Process for the preparation of a catalyst composition

The present invention provides a process for the preparation of a catalyst composition which comprises, as first cracking component, a zeolite beta with a silica to alumina molar ratio of at least 20 comprising crystals less than 100 nm in size, and a second cracking component selected from (i) crystalline molecular sieves having pores with diameters greater than 0.6 nm, and (ii) clays, the process comprising the steps of: PA1 (i) preparing a mixture comprising the first cracking component and the second cracking component, the first cracking component being in the form of a sol, PA1 (ii) extruding the mixture into catalyst extrudates, and PA1 (iii) calcining the extrudates.

The present invention relates to a process for the preparation of a 
catalyst composition. 
Of the many conversion processes known in the refining art, hydrocracking 
has assumed a greater importance over the years since it offers the 
refiner product flexibility combined with product quality. 
There has been considerable effort devoted to the development of 
hydrocracking catalysts which combine high cracking activity with a low 
tendency to overcrack towards light products and, in particular, less 
valuable C.sub.1 -C.sub.3 gaseous by-products. 
Kerosine or gas oil (middle distillates) are often the desired products of 
a hydrocracking process. However, hydrocracking catalysts with a high 
selectivity towards middle distillates tend to have a low cracking 
activity. Such catalysts are typically based on a single, active cracking 
component such as an aluminosilicate, especially a Y zeolite component. 
It is known, e.g. from U.S. Pat. No. 5,279,726 and EP-B-559 646 to form 
composites of two different aluminosilicates, a Y zeolite and zeolite 
beta, for use in hydrocracking. 
More specifically, in U.S. Pat. No. 5,279,726 a hydrocracking catalyst is 
disclosed having high activity and selectivity for gasoline which 
comprises a hydrogenation component on a catalyst support comprising both 
zeolite beta and a Y zeolite having a unit cell size above 2,440 nm (24.40 
.ANG.ngstroms), the zeolites usually and preferably being in further 
combination with a porous, inorganic refractory oxide such as alumina. 
The zeolite beta used in the catalyst support has a silica to alumina molar 
ratio of at least 10 up to 100, but preferably no more than 40 and most 
preferably in the range of 20 to 30. Preferably, the zeolite beta has a 
crystal size of 0.1 to 0.7 micron (100 to 700 nm), a surface area of 500 
to 800 m.sup.2 /g and a cyclohexane adsorption capacity of 15 to 25 g/100 
g. 
The Y zeolite used in the catalyst support preferably has a unit cell size 
between 2.445 and 2.464 nm (24.45 and 24.64 .ANG.ngstroms) and, typically, 
a sorptive capacity for water vapour at 25.degree. C. and a p/p.sub.o 
value of 0.1 of at least 15% w (per cent by weight), as exemplified by 
LZY-82 and LZY-84 zeolites. 
U.S. Pat. No. 5,279,726 contains a single example which details the 
preparation and testing of four hydrocracking catalysts numbered one (1), 
two (2), three (3) and four (4). All of the catalysts contained the same 
amount and type of hydrogenation components but differed in their catalyst 
supports. Catalyst 1 contained a catalyst support of 80% w zeolite beta 
(silica to alumina molar ratio 26) and 20% w alumina; Catalyst 2 contained 
a catalyst support of 40% w zeolite beta (silica to alumina molar ratio 
26), 40% w LZ-10 zeolite (silica to alumina molar ratio 5.2; unit cell 
size 2.430 nm) and 20% w alumina; Catalyst 3 contained a catalyst support 
of 40% w zeolite beta (silica to alumina molar ratio 26), 40% w LZY-82 
zeolite (silica to alumina molar ratio 5.7; unit cell size 2.455 nm) and 
20% w alumina; and Catalyst 4 contained a catalyst support of 80% w LZY-82 
zeolite (silica to alumina molar ratio 5.7; unit cell size 2.455 nm) and 
20% w alumina. Catalysts 1, 2 and 4 were comparative catalysts whilst 
Catalyst 3 was a catalyst according to the invention. 
When the hydrocracking performances of the catalysts were assessed under 
second stage series-flow conditions (referred to in U.S. Pat. No. 
