Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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ORGANOSULFUR OXIDATION PROCESS
s FIELD OF THE INVENTION
This invention relates to a process for oxidizing organosulfur impurites
found in fuel streams. The process comprises reacting the organosulfur
impurities with an organic hydroperoxide in the presence of a titanium-
containing
catalyst. The titanium-containing catalyst is obtained by impregnating a
to siliceous solid with a titanium halide in a hydrocarbon solvent, or a vapor
stream
of titanium tetrachloride, followed by calcination. The catalyst is
particularly
effective at oxidizing the sulfur impurities found in fuels.
BACKGROUND OF THE INVENTION
Hydrocarbon fractions produced in the petroleum industry are typically
is contaminated with various sulfur impurities. These hydrocarbon fractions
include diesel fuel and gasoline, including natural, straight run and cracked
gasolines. Other sulfur-containing hydrocarbon fractions include the normally
gaseous petroleum fraction as well as naphtha, kerosene, jet fuel, fuel oil,
and
the like. The presence of sulfur compounds is undesirable since they result in
a
2o serious pollution problem. Combustion of hydrocarbons containing these
impurities results in the release of sulfur oxides which are noxious and
corrosive.
Federal legislation, specifically the Clean Air Act of 1964 as well as the
amendments of 1990 and 1999 have imposed increasingly more stringent
requirements to reduce the amount of sulfur released to the atmosphere. The
2s United States Environmental Protection Agency has lowered the sulfur
standard
for diesel fuel to 15 parts per million by weight (ppmw), effective in mid-
2006,
from the present standard of 500 ppmw. For reformulated gasoline, the current
standard of 300 ppmw has been lowered to 30 ppmw, effective Jan. 1, 2004.
Because of these regulatory actions, the need for more effective
so desulfurization methods is always present. Processes for the
desulfurization of
hydrocarbon fractions containing organosulfur impurities are well known in the
art. The most common method of desulfurization of fuels is
hydrodesulfurization, in which the fuel is reacted with hydrogen gas at
elevated
temperature and high pressure in the presence of a costly catalyst. U.S. Pat.
3s No. 5,985,136, for example, describes a~hydrodesulfurization process to
reduce
i
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sulfur level in naptha feedstreams. Organic sulfur is reduced by this reaction
to
gaseous H2S, which is then oxidized to elemental sulfur by the Claus process.
Unfortunately, unreacted H2S from the process is harmful, even in very small
amounts. Although hydrodesulfurization readily converts mercaptans,
s thioethers, and disulfides, other organsulfur compounds such as substituted
and
unsubstituted thiophene, benzothiophene, and dibenzothiophene are difficult to
remove and require harsher reaction conditions.
Because of the problems associated with hydrodesulfurization, research
continues on other sulfur removal processes. For instance, U.S. Pat. No.
io 6,402,939 describes the ultrasonic oxidation of sulfur impurities in fossil
fuels
using hydroperoxides, especially hydrogen peroxide. These oxidized sulfur
impurities may be more readily separated from the fossil fuels than non-
oxidized
impurities. Another method involves the desulfurization of hydrocarbon
materials where the fraction is first treated by oxidizing the sulfur-
containing
is hydrocarbon with an oxidant in the presence of a catalyst. U.S. Pat. No.
3,816,301, for example, discloses a process for reducing the sulfur content of
sulfur containing hydrocarbons by oxidizing at least of portion of the sulfur
impurities with an organic hydroperoxide such as t-butyl hydroperoxide in the
presence of certain catalysts. The catalyst described is preferably a
2o molybdenum-containing catalyst.
In sum, new methods to oxidize the sulfur compound impurities in
hydrocarbon fractions are required. Particularly required are processes which
effectively oxidize the difficult to oxidize thiophene impurities. We have
discovered an effective process for oxidizing organosulfur impurites found in
fuel
zs streams.
