Note: Descriptions are shown in the official language in which they were submitted.
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T 5788
PROCESS FOR CONVERTING A HYDROCARBONACEOUS FEEDSTOCK
The present invention relates to a process for
converting a hydrocarbonaceous feedstock into products
of lower average boiling point by contacting the feed-
stock with hydrogen over a series of beds of catalysts.
It is known to subject a heavy hydrocarbonaceous
feedstock to a hydrocracking process which makes use of
more than one bed of catalyst. US-A-4,211,634 describes
a hydrocracking process by contacting a
hydrocarbonaceous feedstock with hydrogen over a first
zeolitic catalyst comprising nickel and tungsten or
nickel and molybdenum, and contacting the resulting
hydrocracked product with hydrogen over a second
zeolitic catalyst containing cobalt and molybdenum. In
EP-A-0,183,283 a hydrotreating process is described in
which a residual oil is passed together with hydrogen
over a stacked-bed catalyst, wherein said stacked-bed
comprises an upper zone containing an amorphous
cracking catalyst with a compound of a Group VIB and
Group VIII metal and a phosphorus compound, and a lower
zone containing a different amorphous cracking catalyst
with a compound of a Group VIB and VIII metal and
substantially without a phosphorus compound.
It is further known that fluoriding a hydrocarbon
conversion catalyst can improve the suitability of such
a catalyst in hydrocarbon conversion processes. The
improved suitability is shown by a greater activity in
the conversion of the heavy hydrocarbonaceous feed-
stock. In this respect reference is made to
GB-A-1,545,828, describing a process for incorporating
fluorine into an amorphous or zeolitic hydrocracking
.~
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catalyst by contacting said catalyst with a fluorine-
containing compound and using a constant or varying
fluorine slip. The catalyst thus fluorided is capable
of giving a higher yield of desired product at a lower
temperature than a catalyst not fluorided that way.
It has now surprisingly been found that an un-
expectedly high activity gain is obtained when in an
operation employing a series of beds of catalysts a
fluorided amorphous catalyst is used, a first bed
containing the fluorided amorphous catalyst and a
second bed containing a zeolitic catalyst. Accordingly,
the present invention provides a process for converting
a hydrocarbonaceous feedstock into products of lower
average boiling point by contacting the feedstock at
elevated pressure and temperature with hydrogen over a
bed of a catalyst A producing a hydrocracked effluent
and subsequently contacting at least part of said
hydrocracked effluent with hydrogen over a bed of a
catalyst B, whereby catalyst A comprises an amorphous
cracking component, at least one metal of Group VIB
and/or Group VIII of the Periodic Table of the Elements
and fluorine, and whereby catalyst B comprises a
faujasite-type zeolite and at least one metal of Group
VIB and/or VIII of the Periodic Table of the Elements.
Catalyst A contains an amorphous cracking
component. Suitable amorphous cracking components
include refractory oxides, such as alumina, silica,
silica-alumina, magnesia, titania, zirconia and clays.
The use of alumina as amorphous cracking component is
preferred.
The catalytically active metals on catalyst A are
selected from Groups VIB and VIII of the Periodic Table
of the Elements. Suitably these metals are molybdenum
and/or tungsten, and/or cobalt and/or nickel, and/or
palladium and/or platinum. When the catalytically
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- active metals are non-noble, they are preferably
present on catalyst A in their oxidic form and in
particular in the form of their sulphides. Thereto, the
catalyst can be (pre)sulphided, converting the metal
oxides into metal sulphides. This can be achieved by
using either H2S as such or H2S obtained by hydro-
genation of organic sulphur compounds such as sulphur-
containing oil fractions, as is known in the art.
To obtain the synergistic effect the catalyst A
contains fluorine. Various ways to incorporate fluorine
into catalysts are known in the art. In this respect
reference is made by the above-mentioned
GB-A-1,545,828, and further to US-A-4,598,059 and
GB-B-2,024,642, all specifications describing the use
of gaseous fluorine-containing compounds, such as
l,l-difluoroethane and ortho-fluorotoluene. Another way
of preparing fluorine-containing amorphous catalysts is
by impregnation, e.g. as described in GB-A-1,156,897.
Other suitable methods include those described in
US-A-3,673,108 and US-A-3,725,244.
The amounts of all components on catalyst A are
not critical. Preferably the catalyst A comprises from
6 to 24 %w of at least one metal of Group VIB, from 1
to 16 %w of at least one metal of Group VIII and from
0.5 to 10 ~w of fluorine, the weight percentages being
based on total catalyst. During operation the amount of
fluorine on the catalyst tends to decrease as fluorine
compounds are detached from the catalyst and entrained
by the streams of hydrogen and hydrocracked products.
Therefore, it is preferred to add a fluorine-containing
compound to the feedstock in order to maintain the
fluorine content of catalyst A at the desired level.