5,279,726 as first stage simulation under ammonia-rich conditions), the 
results in Table II, Column 14 show that Catalyst 3 of the invention 
yielded more gasoline than comparative Catalyst 4 (a commercial gasoline 
hydrocracking catalyst) with some slight reduction in the amount of 
C.sub.1- C.sub.3 gaseous by-product. 
Similarly, EP-B-559 646 discloses a hydrocracking catalyst having high 
activity and selectivity for gasoline which comprises a hydrogenation 
component on a catalyst support comprising both zeolite beta and a 
dealuminated Y zeolite having an overall silica to alumina molar ratio 
greater than 6.0. The support may further contain a porous, inorganic 
refractory oxide such as alumina or silica-alumina. 
The zeolite beta used in the catalyst support has a silica to alumina molar 
ratio of at least 10 up to 100, but preferably no more than about 40 and 
most preferably in the range of 20 to 30. Preferably, the zeolite beta has 
a crystal size of 0.1 to 0.7 micron (100 to 700 nm), a surface area of 500 
to 800 m.sup.2 /g and a cyclohexane adsorption capacity of 15 to 25 g/100 
g. 
The dealuminated Y zeolite used in the catalyst support preferably has an 
overall silica to alumina molar ratio between 6.1 and 20.0, and most 
preferably between 8.0 and 15.0. The unit cell size for the dealuminated Y 
zeolite is normally between 2.440 and 2.465 nm (24.40 and 24.65 
.ANG.ngstroms). The preferred dealuminated Y zeolites to use are the 
LZ-210 zeolites as described in U.S. Pat. Nos. 4,503,023 and 4,711,770. 
There is a single example in EP-B-559 646 which details the preparation and 
testing of four hydrocracking catalysts numbered one (1), two (2), three 
(3) and four (4). All of the catalysts contained the same amount and type 
of hydrogenation components but differed in their catalyst supports. 
Catalyst 1 contained a catalyst support of 80% w zeolite beta (silica to 
alumina molar ratio 26) and 20% w alumina; Catalyst 2 contained a catalyst 
support of 30% w zeolite beta (silica to alumina molar ratio 26), 50% w 
LZ-210 zeolite (silica to alumina molar ratio 12; unit cell size 2.441 nm) 
and 20% w alumina; Catalyst 3 contained a catalyst support of 30% w 
zeolite beta (silica to alumina molar ratio 26), 50% w LZ-10 zeolite 
(silica to alumina molar ratio 5.2; unit cell size 2.430 nm) and 20% w 
alumina; and Catalyst 4 contained a catalyst support of 80% w LZY-82 
zeolite (silica to alumina molar ratio 5.7; unit cell size 2.455 nm) and 
20% w alumina. Catalysts 1, 3 and 4 were comparative catalysts whilst 
Catalyst 2 was a catalyst according to the invention. 
When the hydrocracking performances of the catalysts were assessed under 
second state series-flow conditions (referred to in EP-B-559 646 as first 
stage simulation under ammonia-rich conditions), the results in Table 3 
show that whilst Catalyst 2 of the invention produced the highest yield of 
gasoline of the catalysts tested, it also produced a significant amount of 
undesired C.sub.1- C.sub.3 gaseous by-product. Indeed, Catalyst 2 produced 
more gaseous by-product (i.e. had a higher gas make) than comparative 
Catalyst 4 (a commercial gasoline hydrocracking catalyst) which is known 
to yield high gas makes. 
In WO 94/26847 a process is disclosed for simultaneously hydrocracking, 
hydroesulphurizing and hydrodenitrogenating a hydrocarbonaceous feed by 
contacting a feedstock which contains sulphur compounds and nitrogen 
compounds, has a boiling range of more than 80% v boiling above 
300.degree. C., and has not been subjected to any preparatory catalytic 
hydrodesulphurization or hydrodenitrogenation, at elevated temperature and 
pressure, in the presence of hydrogen, with a catalyst containing a 
carrier such as alumina or silica-alumina, a Group VIB metal component, a 
Group VIII metal component, and an inorganic, crystalline, non-layered 
aluminosilicate with pores of diameter greater than 1.3 nm and exhibiting, 
after calcination, an X-ray diffraction pattern with at least one peak at 
a d-spacing greater than 1.8 nm, such as an aluminosilicate as described 
in WO 93/02159, in particular the aluminosilicate designated MCM-41. 
