[0001] The present invention relates to a process for converting a hydrocarbonaceous feedstock
into products of lower average boiling point by contacting the feedstock with hydrogen
over a series of beds of catalysts.
[0002] 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.
[0003] 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
feedstock. In this respect reference is made to GB-A-1,545,828, describing a process
for incorporating fluorine into an amorphous or zeolitic hydrocracking 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.
[0004] It has now surprisingly been found that an unexpectedly 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.
[0005] 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.
[0006] 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 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 hydrogenation
of organic sulphur compounds such as sulphur-containing oil fractions, as is known
in the art.
[0007] 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 1,1-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.
[0008] 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.
[0009] In the first bed the feedstock is hydrocracked and organic nitrogen compounds and/or
organic sulphur-containing compounds, if present therein, are converted 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 hydrocracked effluent. The separation can e.g. be effected by
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.
[0010] 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 100 to
3000 Nl/kg.
[0011] It is remarked that when the present process is carried out such that substantially
the whole hydrocracked effluent from the bed of catalyst A is passed over the bed
of catalyst B the hydrocracked effluent may contain fluorine compounds. These fluorine
compounds may incur incorporation of fluorine into catalyst B.
[0012] 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 10 %w, based on the
total catalyst.
[0013] 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 is possible
to start the process with a bed of fluorinecontaining catalyst A and a bed of fluorine-free
catalyst B. During operation some of the fluorine from 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.
[0014] 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
zeolite is zeolite Y. The zeolite Y is characterized by the faujasite X-ray diffraction
pattern and suitably has a SiO₂/Al₂O₃ 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 applicaton No. 87200919.6
or in European patent application No. 87200920.4 (Applicants reference T 5011 and
T 5012, respectively). 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 a
p/p
ovalue 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/p
o stands for the ratio of the partial water pressure in the apparatus in which the
water adsorption capacity is determined and the saturation pressure of water at 25
°C).
[0015] 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 (1951) 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%.
[0016] 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.
[0017] 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 molybdenum and/or tungsten compounds and/or one or more
platinum and/or palladium compounds. The metal compounds in catalyst B are preferably
in the oxidic and/or sulphidic form. The metal compounds are more preferably in sulphidic
form. Conveniently, the catalyst has been subjected to a sulphiding treatment prior
to actual use in a hydrocracking process.
[0018] Preparation of metals-containing catalyst B is known in the art. Preparation methods
include impregnation, ion exchange, and co-mulling of the ingredients.
[0019] 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 1 to 10 pbw of one or more
Group VIII metals, calculated as metals per 100 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 100 pbw of total of zeolite,
metal compounds and refractory oxide, if present.
[0020] 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 100 to 3000 Nl/kg.
[0021] 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 1:5 to 10:1. 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 obtained after one sequence
of one bed of catalyst A and one of catalyst B.
[0022] 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.
[0023] Combinations of various hydrocarbonaceous feedstock 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.
[0024] The invention will be further illustrated by means of the following Example.
EXAMPLE
[0025] 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 1100 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 comprising 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, 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 in product, %w on feed |
73.4 |
73.4 |
64.9 |
57.5 |
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.
1. 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 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 Element and
fluorine, and whereby catalyst B comprises a faujasite-type zeolite and at least one
metal of Group VIB and/or Group VIII of the Periodic Table of the Elements.
2. Process according to claim 1, in which the amorphous cracking component is alumina.
3. Process according to claim 1 or 2, in which catalyst A comprises molybdenum and/or
tungsten and/or cobalt and/or nickel and/or platinum and/or palladium.
4. Process according to any one of claims 1 to 3, in which 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.
5. Process according to any one of claims 1 to 4, in which the process conditions
prevailing in the bed of catalyst A are 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/feedstock ratio of from 100 to 3000 Nl/kg.
6. Process according to any one of claims 1 to 5, in which catalyst B further comprises
fluorine.
7. Process according to claim 6, in which catalyst B comprises from 0.5 to 10 %w of
fluorine.
8. Process according to any one of claims 1 to 7, in which the faujasite-type zeolite
of catalyst B is zeolite Y.
9. Process according to any one of claims 1 to 8 in which catalyst B contains one
or more nickel and/or cobalt compounds and one or more tungsten and/or molybdenum
compounds, and/or one or more platinum and/or palladium compounds.
10. Process according to any one of claims 1 to 9, in which the following conditions
prevail in the bed of catalyst B: a temperature from 280 to 450 °C, a hydrogen (partial)
pressure from 25 to 200 bar, a space velocity of 0.3 to 5 kg/l.h, and a gas/feedstock
ratio of 100 to 3000 Nl/kg.