In the first bed the feedstock is hydrocracked and
organic nitrogen compounds and/or organic sulphur-
containing compounds, if present therein, are converted
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into products with lower boiling points and NH3 and
H2S, respectively. The present invention includes
processes in which the NH3 and H2S and optionally part
of the light hydrocarbons are separated from the hydro-
cr~c~ed effluent. The separation can e.g. be effectedby washing with water (to remove NH3 and H2S) and/or a
distillation (to remove at least some hydrocarbons with
a boiling point below e.g. 350 C~. However, preferably
the process is carried out such that substantially the
whole hydrocracked effluent from the bed of catalyst A
is contacted with hydrogen over the bed of catalyst B,
i.e. without an intermediate separation or liquid
recycle.
The process conditions prevailing in the bed of
catalyst A are preferably a temperature of from 280 to
450 C, a hydrogen (partial) pressure of from 25 to 200
bar, a space velocity of from 0.3 to 5 kg/l.h and a
hydrogen to feedstock ratio of from lO0 to 3000 Nl/kg.
It is remarked that when the present process is
carried out such that substantially the whole hydro-
cracked effluent from the bed of catalyst A is passed
over the bed of catalyst B the hydrocracked effluent
may contain fluorine compounds. These fluorine com-
pounds may incur incorporation of fluorine into
catalyst B.
Hence the present invention also covers processes using
a bed of catalyst A and a bed of catalyst B wherein not
only catalyst A but also catalyst B contains fluorine.
Conveniently catalyst B used in the present process
further comprises fluorine. The preferred amount of
fluorine in catalyst B ranges from 0.5 to lO %w, based
on the total catalyst.
Fluorine may be applied on catalyst B during the
operation or before the catalyst B is used in the
hydroconversion process of the present invention. So it
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is possible to start the process with a bed of fluorine containing
catalyst A and a bed of fluorine-free catalyst B. During
operation some of the fluorine from a catalyst A detaches from the
catalyst and may be contacted with catalyst B together with ~part
of) the hydrocracked effluent, thereby partly attaching to
catalyst B. In the state of the art several methods are known to
prepare fluorine-containing zeolites. Suitable methods include
those described in the above-mentioned GB-A-1,545,828, and US-A-
4,598,059. Further suitable methods are described in US-A-
3,575,887 and US-A-3,702,312. The amount of fluorine on catalyst
A may be kept constant, e.g. by supplying a fluorine compound via
the feedstock.
Catalyst B comprises a faujasite-type zeolite. Such a
zeolite includes naturally occurring faujasite, synthetic zeolite
X and synthetic zeolite Y. Preferably the faujasite-type zeoiite
is zeolite Y. The zeolite Y is characterized by the faujasite X-
ray diffraction pattern and suitably has a SiO2/Al203 molar ratio
of 4 to 25, in particular from 6 to 15. The unit cell size of Y
zeolites preferably ranges from 2.420 to 2.475 nm. Suitably the
zeolite Y is one as described in European patent application No.
247,678 or in European patent application No. 247,679, both
published on December 2, 1987. Such zeolites are characterized by
a unit cell size below 2.440 nm, preferably below 2.435 nm, a
degree of crystallinity which is at least retained at increasing
SiO2/Al2O3 molar ratios, a water adsorption capacity (at 25 C and
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~L
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a p/pO value of 0.2) of at least 8% by weight of zeolite and a
pore volume of at least 0.25 ml/g wherein between 10% and 60% of
the total pore volume is made up of pores having a diameter of at
least 8 nm (p/pO stands for the ratio of the partial water
pressure in
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the apparatus in which the water adsorption capacity is
determined and the saturation pressure of water at
25 C)
More preferably zeolites are used wherein between
10% and 40% of the total pore volume is made up of
pores having a diameter of at least 8 nm. The pore
diameter distribution is determined by the method
described by E.P. Barrett, G. Joyner and P.P. Halenda
(J. Am. Chem. Soc. 73, 373 t1951) and is based on the
numerical analysis of the nitrogen desorption isotherm.
It should be noted that inter-crystalline voids are
excluded in the determination of the percentage of the
total pore volume made up in pores having a diameter of
at least 8 nm when said percentage is between 10% and
40%.
Apart from the faujasite-type zeolite, catalyst B
preferably also comprises an amorphous refractory
oxide. Suitable amorphous oxides include silica,
alumina, silica-alumina, thoria, zirconia, titania,
magnesia and mixtures of two or more thereof. The
refractory oxides may be used as binder and/or as an
amorphous cracking component. It is advantageous to use
alumina as amorphous cracking component which also acts
as binder. The amount of refractory oxide may suitably
vary from 10 to 90 %w based on the total of refractory
oxide and faujasite-type zeolite.
