HYDRODESULFURIZATION CATALYST FOR HYDROCARBON OIL
Technical Field
[0001] The present invention relates to a
hydrodesulfurization catalyst for hydrocarbon oils.
Background Art
[0002] Conventionally, a catalyst comprising metal
components selected from VIA and VIII groups of the
periodic table, supported on a s port comprising
porous inorganic oxides such as alumina,
alumina-silica, titania, and alumina titania has been
used widely for the purpose of hydrotreating of
hydrocarbon oils.
Currently, regulations on the sulfur
contents of fuel oils have been tightened from the
viewpoint of environmental protection. In particular,
the sulfur content of gas oil has been more severely
regulated to be 10 ppm by mass or less. Under these
circumstances, develo nt of gas oil ultra-deep
desulfurization catalysts has been proceeded so as to
cope with these regulations.
Patent Literature 1 discloses catalyst
comprising metal c onents selected from VIA and VIII
groups of the periodic table, supported on a
silica titania alumina support. This catalyst has
-1accomplished
a high hydrodesulfurization activity by
adjusting the content and crystalline structure of
titania and the specific surface area and pore volume
of the support. However, a further enhancement in the
hydrodesulfurization activity has been demanded.
Citation List
Patent Literature
[0003] Patent Literature 1: Japanese Patent
Application Laid-Open Publication No. 2011 072928
Summary of Invention
Technical Problem
[0004] The present invention has an object to
provide a hydrodesulfurization catalyst with higher
performances than those of conventional catalysts,
particularly for gas oil fractions and a process for
producing the catalyst.
Solution to Problem
[0005] As the results of extensive study and
research, it has been found that the use of a support
having specific properties for a catalyst
significantly improves the hydrodesulfurization
activity thereof and thus enables the above object to
be achieved.
[0006] That is, the present invention relates to a
hydrodesulfurization catalyst comprising at least one
-2type
of metal component selected from VIA and VIII
groups of the periodic table, supported on a support
having a diffraction peak area indicating a crystal
structure of boehmite (020) planes measured by an X ray
diffraction analysis that is 1/10 or greater of a
diffraction peak area indicating the aluminum
crystalline structure assigned to y alumina (440)
planes, the molar ratio of the metal component selected
from VIII group to the metal component selected from
VIA group being from 0.13 to 0.22.
[0007J The present invention also relates to a
method for producing a hydrodesulfurization catalyst
comprising: a first step of mixing a mixed aqueous
solution of a titanium mineral acid salt and an acidic
aluminum salt and a basic aluminum salt aqueous
solution in the presence of silicate ions so that the
pH is from 6.5 to 9.5 to produce a hydrate; a second
step of washing, extruding, drying and calcining the
hydrate in turn to produce a support; and a third step
of loading at least one type of metal component selected
from VIA and VIII groups of the periodic table on the
support.
Advantageous Effect of Invention
[0008J The hydrodesulfurization catalyst of the
present invention has more excellent performance than
-3conventional
catalysts and are particularly suitable
for hydrodesulfurization of gas oil fractions.
Brief Description of Drawings
[0009J Fig. 1 is a graph indicating X-ray
diffraction spectra of support a and support e produced
in Ex le 1 and Comparative Example 1, respectively.
Fig. 2 is a graph indicating transmission
type Fourier transform infrared absorption spectra of
support a and support e produced in Example 1 and
Comparative Example 1, respectively.
Fig. 3 is a graph indicating the maximal peak
positions of the absorption spectra caused by the
acidic OR group and weakly basic OR group of a support.
Description of Embodiments
[0010] The present invention will be described in
detail below.
The hydrodesulfurization catalyst of the
present invention is characterized in that the support
comprises at least both boehmite and v-alumina and has
a diffraction peak area indicating the crystal
structure of boehmite (020) planes measured by an X-ray
diffraction analysis that is 1/10 or greater of the
diffraction peak area indicating the aluminum
crystalline structure assigned to y alumina (440)
planes.
4[
0011] The support contains boehmite and v-alumina
each in the form of Al 2 0 3 in the total amount of
preferably 50 to 96 percent by mass, more preferably
58 to 83 percent by mass, more preferably 70 to 83
percent by mass. An alumina content of less than 50
percent by ma s sis not pre ferable beca us e the re suI t ing
catalyst tends to degrade significantly. An alumina
content of more than 96 percent by mass is also not
preferable because the catalyst performances tend to
deteriorate.
