or group 10 component, such as cobalt or
nickel, supported on a refractory oxide support.
[0004] One early patent, U.S. Pat. No. 3,669,904, discloses a
method of making a gas oil hydrodesulfurization catalyst prepared
from a precursor mixture of mildly calcined boehmite and uncalcined
boehmite. The disclosed method addresses certain of the
disadvantages and limitations with the use of technical grade
boehmite in forming extruded pellets for use in making certain
catalysts. The gamma alumina pellets are made by mixing a mildly
calcined technical grade boehmite with uncalcined technical grade
boehmite and an extrusion aid followed by forming a pellet that is
calcined.
[0005] U.S. Pat. No. 3,853,789 discloses a method of making a
mechanically strong alumina extrudate that may be used as a
catalyst carrier. The extrudate is prepared by mixing with water
specific proportions of gamma alumina powder having a certain
particle size and alumina monohydrate (boehmite) having a certain
particle size to form an extrudable paste from which an extrudate
is formed. The extrudate is dried and then heat-treated at
temperatures of 1150 to 1250.degree. F.
[0006] U.S. Pat. No. 4,066,574 discloses a catalyst for use in the
hydrodesulfurization of a heavy oil feedstock. The catalyst is an
alumina support that is impregnated with Group VIB and Group VIII
metals or metal compounds. The alumina support has a specific pore
structure that provides for certain desired catalyst properties.
The alumina support is made by mixing water and a strong mineral
acid with amorphous or crystalline hydrate alumina powder to form a
paste that is extruded. The density of the extrudate may be
controlled by the addition of ammonium hydroxide to the extrudable
paste. The extrudate is calcined at a temperature of 500.degree. F.
to 1600.degree. F. The support has at least 70 volume percent of
its pore volume in pores having a diameter between 80 and 150
Angstroms and less than 3 volume percent of its pore volume in
pores having a diameter above 1000 Angstroms.
[0007] U.S. Pat. No. 4,089,811 discloses a method of making an
alumina catalyst support by calcining alpha alumina monohydrate
(boehmite) at a temperature of from about 800.degree. F. to
900.degree. F. to form calcined alumina containing gamma alumina
and mixing the calcined alumina with water to form a wetted
alumina. The wetted alumina at a pH of from 6 to 12.5 is heated to
a temperature of from 190.degree. F. to 250.degree. F. for from 8
to 24 hours to convert the calcined alumina to beta alumina
trihydrate. Maintaining the calcination temperature within the
range of 800 to 900.degree. F. is important to achieve the desired
results. The calcined alumina contains at least about 80% gamma
alumina with the remaining portion of the alumina being
substantially entirely alpha alumina monohydrate.
[0008] U.S. Pat. No. 4,271,042 discloses a desulfurization catalyst
that comprises a hydrogenation catalytic component composited with
gamma alumina that contains dispersed delta and/or theta phase
alumina. The catalyst is prepared by precalcining gamma alumina or
boehmite at a temperature of from 1600.degree. F. to 2000.degree.
F. to induce the formation of delta and/or theta phase alumina. The
resulting powder is then mixed with alpha alumina monohydrate
(boehmite) and formed into pellets or extrudates that are calcined
at a temperature of from 900.degree. F. to 1400.degree. F. to form
a catalyst support consisting of an intimate mixture of gamma
alumina with delta and/or theta phase alumina. The catalyst support
may be composited with the hydrogenation component.
[0009] U.S. Pat. No. 5,300,217 discloses a hydroprocessing catalyst
that comprises a hydrogenation component supported on a porous,
amorphous refractory oxide containing delta alumina. The finished
catalyst contains greater than 5 weight percent delta alumina. The
amorphous, porous refractory oxide support material is prepared by
extruding a precursor of the desired support, such as a refractory
gel, followed by calcination of the extrudate. To obtain the
desired delta-gamma alumina combination for the support, it is
precalcined, prior to impregnation with the hydrogenation
component, at a temperature above about 900.degree. F. and
preferably above 1800.degree. F.
[0010] With the increasingly stricter sulfur concentration
requirements for diesel fuels there is an ongoing need to develop
improved catalysts and processes for the manufacture of the low
sulfur diesel fuels.
[0011] It is, thus, an object of the invention to provide an
improved catalyst for use in processes for the manufacture of a
distillate product having a low concentration of sulfur.
[0012] Another object of the invention is to provide a process for
making low sulfur distillate product.
[0013] Thus, in accordance with the invention, provided is a
catalyst composition that comprises a shaped support material
having incorporated therein a catalytic hydrogenation component
wherein the shaped support material is a calcined alumina having a
material absence of aluminum hydroxide and a material absence of
crystalline transitional phase of alumina other than gamma alumina.
Another embodiment of the catalyst composition comprises a calcined
impregnated shaped support, wherein the shaped support of the
impregnated shaped support comprises, prior to its impregnation and
calcination, at least 90 weight percent alumina that is in the
crystalline transitional phase of gamma-alumina, less than 5 weight
percent alumina that is in the crystalline transitional phase of
delta-alumina, and less than 5 weight percent alumina that is in
the crystalline transitional phase other than gamma-alumina, and
wherein the shaped support has incorporated therein a hydrogenation
catalytic component thereby providing the impregnated shaped
support, and wherein the impregnated shaped support is
calcined.
