Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR EFFECTING ULTRA-DEEP HDS OF HYDROCARBON
FEEDSTOCKS
The present invention relates to a process for effecting ultra-deep HDS of
hydrocarbon feedstocks.
In an effort to regulate S02 emissions from the burning of fuels and to
optimise
the performance of tail-end catalysts, in particular exhaust treatment
catalysts,
the regulations as to the sulphur content of fuels, in particular diesel
fuels, are
becoming more and more strict. In Europe diesel feedstocks will be required as
of 2000 to have a sulphur content below 350 ppm, while as of 2005, the sulphur
content should be below 50 ppm, with even further decreases not being
excluded.
In consequence, there is an increasing need for catalyst systems which can
decrease the sulphur content of a hydrocarbon feedstock with a 95% boiling
point of 450°C or less to below 200 ppm, preferably below 100 ppm, even
more
preferably below 50 ppm, calculated by weight as elemental sulphur on the
total
liquid product.
In the context of the present specification the term ultra-deep HDS means the
reduction of the sulphur content of a hydrocarbon feedstock to a value of less
than 200 ppm, preferably less than 100 ppm, and even more preferably to a
value of less than 50 ppm, calculated by weight as elemental sulphur on the
total liquid product, as determined in accordance with ASTM D-4294. The
indications Group VIB and Group VIII correspond to the Periodic Table of
Elements applied by Chemical Abstract Services (CAS system).
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The problem associated with effecting this ultra-deep HDS is that the only
"- sulphur compounds still present in the feed are those which are very
difficult to
remove. Depending on their source, petroleum fractions can comprise various
types of sulphur compounds. In middle distillate fractions, the major sulphur
components are benzothiophenes and dibenzothiophenes. In straight-run
materials significant quantities of other components are present, such as
thiophenes, mercaptanes, sulphides and disulphides. Of these, the sulphides
and disulphides are the most reactive, followed by the thiophenes,
benzothiophenes, and dibenzothiophenes. Within the group of
dibenzothiophenes some components are more reactive than others. In
consequence, in conventional HDS, in which the sulphur level is reduced to a
value of, say, about 0.3 wt.%, the sulphides and thiophenes are removed. In
deep HDS, to a sulphur level of, say, 200-500 ppm, the benzothiophenes are
removed. The only compounds remaining then are a limited number of
alkylated benzothiophenes, with the alkyldibenzothiophenes which have the
alkyl on the 4- or 6- position being particularly difficult to remove.
It has also been found that the reaction mechanisms by which these very
refractive sulphur compounds are decomposed is different from that by which
the less refractive compounds are decomposed. This is evidenced, e.g., by the
fact that the catalysts which are known as particularly suitable for HDS
appear
to function less well in ultra-deep HDS. For example, conventionally cobalt-
molybdenum catalysts are more active in HDS than nickel-molybdenum
catalysts. However, ~ for ultra-deep HDS it has been found that nickel-
molybdenum catalysts show better results than cobalt-molybdenum catalysts.
Reference is made to the paper entitled " Ultra low sulphur diesel: Catalyst
and
Process options" presented at the 1999 NPRA meeting by T. Tippet, et al.
The consequence of this difference in reaction mechanisms implies that the
refiner who is faced with having to produce material with a lower sulphur
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content cannot just apply his usual hydrodesulphurisation catalyst under more
stringent conditions. On the contrary, he will have to specifically select the
hydrotreating catalyst which is most effective in effecting ultra-deep HDS.
This
is the more so since the reaction conditions necessary to effect ultra-deep
HDS
are rather severe in themselves, and the use of a better catalyst makes it
possible to select less severe reaction conditions, resulting in energy saving
and a longer catalyst lifespan.
We have now found that a that a catalyst which before sulphidation comprises
a Group VIB metal component, a Group VIII metal component, and an organic
additive is very efficient in reducing the sulphur content of a hydrocarbon
feedstock to a value of less than 200 ppm. Additionally, it has appeared that
this catalyst makes it possible to effect ultra-deep HDS in combination with
improved nitrogen removal, total aromatics removal, and removal of polynuclear
aromatics.