[0012] The support may contain any compound other
than boehmite and y alumina, such as silica, titania,
boria, diphosphorus pentaoxide, and zirconia and
contains particularly preferably silica and titania.
[0013] The support contains silica in the form of
Si02 in an amount of preferably 1 to 10 percent by mass,
more preferably 2 to 7 percent by mass, more preferably
2 to 5 percent by mass on the support basis. A silica
content of less than 1 percent by mass decreases the
specific surface areas of the resulting support and
causes titania particles to be likely to aggregate upon
calcination of the support, resulting in larger
diffraction peak areas indicating the crystal
structures of anatase titania and rutile titania
measured by an X-ray diffraction analysis. When
5
titania particles aggregate, the resulting support is
small in the specific surface area and thus the content
of a metal component of Group VIA of the periodic table
and a metal component of Group VIII of the periodic table
is less and cause the activity to be reduced. A silica
content of more than 10 percent by mass causes the
resulting support to be poor in sharpness of the pore
distribution and thus possibly to fail to obtain a
desired hydrodesulfurization activity.
[0014] The support contains titania in the form of
Ti02 in an amount of preferably 3 to 40 percent by mass,
more preferably 15 to 35 percent by mass, more
preferably 15 to 25 percent by mass on the support basis.
A titania content of less than 3 percent by mass is too
less in effect achieved by addition of titania,
resulting in a catalyst that may not obtain a sufficient
hydrodesulfurization activity. A titania content of
more than 40 percent by mass is not preferable because
not only the mechanical strength of the resulting
catalyst is reduced but also the specific surface area
is decreased due to the increased tendency for titania
particles to accelerate in crystallization upon
calcination of the support and thus the resulting
catalyst may not exhibit a hydrodesulfurization
performance corresponding to the economic efficiency
-6
according to the increased amount of titania.
[0015] The hydrodesulfurization catalyst of the
present invention comprises at least one or more types
of metal components selected from Group VIA (IUPAC
Group 6) and Group VI I (IUPAC Groups 8 to 10) of the
periodic table s ported on the support.
[0016] Examples of metal components of Group VIA of
the periodic table to be used in the present invention
include molybdenum (Mo) and tungsten (W) while examples
of metal components of Group VIII of the periodic table
include cobalt (Co) and nickel (Ni). These metal
components may be used alone or in combination. In view
of catalyst properties, the metal components are
preferably a combination of nickel-molybdenum,
cobalt-molybdenum, nickel-molybdenum-cobalt,
nickel-tungsten, cobalt-tungsten, or
nickel-tungsten-cobalt, in particular more preferably
a combination of nickel-molybdenum, cobalt molybdenum,
or nickel-mol denum cobalt.
[0017] The total content of the metal component (s)
is preferably from 1 to 35 percent by mass, more
preferably from 15 to 30 percent by mass in the form
of oxide on the catalyst basis. In particular, the
content of the metal component of Group VIA of the
periodic table is preferably from 10 to 30 percent by
7
mass, more preferably from 13 to 24 percent by mass in
the form of oxide while the content of the metal
component of Group VIII of the periodic table is
preferably from 2.6 to 4.4 percent by mass, more
preferably from 2.S to 4.2 percent by mass in the form
of oxide.
[OOlS] The molar ratio of the metal component
selected from VIII group of the periodic table to the
metal component selected from VIA group of the periodic
table is necessarily 0.13 to 0.22, preferably 0.14 to
0.21, more preferably 0.16 to O.lS. A structure
wherein a metal of VIII group of the periodic table
coordinates to the edge sights of a sulfide of metal
of VIA group of the periodic table (for Co and Mo, CoMoS
phase) is referred to as "high active species". If the
molar ratio of the metal component selected from VIII
group of the periodic table to the metal component
selected from VIA group of the periodic table is less
than 0 .13, the CoMoS phase is not sufficiently formed.
Whilst, if the molar ratio of the metal component
selected from VIII group of the periodic table to the
metal component selected from VIA group of the periodic
table exceeds 0.22, the CoMoS phase is covered with
inactive cobalt sulfide.