SUMMARY OF THE INVENTION
This invention is a process for oxidizing organosulfur impurites found in
fuel streams to sulfones. The process comprises oxidizing the organosulfur
impurities in the presence of an organic hydroperoxide and a titanium-
containing
3o catalyst. The titanium-containing catalyst is obtained by the method
comprising:
(a) impregnating an inorganic siliceous solid with a titanium source; (b)
calcining
the impregnated solid; and (c) optionally, heating the catalyst in the
presence of
water. The titanium source can be either a solution of a titanium halide in a
non-
oxygenated hydrocarbon solvent or a vapor stream of titanium tetrachloride.
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Optionally, the catalyst preparation method comprises the additional step of
treating the catalyst with a silylating agent. The catalyst is particularly
effective
at oxidizing the sulfur impurities found in fuels. The sulfones may then be
extracted from the fuel stream to form a purified fuel stream.
s DETAILED DESCRIPTION OF THE INVENTION
The oxidation process of the invention utilizes a titanium-containing ,
heterogeneous catalyst that has unexpectedly been found to give superior
oxidation performance compared to materials made using other impregnation
methods. The catalyst useful in the invention is prepared by impregnating an
io inorganic siliceous solid with a titanium halide.
The impregnation step may be performed by impregnating an inorganic
siliceous solid with a solution of titanium halide in a non-oxygenated
hydrocarbon solvent. Suitable solvents for this purpose are those hydrocarbons
that do not contain oxygen atoms, are liquid at ambient temperatures, and are
is capable of solubilizing the titanium halide. Generally speaking, it will be
desirable to select hydrocarbon solvents wherein titanium halide
concentrations
of at least 0.5 percent by weight at 25°C can be achieved. The
hydrocarbon
solvent should preferably be relatively volatile so that it may be readily
removed
from the inorganic siliceous solid following impregnation. Solvents having
2o normal boiling points of from 25°C to 150°C thus may
advantageously be
utilized. Particularly preferred classes of hydrocarbons include C5-C~2
aliphatic
hydrocarbons (straight chain, branched, or cyclic), C6-C~2 aromatic
hydrocarbons
(including alkyl-substituted aromatic hydrocarbons), C~-Cep halogenated
aliphatic
hydrocarbons, and C6-Coo halogenated aromatic hydrocarbons. Most preferably,
zs the solvent does not contain elements other than carbon, hydrogen, and
(optionally) halogen. If halogen is present in the solvent, it is preferably
chloride.
Mixtures of non-oxygenated hydrocarbons may be used, if so desired.
Preferably, the solvent used for impregnation purposes is essentially free of
water (i.e., anhydrous). While oxygen-containing hydrocarbons such as
3o alcohols, ethers, esters, ketones and the like could be present in
admixture with
the required non-oxygenated hydrocarbon, in one desirable embodiment of the
invention only non-oxygenated hydrocarbon is present as a solvent during
impregnation. Examples of suitable hydrocarbon solvents include n-hexane, n-
heptane, cyclopentane, methyl pentanes, methyl cyclohexane, dimethyl
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hexanes, toluene, xylenes, methylene chloride, chloroform, dichloroethanes,
chlorobenzene, benzyl chloride, and the like.
The impregnation process in preferred embodiments is characterized by
the substantial exclusion of water until at least after impregnation is
completed
s and preferably until after calcination. "Substantial exclusion" in the
context of
this invention means that water is not deliberately added or introduced or, if
deliberately added or introduced, is removed prior to introduction of titanium
halide. The use of reagents and starting materials having water present at the
trace levels normally and customarily found in such substances when sold on a
io commercial scale is within the scope of the present invention. Preferably,
less
than 500 ppm water (more preferably, less than 100 ppm water) is present in
the
non-oxygenated hydrocarbon.
Suitable titanium halides include tri- and tetra-substituted titanium
complexes that have from one to four halide substituents with the remainder of
is the substituents, if any, being alkoxide or amino groups. Suitable titanium
halides include titanium tetrachloride, titanium tetrafluoride, titanium
tetrabromide, titanium tetraiodide, titanium trichloride, as well as the mixed
halides of Ti(III) or Ti(IV) titanium halides, diisopropoxytitanium
dichloride,
bis(diethylamino)titanium dichloride, and the like. Preferably, all the
substituents
ao attached to titanium are halide. Most preferably, the titanium halide is
titanium
tetrachloride.