Therefore, the present invention is directed to a process for reducing the
sulphur content of a hydrocarbon feedstock to a value of less than 200 ppm,
comprising subjecting a catalyst comprising a Group VIB metal component, a
Group VIII metal component, and an organic additive on a carrier to a
sulphidation step, and contacting a feedstock with a 95% boiling point of
450°C
or less and a sulphur content of 500 ppm or less with the sulphided catalyst
under conditions of elevated temperature and pressure to form a product with a
sulphur content of less than 200 ppm.
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The catalyst
Catalysts which before sulphidation comprise a Group VIB metal component, a
Group VIII metal component, and an organic additive are known in themselves
in the art.
For example, European patent application 0 601 722 describes a process for
preparing a catalyst in which a gamma-alumina support is impregnated with an
impregnation solution comprising a Group VIB metal component, a Group VIII
metal component, and an organic additive which is at least one compound
selected from the group of compounds comprising at least two hydroxyl groups
and 2-10 carbon atoms, and the (poly)ethers of these compounds.
WO 96/41848 describes a process in which an additive-containing catalyst is
prepared by incorporating the additive mentioned above into a finished
catalyst
composition. That is, a catalyst composition comprising hydrogenation metal
components in the oxidic form, brought into that form by calcination, is
contacted with the specified additive.
Japanese patent application 04-166231 describes a process for preparing a
hydrotreating catalyst in which a support is impregnated with an impregnation
solution comprising a Group VIB metal component, a Group VIII metal
component, and, optionally, a phosphorus component. The support is dried at a
temperature below 200°C, contacted with a polyol, and then dried again
at a
temperature below 200°C.
Japanese patent application 04-166233 describes substantially the same
process as the above-mentioned patent application, except that instead of a
polyol an alkoxycarboxylic acid is used.
Japanese patent application 06-339635 describes a process in which a support
is impregnated with an impregnation solution comprising an organic acid, Group
VIB and Group VIII hydrogenation metal components, and preferably a
phosphorus component. The impregnated support is dried at a temperature
below 200°C. The dried impregnated support is contacted with an organic
acid
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or polyol, after which the thus treated support is dried at a temperature
below
200°C.
Japanese patent application 06-210182 describes a process for preparing a
catalyst in which a boric-alumina support comprising 3-15 wt.% of boric is
5 impregnated with an impregnation solution comprising a Group VIB metal
component, a Group VIII metal component, and a polyol. The impregnated
support is dried at a temperature of 110°C to form a catalyst.
Non-prepublished European patent application No. 99201051.2 in the name of
Akzo Nobel filed on April 8, 1999, describes a catalyst containing an organic
compound comprising N and carbonyl.
In principle, any catalyst prepared by any process according to any one of the
above references or not which comprises a Group VIB hydrogenation metal, a
Group VIII hydrogenation metal, and an organic additive on a carrier is
suitable
for use in the process of the present invention. As Group VIB metals may be
mentioned molybdenum, tungsten, and chromium. Group VIII metals include
nickel, cobalt, and iron. In the ultra-deep HDS process of the present
invention,
it is preferred to use a catalyst comprising molybdenum as Group VIB metal
component and nickel and/or cobalt as Group VIII metal component. The use of
nickel as Group VIII metal component is particularly preferred.
The catalyst usually has a metal content in the range of 0.1 to 50 wt.%,
calculated on the dry weight of the catalyst not containing the additive. The
Group VIB metal will frequently be present in an amount of 5-30 wt.%,
preferably 15-25 wt.%, calculated as trioxide. The Group VIII metal will
frequently be present in an amount of 1-10 wt.%, preferably 2-6 wt.%,
respectively, calculated as monoxide. If so desired, the catalyst may also
contain other components, such as phosphorus, halogens, and boron.