[0019] When the metal component of Group VIA of the
S
periodic table is loaded on/contained in the support
of the hydrodesulfurization catalyst of the present
invention, the metal components are preferably
dissolved with an acid. The acid is preferably
phosphoric acid and/or an organic acid.
[0020] In the case of using phosphoric acid, it is
supported in an amount of preferably 3 to 25 percent
by mass, more preferably 10 to 15 percent by mass of
phosphorus on an oxide basis with respect to 100 percent
by mass of the metal components of Gro VIA of the
periodic table. If the amount exceeds 25 percent by
mass, the catalyst performance tends to be degraded
whilst if the amount is less than 3 percent by mass,
a solution of the metal to be supported is poor in
stability.
[0021] No particular limitation is imposed on the
method for loading and including the above described
metal components or the above-described metal
components and further phosphorous into the support.
Any conventional method such as impregnation
(equilibrium adsorption, pore filling, incipient
wetness impregnation methods) or ion-exchange may be
used. Impregnation referred herein is a method wherein
the s port is impregnated with an impregnating
solution containing active metals and then dried and
9
calcined.
[0022] In the impregnation method, a metal
component of Group VIA of the periodic table and a metal
component of Group VIII of the periodic table are
preferably loaded at the same time. When metal
components are loaded separately, the resulting
catalyst would be insufficient in desulfurization
activity or denitrogenation activity. In the case
where the metal components are loaded by an
impregnation method, they are loaded in the coexistence
of an acid, preferably phosphoric acid or an organic
acid because the metal component of Group VIA of the
periodic table is highly dispersed on the support and
thus the resulting catalyst is further enhanced in
desulfurization activity and denitrogenation activity.
Whereupon, phosphoric acid is preferably added in an
amount of 3 to 25 percent by mass based on 100 percent
by mass of the metal component of Group VIA of the
periodic table.
[0023] The hydrodesulfurization catalyst of the
present invention has a specific surface area (SA)
measured by BET method 0 preferably 150 m2 jg or larger,
more preferably 170 m2 jg or larger. If the specific
surface area (SA) is smaller than 150 m2 jg, the catalyst
has fewer active sites for hydrodesulfurization
-10reaction
and thus is degraded in hydrodesulfurization
activity. Whilst, no particular limitation is imposed
on the upper limit. However, when the specific surface
area (SA) exceeds 300 m2 /g, the catalyst strength tends
to be reduced and thus the upper limit is preferably
300 m2 /g or smaller, more preferably 280 m2 /g or smaller.
[0024] The support of the hydrodesulfurization
catalyst of the present invention has a diffraction
peak area indicating the crystal structure of boehmite
(020) planes measured by an X-ray diffraction analysis
that is necessarily 1/10 or greater, preferably 1/5 or
greater, more preferably 1/4 or greater of the
diffraction peak area indicating the aluminum
crystalline structure assigned to v-alumina (440)
planes. No particular limitation is imposed on the
upper limit, which is, however, preferably 1 or less,
more preferably 4/5 or less. I the diffraction peak
area indicating the crystal structure of boehmite (020)
planes measured by an X-ray diffraction analysis is
less than 1/10 of the diffraction peak area indicating
the aluminum crystalline structure assigned to
y alumina (440) planes, the metal component of Group
VIA of the periodic table and the metal component of
Group VIII of the periodic table are less dispersed and
as the result sufficient activity cannot be obtained.
11
Whilst, the upper limit exceeds 1, the ratio of boehmite
is too large and thus the resulting catalyst is reduced
in strength.
The diffraction peak indicating the crystal
structure of boehmite (020) planes is measured at
28=14° while the diffraction peak indicating the
aluminum crystal structure assigned to v-alumina (440)
planes is measured at 28=67°.
[0025] Each of the diffraction peak areas is
calculated by fitting a graph obtained through X-ray
diffraction analysis with an X-ray diffraction device,
with a least square method, followed by baseline
correction, and finding the height (peak intensity W)
from the maximum peak value to the baseline so as to
derive the peak width (full width at half maximum) when
the resulting peak strength is half (1/2W) thereby
defining the product of the full width at half maximum
and peak intensity as a diffraction peak area.