[0014] In accordance with another invention is a method of making a
catalyst composition useful in the manufacture of a low sulfur
distillate product. This method includes providing a shaped
support, having a material absence of aluminum hydroxide and a
material absence of crystalline transitional phase of alumina,
comprising gamma-alumina, and incorporating therein a catalytic
component to thereby provide an intermediate, and calcining the
intermediate to thereby provide the catalyst composition. Another
embodiment of the inventive method of making the catalyst
composition includes forming a shaped particle comprising at least
90 weight percent, exclusive of water, boehmite, and calcining the
shaped particle under a controlled temperature condition to convert
the boehmite of the shaped particle to gamma-alumina. The
controlled temperature condition is controlled to within a
calcination temperature range of from about 850.degree. F. and
950.degree. F. so that essentially all of the boehmite of the
shaped particle is converted to a crystalline transitional phase of
alumina but less than a material amount of the boehmite of the
shaped particle is converted to a crystalline transitional phase
other than gamma-alumina to thereby provide a calcined shaped
particle. The calcined shaped particle is impregnated with a
hydrogenation catalytic component to thereby provide an impregnated
calcined shaped particle that is calcined to thereby provide the
catalyst composition.
[0015] In accordance with yet another invention is a process for
manufacturing a low sulfur distillate product by contacting under
hydrodesulfurization conditions a middle distillate hydrocarbon
feedstock having a high sulfur concentration with the
aforedescribed catalyst or a catalyst made by the aforedescribed
method and yielding a low sulfur middle distillate product having a
low sulfur concentration.
[0016] FIG. 1 presents the X-ray diffraction spectrum for a shaped
support calcined at a calcination temperature of 750.degree. F.
[0017] FIG. 2 presents the X-ray diffraction spectrum for a shaped
support calcined at a calcination temperature of 850.degree. F.
[0018] FIG. 3 presents the X-ray diffraction spectrum for a shaped
support calcined at a calcination temperature of 900.degree. F.
[0019] FIG. 4 presents plots of the reaction temperature required
for the desulfurization of a diesel feed stock under certain test
conditions to yield a diesel product having a 10 ppm sulfur
concentration as a function of catalyst age for an inventive
catalyst and for a comparative catalyst.
[0020] FIG. 4 presents a contour plot with each contour line
representing a single sulfur concentration of a desulfurized middle
distillate product resulting from the use of a catalyst made by an
embodiment of the inventive method which uses a carefully
controlled heat treatment of the catalyst support followed by a
carefully controlled heat treatment of the impregnated heat treated
catalyst support.
[0021] A novel catalyst composition has been discovered that has a
particularly high activity when used in the hydrodesulfurization of
a hydrocarbon distillate feed stock, such as, for example, diesel
oil, that has a high concentration of sulfur or sulfur compounds
such as organosulfur compounds. This catalyst composition can
provide for significantly improved diesel desulfurization activity
when compared to other known hydrodesulfurization catalyst
compositions. It is especially useful in the manufacture of an
ultra-low sulfur diesel product that has a sulfur concentration of
less than 15 parts per million (ppm) and even less than 10 ppm or
less than 8 ppm.
[0022] It has been discovered that the inventive high activity
catalyst composition is a supported catalyst in which a
hydrogenation component is supported on a specially made shaped
support that comprises gamma (.gamma.) alumina. This shaped support
can have a material absence of the transition alumina phases of
delta (.delta.) alumina, theta (.theta.) alumina and kappa
(.kappa.) alumina. The shaped support further can have a material
absence of aluminum hydrate, and it can even further have a
material absence of aluminum hydrate and transition alumina phases
other than gamma alumina. Thus, the shaped support of the inventive
catalyst composition can comprise gamma alumina and have a material
absence of aluminum hydroxide and forms of transitional crystalline
phases of alumina other than gamma alumina. Indeed, one important
embodiment of the invention is that the shaped support, upon or
into which is incorporated the hydrogenation catalytic component,
has a material absence of the transitional crystalline phases of
alumina, such as, for example, alpha (.alpha.) alumina, delta
(.delta.) alumina, eta (.eta.) alumina, kappa (.kappa.) alumina,
and theta (.theta.) alumina, and additionally, a material absence
of aluminum hydroxide, such as, for example, alpha mono aluminum
monohydrate (boehmite).
[0023] A particularly important aspect of the inventive method for
preparing the catalyst composition includes the use of certain
starting materials and the formation of a shaped particle that is
heat treated under carefully controlled temperature and heat
treatment conditions so as to provide a heat treated shaped
particle having the desired composition required for forming the
final catalyst composition having high activity when used for the
desulfurization of a distillate feed stock. The controlled heat
treatment of the shaped particle is followed by the incorporation
of the catalytic component into the heat treated shaped particle
and a second carefully controlled temperature and heat treatment
step.