Although it is indicated in Page 7, lines 15 to 19 of WO 94/26847 that 
other molecular sieves may be incorporated into the catalyst in addition 
to the aluminosilicate, such as Y zeolites, ultrastable Y zeolites having 
a unit cell size (a.sub.o) of from 2.425 to 2.440 nm (24.25 to 24.40 
.ANG.ngstroms), zeolite beta, mordenite, and materials of the ZSM-5 type 
having a silica to alumina ratio in the range of 12 to 300, there are no 
examples in WO 94/26847 of the preparation and testing of any such 
composite catalysts, nor any suggestion to use a specific zeolite beta for 
this purpose. 
It is also known from WO 91/17829 to hydrocrack feedstocks using a catalyst 
which comprises a hydrogenation component and a support comprising zeolite 
beta and a Y zeolite having either (i) a unit cell size below 2.445 nm 
(24.45 .ANG.ngstroms) or (ii) a water vapour sorptive capacity at 
25.degree. C. and a p/p.sub.o value of 0.10 of less than 10.00% w, the 
zeolites usually and preferably being in further combination with a 
porous, inorganic refractory oxide such as aluminia. 
The zeolite beta present in the catalyst support has a silica to alumina 
molar ratio of at least 10 up to 100, but preferably no more than 40 and 
most preferably in the range of 20 to 30. Preferably the zeolite beta has 
a crystal size of 0.1 to 0.7 micron (100 to 700 nm), a surface area of 500 
to 800 m.sup.2 /g and a cyclohexane adsorption capacity of 15 to 25 g/100 
g. 
Preferred Y zeolites to use are those meeting both of the above 
requirements (i) and (ii), for example, ultrahydrophobic Y (UHP-Y) 
zeolites as exemplified by LZ-10 zeolite. 
The hydrocracking catalyst according to WO 91/17829 may, depending on the 
process conditions selected, be used for gasoline or middle distillates 
production. However, the catalyst is apparently better suited for gasoline 
production. 
U.S. Pat. No. 5,413,977 discloses a hydrocracking catalyst having high 
activity and selectivity for gasoline which comprises a hydrogenation 
component on a catalyst support comprising zeolite beta and a layered 
magnesium silicate including hectorite and saponite (which are both 
smectite minerals) and, especially, sepiolite. 
The zeolite beta used in the catalyst support has a silica to alumina molar 
ratio of at least 10 up to 100, but preferably no more than 40 and most 
preferably in the range of 20 to 30. Preferably the zeolite beta has a 
crystal size of 0.1 to 0.7 micron (100 to 700 nm), a surface area of 400 
to 800 m.sup.2 /g, a cyclohexane adsorption capacity of 15 to 25 g/100 g, 
and a water vapour sorptive capacity at 25.degree. C. and a p/p.sub.o 
value of 0.10 of greater than 5% w. 
WO 97/20016 discloses a stable hydrocracking catalyst having high activity 
combined with good middle distillate selectivity which comprises, as first 
cracking component, a zeolite beta having a silica to alumina molar ratio 
of at least 20 which is in the form of crystals less than 100 nm in size; 
a second cracking component selected from (i) crystalline molecular sieves 
having pores with diameters greater than 0.6 nm, (ii) crystalline 
mesoporous aluminosilicates having pores with diameters of at least 1.3 
nm, and (iii) clays; and at least one hydrogenation component. 
It has been observed when preparing the catalyst of Internation Patent 
Application No. PCT/EP96/05352 that some agglomeration of the zeolite beta 
crystals into larger crystals may occur. It would be desirable if this 
agglomeration could be avoided as the cataylst would then have an even 
higher activity. 
The present invention therefore seeks to overcome this problem. 
In accordance with the present invention, there is provided a process for 
the preparation of a catalyst composition which comprises, as first 
cracking component, a zeolite beta with a silica to alumina molar ratio of 
at least 20 comprising crystals less than 100 nm in size, and a second 
cracking component selected from (i) crystalline molecular sieves having 
pores with diameters greater than 0.6 nm, and (ii) clays, the process 
comprising the steps of: 
(i) preparing a mixture comprising the first cracking component and the 
second cracking component, the first cracking component being in the form 
of a sol, 
(ii) extruding the mixture into catalyst extrudates, and 
(iii) calcining the extrudates. 