While the concentration of titanium halide in the hydrocarbon solvent is
not critical, the titanium halide concentration will typically be in the range
of from
0.01 moleslliter to 1.0 moles/liter. The concentration of the titanium halide
in the
2s hydrocarbon solvent and the amount of solution used is desirably adjusted
to
provide a titanium content in the final catalyst of from 0.1 to 15 percent by
weight
(calculated as Ti based on the total weight of the catalyst). Multiple
impregnations, with or without intervening drying and/or calcination, may be
used to achieve the desired titanium content.
3o Suitable inorganic siliceous solids for purpose of this invention are solid
materials that contain a major proportion of silica (silicon dioxide) and have
a
specific surface area of at least 50 m2/g, and preferably the average specific
surface area of from 300 m2/g to 2000 m2/g. The inorganic siliceous solids are
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porous, in that they have numerous pores, voids, or interstices throughout
their
structures.
Synthetic inorganic oxide materials containing a major proportion of silica
comprise another class of inorganic siliceous solids. Such materials are known
s as refractory oxides and includes silica-alumina, silica-magnesia, silica-
zirconia,
silica-alumina-boric and silica-alumina-magnesia. Molecular sieves,
particularly
large pore or mesoporous molecular sieves such as MCM-41, MCM-48 and
M41 S, may also be utilized as the inorganic siliceous solid.
Preferred inorganic siliceous solids are silica and mesoporous molecular
to sieves such as MCM-41, MCM-48 and M41 S. Particularly preferred are silica
and MCM-41.
It is highly desirable to dry the inorganic siliceous solid prior to
impregnation. Drying may be accomplished, for example, by heating the
inorganic siliceous solid for several hours at a temperature of 100°C
to 700°C,
is preferably at least 200°C. Generally speaking, there is no need to
employ
temperatures in excess of 700°C in order to attain a sufficient degree
of
dryness. Vacuum or a flowing stream of a dry gas such as nitrogen may be
applied to accelerate the drying process.
Any of the conventionally employed means of impregnating a porous
2o solid with a soluble impregnating agent may be used. For example, the
titanium
halide may be dissolved in the hydrocarbon solvent and then added to or
otherwise combined with the inorganic siliceous solids. The inorganic
siliceous
solids could also be added to the hydrocarbon solution of the titanium halide.
"Incipient wetness" impregnation techniques, whereby a minimum
2s quantity of solvent is utilized in order to avoid formation of a slurry,
are also
suitable for use. The resulting mixture may be aged, optionally with agitation
or
other mixing, prior to further processing. Generally speaking, the
impregnating
solution should be placed in contact with the inorganic siliceous solids for a
period of time sufficient for the solution to completely penetrate the
available
so pore volume of the solids. The hydrocarbon solvent used for impregnation
may
thereafter be removed by drying at moderately elevated temperature (e.g.,
50°C
to 200°C) andlor reduced pressure (e.g., 1 mm Hg to 100mm Hg) prior to
calcination. The conditions in the solvent removal step are preferably
selected
so that at least 80%, more preferably at least 90%, of the hydrocarbon solvent
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used for impregnation is removed prior to calcination. The drying step may be
preceded by decantation, filtration or centrifugation to remove any excess
impregnation solution. Washing of the impregnated siliceous solid is not
necessary. Thus, one desirable embodiment of this invention is characterized
s by the absence of such a washing step.
The catalyst useful in the invention may also be prepared by impregnating
an inorganic siliceous solid with a vapor stream of titanium tetrachloride.
The
vapor stream is provided by flowing a gas over liquid titanium tetrachloride.
The
vaporization is conducted at temperatures greater than 50°C at
atmospheric
to pressure. Preferably, the vaporization temperature is greater than
80°C and,
most preferably, greater than 130°C. Alternatively, lower temperatures
are
possible by decreasing reaction pressure. Preferably, the gas is an inert gas
such as nitrogen, helium, argon, carbon dioxide, and the like. The vapor
stream
of titanium tetrachloride is then passed over the high surface area inorganic
is siliceous solid to complete the impregnation step. The inorganic siliceous
solid
is maintained at a temperature greater than 50°C during the
impregnation.
