U.S. patent application number 09/779104 was filed with the patent office on 2002-10-17 for gasoline hydrodesulfurization.
Invention is credited to Chang, Yun-Feng, Dautzenberg, Frits M., Murrell, Lawrence L., Palmen, Luc.
Application Number | 20020148758 09/779104 |
Document ID | / |
Family ID | 25115338 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020148758 |
Kind Code |
A1 |
Chang, Yun-Feng ; et
al. |
October 17, 2002 |
Gasoline hydrodesulfurization
Abstract
Selective hydrodesulfurization of an olefinic gasoline fraction,
e.g., cracked gasoline, is accomplished by use of a catalyst of a
noble metal supported on an acidic support. Such a catalyst reduces
the sulfur content to acceptable levels, while minimizing
hydrogenation of olefins to retain octane quality of the treated
gasoline fraction.
Inventors: |
Chang, Yun-Feng; (Randolph,
NJ) ; Murrell, Lawrence L.; (S. Plainfield, NJ)
; Dautzenberg, Frits M.; (Mahwah, NJ) ; Palmen,
Luc; (Eindhoven, NL) |
Correspondence
Address: |
CARELLA, BYRNE, BAIN, GILFILLAN,
CECCHI, STEWART & OLSTEIN
6 Becker Farm Road
Roseland
NJ
07068
US
|
Family ID: |
25115338 |
Appl. No.: |
09/779104 |
Filed: |
February 8, 2001 |
Current U.S.
Class: |
208/217 ;
208/214; 208/216R |
Current CPC
Class: |
C10G 45/10 20130101 |
Class at
Publication: |
208/217 ;
208/216.00R; 208/214 |
International
Class: |
C10G 045/06; C10G
045/08 |
Claims
What is claimed is:
1. A process for the hydrodesulfurization of an olefinic gasoline
fraction, comprising: hydrodesulfurizing an olefinic gasoline
fraction in the presence of a catalyst comprising a noble metal
supported on an acidic support.
2. The process of claim 1 wherein the gasoline fraction contains at
least 100 ppm of sulfur.
3. The process of claim 1 wherein the gasoline fraction contains at
least 5% wt olefins.
4. The process of claim 1 wherein the catalyst further includes at
least one of Mo, W, Cr, or Re, Mn, Tc.
5. The process of claim 1 wherein the acidic support is at least
one of silica-alumina, alumina or a zeolite.
6. The process of claim 1 wherein the acidic support has pores with
a pore diameter from 0.4 nm to 150 nm and a surface area of from 1
m.sup.2/g to 1500 m.sup.2/g.
7. The process of claim 1 wherein the catalyst has a size of from
0.2 micron to 10 mm.
8. The process of claim 1 wherein the catalyst is installed within
a catalytic distillation column.
9. The process of claim 1 wherein the catalyst is installed in a
fixed bed reactor.
10. The process of claim 1 wherein the hydrodesulfurization is in
the gas phase.
Description
1. FIELD OF THE INVENTION
[0001] The present invention relates to upgrading hydrocarbon
streams containing organo-sulfur compounds. It more particularly
refers to a process for desulfurizing olefinic naphtha boiling
range hydrocarbon fractions containing organic sulfur
impurities.
2. BACKGROUND OF THE INVENTION
[0002] Two major portions of a gasoline fraction may be produced by
fluidized catalytic cracking (FCC) or thermal cracking of a heavy
petroleum fraction. The cracked gasoline forms a major part of the
gasoline product pool in the United States and they are the major
source of sulfur in the gasoline pool. As a result of more
stringent environmental regulations, it is required that the sulfur
content of gasoline is further reduced. In this respect, in
processing a cracked gasoline fraction, it is required to further
reduce the sulfur content thereof and, in many cases, it may be
required to reduce sulfur content of a gasoline fraction by 90-99%.
This increased reduction if necessitated by regulations that may
require refiners to target sulfur content in the final blended
gasoline in the order of 30 parts per million.
[0003] Hydrocarbons of any of the sulfur containing olefinic
fractions, which boil in the gasoline boiling range, causes a
reduction on the olefin content and consequently a reduction in the
octane number. As the degree of desulfurization increases, the
octane number of the treated product decreases.