[0024] The starting material used in preparing the shaped support
particle of the catalyst composition is selected from among
aluminum hydroxides, which are also referred to by those skilled in
the art and herein as alumina hydrate or hydrated alumina, that
when prepared and treated in accordance with the particular
features of the inventive preparation method will provide a heat
treated support particle and catalyst composition having a high
hydrodesulfurization activity. Various aluminum hydroxides are
commercially available, but the preferred aluminum hydroxide for
use in preparing the shaped support particle is alpha alumina
monohydrate, which is also referred to as boehmite, having the
chemical formula .alpha.-AlO(OH).
[0025] In general, the starting boehmite material used in the
preparing the shaped support particle is in the form of a powder,
and it is particularly desirable for the boehmite material to be a
high purity boehmite with more than 98 percent and even more than
99 percent of the boehmite material being in the form of alpha
alumina monohydrate. It is also desirable for the boehmite material
to contain less than small amounts of impurities, such as, silicon
dioxide (SiO.sub.2), iron oxide (Fe.sub.2O.sub.3) and alkali
(Na.sub.2O) and alkaline earth (MgO) metals. For instance, the
silicon dioxide should be present in the boehmite material at a
concentration of less than 200 ppm, and, preferably, less than 150
ppm. But, typically, the silicon dioxide may be present in the
range of from 80-130 ppm. The iron oxide should be present in the
boehmite material at a concentration of less than 200 ppm, but,
typically, the concentration may be present in the range of from 50
to 150 ppm. The alkali metal should be present at a concentration
of less than 50 ppm, but, typically, it may be present in the range
of from 5 to 40 ppm.
[0026] The shaped support of the starting material may be formed by
any suitable method known to those skilled in the art; provided,
that a shaped particle of the starting support material can be
subsequently heat treated in accordance with the invention to
provide a heat treated shaped support particle having the necessary
properties of the invention. Examples of known shaping methods
include tableting, pelletizing, and extrusion methods.
[0027] It is preferred to use an extrusion method to form the
shaped support particle. To make the shaped support particle by
this method, the starting aluminum hydroxide material is mixed with
water and, if required, a suitable acid compound, in proportions
and in a manner so as to form an extrudable paste suitable for
extruding through an extrusion die to thereby form an extrudate.
Generally, the weight ratio of aluminum hydroxide-to-water mixed
together to form the extrudable paste is in the range of from 0.1:1
to 10:1, but, more typically, the weight ratio of aluminum
hydroxide-to-water is in the range of from 0.5:1 to 5:1. The
preferred weight ratio of aluminum hydroxide-to-water used to form
the extrudable paste is in the range of from 0.75:1 to 3:1, and,
most preferred, it is in the range of from 1:0 to 2:0.
[0028] The acid compound added to the mixture of aluminum hydroxide
and water can be any suitable acid that assists in the formation of
a suitable extrudable paste, and it is generally used to control
the pH of the mixture to within the range of from 3 to 7. Strong
mineral acids, such as nitric acid, may be used, but the preferred
acid is acetic acid.
[0029] The formed extrudate used as the shaped support particle of
the invention may have any cross-sectional shape such as
cyclinderical shapes, polylobal shapes or any other suitable shape.
A typical size of extrudate has a cross-sectional diameter in the
range of from about 1/10 inch to 1/32 inch and a length-to-diameter
ratio in the range of from 2:1 to 5:1. The preferred shape is a
tri-lobe.
[0030] It is an important aspect of the method of preparing the
shaped support particle and the final catalyst composition of the
invention for the shaped support particle to substantially entirely
comprise aluminum hydroxide, exclusive of the water content. The
preferred form of the aluminum hydroxide is boehmite, and
especially preferred is high purity boehmite. Thus, the shaped
particle will comprise at least 90 weight percent aluminum
hydroxide, wherein the weight percent is based upon the dry weight
of the shaped support particle, i.e., the weight percent is based
on the total weight of the shaped support particle exclusive of the
weight of the water contained in the shaped support particle. It is
preferred, however, for the shaped particle to comprise at least 95
weight percent aluminum hydroxide, and, most preferred, the shaped
particle can comprise at least 98 weight percent aluminum
hydroxide.
[0031] The shaped support particle is then heat treated under
treatment conditions that include the careful control of the
temperature conditions so as to assure that the resulting heat
treated shaped support particle does not contain undesirable
amounts of delta alumina and theta aluminum and, even, other phases
of alumina; and, preferably, so as to assure that essentially all
the aluminum hydrate is converted to an alumina phase, which is
preferably the gamma alumina phase. Therefore, the heat treatment
temperature is controlled during the heat treatment of the shaped
particle to within a specific temperature range to give a heat
treated shaped particle having a material absence of the transition
alumina phases of delta (.delta.) alumina, eta (.eta.) alumina,
theta (.theta.) alumina and kappa (.kappa.) alumina. Through the
carefully controlled heat treatment of the shaped support it
further can have a material absence of aluminum hydroxide, and even
a material absence of aluminum hydroxide and a material absence of
transition alumina phases other than gamma alumina.