In the present specification, unless otherwise indicated, the silica to 
alumina molar ratio of a zeolite is the molar ratio as determined on the 
basis of the total or overall amount of aluminum and silicon (framework 
and non-framework) present in the zeolite. 
In step (i) of the present process, zeolite beta (the first cracking 
component), which is in the form of a sol (i.e. a suspension of zeolite 
beta crystals of colloidal size in a liquid), is combined with the second 
cracking component to form a mixture. The zeolite beta has a silica to 
alumina molar ratio of at least 20, preferably at least 25. Zeolite beta 
with a higher silica to alumina molar ratio, e.g. up to, and including 60, 
80, 100, 120 or 150, may also be used if desired. Thus, the zeolite beta 
may have a silica to alumina molar ratio in the range of from 20 to 60, 25 
to 60, 20 to 80, 25 to 80, 20 to 100, 25 to 100, 20 to 120, 25 to 120, 20 
to 150 or 25 to 150. The zeolite beta crystals in the sol are less than 
100 nm in size, e.g. up to 99 nm in size. Preferably, the crystals are in 
the range of from 20 to 95 nm in size, more preferably from 30 to 75 nm in 
size, still more preferably from 40 to 75 nm size and particularly from 50 
to 70 nm in size. 
The zeolite beta sol may conveniently be prepared by the method of Camblor 
et al., "Progress in Zeolite and Microporous Materials", Vol. 105, pp. 
341-348, Elsevier (1997). 
Without wishing to be bound to any particular theory, the zeolite beta sol 
used in the process of the present invention surprisingly appears to 
provide a better dispersion of zeolite beta crystals, thereby reducing the 
risk that the zeolite beta crystals will agglomerate in the catalyst 
composition. 
The second cracking component which is combined with the zeolite beta sol 
is selected from (i) crystalline molecular sieves having pores with 
diameters greater than 0.6 nm (e.g. as determined by nitrogen adsorption 
techniques), and (ii) clays. 
In the context of the present specification, the term "molecular sieve" 
also includes the corresponding (hydrothermally) stabilised and 
dealuminated derivatives and such derivatives as may be obtained by 
isomorphous substitution and cation exchange. Methods for the cation 
exchange, (hydrothermal) stabilisation, dealumination and isomorphous 
substitution of molecular sieves are well known in the art and are not 
therefore further discussed in the present specification. 
The second cracking component may be a single material (i) or (ii), or a 
combination of two or more such materials. 
Preferably, the second cracking component is selected from (i) crystalline 
molecular sieves of structure type FAU, EMT, MOR, LTL, MAZ, MTW, OFF, BOG, 
AET, AFI, AFO, AFR, AFS, AFY, ATS, VFI and CLO as described in "Atlast of 
Zeolite Structure Types", 3rd Edition, published in 1992 on behalf of the 
Structure Commission of the International Zeolite Association; and (ii) 
clays of the non-pillared smectite type, e.g. montmorillonites, 
hectorites, saponites and beiddelites. 
Most preferably, the second cracking component is (i) a crystalline 
molecular sieve of structure type FAU, e.g. a very ultrastable zeolite Y 
(VUSY) of unit cell size (a.sub.o) less than 2.440 nm (24.40 
.ANG.ngstroms), in particular less than 2.435 nm (24.35 .ANG.ngstroms) as 
are known, for example, from EP-A-247 678 and EP-A-247 679. 
The VUSY zeolite of EP-A-247 678 or EP-A-247 679 is characterised by a unit 
cell size below 2.445 nm (24.45 .ANG.ngstroms) or 2.435 nm (24.35 
.ANG.ngstroms), a water adsorption capacity (at 25.degree. C. and a 
p/p.sub.o value of 0.2) of at least 8% w of the 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. 
In addition to the first and second cracking components, the mixture may 
further comprise a binder, in particular an inorganic oxide binder. 
Examples of suitable binders include alumina, silica, aluminium phosphate, 
magnesia, titania, zirconia, silica-alumina, silica-zirconia, silica-boria 
and combinations thereof. Alumina is the most preferred binder. 