3. SUMMARY OF THE INVENTION
[0004] It has now been discovered that the problems encountered in
the prior art can be overcome by the present invention, which
provides a process for reducing sulfur content of olefinic
hydrocarbon stream while substantially maintaining the olefinic
content, more particularly octane number. The process includes
contacting an olefinic hydrocarbon stream containing organic sulfur
with a noble metal catalyst supported on a solid acid support. The
containing organic sulfur with a noble metal catalyst supported on
a solid acid support. The metal catalyst is a VIII noble metal(s)
which may be used with or without a metal(s) catalyst that is not a
noble metal combined with other metals from Group VI.
[0005] From the literature it is known that bimetallic noble metal
catalysts have excellent activity for aromatic saturation (U.S.
Pat. No. 5,345,612; U.S. Pat. No. 5,308,814; U.S. Pat. No.
5,271,828; U.S. Pat. No. 5,225,383; U.S. Pat. No. 5,151,172; U.S.
Pat. No. 5,147,626). From this work it would be expected that such
catalysts would also be good catalysts for olefin saturation.
Surprisingly, we have found that noble metal catalysts supported on
acid supports are highly effective in desulfurization of olefinic
hydrocarbon streams while substantially maintaining olefin
content.
4. DETAILED DESCRIPTION OF THE INVENTION
[0006] In order to further reduce the sulfur content, it is
desirable to effect such a reduction without decreasing the olefin
and aromatic content of the gasoline stream in that such a
reduction results in a loss of octane number.
[0007] The present invention is directed to providing for improved
hydrodesulfurization wherein the sulfur content of a gasoline
fraction can be reduced to required levels, without high olefin and
aromatic hydrogenation, which leads to high octane losses.
[0008] More particularly, in accordance with an aspect of the
present invention, a gasoline fraction is subjected to
hydrodesulfurization conditions in the presence of a catalyst that
contains at least one noble metal from Group VIII supported on a
solid acid support and which may also contain one or more other
metals, e.g., a Group VIB metal (Mo, W, Cr), or Group VIIB metal
(Re, Mn, Tc). The noble metal is preferably at least one of
platinum, palladium, and ruthenium, with platinum and/or palladium
being particularly preferred. In a preferred embodiment, the
catalyst includes both platinum and palladium. The noble metal is
generally present in the catalyst in a sulfided form. The term
"metal" or "noble metal" includes the sulfided form of a metal.
[0009] Temperature programmed desorption (TPD) of basic molecules
such as ammonia, isopropylamine (IPA), pyridine, n-butylamine, etc.
is frequently used to characterize the acid strength as well as
acid amounts on a solid surface (G. Wang, H. Itoh, H. Hattori, K.
Tanabe, J. Chem. Soc., Faraday Trans. 1, 79, 1373 (1983)).
[0010] In accordance with the invention, the solid acid supports
are those supports that, when tested by the hereinabove-described
temperature programmed desorption of ammonia or isopropylamine
(IPA), desorbs at least 100 micromoles of ammonia or IPA per gram
of support material at temperatures above 100.degree. C. Preferred
materials are those that desorb at least 25 micromoles of ammonia
per gram of support at temperatures above 200.degree. C. and still
more preferred are those that desorb at least 20 micromoles of
ammonia per gram of support at temperatures above 300.degree.
C.
[0011] Although as hereinabove described, the support is an acidic
support, the selected acid support should not have such a high
level of acid sites that the catalyst in effect becomes a cracking
catalyst in that cracking of the feed lowers the octane number.
[0012] In accordance with the above definition, a summarized list
of acidic supports is given in Table 1.
1TABLE 1 IMPORTANT SOLID ACIDS ACID TYPE EXAMPLES 1. Natural Clay
Kaolinite, bentonite, attapulgite, Minerals montmorillonite,
clarite, fuller's earth, zeolites (X, Y, A, H-ZSM etc), cation
exchanged zeolites and clays 2. Mounted Acids H.sub.2SO.sub.4,
H.sub.3PO.sub.4, CH.sub.2(COOH).sub.2 mounted on silica, quartz
sand, alumina or diatomaceous earth 3. Cation Nafion, Amberlyst 15,
Amberlite IR-120, Exchange Nafion-silica composite Resins 4.