Preferably, the temperature of impregnation is maintained at greater than
80°C
and, most preferably, greater than 130°C.
Following impregnation, the vapor phase and liquid phase impregnated
zo siliceous solids are calcined by firing at an elevated temperature.
Calcination
may be performed in the presence of oxygen (from air, for example) or, more
preferably, an inert gas which is substantially free of oxygen such as
nitrogen,
argon, neon, helium or the like or mixture thereof. In one embodiment of the
invention, calcination is first performed in a substantially oxygen-free
2s atmosphere with oxygen being introduced thereafter. Preferably, the
calcination
atmosphere contains less than 10,000 ppm mole oxygen. More preferably, less
than 2000 ppm mole oxygen is present in the calcination atmosphere. Ideally,
the oxygen concentration during calcination is less than 500 ppm. It is
recognized, however, that substantially oxygen-free conditions are difficult
to
3o attain in large-scale commercial operations. Optionally, the calcination
may be
performed in the presence of a reducing gas, such as carbon monoxide, when
the some oxygen (e.g., up to 25,000 ppm mole) is present. The optimum
amount of the reducing gas will, of course, vary depending upon a number of
factors including the oxygen concentration in the calcination atmosphere and
the
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identity of the reducing gas, but reducing gas levels of from 0.1 to 10 mole %
in
the calcination atmosphere are typically sufficient. In one embodiment of the
invention, calcination is performed in an atmosphere comprised of oxygen, a
reducing gas (preferably carbon monoxide) and, optionally, one or more inert
s gases (e.g.,-nitrogen, helium, argon, carbon dioxide).
The catalyst may be maintained in a fixed bed during calcination with a
stream of gas being passed through the catalyst bed. To enhance the oxidation
activity of the catalyst, it is important that the calcination be performed at
a
temperature of at least 500°C. More preferably, the calcination
temperature is
to at least 700°C but no greater than 1000°C. Typically,
calcination times of from
about 0.1 to 24 hours will be sufficient.
The catalyst may be reacted with water after and/or during calcination.
Such reaction can be effected by, for example, contacting the catalyst with
steam at an elevated temperature (preferably, a temperature in excess of
is 100°C, more preferably, a temperature in the range of 150°C
to 650°C) for from
about 0.1 to 6 hours. Reaction with water is desirable in order to reduce the
amount of residual halide in the catalyst derived from the titanium halide
reagent
and to increase the hydroxy density of the catalyst.
The catalyst may also be treated with an organic silylating agent at
2o elevated temperature. Silylation is preferably performed after calcination
and
most preferably after both calcination and reaction with water. Suitable
silylation
methods adaptable for use in the present invention are described in U.S. Pat.
Nos. 3,829,392 and 3,923,843. Suitable silylating agents include
organosilanes,
organohalosilanes, and organodisilazanes.
2s Organosilanes containing from one to three organic substituents may be
utilized, including, for example, chlorotrimethylsilane, dichlorodimethyl
silane,
nitrotrimethyl-silane, chlorotriethylsilane, chlorodimethylphenylsilane and
the
like. Preferred organohalosilane silylating agents include tetra-substituted
silanes having from 1 to 3 halo substituents selected from chlorine, bromine,
and
3o iodine with the remainder of the substituents being methyl, ethyl, phenyl
or a
combination thereof.
Organodisilazanes are represented by the formula R3Si-NH-SiR3, wherein
the R groups are independently hydrocarbyl groups (preferably, C~-C4 alkyl) or
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hydrogen. Especially preferred for use are the hexaalkyl substituted
disilazanes
such as, for example, hexamethyldisilazane.
Treatment with the silylating agent may be performed either in the liquid
phase (i.e., where the silylating agent is applied to the catalyst as a
liquid, either
s by itself or as a solution in a suitable solvent such as a hydrocarbon) or
in the
vapor phase (i.e., where the silylating agent is contacted with the catalyst
in the
form of a gas). Treatment temperatures are preferably in the range of from
about 80°C to 450°C, with somewhat higher temperatures (e.g.,
300°C to
425°C) being generally preferred wherein the silylating agent is an
to organohalosilane and somewhat lower temperatures (e.g., 80°C to
300°C) being
preferred for the organodisilazanes. The silylation may be carried out in a
batch,
semi-continuous, or continuous manner.