[0032] The temperature at which the heat treatment is conducted is
controlled to within a narrow range and for a heat treatment time
period so as to provide the heat treated shaped particle that has
the properties as described herein. The temperature during the heat
treatment be can controlled to within the range of from about
850.degree. F. to about 950.degree. F. for a heat treatment time
period in the range of from about 0.5 hours to about 72 hours or
even a longer time period as is required to provide the necessary
conversion of the starting aluminum hydroxide material to the
desired alumina phase. More specifically, the controlled
temperature condition is controlled so that the heat treatment
temperature does not exceed 940.degree. F. so as to minimize the
conversion of the starting aluminum hydroxide material to the
undesirable delta alumina, eta alumina, theta alumina, kappa
alumina, and alpha alumina phases. It is preferred for the
controlled heat treatment temperature to not exceed 920.degree. F.,
and, most preferred, the controlled heat treatment temperature
should not exceed 910.degree. F. In order to provide for the
required conversion of the starting aluminum hydroxide material to
the desirable alumina phase of gamma alumina, the controlled heat
treatment temperature should exceed 850.degree. F., and,
preferably, the controlled heat treatment temperature should exceed
875.degree. F. Most preferably, the controlled heat treatment
temperature should exceed 890.degree. F.
[0033] What is meant when referring herein to the "material
absence" of a particular component of the heat treated shaped
particle is that the relevant component is not present therein in
an amount that significantly affects the ultimate catalytic
properties of the final catalyst composition of the invention. It
is believed that the significant presence of various phases of
alumina other than gamma alumina and of aluminum hydrate in the
heat treated shaped particle used to make the final catalyst
composition can have a negative impact on the diesel
hydrodesulfurization activity of the final catalyst composition.
Thus, while small amounts of the alumina phases other than gamma
alumina and of aluminum hydrate may be present in the heat treated
shaped particle used in the preparation of the final catalyst
composition, such amounts should be insignificant so that they do
not materially negatively affect the activity of the final
catalyst. But, in any event, less than 5 weight percent of the
alumina of the heat treated shaped particle is in a crystalline
alumina phase other than gamma alumina, such as the alumina phases
of delta alumina, theta alumina, eta alumina, kappa alumina and
alpha alumina, and preferably less than 2 weight percent, and, most
preferably, less than 1 weight percent, of the alumina of the heat
treated shaped particle is in a crystalline transitional phase
other than gamma alumina.
[0034] It is also an important aspect of the invention that the
heat treated shaped particle contain a material absence of aluminum
hydroxide. Therefore, a substantial portion of the aluminum
hydroxide contained in the shaped particle prior to its heat
treatment should be converted by the heat treatment to a
crystalline phase of alumina, preferably, gamma alumina. The heat
treated shaped particle, thus, should contain an insubstantial
amount of aluminum hydroxide, for instance, less than 5 weight
percent based on the total weight of the heat treated shaped
particle. Preferably, the heat treated shaped particle contains
less than 2 weight percent, and, most preferably, less than 1
weight percent aluminum hydroxide.
[0035] The heat treated shaped particle has a specific pore
structure including a characteristic median pore diameter, total
pore volume and pore size distribution. Generally, the median pore
diameter of the heat treated shaped particle is in the range of
from about 70 angstroms to 120 angstroms, but, preferably, the
median pore diameter is in the range of from 80 angstroms to 110
angstroms. More preferably, the median pore diameter of the heat
treated shaped particle is in the range of from 90 angstroms to 100
angstroms.
[0036] The total pore volume of the heat treated shaped particle is
generally in the range of from about 0.5 cubic centimeters per gram
(cc/gram) to about 1.1 cc/gram. Preferably, the total pore volume
is in the range of from 0.6 cc/gram to 1 cc/gram, and, most
preferably, from 0.7 cc/gram to 0.9 cc/gram.
[0037] The percentage of the total pore volume contained in the
pores of the heat treated shaped particle having a pore diameter
less than 80 angstroms is less than 25 percent and, among these
pores, less than 3 percent of the total pore volume of the heat
treated shaped particle is in the pores having a diameter smaller
than 50 angstroms. As for the pores having a diameter between 80
angstroms to 350 angstroms, more than 70 percent of the total pore
volume of the heat treated shaped particle is contained in such
pores. It is preferred, however, for at least 75 percent, and, most
preferred, at least 80 percent, of the total volume to be in the
pores having a diameter between 80 to 350 angstroms. Less than 3
percent of the total pore volume of the heat treated shaped
particle is in the pores having a pore diameter greater than 350
angstroms.
[0038] The references herein to the pore size distribution and pore
volume of the alumina support material are to those properties as
determined by mercury penetration porosimetry. The measurement of
the pore size distribution of the alumina support material is by
any suitable measurement instrument using a contact angle of
140.degree. with a mercury surface tension of 474 dyne/cm at
25.degree. C.
[0039] Following the formation of the heat treated shaped particle,
the catalytic components are incorporated into the heat treated
shaped particle, which is thereafter subjected to a second heat
treatment, again, under carefully controlled heat treatment
conditions so as to assure that an insignificant amount of the
alumina support is converted to undesirable crystalline alumina
phases. Any suitable means or method may be used to incorporate the
catalytic components into the heat treated shaped particle, but any
of the known impregnation methods, such as, spray impregnation,
soaking, multi-dip procedures, and incipient wetness impregnation
methods, are preferred. The catalytic components include
hydrogenation catalytic components such as those selected from
Group 6 of the IUPAC Periodic Table of the Elements (e.g. chromium
(Cr), molybdenum (Mo), and tungsten (W)) and Groups 9 and 10 of the
IUPAC Periodic Table of the Elements (e.g. cobalt (Co) and nickel
(Ni)). Phosphorus (P) is also a desired catalytic component.