Charcoal heat- treated at 300.degree. C. 5. Metal Oxides ZnO, CdO,
Al.sub.2O.sub.3, CeO.sub.2, ThO.sub.2, ZrO.sub.2, SnO.sub.2, and
Sulfides PbO, MnO.sub.2, As.sub.2O.sub.3, Bi.sub.2O.sub.3,
Cr.sub.2O.sub.3, Sb.sub.2O.sub.5, Nb.sub.2O.sub.5, Ta.sub.2O.sub.5,
V.sub.2O.sub.5, MoO.sub.3, WO.sub.3, CdS, ZnS 6. Metal Salts
MSO.sub.4 (M = Mg, Ca, Sr, Ba, Cu, Zn, Cd, Fe, Co, Ni), M(NO.sub.3)
.sub.2 (M = Zn, Ca, Bi, Fe, Ca), M.sub.2 (SO.sub.4).sub.3 (M = Al,
Fe, Cr), KHSO.sub.4, (NH.sub.4) .sub.2SO.sub.4, Fe(NO.sub.3).sub.3,
MPO.sub.4 (M = B, AL, Cr, Fe), Cu.sub.3 (PO.sub.4) .sub.2 (M = Cu,
Zn, Mg, Ni), Cu.sub.3(PO.sub.4).sub.4 (M = Ti, Zr), AgCl, CuCl,
CaCl.sub.2, AlCl.sub.3, TiCl.sub.3, SnCl.sub.2, CaF.sub.2,
BaF.sub.2, AgClO.sub.4, Mg(ClO.sub.4).sub.2. 7. Mixed Oxides
SiO.sub.2-M.sub.2O.sub.3(M = Al, Ga, Y, La), SiO.sub.2-MO.sub.2 (M
= Ti, Sn, Zr, Th), SiO.sub.2-MO (M = Ca, Mg, Be, Sr, Zn),
SiO.sub.2-MO.sub.3 (M = Mo, W), Al.sub.2O.sub.3-MO (M = Mg, Zn, Ca,
Ni), Al.sub.2O.sub.3-M.sub.2- O.sub.3(M = Cr, Mn, Fe),
Al.sub.2O.sub.3--Co.sub.3O.sub.4, Al.sub.2O.sub.3--V.sub.2O.sub.5,
TiO.sub.2-MO (M = Cu, Mg, Zn, Cd, Ni), ), TiO.sub.2-MO.sub.2 (M =
Zr, Sn), TiO.sub.2--V.sub.2O.sub.5 (M = V, Sb), TiO.sub.2-MO.sub.3
(M = Mo, W), TiO.sub.2-M.sub.2O.sub.3(M = Mn, Fe, Cr),
ZrO.sub.2--CdO, ZnO--MgO, ZnO--Fe.sub.2O.sub.3, MoO.sub.3--
CoO-Al.sub.2O.sub.3, MoO.sub.3--NiO--Al.sub.2O.sub.3,
TiO.sub.2--SiO.sub.2-- MgO, MoO.sub.3--Al.sub.2O.sub.3--MgO,
heteropoly acids 8. Supported Oxides supported on supports like
alumina, Oxides silica, titania, zirconia, minerals, clays,
zeolites, molecular sieves, and mixed oxides 9. Synthetic
Microporous and mesoporous aluminislicates, zeolites or
AlPO.sub.4's, SAPO's, MePO.sub.4's molecular sieves
[0013] A solid superacid is defined as a solid whose acid strength
is higher than the acid strength of 100% sulfuric acid" (K. Tanabe,
M. Misono, Y. Ono, and H. Hattori, NEW SOLID ACIDS AND BASES-THEIR
CATALYTIC PROPERTIES, p.3, Elsevier, Amsterdam, 1989) . Since the
acid strength of 100% sulfuric acid expressed by the Hammett (L. P.
Hammett, A. J. Deyrup, J. Amer. Chem. Soc., 54, 2721 (1932))
acidity function, Ho, is -11.9, a solid of Ho <-11.9 is called a
solid superacid. The kinds of solid superacids are given in Table
2.