The length of time required for the silylating agent to react with the
surface of the catalyst depends in part on the temperature and agent employed.
is Lower temperatures generally require longer reaction times. Generally,
times of
from 0.1 to 48 hours are suitable.
The amount of silylating agent employed can vary widely. Suitable
amounts of silylating agent can range from about 1 percent by weight (based on
the weight of the entire catalyst composition) to about 75 percent by weight,
with
zo amounts of from 2 to 50 percent by weight typically being preferred. The
silylating agent can be applied to the catalyst either in one treatment or a
series
of treatments.
The catalyst composition obtained by the aforedescribed procedure will
generally have a composition comprising from about 0.1 to 15 percent
2s (preferably, 1 to 10 percent) by weight titanium (in the form of titanium
oxide,
typically, and preferably, in a high positive oxidation state). Where the
catalyst
has been silylated, it will typically also contain 1 to 20 percent by weight
carbon
in the form of organic silyl groups. Relatively minor quantities of halide
(e.g., up
to about 5000 ppm) may also be present in the catalyst.
so The catalyst compositions may optionally incorporate non-interfering
andlor catalyst promoting substances, especially those which are chemically
inert to the oxidation reactants and products. The catalysts may contain minor
amounts of promoters, for example, alkali metals (e.g., sodium, potassium) or
alkaline earth metals (e.g., barium, calcium, magnesium) as oxides or
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hydroxides. Alkali metal and/or alkaline earth metal levels of from 0.01 to 5%
by
weight based on the total weight of the catalyst composition are typically
suitable.
The catalyst compositions may be employed in any convenient physical
s form such as, for example, powder, flakes, granules, spheres or pellets. The
inorganic siliceous solid may be in such form prior to impregnation and
calcination or, alternatively, be converted after impregnation andlor
calcination
from one form to a different physical form by conventional techniques such as
extrusion, pelletization, grinding or the like.
io The organosulfur oxidation process of the invention comprises contacting
a fuel stream that contains organosulfur impurites with an organic
hydroperoxide
in the presence of the titanium-containing catalyst. Suitable fuel streams
include
diesel fuel and gasoline, including natural, straight run and cracked
gasolines.
Other sulfur-containing hydrocarbon fractions include the normally gaseous
is petroleum fraction as well as naphtha, kerosene, jet fuel, fuel oil, and
the like.
Diesel fuel is a particularly preferred fuel stream.
Preferred organic hydroperoxides are hydrocarbon hydroperoxides having
from 3 to 20 carbon atoms. Particularly preferred are secondary and tertiary
hydroperoxides of from 3 to 15 carbon atoms. Exemplary organic
2o hydroperoxides suitable for use include t-butyl hydroperoxide, t-amyl
hydroperoxide, cyclohexyl hydroperoxide, ethylbenzene hydroperoxide, and
cumene hydroperoxide. T-butyl hydroperoxide is especially useful.
Organic hydroperoxides are typically produced by oxidation of the
corresponding alkane with coproduction of the corresponding alcohol. For
2s example, the oxidation of isobutane produces a mixture of t-butyl
hydroperoxide
and t-butanol. Although it is suitable to use the organic hydroperoxide with
the
corresponding alcohol in the organosulfur oxidation process of the invention,
it is
preferable that the organic peroxide is substantially alcohol-free before use
in
the oxidation process. By "alcohol free", it is meant that the organic
3o hydroperoxide:alcohol molar ratio is greater than about 25:1.
In such an oxidation process the sulfur compound:hydroperoxide molar
ratio is not particularly critical, but it is preferable to employ a molar
ratio of
approximately 2:1 to about 1:2.
9
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The oxidation reaction is conducted in the liquid Phase at moderate
temperatures and pressures. Suitable reaction temperatures vary from
0°C tv
20D°C, but preferably from 25°C to 15D°C. The reaction is
preferably conducted
at or above atmospheric pressure. The precise pressure is not critical. The
s titanium-containing catalyst composition, of course, is heterogeneous in
character and thus is present as a solid phase during the oxidation process of
this invention. Typical pressures vary from 1 atmosphere to 100 atmospheres.