Particularly, the presence of phosphorus in an amount of 1-10 wt.%, calculated
as PZOS, can be preferred.
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The catalyst carrier may comprise the conventional oxides, e.g., alumina,
silica,
silica-alumina, alumina with silica-alumina dispersed therein, silica-coated
alumina, magnesia, zirconia, boria, and titania, as well as mixtures of these
oxides. As a rule, preference is given to the carrier comprising alumina,
silica-
alumina, alumina with silica-alumina dispersed therein, or silica-coated
alumina.
Special preference is given to the carrier consisting essentially of alumina
or
alumina containing up to 20 wt.% of silica, preferably up to 10 wt.%. A
carrier
containing a transition alumina, for example an eta, theta, or gamma alumina
is
preferred within this group, with a gamma-alumina carrier being especially
preferred.
The catalyst's pore volume (measured via mercury penetration) is not critical
to
the process according to the invention and will generally be in the range of
0.25
to 1 mllg. The specific surface area is not critical to the process according
to the
invention either and will generally be in the range of 50 to 400 m2lg
(measured
using the BET method). Preferably, the catalyst will have a median pore
diameter in the range of 7-15 nm, as determined by mercury porosimetry
(contact angle 130°), and at least 60% of the total pore volume will be
in the
range of ~ 2 nm from the median pore diameter. This data is determined on the
catalyst after it has been calcined for one hour at a temperature of
500°C.
The catalyst is suitably in the form of spheres or extrudates. Examples of
suitable types of extrudates have been disclosed in the literature (see, int.
al.,
US 4 028 227). Highly suitable for use are cylindrical particles (which may be
hollow or not) as well as symmetrical and asymmetrical polylobed particles (2,
3
or 4 lobes).
The organic additive present in the catalyst to be used in the process
according
to the invention before sulphidation may be any organic additive. Preferably
the
organic additive is selected from the group of compounds comprising at least
two oxygen atoms and 2-10 carbon atoms and the compounds built up from
these compounds. Organic compounds selected from the group of compounds
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7
comprising at least two oxygen-containing moieties, such as a carboxyl,
carbonyl or hydroxyl moieties, and 2-10 carbon atoms and the compounds built
up from these compounds are preferred. Examples of suitable compounds
include citric acid, tartaric acid, oxalic acid, malonic acid, malic acid,
butanediol,
pyruvic aldehyde, glycolic aldehyde, and acetaldol. At this point in time,
preference is given to an additive that is selected from the group of
compounds
comprising at least two hydroxyl groups and 2-10 carbon atoms per molecule,
and the (poly)ethers of these compounds. Suitable compounds from this group
include aliphatic alcohols such as ethylene glycol, propylene glycol,
glycerin,
trimethylol ethane, trimethylol propane, etc. Ethers of these compounds
include
diethylene glycol, dipropylene glycol, trimethylene glycol, triethylene
glycol,
tributylene glycol, tetraethylene glycol, tetrapentylene glycol. This range
can be
extrapolated to include polyethers like polyethylene glycol. For this last
compound, polyethylene glycol with a molecular weight between 200 and 600 is
preferred. Other ethers which are suitable for use in the present invention
include ethylene glycol monobutyl ether, diethylene glycol monomethyl ether,
diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, and
diethylene glycol monobutyl ether. Of these, ethylene glycol, diethylene
glycol,
triethylene glycol, tetraethylene glycol, proplylene glycol, dipropylene
glycol and
polyethylene glycol with a molecular weight between 200 and 600 are
preferred.
Another group of compounds comprising at least two hydroxyl groups and 2-10
carbon atoms per molecule are the saccharides. Preferred saccharides include
monosaccharides such as glucose and fructose. Ethers thereof include
disaccharides such as lactose, maltose, and saccharose. Polyethers of these
compounds include the polysaccharides.