2TABLE 2 Solid Superacids Acid Support SbF.sub.5
SiO.sub.2--Al.sub.2O.sub.3, SiO.sub.2--TiO.sub.2,
SiO.sub.2--ZrO.sub.2, TiO.sub.2-- ZrO.sub.2,
Al.sub.2O.sub.3--B.sub.2O.sub.3, SiO.sub.2, , SiO.sub.2--WO.sub.3,
, HF--Al.sub.2O.sub.3 SbF.sub.5, TaF.sub.5 Al.sub.2O.sub.3,
MoO.sub.3, ThO.sub.2, Cr.sub.2O.sub.3, Al.sub.2O.sub.3--WB
SbF.sub.3, BF.sub.3 Graphite, Pt-graphite BF.sub.3, AlCl.sub.3,
AlBr.sub.3 Ion exchange resin, sulfate, chloride SbF.sub.5--HF,
SbF.sub.5-- Metal (Pt, Al), alloy (Pt--Au, Ni--Mo, Al--Mg),
FSO.sub.3H polyethylene, SbF.sub.3, porous substance (SiO.sub.2--
Al.sub.2O.sub.3, kaolin, active carbon, graphite)
SbF.sub.5--CF.sub.3SO.sub.3H F--Al.sub.2O.sub.3, AlPO.sub.4,
charcoal Nafion (polymeric perfluororesin sulfuric acid)
TiO.sub.2--SO.sub.4.sup.2-, ZrO.sub.2-- SO.sub.4.sup.2-,
Al.sub.2O.sub.3--SO.sub.4.sup.2- H-ZSM-5 zeolite
[0014] As representative examples of suitable acidic supports,
there may be mentioned silica-alumina, and particularly, amorphous
silica-alumina, an acidic zeolite, such as ZSM-5, USY, beta, ZSM-4,
ZSM-5, zeolite Omega, ZSM-11, ZSM-20, ZSM-22, Theta-1, MCM-41,
ZSM-35, ferrierite, ZSM-48, ZSM-50, ZSM-57, MCM-22, MCM-36, MCM-48,
MCM-56, SSZ-32, and SAPO's, AlPO.sub.4's, or other
MeAPO.sub.4's.
[0015] As hereinabove noted, in a preferred embodiment, more than
one noble metal is employed, with a combination of palladium and
platinum giving particularly good result.
[0016] Preferred acidic supports are those that have a pore size
wherein the pore diameters are within a range from 0.4 nm to 150
nm. In a preferred embodiment, the surface area of the support is
within a range of from 1 m.sup.2/g to 1500 m.sup.2/g. The catalyst
is preferably in particulate form wherein the particles fall within
the range of from 0.2 micron to 10 mm.
[0017] In preparing the noble metal catalyst supported on an acidic
support, in general, the support contains from about 0.01% to about
5.0% of noble metal, based on noble metal and support, all by
weight.
[0018] The present invention is particularly applicable to the
hydrodesulfurization of gasoline fractions that have a high sulfur
content, and in particular, with a feed sulfur content of at least
100 ppm, and generally at least 500 ppm.
[0019] In proceeding in accordance with the present invention, it
is possible to reduce the sulfur content by at least 25%, and
preferably at least 90%, by weight, without significantly reducing
the olefin and aromatic content. In particular, in a preferred
embodiment, the product from the hydrodesulfurization contains at
least 30%, and preferably at least 50% of the olefins contained in
the feed.
[0020] The hydrodesulfurization may be effected at conditions
generally known in the art. In particular, in general, such
hydrodesulfurization is effected at a temperature from 200.degree.
F. to about 800.degree. F. (preferably from about 300.degree. F. to
about 550.degree. F.); a total pressure of from about 50 to about
900 psig (preferably from about 100 to about 500 psig); at a
hydrogen feed rate of from about 100 SCF/Bbl to about 5000 SFC/Bbl,
and preferably from about 300 to about 3000 SCF/Bbl.