Step (i) of the present process may conveniently be carried out by mulling 
the zeolite beta sol and the second cracking component, optionally 
together with binder, in the presence of water and a peptising agent, e.g. 
acetic acid or nitric acid, to form a mixture which is subsequently 
extruded into catalyst extrudates in step (ii) and the catalyst extrudates 
calcined in step (iii). 
The zeolite beta sol, second cracking component and binder are combined in 
amounts such that the eventual calcined catalyst extrudates comprise 
preferably in the range of from 0.5 to 40% w zeolite beta (first cracking 
component), in the range of from 0.5 to 90% w second cracking component 
and in the range of from 0 to 99% w binder; more preferably from 1 to 15% 
w, particularly from 5 to 10% w, zeolite beta, from 5 to 80% w, 
particularly from 40 to 60% w, second cracking component, and the 
remainder being binder, all percentages by weight (% w) being calculated 
on the basis of the combined dry weight of the first cracking component, 
second cracking component and binder. 
Step (ii) of the present process may be effected using any conventional, 
commercially available extruder. In particular, a screw-type extruding 
machine may be used to force the mixture through orifices in a die plate 
to yield catalyst extrudates of the required form, e.g. cylindrical or 
trilobed. The strands formed on extrusion may then be cut to the 
appropriate length. If desired, the catalyst extrudates may be dried, e.g. 
at a temperature from 100 to 300.degree. C. for a period of 30 minutes to 
3 hours, prior to calcination in step (iii). Calcination is conveniently 
carried out in air at a temperature in the range of from 300 to 
800.degree. C. for a period of from 30 minutes to 4 hours. 
The catalyst composition prepared by the process of the present invention 
will usually further comprise at least one hydrogenation component. 
Examples of hydrogenation components that may suitably be used include 
Group VI components (such as molybdenum and tungsten) and Group VIII 
components (such as cobalt, nickel, iridium, platinum and palladium). 
Preferably, at least two hydrogenation components are used, e.g. a 
molybdenum and/or tungsten component in combination with a cobalt and/or 
nickel component or platinum in combination with palladium. Particularly 
preferred combinations are nickel/tungsten, nickel/molybdenum, and 
platinum/palladium. 
The at least one hydrogenation component may be incorporated at various 
stages during the preparation of the catalyst composition, according to 
techniques conventional in the art. For example, the at least one 
hydrogenation component may be loaded onto one or both of the cracking 
components by means of cation exchange or pore volume impregnation before 
the cracking components are combined in step (i) of the present process. 
Alternatively, the at least one hydrogenation component may be added in 
step (i) and/or may be added to the calcined extrudates of step (iii) in a 
further step (iv), typically as one or more aqueous (impregnating) 
solutions of Group VI and/or Group VIII metal salts. 
In a preferred aspect of the present invention, the at least one 
hydrogenation component is added during step (iv) only. Thus, the present 
invention further provides a process for the preparation of a catalyst 
composition which comprises, as first cracking component, a zeolite beta 
with a silica to alumina molar ratio of at least 20 comprising crystals 
less than 100 nm in size; a second cracking component selected from (i) 
crystalline molecular sieves having pores with diameters greater than 0.6 
nm, and (ii) clays; and at least one hydrogenation component, the process 
comprising the steps of: 
(i) preparing a mixture comprising the first cracking component and the 
second cracking component, the first cracking component being in the form 
of a sol, 
(ii) extruding the mixture into catalyst extrudates, 
(iii) calcining the extrudates, and 
(iv) adding the at least one hydrogenation component to the calcined 
extrudates. 
In another preferred aspect of the invention, step (iv) is followed by a 
further step (v) in which the extrudates are again calcined as 
hereinbefore described. 
The catalyst composition may contain up to, and including 50 parts by 
weight of hydrogenation component, calculated as metal per 100 parts by 
weight of total, dry catalyst composition. For example, the catalyst 
composition may contain in the range of from 2 to 40, more preferably from 
5 to 30 and especially from 10 to 20, parts by weight of Group VI metal(s) 
and/or in the range of from 0.05 to 10, moe preferably from 0.5 to 8 and 
advantageously from 1 to 6, parts by weight of Group VIII metal(s), 
calculated as metal per 100 parts by weight of total, dry catalyst 
composition. 