"Boehmite diffraction peak area/alumina diffraction
peak area" is derived from each of the diffraction peak
areas thus obtained.
[0026] In the support of the hydro sulfurization
catalyst of the present invention, the ratio of the
absorbance per unit surface area of the support caused
by the acidic OH group to the absorbance per unit surface
-12
area of the support caused by the weakly basic OH group,
both measured with a transmission type Fourier
transform infrared absorption spectrum apparatus
(FT IR) is preferably 0.9 or greater, more preferably
1.0 or greater, more preferably 1.1 or greater. It is
preferred that the ratio of the acidic OH group increase
because the metal component of Group VIA of the periodic
table and the metal component of Group VIII of the
periodic table are highly dispersed on the support, and
as the result the number of active sites increases and
the activity is enhanced.
The wavenumber of maximal peak position of
the absorption spectrum caused by the acidic OH group
is within the range of 3670 to 3695 cm- 1 while the
wavenumber of maximal peak position of the absorption
spectrum caused by the weakly basic OH group is within
the range of 3720 to 3740 cm- 1 (see Figure 3).
The above-mentioned measurement with FT- R
will be described later.
[0027] The hydrodesulfurization catalyst of the
present invention is suitably used for hydrotreating
hydrocarbon oils, in particular gas oil fractions.
Hydrodesulfurization using the catalyst is carried out
under a hydrogen atmosphere at a high t erature and
a high pressure after charging the catalyst into a fixed
-13
bed reactor.
Examples of the gas oil fraction used in the
present invention include straight-run gas oil
produced through an atmospheric distillation unit for
crude oil; vacuum gas oil produced through a vacuum
distillation unit by distilling straight heavy oil or
residue obtained from an atmospheric distillation
unit; light cycle gas oil produced by fluid
catalytic cracking vacuum heavy gas oil or
desulfurized heavy oil; and hydrocracked gas oil
produced by hydro cracking vacuum heavy gas oil or
desulfurized heavy oil.
[0028] The reaction pressure (hydrogen partial
pressure) is preferably from 3 to 15 MPa, more
preferably from 4 to 10 MPa. At a reaction pressure
of lower than 3 MPa, desulfurization and
denitrogenation activities tend to significantly
degrade. A reaction pressure of higher than 15 MPa is
not preferable because hydrogen consumption increases,
resulting in a higher running cost.
[0029] The reaction temperature is preferably from
300 to 420°C, more preferably 320 to 380°C. A reaction
temperature of lower than 300°C is not practical
because desulfurization and denitrogenation
activities tend to significantly degrade. A reaction
-14t
erature of higher than 420°C is not preferable
because the catalyst is drastically degraded and the
t erature is close to the service temperature limit
(usually 425°C) of the reactor.
[0030] No particular limitation is imposed on the
liquid space velocity, which is, however, preferably
from 0.5 to 4.0 h- 1
, more preferably from 0.5 to 2.0
h- 1
• A liquid-space velocity of less than 0.5 h 1 is
not practical because the productivity is reduced due
to the reduced amount of the throughput. A
liquid space velocity of greater than 4.0 h 1 is not
preferable because the reaction temperature is
increased, and as the result the decomposition of the
catalyst accelerates.
[0031] The hydrogen/oil ratio is preferably from
120 to 420 NL/L, more preferably from 170 to 340 NL/L.
A hydrogen/oil ratio of less than 120 NL/L is not
preferable because the hydrodesulfurization rate
decreases. A hydrogen/oil ratio of greater than 420
NL/L is not also preferable because it cannot change
the hydrodesulfurization activity to a large extent and
only increases the running cost.
[0032] Next, the process for producing the
hydrodesulfurization catalyst of the present invention
will be described.
-15The
process for producing the
hydrodesulfurization catalyst of the present invention
comprises: a first step of mixing a mixed aqueous
solution of titanium mineral acid salt and acidic
aluminum salt (hereinafter simply referred to as "mixed
aqueous solution") and a basic aluminum salt aqueous
solution in the presence of silicate ion so that the
pH is from 6.5 to 9.5 to produce a hydrate; a second
step of washing, extruding, drying and calcining the
hydrate in turn to produce a support; and a third step
of loading at least one type of metal component selected
from VIA group (IUPAC Group 6) and VIII group (IUPAC
groups 8 to 10) of the periodic table. Each of the steps
will be described below.