[0021] The hydrodesulfurization may be effected in any one of a
wide variety of reactor systems, such as a catalytic distillation
column (CD Technology.sup.R), a fixed bed, ebullated bed, a
fluidized bed, a moving bed, slurry reactor and the like. In the
case of a fixed bed, the reactor may contain more than one bed. The
catalyst may be in the form of extrudates, pellets, spheres,
granules, etc.
[0022] The reaction may be effected in either the liquid or the
vapor phase, and is preferably effected in the gas phase for better
selectivity.
[0023] The gasoline fraction which is hydrodesulfurized in
accordance with the present invention is preferably one in which
the 5% boiling point is at least 150.degree. F., and wherein the
95% boiling point is no greater than 500.degree. F., preferably no
greater than 400.degree. F. and more preferably no greater than
300.degree. F. As hereinabove indicated, such gasoline fractions
are generally produced by a fluidic catalytic cracking or thermal
cracking, or may be a coker or visbreaker naphtha.
[0024] In accordance with the present invention, it is possible to
significantly reduce the sulfur content of such gasoline fractions,
while maintaining a high selectivity with respect to
hydrodesulfurization, whereby hydrogenation of olefins and
aromatics is reduced, whereby the product retains a high proportion
of the octane number of the feed. For example, in a preferred
embodiment, the octane number of the hydrodesulfurization product
is at least 90% and preferably at least 95% and more preferably at
least 99% of the octane number of the feed.
[0025] The invention will be further described with respect to the
following examples; however, the scope of the invention is not
limited thereby. Unless otherwise specified, all parts and
percentages are by weight.
EXAMPLES
[0026] 1. Synthetic Gasoline Feed
[0027] A synthetic gasoline feed was used for a catalyst activity
test. It contained two olefins, octene-1,2,4,4-trimethylpentene-1,
toluene, thiophene, pyridine, and n-heptane. The olefins were
chosen to represent olefin distribution of typical cracking naphtha
gasolines, that is 10-20% terminal olefins and 80-90% of branched
olefins. Toluene was chosen to represent aromatics in gasoline
factions. Thiophene was used to represent organic sulfur components
in cracked naphtha gasoline. Pyridine was added to mimic basic
components presented in cracked naphtha gasoline.
[0028] The amount of total olefins was varied in the range of
10-40%. The amount of aromatics was fixed to 40%. The amount of
sulfur in the feed was varied in the range of 500-2500 ppm wt. The
amount of pyridine was varied in the range of 50-250 ppm wt.
[0029] 2. Reactor Set-up
[0030] Catalyst in the form of pellets or small particles mixed
with a diluent, e.g., silicon carbide, was loaded into the reactor.
The reactor was made of stainless steel (OD: 1/2", wall thickness
of {fraction (1/16)}", length: 8"). Typical diluent to catalyst
ratio was 5-15 wt/wt.
[0031] The catalyst was positioned in between two quartz wool plugs
to prevent catalyst from being carried away.
[0032] The reactants (hydrocarbon feed and hydrogen) were fed from
the bottom. The liquid feed was delivered by an Eldex metering
pump. Hydrogen was controlled by a Brooks mass flow controller.
[0033] Reactor pressure was controlled by a Mighty-Mite
backpressure regulator.
[0034] Reaction products were analyzed by an on-line GC.
[0035] 3. Catalyst Activation
[0036] The catalyst was normally pre-sulfided with a sulfidation
feed containing 2.7% dimethyldisulfide in n-heptane co-fed with
hydrogen. Typical sulfiding conditions are: 0.1-0.3 g/min feed,
10-30 cc/min of hydrogen flow, final sulfiding temperature of
250-350.degree. C. for 4-12 hours; total pressure: 100-400
psig.
[0037] 4. Hydrodesulfurization (HDS) Run
[0038] HDS feed was introduced once the reactor temperature was
lowered to below 150.degree. C. The reactor temperature was raised
to the desired temperature for HDS. Typical HDS conditions were:
1-3 g catalyst, feed rate: 0.1-2 g/min; hydrogen flow: 10-200
cc/min; total pressure: 100-900 psig.