Such a catalyst composition containing a hydrogenation component may 
advantageously be used in a process for converting a hydrocarbonaceous 
feedstock into lower boiling materials which comprises contacting the 
feedstock with hydrogen at elevated temperature and elevated pressure in 
the presence of the catalyst composition (a hydrocracking process). 
Hydrocarbonaceous feedstocks that may be converted by the above process 
include atmopsheric gas oils, coker gas oils, vacuum gas oils, deasphalted 
oils, waxes obtained from a Fischer-Tropsch synthesis process, long and 
short residues, catalytically cracked cycle oils, thermally or 
catalytically cracked gas oils, and syncrudes, optionally originating from 
tar sand, shale oils, residue upgrading processes and biomass. 
Combinations of various hydrocarbon oils may also be used. The feedstock 
may comprise hydrocarbons having an initial boiling point of from at least 
330.degree. C. down to at least 50.degree. C. The boiling range (from 
initial to final boiling point) may be in the range of from about 50 to 
800.degree. C., with preference being given to feedstocks having a boiling 
range of from about 60 to 700.degree. C. The feedstock may have an 
nitrogen content of up to 5000 ppmw (parts per million by weight) and a 
sulphur content of up to 6% w. Typically, nitrogen contents are in the 
range from 250 to 2000 ppmw and sulphur contents are in the range from 0.2 
to 5% w. However, the feedstock may normally have a lower nitrogen and/or 
sulphur content, furthermore it is possible and may sometimes be desirable 
to subject part or all of the feedstock to a pre-treatment, for example, 
hydroenitrogenation, hydrodesulphurization or hydrodemetallization, 
methods for which are known in the art, such that the feedstock subjected 
to hydrocracking has a much lower nitrogen, sulphur and/or metal content. 
The hydrocracking process may be carried out at a reaction temperature in 
the range of from 200 to 500.degree. C., conveniently from 250 to 
500.degree. C., preferably in the range from 300 to 450.degree. C. 
The process is preferably carried out at a total pressure (at the reactor 
inlet) in the range from 3.times.10.sup.6 to 3.times.10.sup.7 Pa (30 to 
300 bar), more preferably from 4.times.10.sup.6 to 2.5.times.10.sup.7 Pa 
(40 to 250 bar), e.g. from 8.times.10.sup.6 to 2.times.10.sup.7 Pa (80 to 
200 bar). 
The hydrogen partial pressure (at the reactor inlet) is preferably in the 
range from 3.times.10.sup.6 to 2.9.times.10.sup.7 Pa (30 to 290 bar), more 
preferably from 4.times.10.sup.6 to 2.4.times.10.sup.7 Pa (40 to 240 bar) 
and still more preferably from 8.times.10.sup.6 to 1.9.times.10.sup.7 Pa 
(80 to 190 bar). 
A space velocity in the range from 0.1 to 10 kg feedstock per liter 
catalyst per hour (kg.1.sup.-1.h.sup.-1) is conveniently used. Preferably 
the space volocity is in the range of from 0.1 to 8, particularly from 0.2 
to 5 kg.1.sup.-1.h.sup.-1. 
The ratio of hydrogen gas to feedstock (total gas rate) used in the process 
will generally be in the range from 100 to 5000 Nl/kg, but is preferably 
in the range from 200 to 3000 Nl/kg. 
The present invention will be further understood from the following 
illustrative examples in which the silica to alumina molar ratio of an 
aluminosilicate (zeolite) was determined on the basis of the total amount 
of aluminum and silicon (framework and non-framework) present in the 
zeolite and the unit cell size (a.sub.o) of an aluminosilicate (zeolite) 
was determined according to standard test method ASTM D 3942-80. 
Furthermore, the boiling points and density of the hydrocarbonaceous 
feedstocks were determined according to standard test methods ASTM D 86 
and D 1298 respectively.

EXAMPLE 1 
(i) Preparation of a Zeolite Beta Sol 
A zeolite beta sol was prepared by the method of Camblor et al., "Progress 
in Zeolite and Microporous Materials", Vol. 105, pp. 341-348, Elsevier 
(1997), as follows. 