A further group of additives are those compounds comprising at least one
covalently bonded nitrogen atom and at least one carbonyl moiety. Examples
include aminopolycarboxylic acids, such as nitrilo-triacetic acid and
diethylene-
triamine-pentaacetic acid. In this case the organic compound preferably
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comprises at least two nitrogen atoms and preferably at least two carbonyl
moieties. It is further preferred that at least one carbonyl moiety is present
in a
carboxyl group. It is furthermore preferred that at least one nitrogen atom is
covalently bonded to at least two carbon atoms. A preferred organic compound
is a compound satisfying formula (I)
(R1 R2)N - R3 - N(R1'R2') (I)
wherein R1, R2, R1' and R2' are independently selected from alkyl, alkenyl,
and
allyl with up to 10 carbon atoms optionally substituted with one or more
groups
selected from carbonyl, carboxyl, ester, ether, amino, or amido. R3 is an
alkyiene group with up to 10 carbon atoms which may be interrupted by -O- or -
NR4-. R4 is selected from the same group as indicated above for R1. The R3
alkylene group may be substituted with one or more groups selected from
carbonyl, carboxyl, ester, ether, amino, or amido. As has been set out above,
it
is essential that the organic compound of formula (I) comprises at least one
carbonyl moiety.
Preferably, at least two of R1, R2, R1' and R2' have the formula - R5 - COOX,
wherein R5 is an alkylene group having 1-4 carbon atoms, and X is hydrogen
or another cation, such as an ammonium, a sodium, a potassium, and/or a
lithium cation. If X is a multivalent cation, one X can adhere to two or more -
R5
- COO groups. Typical examples of such a compound are
ethylenediamine(tetra)acetic acid (EDTA), hydroxyethylenediaminetriacetic
acid, and diethylenetriaminepentaacetic acid.
It is possible to use a single compound or a combination of compounds as
add itive.
The amount of additive present in the catalyst before sulphidation depends on
the specific situation. It was found that the appropriate amount of additive
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generally lies in the range of 0.01-2.5 moles of additive per mole of
hydrogenation metals present in the catalyst. If the amount of additive added
is
too low, the advantageous effect of the present invention will not be
obtained.
On the other hand, the addition of an exceptionally large amount of additive
will
not improve the effect of the present invention. It is well within the scope
of the
person skilled in the art to determine the optimum amount of additive to be
used in each specific situation, depending also on the solubility and the
viscosity of the additive.
The way in which the additive is incorporated into the catalyst composition is
at
present considered not critical to the process according to the invention. The
additive can be incorporated into the catalyst composition prior to,
subsequent
to or simultaneously with the incorporation of the hydrogenation metal
components.
For example, the additive can be incorporated into the catalyst composition
prior to the hydrogenation metal components by being added to the carrier
before the hydrogenation metal components are. This can be done by mixing
the additive with the carrier material before it is shaped, or by impregnating
the
shaped carrier material with the additive.
It is also possible to incorporate the additive into the catalyst composition
simultaneously with the hydrogenation metal components. This can be done,
e.g., by mixing the additive and the hydrogenation metal components with the
carrier material before shaping. However, a preferred way to incorporate the
additive into the catalyst composition simultaneously with the hydrogenation
metal components is by impregnating the carrier with an impregnation solution
comprising the hydrogenation metal components and the additive, followed by
drying under such conditions that at least part of the additive is maintained
in
the catalyst. This is the process described in EP 601 722.
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It is also possible to incorporate the additive into the catalyst composition
subsequent to the hydrogenation metal components. This can be done, e.g., by
- first incorporating the hydrogenation metal components into the catalyst
composition, e.g., by mixing them with the carrier material or by impregnating
5_ . the carrier with them, optionally followed by drying and/or calcining,
and
subsequently incorporating the additive, e.g., by impregnation. A preferred
embodiment of this process is the embodiment described in WO 96/41848, in
which first a catalyst composition is prepared by incorporating hydrogenation
metal components into a catalyst composition, e.g., by impregnation of a
10 carrier, after which the catalyst is subjected to a calcination step to
convert the
hydrogenation metal components into their oxides, followed by incorporating
the additive into the catalyst composition by impregnation. In this embodiment
it
is possible, e.g., to composite a conventional hydrotreating catalyst
comprising
a hydrogenation metal component on a carrier with the additive. The
conventional hydrotreating catalyst used in this process can be either a
freshly
prepared hydrotreating catalyst or a used hydrotreating catalyst which has
been
regenerated.