[0033] (First Step)
First of all, in the presence of silicate ion,
a mixed solution of a titanium mineral acid salt and
an acidic aluminum salt (this is an acidic aqueous
solution) is mixed with a basic aluminum salt aqueous
solution (this is an alkaline aqueous solution) such
that the pH is from 6.5 to 9.5, preferably from 6.5 to
8.5, more preferably from 6.5 to 7.5 to produce a hydrate
containing silica, titania and alumina.
[0034] In this step, there are two alternative cases
(I) where the mixed aqueous solution is added to the
-16
basic aluminum salt aqueous solution containing
silicate ion and (2) where the basic aluminum salt
aqueous solution is added to the mixed solution
containing silicate ion.
In case (1), silicate ion contained in the
basic aluminum aqueous solution may be basic or neutral.
The basic silicate ion source may be a silicic acid
compound such as sodium silicate, which can generate
silicate ions in water. In case (2), silicate ion
contained in the mixed aqueous solution of a titanium
mineral acid salt and an acidic aluminum salt aqueous
solution may be acidic or neutral. The acidic silicate
source may be a silicic acid compound such as silicic
acid, which can generate silicate ions in water.
[0035] Examples of the basic aluminum salt include
sodium aluminate and potassium aluminate. Examples of
the acidic aluminum salt include aluminum sulfate,
aluminum chloride, and aluminum nitrate. Examples of
the titanium mineral acid salt include titanium
tetrachloride, titanium trichloride, titanium sulfate,
and titanium nitrate. In particular, titanium sulfate
is preferably used because it is inexpensive.
[0036] For example, a predetermined amount of a
basic aluminum salt aqueous solution containing basic
silicate ion is charged into a tank with a stirrer and
-17heated
at and maintained to a temperature of usually
40 to 90°C, preferably 50 to 70°C, and to the solution
was continuously added a predetermined amount of a
mixed aqueous solution of a titanium mineral acid salt
and acidic aluminum salt aqueous solution heated to a
temperature of ±5°C, preferably ±2°C, more preferably
±loC of the heated basic aluminum salt aqueous solution
for usually 5 to 20 minutes, preferably 7 to 15 minutes
so that the pH is from 6.5 to 9.5, preferably from 6.5
to 8.5, more preferably from 6.5 to 7.5 to produce a
precipitate, which is a slurry of hydrate. It is noted
that since addition of the basic aluminum salt aqueous
solution to the xed solution for a too long period
of time would cause the production of crystals of
pseudoboehmite, bayerite or gibbsite, which are not
preferable, the addition is carried out for desirously
15 minutes or shorter, more desirously 13 minutes or
shorter. Bayerite and gibbsite are not preferable
because they reduce the specific surface area after
calcination.
[0037] (Second Step)
The hydrate slurry produced in the first step
is aged if necessary and then washed to remove
by produced salts thereby producing a hydrate slurry
containing silica, ti tania and alumina. The resul ting
-18
hydrate slurry is further heated and aged if necessary
and then formed into an extrudable kneaded product by
a conventional method, such as heat kneading. The
extrudable product is extruded into a desired shape by
extrusion and then dried at a temperature of 70 to 150°C,
preferably 90 to 130°C and calcined at a temperature
of preferably 400 to 500°C, more preferably 400 to 480°C,
more preferably 430 to 470°C, most preferably 440 to
460°C for 0.5 to 10 hours, preferably 2 to 5 hours
thereby producing a silica titania-alumina support.
During the second step, adjustment of
conditions for calcination, in particular calcining
t erature enables the preparation of a support having
a diffraction peak area indicating the crystal
structure of boehmite (020) planes measured by an X-ray
diffraction analysis that is 1/10 or greater of the
diffraction peak area indicating the aluminum
crystalline structure assigned to v-alumina (440)
planes.
[0038] (Third Step)
On the resulting silica-titania alumina
support is loaded by a conventional manner
(impregnation, immersion) at least one type of metal
component selected from VIA and VIII groups of the
periodic table as described above, followed by
-19calcination
at preferably 400 to 500°C, more preferably
400 to 480°C, more preferably 430 to 470°C for usually
0.5 to 10 hours, preferably 2 to 5 hours to produce the
hydrodesulfurization catalyst of the present
invention.