[0040] The catalytic components may be incorporated into the heat
treated shaped particle using one or more impregnation solutions
containing one or more of the catalytic components. The preferred
impregnation solution is an aqueous solution of the desired
catalytic component or precursor thereof. In the case of a Group 9
or 10 metal, Group 9 or 10 metal acetates, carbonates, nitrates,
and sulfates or mixtures of two or more thereof may be used, with
the preferred compound being a metal nitrate such as nitrates of
nickel or cobalt. In the case of a Group 6 metal, a salt of the
Group 6 metal, which may be a precursor of the metal oxide or
sulfide, may be used in the impregnation solution. Preferred are
salts containing the Group 6 metal and ammonium ion, such as
ammonium heptamolybdate and ammonium dimolybdate. The concentration
of the metal compounds in the impregnation solution is selected so
as to provide the desired metal concentration in the final catalyst
composition of the invention. Typically, the concentration of the
metal compound in the impregnation solution is in the range of from
0.01 to 100 moles per liter.
[0041] The amounts of catalytic metal compound and, if desired,
phosphorous compound, incorporated or impregnated into the heat
treated shaped particle is such that when the impregnated, heat
treated shaped particle is subsequently subjected to a heat
treatment, the final catalyst composition of the invention has the
desired concentrations of the catalytic components. The amount of
Group 6 metal contained in the final catalyst composition generally
should be in the range of from about 3 to about 30, preferably from
4 to 27, and, most preferably, from 5 to 20 weight percent,
calculated as a Group 6 metal trioxide and based on the total
weight of the final catalyst composition inclusive of the catalytic
components. The amount of Group 9 or 10 metal contained in the
final catalyst composition generally should be in the range of from
about 0.01 to about 10, preferably from 0.1 to 8, and, most
preferably, from 1 to 6 weight percent, calculated as a Group 9 or
10 metal monoxide and based on the total weight of the final
catalyst composition inclusive of the catalytic components. If the
final catalyst contains a phosphorous component, it is present at a
concentration in ther range of from about 0.01 to about 5 weight
percent, calculated as phosphorous.
[0042] The heat treatment of the impregnated heat treated shaped
particle, as in the heat treatment of the shaped particle, is also
conducted under carefully controlled heat treatment temperature
conditions so as to assure that an insignificant portion of the
alumina therein is converted to the undesirable crystalline
transitional phases of alumina. Indeed, one embodiment of the
invention includes the combined use of specific heat treatment
conditions for each of the two heat treatment steps to provide the
final catalyst having unexpectedly better middle distillate
hydrodesulfurization catalytic performance. It has been found that
an unexpected improvement in the desulfurization performance of the
final catalyst is achieved when the temperature conditions of the
second heat treatment step shifted to somewhat higher temperatures
than those used in the first heat treatment step.
[0043] A final catalyst having especially good middle distillate
desulfurization properties is obtained when the temperature range
of the first heat treatment step to yield the heat treated particle
is, as discussed above, from about 850.degree. F. to about
950.degree. F. and the temperature range of the second heat
treatment step to yield the final catalyst is from about
870.degree. F. to about 1000.degree. F. A preferred temperature
range at which the second heat treatment step is conducted is from
880.degree. F. to 990.degree. F., and, most preferred, from
900.degree. F. to 980.degree. F. The second heat treatment step is
conducted for a time period necessary to provide the desired final
catalyst composition and can generally be in the range of from
about 0.5 hours to about 72 hours. Relative to the upper
temperature limit for the first heat treatment step, the upper
limit for the temperature for the second heat treatment step should
be no more than about 35.degree. C. (63.degree. F.) above the upper
temperature limit of the first heat treatment step, and,
preferably, it is no more than 30.degree. C. (54.degree. F.). Most
preferably, the upper temperature limit for the second heat
treatment step in which the impregnated heat treated shaped
particle is heat treated is no more than 25.degree. C. (45.degree.
F.) of the upper temperature limit of the first heat treatment
step.
[0044] The final catalyst composition, i.e., the impregnated heat
treated shaped particle that itself has been heat treated, has a
specific pore structure including a characteristic median pore
diameter, total pore volume and pore size distribution. Generally,
the median pore diameter of the final catalyst composition is in
the range of from about 80 angstroms to 110 angstroms, but,
preferably, the median pore diameter is in the range of from 85
angstroms to 105 angstroms. More preferably, the median pore
diameter of the final catalyst composition is in the range of from
90 angstroms to 100 angstroms.
[0045] The total pore volume of the final catalyst composition is
generally in the range of from about 0.6 cubic centimeters per gram
(cc/gram) to about 1.1 cc/gram. Preferably, the total pore volume
is in the range of from 0.65 cc/gram to 1 cc/gram, and, most
preferably, from 0.7 cc/gram to 0.9 cc/gram.