At present the catalysts prepared by the processes described in EP 0601 722
and WO 96141848 are considered preferred.
The su~hidation stew
The first step of the process according to the invention is to subject the
additive-containing hydrotreating catalyst to a sulphiding step. In the
context of
the present specification, the indication sulphiding step or sulphidation step
is
meant to include any process step in which at least a portion of the
hydrogenation metal components present in the catalyst is converted into the
sulphidic form, either directly or after an activation treatment with
hydrogen.
Suitable sulphidation processes are known in the art. Ex situ sulphidation
processes take place outside the reactor in which the catalyst is to be used
in
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11
hydrotreating hydrocarbon feeds. In such a process the catalyst is contacted
with a sulphur compound, e.g. a polysulphide or elemental sulphur, outside the
reactor and, if necessary, dried. In a second step, the material is treated
with
hydrogen gas at elevated temperature in the reactor, optionally in the
presence
of a feed, to activate the catalyst, i.e. bring it into the sulphided state.
In situ sulphidation processes take place in the reactor in which the catalyst
is
to be used in hydrotreating hydrocarbon feeds. Here, the catalyst is contacted
in the reactor at elevated temperature with a hydrogen gas stream mixed with a
sulphiding agent, such as hydrogen sulphide or a compound which under the
prevailing conditions is decomposable into hydrogen sulphide. It is also
possible to use a hydrogen gas stream combined with a hydrocarbon feed
comprising a sulphur compound which under the prevailing conditions is
decomposable into hydrogen sulphide. In the latter case it is possible to use
a
hydrocarbon feed comprising an added sulphiding agent (a so-called spiked
feed), but it is also possible to use a sulphur-containing hydrocarbon feed
without any added sulphiding agent, since the sulphur components present in
the feed will be converted into hydrogen sulphide in the presence of the
catalyst. The hydrocarbon feed may be the feed to be subjected to ultra-deep
HDS in the process according to the invention, but it may also be a different
feed, later to be replaced with the feed to be subjected to ultra-deep HDS.
Combinations of the various sulphiding techniques may also be applied.
In the context of the present invention it is presently preferred to sulphide
the
catalyst by contacting it with an, optionally spiked, hydrocarbon feed.
The feed
The feedstock suitable for use in the process according to the invention has a
95% boiling point, as determined in accordance with ASTM D-2887, of
450°C or
less, preferably 420°C or less, more preferably 400°C or less.
That is, 95 vol.%
of the feedstock boils at a temperature of 450°C or less, preferably
420°C or
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less, more preferably 400°C or less. Generally, the initial boiling
point of the
feedstock is above 100°C, preferably above 180°C. The feed
contains less than
500 ppm of sulphur, preferably 150-500 ppm of sulphur.
The feedstock to be used in the process according to the invention may be
prepared by hydrodesulphurisation of starting hydrocarbon feedstocks
containing 0.1 wt.% or more of sulphur, preferably 0.2 to 3.5 wt.% of sulphur,
more preferably 0.5 to 2.0 wt.% of sulphur. This starting feedstock generally
has a 95% boiling point, as determined in accordance with ASTM D-2887, of
450°C or less, preferably 420°C or less, more preferably
400°C or less.
Generally, the initial boiling point of the feedstock is above 100°C,
preferably
above 180°C. The feedstock generally contains 20-1200 ppm nitrogen,
preferably 30-800 ppm, more preferably 70-600 ppm. The metal content of the
feedstock preferably is less than 5 ppm, more preferably less than 1 ppm
(Ni+V). Examples of suitable starting feedstocks are feedstocks comprising one
or more of straight run gas oil, light catalytically cracked gas oil, and
light
thermally cracked gas oil.