Catalyst B comprises at least one metal of Group
VIB and/or Group VIII of the Periodic Table of the
Elements. Preferably catalyst B comprises one or more
nickel and/or cobalt compounds and one or more molyb-
denum and/or tungsten compounds and/or one or more
platinum and/or palladium compounds. The metal com-
pounds in catalyst B are preferably in the oxidic
and/or sulphidic form. The metal compounds are more
preferably in sulphidic form. Conveniently, the
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catalyst has been subjected to a sulphiding treatment
prior to actual use in a hydrocracking process.
Preparation of metals-containing catalyst B is
known in the art. Preparation methods include impreg-
nation, ion exchange, and co-mulling of the
ingredients.
The amounts of metal compounds in catalyst B may
suitably range from 2 to 20 parts by weight (pbw) of
one or more Group VIB metals and from l to lO pbw of
one or more Group VIII metals, calculated as metals per
lO0 pbw of the total of faujasite-type zeolite, metal
compounds and refractory oxide, if present. For
platinum and/or palladium compounds the amount is
suitably from 0.2 to 2 pbw per lO0 pbw of total of
zeolite, metal compounds and refractory oxide, if
present.
The process conditions prevailing in the bed of
catalyst B can be the same or different from these
prevailing in the bed of catalyst A and are suitably
selected form a temperature from 280 to 450 C, a
hydrogen (partial) pressure from 25 to 200 bar, space
velocity from 0.3 to 5 kg/l.h, and a gas/feedstock
ratio from lO0 to 3000 Nl/kg.
It is evident that the beds with catalysts A and
B, respectively, can be constituted of one or more beds
of catalyst A and one or more beds of catalyst B. And
it is also evident that the bed or beds with catalyst A
and the bed or beds with catalyst B can be located in
one or more reactors. The ratio of the volume of the
bed of catalyst A to that of the bed of catalyst B can
be varied within wide ranges and may preferably be
selected from the range l:5 to lO:l. It is evident that
the bed of catalyst B may be followed by another bed of
catalyst A which may be followed by a bed of catalyst B
and so on. The advantageous activity gain is already
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obtained after one sequence of one bed of catalyst A
and one of catalyst B.
Hydrocarbonaceous feedstocks that can be used in
the present process include gas oils, vacuum gas oils,
deasphalted oils, long residues, short residues,
catalytically cracked cycle oils, thermally cracked gas
oils and syncrudes, optionally originating from tar
sands, shale oils, residue upgrading processes or
biomass.
Combinations of various hydrocarbonaceous feed-
stock can also be employed. The hydrocarbonaceous
feedstock will generally be such that a major part, say
over 50 %wt, has a boiling point above 370 C. The
present process is most advantageous when the feedstock
contains nitrogen. Typical nitrogen contents start from
50 ppmw. The feedstock will generally also comprise
sulphur compounds. The sulphur content will usually be
in the range from 0.2 to 6 %wt.
The invention will be further illustrated by means
of the following Example.
EXAMPLE
Four catalyst systems are compared in 4 tests. In
all tests a Middle East flashed distillate feedstock is
used of which 95 %w has a boiling point of at least
370 C (370 C ), and a nitrogen content of llO0 ppmw.
In the tests three catalysts are investigated: catalyst
A being a commercial hydroconversion catalyst comprising
13.0 %w Mo, 3.0 %w Ni and 3.2 %w P on alumina, catalyst
A' being like catalyst A but containing in addition 3
%w F, and catalyst B being a zeolitic catalyst compris-
ing 7.7 %w W and 2.3 %w Ni. The carrier of catalyst B
consists of 25 %w alumina and 75 %w zeolite Y, the
zeolite Y having a unit cell size of about 2.451 nm.
During the tests the following conditions are applied:
a temperature of 375 C, a hydrogen pressure of 90 bar,
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an overall space velocity of 0.5 kg/l.catalyst.h and a
gas/oil ratio of 1500 Nl/Kg. The total amount of
catalyst used is the same in all tests, but in tests 1
and 3 the catalyst consists of catalyst A and A',
respectively, whereas in tests 2 and 4 the total amount
of catalyst is divided into a first bed of catalyst A
or A', amounting to half the total amount, and a second
bed of catalyst B, also amounting to half the total
amount. During the latter tests no liquid recycle or
intermediate separation between the two catalyst beds
occurs. Further conditions and results of the tests are
indicated in the following Table.
TABLE
Test No. 1 2 3 4
Catalyst
system A A+B A' A'+B
370 C+-fraction 73.4 73.4 64.9 57.5
in product,
%w on feed
From the comparison of the results of tests 1 and 3 it
is apparent that the conversion of 370 C+ material is
increased if a fluorine-containing catalyst is used.
Comparison of the results of tests 1 and 2 teaches that
the conversion of 370 C material is the same in these
tests. Hence, it would be expected that in test 4 about
half the improvement as obtained in test 3, would be
attained. It is therefore very surprising that the
conversion of the heavy hydrocarbons in test 4 is far
better than the conversion obtained in test 3.