Raw materials of the metal component are
preferably for example, nickel nitrate, nickel
carbonate, cobalt nitrate, cobalt carbonate,
molybdenum trioxide, ammonium molybdate, and ammonium
paratungstate.
[0039J
A transmission type Fourier transform
infrared spectrophotometer (FT-IR/6100 manufactured
by JASCO Corporation) was used to measure the maximal
peak wavenumber of the acidic OH group and the
absorbance at the wavenumber and the maximal peak
wavenumber of the weakly basic OR group and the
absorbance at the wavenumber as described below.
[0040] (Measurement)
Into a molding container (inner diameter 20
mm) were charged 20 mg of a sample, which were then
compressed by applying pressure of 4 ton/cm2 (39227
N/cm2
) to be molded into a thin disk-shape. This molded
product was kept under a condition of a pressure of
-20
1.0x10-3 Pa or lower at a temperature of 400 to 500°C
for 2 hours and then cooled to room temperature to
measure the absorbance of the product.
Specifically, a baseline correction was
carried out at a resolution of 4 cm- 1 and a cumulated
number of 200 within the wavenumber range of 3000 to
4000 cm- 1 with a TGS detector, followed by correction
with the specific surface area. The absorbance was
converted to that per unit surface area.
Ab so r ban c e per un itsu r fa c eare a (m 2)
(absorbance)/(molded body mass x specific surface
area)
[0041] In all of the following examples and
comparative examples, the wavenumber of the maximal
peak position of the absorption spectrum caused by the
acidic OH group was within the range of 3670 to 3695
1 while the wavenumber of the maximal peak position
of the absorption spectrum caused by the weakly basic
OH group was within the range of 3720 to 3740 cm 1
Examples
[0042] The present invention will be described in
more details with reference to the following examples
and comparative examples but is not limited thereto.
[0043] [Example 1: Preparation of
hydrodesulfurization catalyst a]
-21Into
a 100 L volume tank equi ed wi th a steam
jacket were put 8.16 kg of an a eous solution
containing sodium aluminate (manufactured by JGC C&C)
in an amount of 22 percent by mass on an A1203
concentration basis. The solution was diluted with 41
kg of ion-exchange water, to which 1.80 kg of a solution
containing sodium silicate (manufactured by AGC
Si-Tech. Co., Ltd.; Si02 concentration 24 percent by
mass) in an amount of 5 percent by mass on an Si02
concentration basis were then added, stirring. The
resulting mixture was heated at a temperature of 60°C
thereby preparing a basic aluminum salt aqueous
solution. An acidic aluminum salt aqueous solution was
prepared by diluting 7.38 kg of an aqueous solution
containing aluminum sulfate (manufactured by JGC C&C)
in an amount of 7 percent by mass on an A1 203
concentration basis with 13 kg of ion-exchanged water
while a titanium mineral acid salt aqueous solution was
prepared by dissolving 1.82 kg of 33 percent by mass
on a Ti02 concentration basis of titanium sulfate
(manufactured by Tayca Corporation) in 10 kg of
ion-exchanged water. These aqueous solutions were
mixed and heated to a temperature of 60°C thereby
preparing a mixed aqueous solution. This mixed aqueous
solution was added at a constant rate (addition time:
-22
10 minutes) into the tank containing therein the basic
aluminum salt aqueous solution using a roller pump
until the pH was 7.2 thereby preparing hydrate slurry
a containing silica, titania, and alumina.
[0044J The resulting hydrate slurry a was aged,
stirring at a temperature of 60°C for one hour, and then
dewatered with a flatsheet filter and washed with 150
L of a 0.3 percent by mass ammonium aqueous solution.