[0039] The selectivity of the hydrodesulfurization of the present
invention may be expressed as a Selectivity Factor, as follows:
Selectivity Factor=A*(A/B)
[0040] wherein A is the rate of hydrodesulfurization and B is the
rate of hydrogenation of olefins, as a first order rate expressed
per mole of metal in the catalyst.
[0041] The following examples compare the Selectivity Factor for
conventional catalysts with the Selectivity Factor achieved in
accordance with the invention (Table 3).
[0042] 5. Catalysts
[0043] 5.1 Commercial CoMo/Al.sub.2O.sub.3
[0044] A commercial CoMo/Al.sub.2O.sub.3 catalyst (DC130) from
Criterion was used for HDS activity test. This catalyst contains
4.3 wt % CoO and 20.5 wt % MoO.sub.3.
[0045] 5.2 Commercial NiMo/Al.sub.2O.sub.3
[0046] A commercial NiMo/Al.sub.2O.sub.3 catalyst from Sud Chemie
was also tested for HDS. This catalyst contains 3.5 wt. % NiO and
13.5 wt % MoO.sub.3.
[0047] 5.3 PdPt/Ce-ZSM-5
[0048] The catalyst was prepared by incipient wetness impregnation
of a Ce-ZSM-5 zeolite. For bimetallic, Pt was introduced first
followed with Pd. An amount of 20 g of Ce-ZSM-5 (Ce: 5.3 wt %,
SiO.sub.2/Al.sub.2O.sub.- 3=53, from Zeolyst International) was
impregnated with a solution containing 0.1195 g of
platinumtetraamine nitrate (Alfa Aesar, 99.9% metal purity) to give
0.3 wt % Pt. The mixture was dried at 110.degree. C. for two hours
before calcined at 500.degree. C. in air for 3 hours. Pd was
introduced by incipient wetness impregnation of the 0.3 Pt
%/Ce-ZSM-5 with a solution containing 0.5369 g of
palladiumtetraamine nitrate (Alfa Aesar, 99.9% metal purity) to
give 0.9 wt % Pd. It then followed the same procedure for drying
and calcination to give the PtPd/Ce-ZSM-5 that contained 0.3%
Pt-0.9% Pd.
[0049] 5.4 PdPt/H-ZSM-5
[0050] The catalyst was prepared by incipient wetness impregnation
of an H-ZSM-5 zeolite. For bimetallic, Pt was introduced first
followed with Pd. An amount of 20 g of H-ZSM-5
(SiO.sub.2/Al.sub.2O.sub.3=53, from Zeolyst International) was
impregnated with a solution containing 0.1195 g of
platinumtetraamine nitrate (Alfa Aesar, 99.9% metal purity) to give
0.3 wt % Pt. The mixture was dried at 110.degree. C. for two hours
before calcined at 500.degree. C. in air for 3 hours. Pd was
introduced by incipient wetness impregnation of the 0.3Pt %/H-ZSM-5
with a solution containing 0.5369 g of palladiumtetraamine nitrate
(Alfa Aesar, 99.9% metal purity) to give 0.9 wt % Pd. It then
followed the same procedure for drying and calcination to give the
PtPd/H-ZSM-5 that contained 0.3% Pt-0.9% Pd.
[0051] 5.5 Pd/TF-Al.sub.2O.sub.3
[0052] This catalyst was prepared by incipient wetness impregnation
of a thin film alumina. The thin film alumina contains 20 wt % of
.gamma.-alumina on .alpha.-alumina. This thin film support was
prepared by fluid bed coating of 1-2 mm .alpha.-alumina
micro-spheres (Norton Chemicals) with an alumina sol (Nyacol
Chemicals). An amount of 20 grams of the thin film catalyst support
was incipient wetness impregnated with a solution containing 0.2311
g of palladium tetraamine nitrate (Alfa Aesar, 99.9% metal purity)
to give 2.0 wt % Pd on the basis of the thin film .gamma.-alumina.
The mixture was dried at 110.degree. C. for two hours before being
calcined at 500.degree. C. in air for 3 hours. This catalyst was
designated as 2.0% Pd/TF-Al.sub.2O.sub.3.