[0046] The percentage of the total pore volume contained in the
pores of the final catalyst composition having a pore diameter less
than 80 angstroms is less than 25 percent and, among these pores,
less than 3 percent of the total pore volume of the final catalyst
composition is in the pores having a diameter smaller than 50
angstroms. As for the pores having a diameter between 80 angstroms
to 350 angstroms, more than 70 percent of the total pore volume of
the final catalyst composition is contained in such pores. It is
preferred, however, for at least 75 percent, and, most preferred,
at least 80 percent, of the total volume to be in the pores having
a diameter between 80 to 350 angstroms. Less than 3 percent of the
total pore volume of the final catalyst composition is in the pores
having a pore diameter greater than 350 angstroms.
[0047] The catalyst composition of the invention is particularly
suitable for use in a process for the hydrodesulfurization of a
middle distillate hydrocarbon feed stock, having a concentration of
sulfur or sulfur compounds, in order to make a low sulfur middle
distillate hydrocarbon product. More specifically, the catalyst
composition may be used in a process for the manufacture of an
ultra-low sulfur diesel product having a sulfur concentration of
less than 15 ppm, preferably, less than 10 ppm, and, most
preferably, less than 8 ppm.
[0048] The middle distillate hydrocarbon feed stock as referred to
herein is intended to include refinery hydrocarbon streams having
boiling temperatures at atmospheric pressure in the range of from
about 140.degree. C. (284.degree. F.) to about 410.degree. C.
(770.degree. F.). These temperatures are approximate initial and
final boiling temperatures of the middle distillate. Examples of
the refinery streams intended to be included within the meaning of
middle distillate hydrocarbon include straight run distillate fuels
boiling in the referenced boiling range, such as, kerosene, jet
fuel, light diesel oil, heating oil, and heavy diesel oil, and the
cracked distillates, such as FCC cycle oil, coker gas oil, and
hydrocracker distillates. The preferred feedstock of the inventive
process is a middle distillate boiling in the diesel boiling range
of from about 140.degree. C. (284.degree. F.) to about 400.degree.
C. (752.degree. F.).
[0049] The sulfur concentration of the middle distillate feedstock
can be a high concentration, for instance, being in the range of
upwardly to about 2 weight percent of the middle distillate
feedstock based on the weight of elemental sulfur and the total
weight of the middle distillate feedstock inclusive of the sulfur
compounds. Typically, however, the middle distillate feedstock of
the inventive process has a sulfur concentration in the range of
from 0.01 wt. % (100 ppm) to 1.8 wt. % (18,000 ppm). But, more
typically, the sulfur concentration is in the range of from 0.1 wt.
% (1000 ppm) to 1.6 wt. % (16,000 ppm), and, most typically, from
0.18 wt. % (1800 ppm) to 1.1 wt. % (11,000 ppm). It is understood
that the references herein to the sulfur content of the distillate
feedstock are to those compounds that are normally found in a
distillate feedstock or in the hydrodesulfurized distillate product
that contain a sulfur atom and generally include organosulfur
compounds.
[0050] The final catalyst of the invention may be employed as a
part of any suitable reactor system that provides for the
contacting of the catalyst with the middle distillate feedstock
under suitable hydrodesulfurization reaction conditions that
include the presence of hydrogen and an elevated total pressure and
temperature. Such suitable reactor systems can include fixed
catalyst bed systems, ebullating catalyst bed systems, slurried
catalyst systems, and fluidized catalyst bed systems. The preferred
reactor system is that which includes a fixed bed of the inventive
final catalyst composition contained within a reactor vessel
equipped with an reactor feed inlet means, such as a feed inlet
nozzle, for introducing the feedstock into the reactor vessel, and
a reactor effluent outlet means, such as an effluent outlet nozzle,
for withdrawing the reactor effluent or the low sulfur distillate
product from the reactor vessel.
[0051] For the desulfurization of a diesel feedstock, having a
sulfur concentration, the hydrodesulfurization reaction temperature
is generally in the range of from about 200.degree. C. (392.degree.
F.) to 420.degree. C. (788.degree. F.). The preferred
hydrodesulfurization reaction temperature is in the range of from
260.degree. C. (500.degree. F.) to 400.degree. C. (752.degree. F.),
and, most preferred, from 320.degree. C. (608.degree. F.) to
380.degree. C. (716.degree. F.). It is recognized that one of the
unexpected features of the use of the inventive catalyst
composition is that it has a higher hydrodesulfurization activity
than certain conventional catalysts, and, thus, will in general
provide for a comparatively lower process temperature than such
conventional catalysts.
[0052] The inventive process generally operates at a
hydrodesulfurization reaction pressure in the range of from about
100 psig to about 2000 psig, preferably, from 275 psig to 1500
psig, and, most preferably, from 290 psig to 1000 psig. The flow
rate at which the distillate feedstock is charged to the reaction
zone of the inventive process is generally such as to provide a
liquid hourly space velocity (LHSV) in the range of from about 0.1
hr.sup.-1 upwardly to about 10 hr.sup.-1. The term "weight average
space velocity", as used herein, means the numerical ratio of the
rate at which the distillate feedstock is charged to the reaction
zone of the process in volume per hour divided by the volume of
catalyst composition contained in the reaction zone to which the
distillate feedstock is charged. The preferred LHSV is in the range
of from 0.1 hr.sup.-1 to 250 hr.sup.-1, and, most preferred, from
0.5 hr.sup.-1 to 5 hr.sup.-1.