After washing, the resulting cake-like slurry was
diluted with ion-exchanged water so that the amount of
the slurry was 10 percent by mass on an Al 2 0 3
concentration basis and then adjusted in pH to 10.5 with
15 percent by mass of ammonium aqueous solution. The
slurry was transferred to an aging tank with a reflux
condenser and aged, stirring at a temperature of 95°C
for 10 hours. The resulting slurry was dewatered and
then concentrated and kneaded to have a certain
moisture level with a double armed kneader with a steam
jacket. The resulting kneaded product was extruded
in t 0 a c y lind ric a Ishape withadi arne t e r 0 fl. 8 mm wit h
an extruder and dried at a temperature of 110°C. The
dried extruded product was calcined at a temperature
of 450°C in an electric furnace for 3 hours thereby
producing support a. Support a contained silica in an
amount of 3 percent by mass on an SiOz concentration
23basis
(on the support basis), titania in an amount of
20 percent by mass on a TiOz concentration basis (on
the support basis), and aluminum in an amount of 77
percent by mass on an Alz03 concentration basis (on the
support basis) .
[0045J Support a was subjected to an X ray
diffraction analysis with an X ray diffraction
apparatus "RINT 2100" manufactured by Rigaku
Corporation (the same applies hereafter) The results
are set forth in Fig. 1. Least square fitting was
applied to the resulting graph, followed by baseline
correction so as to find the full width at half maximum
of the peak assigned to the boehmite (020) planes
indicated at 28=14 0. The product of the full width at
half maximum and the peak intensity from the baseline
to the maximum peak was defined as a boehmite
diffraction peak area. The same procedures were
carried out to find the full width at half maximum of
the peak assigned to the v-alumina (440) planes
indicated at 28=67°, and the product of the full width
at half maximum and the peak intensity from the baseline
was defined as a y alumina diffraction peak area. The
diffraction peak area indicating the crystalline
structure of boehmite was 1/3 of the diffraction peak
area indicating the crystalline structure assigned to
-24
v-alumina (boehmite diffraction peak area/v-alumina
diffraction peak area = 1/3, and the same applies
hereafter)
Figure 2 shows the transmission type Fourier
transform infrared absorption spectrum of support a.
[0046J Next, 268 g of molybdenum trioxide
(manufactured by Climax; Mo0 3 concentration 99 percent
by mass) and 66 g of cobalt carbonate (manufactured by
Tanaka Chemical Corporation; CoO concentration 61
percent by mass) were suspended in 500 ml of
ion-exchanged water, and then heated at a temperature
of 95°C for 5 hours, applying a suitable reflux
treatment so that the volume is not decreased, followed
by dissolving of 54 g of phosphoric acid (manufactured
by KANTO CHEMICAL CO., INC.; P20S concentration 62
percent by mass) in the suspension thereby preparing
an impregnating solution. After 1000 g of support a
was impregnated with an impregnating solution by spray,
it was dried at a temperature of 250°C and calcined at
a temperature of 450°C for one hour in an electric
furnace thereby producing hydrodesulfurization
catalyst a (hereinafter, simply referred to as
"catalyst a", the same applies hereafter). Properties
of catalyst a are set forth in Table 1.
[0047J [Example 2: Preparation of
-25hydrodesulfurization
catalyst b]
S port a was used and the same preparation
procedures for catalyst a were followed except for
using 270 g of molybdenum trioxide, 78 g of cobalt
carbonate and 55 g of phosphoric acid in the preparation
of the impregnation solution thereby producing
catalyst b. Properties of catalyst b are set forth in
Table 1.
[0048] [Example 3: Preparation of
hydrodesulfurization catalyst c]
Support a was used and the same preparation
procedures for catalyst a were followed except for
using 272 g of molybdenum trioxide, 90 g of cobalt
carbonate and 55 g of phosphoric acid in the preparation
of the impregnation solution thereby producing
catalyst c. Properties of catalyst c are set forth in
Table 1.
[0049] [Example 4: Preparation of
hydrodesulfurization catalyst d]
The same preparation procedures for catalyst
a were followed except for calcining the dried extruded
product at a temperature of 480°C in an electric furnace
in the preparation of the support thereby producing
support d. As the result of an X-ray diffraction
analysis carried out as with Example 1 (not shown), the
-26boehmite
diffraction peak area/v-alumina diffraction
peak area was 1/9. The impregnation solution was
prepared in the same manner as that for catalyst a
thereby producing catalyst d. Properties of catalyst
d are set forth in Table 1.