The oxidation reaction may be perFormed using any of the conventional
reactor configurations known in the art for such oxidation processes_
io t:ontinuous es well as batch procedures may be used. For example, the
catalyst may be deployed in the form of a fixed bed ar slurry.
The oxidation process of the invention converts a substantial portion of
the organosu(fur impurities into s~tfanes. Typically, greater than about 50
percent of the arganosulfur impurities are converted into sulfones, preferably
is greater than about 80 percent, and most preferably greater than about 90
percent. When the oxidation has proceeded to the desired extent, the product
. mixfure may be treated to remove the sulfones firorn the fuel stream.
Typical
suifone removal processes include solid-liquid extraction using absorbents
such
as silica, afumina, polymeric resins, and zeolites. Alternatively, the
sulfones can
2a be removed by liquid-liquid extraction using polar solvents such as
methanol,
dimethyl farmamide, N-methylpyrrolidvne, or acetanitrile. Other extraction
media, both solid and liquid, wiH be readily apparent to those skilled in the
art of
exftacting polar species.
The following examples merely illustrate the invention.
s
E~;AMPLE 1. CATALYST f'REPARATI~JN IN ACCORDANCE WITH THE
INVENTION
Catalyst 1A: The silica support (Grace Davison DAVICAT P-732, particle
size 0.6 -1.4 mm, surface area 300 m~lg) is dried at 4D0°C in air for 4
hours.
3o The dried silica (47 g) is charged into a 1-L round-bottom flask. A
solution
containing titanium (IVy diisapropoxide bis(acetylacetonate) (15_1 g, 75%
solution in isopropanol) and isopropanal (89 g) is then added to the silica
and
mixed well. The solvent is removed by rotavaping at 90°C. The
impregnated
to
AMEf~DED SHEET
cm~.~ ~~; ~ a , ct m~ ronn~ ~ ~ ~ ~ ~ a_n.c .~.. ~ n , c o nn~
19-05-2005
CA 02513863 2005-07-20 US0341552
1 U t 1 i./ LVV.~ i1'.JL 1 1 W -1 U11YLLL t-1 !L-I 1' 1-L..p IL VlU W/ L1,~T J
U Nii-IIU.IL~JIITZU..i 1 V 1 r iU
.
material was calcined in air at 800°C for 2 hours. Non-sitylated
Catalyst 1A wa
measured tv contain 3.2 wt.°/'° Ti and X0.1 wt% C.
. Catalyst 1B: Silylated Catalyst 1B is made by the procedure for nan-
silyiated Catalyst 1A, except that the silica is dried at 450°C and 51
g of the
s dried silica is impregnated with a solution containing titanium (I~
diisopropoxide
bis(acetylacetonate) (16.8 ~, 75°J° solution in isopropanol) and
isoprvpanol (82
g). The catalyst is then silylated in a by charging the material into a 500-mL
3-
neck round-bottom flask equipped with a condenser, a thermometer, and an
inert gas infet_ The flask is charged with the nonsilylated catalyst (52.9 g}
and
~ o hexamethyldisilazane (9.03 g) and n-heptane (99 g). The system is heated
with
an oil bath to reflux (98°G) under inert atmosphere for 2 hours. The
system is
cooled down under inert gas atmosphere and tha catalyst is flitered and washed
with heptane (100 mL). Obtained silylated Catalyst 1 B is then dried in a
flask
under inert gas flow at 160-200°G for 2 hours. Measured Ti, 2.73 v~it%;
C, 2_a
ZS wt°/D_
Catal sue: Silica (Grace Davison DAVICAT P-732) is dried at 400°C in
air for 4 hvurs_ The dried silica (39_62 g) is charged into a 500-mL 3-neck
round-bottom flask equipped with an inert gas inlet. a gas outlet, and a
Scrubber
containing aqueous sodium hydroxide solution. into the flask described above.
zo a solution consisting of n-heptane (84.21 g, 99~%, water <50 ppm) and
titanium
(11I) tetrachloride (S.OZ g) is added under dry inert gas atmosphere. The
mixture
_ is mixed well by swirling. The solvent is removed by heating with an ail
bath at
9 25°G under nitrogen flow for 1.5 hours.