The above-mentioned starting hydrocarbon feedstock is subjected to
hydrodesulphurisation to reduce its sulphur content to a value below 500 ppm.
This hydrodesulphurisation process can be carried out using conventional
hydrodesulphurisation catalysts comprising a Group VIB metal component, a
Group VIII metal component, and, optionally, phosphorus on a carrier
comprising alumina. Suitable hydrodesulphurisation catalysts are commercially
available, and include for example KF 756 and KF 901 of Akzo Nobel. It is also
possible to obtain the feedstock for the process according to the invention
from
a starting feedstock containing more sulphur by means of a two-step process,
such as those described in EP 0 464 931, EP-A 0 523 679 or EP 870 807.
Additionally, it is also possible to obtain the feedstock for the process of
the
invention from the above-mentioned starting feedstock by using an additive-
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13
based catalyst. The present invention thus also relates to a two-step process
for converting a starting feedstock having a sulphur content of above 0.1 wt.%
into a product having a sulphur content of 200 ppm or less, wherein the
process
comprises sulphidation of a first and a second catalyst comprising a Group VIB
metal component, a Group VIII metal component, and an organic additive on a
carrier, contacting a feedstock with a 95% boiling point of 450°C or
less and a
sulphur content of 0.1 wt.% or more with the first sulphided catalyst under
conditions of elevated temperature and pressure to form a product with a
sulphur content of less than 500 ppm, and contacting the effluent from the
first
catalyst, optionally after fractionation or intermediate phase separation,
optionally including removal of H2S and NH3 formed, with the second sulphided
catalyst under conditions of elevated temperature and pressure to form a
product with a sulphur content of less than 200 ppm.
In this process, the first and second catalysts containing an organic additive
before sulphidation may be the same or different. It is considered preferred
at
this point in time for the first catalyst to comprise molybdenum as Group VIB
metal component and cobalt andlor nickel as Group VIII metal component, with
the second catalyst comprising molybdenum as Group VIB metal component
and nickel as Group VIII metal component. The two-step process can be
carried out in one or two reactors, as may be desired.
The process conditions
The process according to the invention is carried out at elevated temperature
and pressure. The temperature generally is 200-450°C, preferably 280-
430°C.
The reactor inlet hydrogen partial pressure generally is 5-200 bar, preferably
10-100 bar, more preferably 10-50 bar. The liquid hourly space velocity
preferably is between 0.1 and 10 vol.lvol.h, more preferably between 0.5 and 4
vol.lvol.h. The H2/oil ratio generally is in the range of 50-2000 NI/I,
preferably in
the range of 80-1000 NIII.
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The process conditions are selected in such a way that the sulphur content of
the total liquid effluent is less than 200 ppm, preferably less than 100 ppm,
more preferably less than 50 ppm. The exact process conditions will depend,
int. al., on the nature of the feedstock, the desired degree of
hydrodesulphurisation, and the nature of the catalyst. In general, a higher
temperature, a higher hydrogen partial pressure, and a lower space velocity
will
decrease the sulphur content of the final product. The selection of the
appropriate process conditions to obtain the desired sulphur content in the
product is well within the scope of the person skilled in the art of
hydroprocessing.
Example 1: Nickel-molybdenum cata~sts in ultra-deep HDS
Pr~aration of additive-containing ci atalyst
Extrudates of a gamma-alumina carrier were impregnated to pore volume
saturation with an impregnation solution comprising a molybdenum compound,
a nickel compound, phosphoric acid, and diethylene glycol, after which the
impregnated carrier was dried at a temperature of 140°C for a period of
16
hours. The final catalyst contained 20 wt.% of molybdenum, calculated as
trioxide, 5 wt.% of nickel, calculated as oxide, and 5 wt.% of phosphorus,
calculated as P2O5. All weight percentages are calculated on the dry catalyst
base, not including the additive. The molar ratio between DEG and the total of
Ni and Mo is 0.4.