[0050] [Comparative Example 1: Preparation of
hydrodesulfurization catalyst e]
The same preparation procedures for support
a were followed except for calcining the dried and
extruded product at a temperature of 550°C in an
electric furnace thereby producing support e. As the
result of X-ray diffraction analysis carried out as
with Example 1, there was no boehmite diffraction peak
as shown Figure 1 and the boehmite diffraction peak
area/v-alumina diffraction peak area was O. The
impregnation solution was prepared in the same manner
as that for catalyst a thereby producing catalyst e.
Properties of catalyst e are set forth in Table 1.
[0051] [Comparative Example 2: Preparation of
hydrodesulfurization catalyst f]
Support e was used and the impregnation
solution used for catalyst b was used thereby producing
catalyst f. Properties of catalyst f are set forth in
Table 1.
[0052] [Comparative Example 3: Preparation of
-27hydrodesulfurization
catalyst g]
Support e was used and the impregnation
solution used for catalyst c was used thereby producing
catalyst g. Properties of catalyst g are set forth in
Table 1.
[0053] [Comparative Example 4: Preparation of
hydrodesulfurization catalyst h]
Su ort a was used and the same preparation
procedures for catalyst a were followed except for
using 267 g of molybdenum trioxide and 55 g of cobalt
carbonate in the preparation of the impregnation
solution thereby producing catalyst h. Properties of
catalyst h are set forth in Table 1.
[0054] [Comparative Ex Ie 5: Preparation of
hydrodesulfurization catalyst i]
Support a was used and the same preparation
procedures for catalyst a were followed except for
using 274 g of molybdenum trioxide, 101 g of cobalt
carbonate and 56 g of phosphoric acid in the preparation
of the impregnation solution thereby producing
catalyst i. Properties of catalyst i are set forth In
Table 1.
[0055] [Hydrodesulfurization test]
Feedstock having the following properties
was hydrotreated with a hydrodesulfurization unit
-28manufactured
by ZYTEL Co. using catalysts a to i.
Hydrotreating reaction was carried out under the
following conditions. For each catalyst, the reaction
rate constants at reaction temperatures of 330°C and
340°C were determined and an average of the reaction
rate constants relative to the reaction rate constants
of catalyst c at temperatures of 330°C and 340°C taken
as 100 is defined as a relative hydrodesulfurization
activity and set forth in Table 1.
«Properties of feedstock»
Feedstock: straight-run gas oil (boiling
point range of 208 to 390°C)
Density@15°C: 0.8493 g/cm3
Sulfur content: 1.32 percent by mass
Nitrogen content: 105 ppm by mass
«Reaction condition»
Reaction temperatures: 330°C, 340°C
Li id-space velocity: 1.36 hr 1
Hydrogen pressure: 6.0 MPa
Hydrogen/oil ratio: 250 NL/L
[0056] Table 1
-29Example
I Example 2 Example 3 Example 4
Comparative
Examole 1
Comparative
Examole 2
Comparative
Exam le3
Comparative
Examole 4
Comparative
Exampl.5
Catalyst a b c d e f g h i
Support components
Si (as Si02) mass'h 3 3 3 3 3 3 3 3 3
Ti (as TiO.) mass%' 20 20 20 20 20 20 20 20 20
AI (as AizOs) mass% 77 77 77 77 77 77 77 77 77
B/A .) 1/3 I 1/3 1/3 1/9 0 0 0 1/3 1/3
Supported components I
MoO, (catalyst basis) mass%' 20 20 20 20 20 20 20 20 20
CoO (catalyst basis) mass% 3 3.5 4 3 3 3.5 4 2.5 4.5
Pz0 5 (catalyst basis) mass% 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 i 2.5
i ColMo ratio 0.15 0.175 0.2 0.15 0.15 0.175 0.2 0.125 0,225
LOO desulfurization
ergee,rtie ~-
Relative activity 107 116 100 103 93 92 81 93 92
Specifio surface area 238 234 235 224 201 202 198 250 237
PV(HzO) 0.43 0,43 0,41 0,43 0.44 0.43 0.42 0.44 0,40
Acidic OH group/weakly basic OH
Iwouc .*) 1.2 1.2 1.2 1.1 0.8 0.8 0.8 1.2 1.2
*) A peak are. of y-alumina (440) planes (2 e"67")
B: peak area of boehmite (020) planes (2 e=14')
**)..~_~S\?rbcmGe _~f fMxifYisl p~ak (:;aused by ac;:i