A portion of above material (35 g) is calcined by charging it into a tubular
2s quarts reactor (1 inch (2.54 cm] ID, 16 inch [40.64 cm] long) equipped with
a
thermowell, a 500 mL 3-neck round-bottom flask, a heating mantle, an inert gas
inlet, and a scrubber (containing sodium hydroxide solution). The catalyst bed
is
heated to 850°C under dry nitrogen (99.999%) flow (400 cclmin). After
the bed
is maintained at 850°C for 3D min, the power to the furnace is turned
off and the
3o catalyst bed is cooled to 400°C.
The catalyst is hydrated by the following procedure. Water (3.0 g) is
added into the 3-neck round-bottom flask and the flask is heated with a
heating
mantle to reflux while maintaining tfie nitrogen flaw at 400 cc/min. The wafer
is
distilled through the catalyst bed aver a period of 30 minutes. A heat gun is
n
AMENDED SHEET
,~ ; + ~ 1 a m~ hflfl~ 1? ~ 9 ~ c.~n.~ ~~, o n 9 r n nn~
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P.08i16
used to heat the round-bottom flask to ensure that any residual water is
driven
out of the bask through the bed. The bed is then maintained at 400°C
for an
additional 2 hours befr~re cooling. Catalyst 1C contains 3.7 wt.% Ti.
Catalyst 1 D: Catalyst 1 C is further silylated as fellows.
s A 500 mL 3-neck round-botkvm flask is equipped with a condenser, a
thermometer, and an inerk gas inlet. The flask is charged with heptane (39 g,
water <50 ppm), hexamethyldisila~~ane (3.10 g) and Catalyst 1C (11.B g). The
system is heated v~~ith oil bath to reflux (98°C) for 2 hours under
inert
atmosphere before touting. The catalyst is filtered and washed with heptane
~o (100 mL). The material is then dried in a flask under inert gas flow at 180-
200°C
for 2 hours. Cataiyst r D contains 3.5 wt.% Ti and 1.97 wt.% G.
Catalyst 1 E: Silica (Grace Davison DAVlGAT P-732) is dried in at
450°G
in air for 2 hours. The dried silica (36 g) is charged into a tubular quarts
reactor
(1 inch [2.54 cmj lD. 16 inch [40.64 cm] Ivng) equipped with a thermowell, a
is 500-mL 3-neck round-bottom flask, a heating mantle, an inert gas inlet, and
a
.scrubber (containing sodium hydroxide solution). The catalyst bed is heated
tv
300°G under dry nitrogen (99.999°I°) flow (400 ccJmin).
Titanium tetrachloride
(7.4 g) is transferred to the 3-neck round-botEom flask and the flask is
heated
with a heating mantle to reflux while maintaining the nitrogen flew at 400
cGmin.
zo The titanium tetrachloride is distilled through the catalyst bed in a
period of 1
hour. A heat gun is used to heat the round-bottom flask tv ensure that any
residual titanium tetrachloride is driven out of the flask through the bed_
The
bed is then heated at 1350°C for 0.5 hour before cooling to
400°G.
Water (3.0 g) is added into the 3-neck round-bottom flask and the flask is
2s heated with a heating mantle to retlux while maintaining the ~nitragen flow
at 400
cclmin. The water is distilled through the catalyst bed ever a period of 30
minutes. A heat gun is used tv heat fibs round-bottom flask to ensure that any
residual water is driven out of the flask through the bed. The heat to the
heating
mantle was turned off. The tube reactor was cooled to room temperature.
~o The catalyst is then silylated according to the procedure described for
Catalyst 1 B, except that 15 g of catalyst, 43 g of heptane, and 3.0 g of
hexamethyldisila~ane is used. Catalyst 1 E cvntain5 2.6 wt.°~o Ti and
2.0 wt.°~o C,
t~
AMENDED SHEET
~m~ø -.o; .~ ~ ~afn~eonn~ m~ ~~ cm~.~ ~~ ~n,c o nn~
CA 02513863 2005-07-20
WO 2004/083345 PCT/US2003/041552
Catalyst 1 F: MCM-41 silica support can be made according to any known
literature procedure. See, for example, U.S. Pat. No. 3,556,725, DiRenzo, et.
al., Microporous Materials (1997), Vol. 10,.283, or Edler, et. al., J. Chem.