[0053] 5.6 1 % Ru/(CeO.sub.2+Al.sub.2O.sub.3)
[0054] This catalyst was prepared by incipient wetness impregnation
of a mixed oxide of ceria and alumina. The mixed oxide containing
70% ceria and 30% alumina was prepared by co-gelation of a ceria
sol and alumina sol (both from Nyacol Chemicals) followed with
drying and calcination at 700.degree. C. for 4-10 hours. Amount of
20 grams of the mixed oxide was incipient wetness impregnated with
a solution containing 0.5799 g of ruthenium tetraamine nitrate
(Alfa Aesar, 99.9% metal purity) to give 1 wt % Ru on the mixed
oxide. The mixture was dried at 110.degree. C. for two hours before
calcined at 500.degree. C. in air for 3 hours.
[0055] Table 3 summarizes the HDS results obtained on a number of
commercial and own catalyst formulations at 215.degree. C., 440
psig, hydrocarbon feed rate of 0.1-2 g/min/g-catalyst, and hydrogen
flow of 5-100 cc/min/g-catalyst. The results presented in Table 3
are steady-state performance, typically after a time on stream of
6-20 hours, depending on catalyst and feed rate.
3TABLE 3 Summary of Overall HDS Performance of Commercial Catalysts
and Catalysts of Present Invention Overall HDS Performance
(normalized) Examples Catalyst Liquid Phase Gas Phase 1
CoMo/Al.sub.2O.sub.3 1.0 1.0 2 NiMo/Al.sub.2O.sub.3 0.9 1.5 3
PdPt/Ce-ZSM-5 14.6 42.4 4 PdPt/HZSM-5 22.0 11.1 5 Ru/(CeO.sub.2 +
Al.sub.2O.sub.3) 0.2 0.3 6 Pd/TF-Al.sub.2O.sub.3 4.5 7.5
[0056] Examples 1 and 2 did not include an acidic support and also
did not include a noble metal and did not provide an overall
performance comparable to Examples 3 and 4, which are in accordance
with the invention
[0057] Table 4 presents acidity information of the catalyst
supports. The acidity was measured using a temperature programmed
desorption technique, where isopropylamine was adsorbed first at
100.degree. C., then purged in nitrogen flow until no further
weight change. A temperature ramping was carried in nitrogen at
10.degree. C./min from 100.degree. C. to 600.degree. C. The weight
loss as a function of temperature was a measurement of amount of
isopropylamine adsorbed by the catalyst and peak position was a
measurement of interaction between the acid sites and IPA. Higher
desorption temperature indicates stronger acid sites.
4TABLE 4 Summary of Acidity Measurement Results of Catalysts and
Catalyst Supports of Present Invention using IPA-TPD TPD
Characteristics Strong Weak Acid Sites Acid Sites Example Catalyst
(mmol/g) (.sup.a) (mmol/g) (.sup.b) SWAR (.sup.c) 10 HZSM-5 0.58
0.74 0.79 11 2.36% Ce-HZSM-5 0.55 0.63 0.88 12 4.72% Ce-HZSM-5 0.54
0.58 0.94 13 9.44% Ce-HZSM-5 0.47 0.47 0.99 14 1% Pd-HZSM-5 0.66
0.33 2.00 15 1% Pt-HZSM-5 0.62 0.49 1.26 16 20% TF-Al.sub.2O.sub.3
0.27 0.25 1.07 17 (CeO.sub.2 + Al.sub.2O.sub.3) 0.30 0.20 1.50 18
Silica-Alumina 0.16 0.24 0.66 (.sup.a) Strong acid sites:
corresponding to IPA desorbed at temperature over 300.degree. C.
during TPD; (.sup.b) Weak acid sites: corresponding to IPA desorbed
at temperature below 300.degree. C. during TPD; (.sup.c) ratio of
number of strong acid sites to weak acid sites.
[0058] The number of acid sites and distribution of acid sites,
i.e., strong versus weak can be modified by varying the supports.
Through metal support interaction, optimal performance of catalyst
for gasoline HDS can be achieved by tailoring the support acidity,
i.e., number of acid sites and acid strength.
[0059] Numerous modifications and variations of the present
invention are possible in light of the above teachings and,
therefore, within the scope of the appended claims, the invention
may be practiced otherwise than as specifically described.
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