Preparation of comparative catalyst
A catalyst was prepared in the manner described above, except that the
impregnation was carried out in the absence of DEG, and that the impregnated
catalyst was subjected to a calcination step at 420°C for 1 hour.
The catalyst had the same composition as that described above, except for the
absence of DEG.
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The two catalysts were tested side by side in an upflow tubular reactor. Each
reactor tube contained 75 ml of catalyst homogeneously intermixed with 70 ml
of carborundum particles.
5 The catalysts were sulphided using an SRLGO in which dimethyl disulphide
had been dissolved to a total S content of 2.5 wt.%.
The feed applied was a diesel feedstock with the following properties.
Nitrogen (ASTM D-4629) 28
(PPm~)
Sulphur (ASTM D-4294) 219
(PPm~)
Density 15C (glml) 0.8490
Dist. (C) ASTM D-2887*
IBP 161
5 vol.% 203
10 vol.% 222
30 vol.% 265
50 vol.% 292
70 vol.% 320
90 vol.% 360
95 vol.% 378
FBP 423
10 The catalysts were tested under five test conditions. Conditions 1 and 3
are the
same. Conditions 4 and 5 differ from Condition 1 in terms of the pressure
applied. Condition 2 differs from the first test condition in that the feed
was
spiked with 1 wt.% of S, added as dimethyl disulphide and 100 ppm N added as
t-butyl amine. This was done to simulate the conditions halfway down a
15 commercial unit, where the feed contacting the catalyst contains ammonia
and
hydrogen sulphide generated in the first part of the unit.
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The reaction was carried out at a temperature of 323°C, a H2/oil
ratio of
300N1/I, and a LHSV of 2.0 h-1. The reaction time and pressure are listed in
the
.. following table.
Condition Feed Pressure (bar)Time (h)
1 F1 30 48
2 F1 +S+N 30 24
3 F1 30 24
4 F1 60 24
F1 15 48
5
The products from the different runs were analysed. The results thereof are
given below.
Sulphur analysis of products obtained
Condition ppm S in the product ppm S in the product
produced by the catalystproduced by the
according to the inventioncomparative catalyst
1 20 48
2 79 102
3 12 35
4 < 5 <5
5 37 72
It appears that the catalyst according to the invention shows a much improved
sulphur removal.
Nitrogien analysis of products obtained
Condition ppm N in the product ppm N in the product
produced by the catalystproduced by the
according to the inventioncomparative catalyst
1 <5 8
2 <5 5
3 <5 <5
4 <5 <5
5 15 20
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17
It appears that the catalyst according to the invention shows an improved
nitrogen removal.
Total aromatics anaysis of total liauid r~ oduct
Condition wt.% aromatics in wt.% aromatics in the
the product produced by
product produced by the
the comparative catalyst
catalyst according
to the
invention
1 35.7 36.7
2 36.0 36.5
3 35.5 36.5
4 28.7 32.9
37.1 37.3
5
It appears that the catalyst according to the invention shows improved
aromatics removal under all conditions.
Polynuclear aromatics ~(PNAy analysis of total liauid product
Condition wt.% PNA in the productwt.% PNA in the product
produced by the catalystproduced by the
according to the inventioncomparative catalyst
1 4.5 4.8
2 4.9 4.9
3 4.4 4.6
4 1.6 2.2
5 8.3 8.4
It appears that the catalyst according to the invention shows improved
polynuclear aromatics removal.
Example 2' Cobalt-molybdenum catalysts in ultra-deep HDS
A set of comparative catalysts which are comparable to those of Example 1,
except that the catalysts contained cobalt instead of nickel, was prepared and
tested. It appeared that also in this comparison the catalyst according to the
invention, which before sulphiding contained an additive, showed better
results
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18
than the comparative catalyst, albeit that both for the catalyst according to
the
invention and for the comparative catalyst the results of the nickel-
containing
catalyst of Example 1 were better than the results of the comparable cobalt-
containing catalyst of this example.