Soc.,
Chem. Comm. (1995), 155. The obtained MCM-41 gel is dried at 180°C
and
s then calcined at 550°C for 14 hours before use. BET surface area of
the
material is 1488 m2/g. MCM-41 (4.36 g) is charged into a 500-mL 3-neck round-
bottom flask equipped with an inert gas inlet, a gas outlet, and a scrubber
containing aqueous sodium hydroxide solution. Into the flask described above,
a solution consisting of n-heptane (60 g, 99+%, water <50 ppm) and titanium
to (IV) tetrachloride (0.95 g, 0.55 ml) is added under dry inert gas
atmosphere.
The mixture is mixed well by swirling. The solvent is removed by rotavaping
under vacuum at 80°C for 1 h.
The above obtained material is then calcined and hydrated according to
the procedure described for Catalyst 1 C. The catalyst is then silylated
according
is to the procedure described for Catalyst 1 B, except that 3.72 g of
catalyst, 35 g of
heptane, and 0.96 g of hexamethyldisilazane is used. Catalyst 1 F contains 5.5
wt.% Ti and 5.1 wt.% C.
EXAMPLE 2. OXIDATION OF THIOPHENES WITH TBHP OXIDATE
Catalysts 1A-F are tested in the oxidation of various organosulfur
2o compounds. The test results are shown in Table 1. A feed is prepared by
mixing either toluene or ethyl benzene with dibenzothiophene (DBT) and
Lyondell TBHP oxidate (containing approximately 43 wt% TBHP and 56%
tertiary butyl alcohol). The feed contains 0.175 wt.% (DBT), 0.32 wt.% t-butyl
alcohol (TBA), and 0.24 wt.% t-butyl hydroperoxide (TBHP). The molar ratio of
2s DBT to TBHP is 2.8.
Examples 2A-F: The toluene-based feed (28 g) is heated and stirred in a
round-bottom flask to 50°C under nitrogen atmosphere. The Ti/silica
catalyst
(0.2 g, in powder form) is then added and the reaction proceeds at 50°C
under
nitrogen atmosphere for 0.5 hour. The reaction mixture is analyzed by GC and
3o HPLC. Oxidation products of thiophene are found to be the corresponding
sulfoxide and sulfone as determined by GC and GC-MS.
Example 2G is run under the same procedure as in Examples 2A-F
except that 0.04 g of the particle form of Catalyst 1 D is used, and the
reaction
temperature is 80°C.
13
CA 02513863 2005-07-20
WO 2004/083345 PCT/US2003/041552
Example 2H is run under the same procedure as in Example 2G except
that 4,6-dimethyl dibenzothiophene (DMDBT) is used instead of DBT. The
molar ratio of DMDBT to TBHP was 2.4.
Example 21-J are run under the same procedure as in Examples 2A-F
s except that the ethyl benzene based solution is used, 0.02 g of the particle
form
of Catalyst 1 D is used, the reaction temperature is 80°C, and the
reaction time is
one hour. For Comparative Example 2J, no catalyst is used.
TABLE 1. Organosulfur Oxidation with Ti/silica Catalysts
Run CatalystCatalystSolventSubstrateTemperatureConversion
# Amount (C) (%)
(J)
2A 1A 0.2 TolueneDBT 50 31
*
2B 1 B 0.2 TolueneDBT 50 39
*
2C 1 C 0.2 TolueneDBT 50 90
2D 1 D 0.2 TolueneDBT 50 91
2E 1 E 0.2 TolueneDBT 50 91
2F 1 F 0.2 TolueneDBT 50 97
2G 1 D 0.04 TolueneDBT 80 93
2H 1 D 0.04 TolueneDMDBT 80 56
21 1 D 0.02 EB DBT 80 80
2J - - EB DBT 80 10
*
* Comparative Example
14