[0053] The hydrogen treat gas rate is the amount of hydrogen
charged to reaction zone with the distillate feedstock. The amount
of hydrogen relative to the amount of distillate hydrocarbon
feedstock charged to the reaction zone is in the range upwardly to
about 10,000 cubic meters hydrogen per cubic meter of distillate
hydrocarbon feedstock.
[0054] The desulfurized middle distillate product yielded from the
process of the invention has a low or reduced sulfur concentration
relative to the high sulfur concentration of the middle distillate
feedstock. One particularly advantageous aspect of the inventive
process is that it is capable of more economically providing for a
deeply desulfurized diesel product or an ultra low sulfur diesel
product. The low sulfur middle distillate product can have a sulfur
concentration that is less than 25 ppm. The ultra low sulfur diesel
product can have a sulfur concentration that is less than 15 ppm.
Preferably, the low sulfur middle distillate product and ultra low
sulfur diesel product has a sulfur concentration of less than 10
ppm, and, most preferably, less than 8 ppm.
[0055] The following examples are presented to further illustrate
the invention, but they are not to be construed as limiting the
scope of the invention.
EXAMPLE 1
[0056] This Example 1 describes the preparation of the alumina
support used in the making of the final catalyst composition of the
invention. The alumina support was calcined at various calcination
temperatures in order to determine the effect that calcination
temperature has on the properties of the calcined support used to
make the final catalyst composition of the invention and upon the
catalytic performance of the final catalyst composition of the
invention.
[0057] The shaped support was prepared first by dissolving 150
parts by weight Ni(NO.sub.3).sub.26H.sub.2O in 52 parts by weight
deionized water with heating to form a nickel nitrate solution. The
nickel nitrate solution was mixed with 3000 parts by weight (on dry
basis) of wide pore alumina and 30 parts by weight Superfloc 16
extrusion aid using a muller mixer. The components were mixed for a
sufficient period of time to provide an extrudable paste. The
resulting paste was extruded through 1.3 mm extrusion dies to form
extrusion particles of the shaped support.
[0058] A 700 gram sample of the shaped support was calcined at a
temperature of 750.degree. F. in a muffle furnace for a time period
of two hours to thereby provide a calcined shaped support (Sample
A).
[0059] 700 gram sample of the shaped support was calcined at a
temperature of 850.degree. F. in a muffle furnace for a time period
of two hours to thereby provide a calcined shaped support (Sample
B).
[0060] A 700 gram sample of the shaped support was calcined at a
temperature of 900.degree. F. in a muffle furnace for a time period
of two hours to thereby provide a calcined shaped support (Sample
C).
[0061] Presented in Table 1 are certain of the physical properties
of the calcined samples described above. Presented in Table 2 is
the pore size distribution as determined by mercury porosimetry of
the calcined samples. TABLE-US-00001 TABLE 1 Various properties of
the samples of shaped support calcined at different temperatures.
Pore Diameter Calcination Temperature (.ANG.) 750.degree. F.
(399.degree. C.) 850.degree. F. (454.degree. C.) 900.degree. F.
(482.degree. C.) less than 50 2.14 1.50 1.27 50-60 4.32 2.76 1.97
60-70 9.68 6.18 4.32 70-80 19.33 15.47 10.81 80-90 22.87 22.65
21.11 90-100 29.14 31.04 31.15 100-110 5.68 12.98 19.56 110-120
1.24 1.78 3.45 120-130 0.62 0.68 0.92 130-140 0.61 0.49 0.54
140-150 0.44 0.41 0.48 150-160 0.32 0.33 0.41 160-170 0.27 0.31
0.40 170-180 0.25 0.25 0.22 180-210 0.58 0.63 0.71 210-280 0.73
0.73 0.95 280-350 0.43 0.43 0.51 greater than 1.36 1.36 1.22
350
[0062] TABLE-US-00002 TABLE 2 Pore size distribution of samples of
shaped support calcined at different temperatures. 750.degree. F.
850.degree. F. 900.degree. F. Surface Area (M.sup.2/g) 320.8 296.6
304.71 Median Pore Diameter (.ANG.) 87 91 94 Total Hg Pore Volume
(cc/g) 0.752 0.751 0.772 H.sub.2O Pore Volume (ml/g) 0.77 0.82
0.825
[0063] FIGS. 1, 2 and 3 each presents the X-ray diffraction
spectrum for each of the samples of shaped support calcined at the
different temperatures (i.e., Sample A, Sample B and Sample C). As
may be observed from the spectra of the figures, the spectrum of
Sample C (FIG. 3) indicates that it has no significant amount of
boehmite present; however, the spectra for Samples A (FIG. 1) and B
(FIG. 2) indicate that they both contain a significant amount of
boehmite. Also, the spectrum of Sample C indicates that it is
predominantly gamma alumina with little, if any, amounts of other
phases of alumina being present.
EXAMPLE 2
[0064] This Example 2 describes the preparation of catalyst
compositions using the calcined samples described in Example 1.
These catalyst compositions were used in the hydrodesulfurization
activity tests presented in the following Example 3.
[0065] The catalyst compositions were prepared by impregnating the
samples of Example 1 with an impregnation solution followed by
drying the impregnated samples and calcination of the dried,
impregnated samples. The impregnation solution was prepared by
combining within a container vessel 34 parts by weight molybdenum
trioxide (MoO.sub.3), 8 parts by weight of 86.1% phosphoric acid
(H.sub.3PO.sub.4), and 77 parts by weight deionized water. The
mixture was heated to 180.degree. F. followed by the addition of 9
parts by weight cobalt hydroxide (Co(OH).sub.2). The solution was
then heated to 212.degree. F. followed by the addition of 4 parts
by weight citric acid monohydrate. The container was then covered
and the solution was heated until it became clear. The container
was then uncovered and the solution was heated to reduce the volume
thereof.
EXAMPLE 3
[0066] This Example 3 describes the experimental procedure used to
measure the performance of certain catalyst compositions prepared
as described in the above Examples 1 and 2 in the
hydrodesulfurization of a diesel feedstock having a high
concentration of sulfur (1.6 wt. %).
[0067] A laboratory stainless steel isothermal tube reactor, having
a nominal diameter of 3/4 inch, was packed with a 100 cc volume of
the relevant catalyst. As a part of the startup of the reactor, the
catalyst was presulfided by adding 68 grams of TNPS to 1000 grams
of the feedstock. The feed was introduced to the reactor at a rate
so as to provide an LHSV of 1 hr.sup.-1, and hydrogen was
introduced at a rate of 19.6 liters/hr. The reactor temperature was
ramped up over a 5 hour period to 400.degree. F. and held at
400.degree. F. for a period of 4 hours. Thereafter, the temperature
was ramped up to 650.degree. F. over a 4 hour period and then held
at 650.degree. F. for two hours. After the catalyst was
presulfided, the feed to the reactor was switched to an unspiked
feedstock. The feedstock used was a straight run gas oil containing
1.6 weight percent sulfur having ASTM D2887 distillation as
presented in the following Table 3. TABLE-US-00003 TABLE 3
Distillation Temperature of Straight Run Gas Oil Feedstock % Temp
(.degree. F.) T0 312 T10 455 T50 563 T90 649 T100 696
[0068] The reactor was operated at a pressure of 300 psig, the feed
rate was adjusted to provide a liquid hourly space velocity of 0.5,
and the hydrogen gas feed rate was 1200 standard cubic feed per
barrel of feed (based at 60.degree. F.). The reactor temperature
was adjusted so as to provide an ultra low sulfur diesel product
having a sulfur concentration of 10 ppmw.
[0069] FIG. 4 presents plots of the reaction temperature required
for the desulfurization of the gas oil feedstock to yield a product
having a sulfur concentration of 10 ppmw as a function of the age
for a representative inventive catalyst and for a comparative
catalyst. As can be seen from the plots, the inventive catalyst
demonstrates a significantly higher hydrodesulfurization activity
than does the comparative catalyst by requiring a lower
hydrodesulfurization temperature, which in some cases is as much as
20.degree. F. to 30.degree. F. lower.
EXAMPLE 4
[0070] This Example 4 describes, in general, the approach used to
develop a prediction model for predicting the sulfur concentration
of a desulfurized middle distillate feedstock obtained using
various catalysts prepared generally in accordance with the method
as described in Example 2.
[0071] Final catalyst compositions were made using supports
prepared as described in Example 1 that were calcined at different
temperatures ranging from 750.degree. F. to 1100.degree. F. These
supports were impregnated with catalytic components followed by
drying and then calcining the impregnated support material at
different temperatures ranging from 750.degree. F. to 1050.degree.
F. Each of the compositions was tested for its ability to
desulfurize a middle distillate feedstock having a high sulfur
concentration.
[0072] A graphical representation of the results of this study is
presented in the contour plot of FIG. 5. The X-axis of the contour
plot is the temperature at which the support material used in the
preparation of the final catalyst was calcined, and the Y-axis is
the temperature at which the impregnated calcined support material
was calcined. Each contour line represents a sulfur concentration
of the desulfurized middle distillate feedstock resulting from the
use of a final catalyst composition prepared using the inventive
two-step heat treatment method at the two different calcination
temperatures. The contour lines are a best fit of a number of data
points used to generate the contour plot.
[0073] As illustrated by the contour plot, the best performing
catalysts, based on their properties for middle distillate
desulfurization, are those prepared using a support material
calcined at a calcination temperature in the range of from about
850.degree. F. to 1000.degree. F., which the calcined support
material has been impregnated, dried and calcined at a temperature
in the range of from about 880.degree. F. to 1000.degree. F.
[0074] It is understood that while particular embodiments of the
invention have been described herein, reasonable variations,
modifications and adaptations thereof may be made that are within
the scope of the described disclosure and the appended claims
without departing from the scope of the invention as defined by the
claims.
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