To an aqueous solution of tetraethylammonium hydroxide (TEAH) free of 
alkali metal ions (225 g, 40% w solution, ex-aAlfa) was added aluminum 
metal (2.93 g) and the solution was heated at 50.degree. C. for 5 hours to 
effect total dissolution of the aluminum metal. Once all the aluminium had 
dissolved the solution was added, with stirring, to a mixture made by 
dispersing `Aerosil 200` (trade mark) amorphous silica (162.5 g, 
ex-Degussa) in an aqueous solution of tetraethylammonium hydroxide (311.9 
g TEAH, ex-Alfa, in 407 g water), which resulted in the formation of a gel 
(Si/Al atomic ratio of 25). After stirring for 15 minutes, the gel was 
transferred to an autoclave operated at 140.degree. C. and 300 rpm for 240 
hours. The contents of the autoclave were then quenched with cold water 
and the solids separated by centrifugation. Washing of the solids with 
distilled water until the pH of the wash water was less than pH 9 gave the 
desired product, a zeolite beta sol (Si/Al atomic ratio of 14; silica to 
alumina molar ratio of 28). X-ray diffraction and Transmission Electron 
Microscopy analyses carried out on the dried sol confirmed it to be pure 
zeolite beta with an average crystal size of 70 nm (700 .ANG.ngstroms). 
(ii) Preparation of a Catalyst Composition 
a) A catalyst composition was prepared according to the process of the 
present invention by combining the zeolite beta sol prepared in (i) above 
(35.2 g, loss on ignition (LOI) of 71.6%) with alumina (53.8 g, LOI of 
25.6%) and a very ultrastable zeolite Y (VUSY) according to EP-A-247 678 
and EP-A-247 679 (58.4 g, LOI of 14.4%) having a silica to alumina molar 
ratio of 9.9 and a unit cell size (a.sub.o) of 2.431 nm (24.31 
.ANG.ngstroms). Water and acetic acid were added and the resulting mixture 
was mulled and then extruded, together with an extrusion aid, into pellets 
of cylindrical shape. The pellets were dried statically for 2 hours at 
120.degree. C. and then calcined for 2 hours at 530.degree. C. The pellets 
so obtained had a circular end surface diameter of 1.6 mm and a water pore 
volume of 0.77 ml/g. The pellets comprised 10% w zeolite beta (first 
cracking component), 50% w VUSY zeolite (second cracking component and 40% 
w alumina (binder), on a dry weight basis. 
b) 40.18 g of an aqueous solution of nickel nitrate (14.1% w nickel) and 
39.93 g of an aqueous solution of ammonium metatungstate (67.26% w 
tungsten) were combined and the resulting mixture was diluted with water 
(34.6 g) and then homogenised. The pellets were impregnated with the 
homogenised mixture (69.7 ) ml), dried at ambient temperature (20.degree. 
C.) for 4 hours and then at 120.degree. C. for 2 hours and finally 
calcined for 2 hours at 500.degree. C. The pellets contained 4% w nickel 
and 19% w tungsten (hydrogenation components), based on total composition. 
Comparative Example A 
The process of Example 1(ii) above was repeated except that a commercially 
available powdered zeolite beta (ex-PQ, silica to alumina molar ratio of 
114 and crystal size in the range from 30 to 50 nm (300 to 500 
.ANG.ngstroms)) was used instead of the zeolite beta sol to prepare a 
catalyst composition as described in Example 1 of International Patent 
Application No. PCT/EP96/05352. 
EXAMPLE 2 
The hydrocracking performance of the catalyst composition of Example 1 
(hereinafter referred to as Catalyst 1) was assessed in a second stage 
series-flow simulation test. The testing was carried out in once-through 
microflow equipment which had been loaded with a top catalyst bed 
comprising 1 ml C-424 catalyst (commercially available from the Criterion 
Catalyst Company) diluted with 1 ml of 0.1 mm SiC particles and a bottom 
catalyst bed comprising 10 ml Catalyst 1 diluted with 10 ml of 0.1 mm SiC 
particles. Both catalyst beds were presulphided prior to testing. 
The test involved the sequential contact of a hydrocarbonaceous feedstock 
(a heavy gas oil) with the top catalyst bed and then the bottom catalyst 
bed in a once-through operation under the following process conditions: a 
space velocity of 1.5 kg heavy gas oil per liter catalyst per hour 
(kg.1.sup.-1.h.sup.-1), a hydrogen gas/heavy gas oil ratio of 1450 Nl/kg, 
a hydrogen sulphide partial pressure of 4.7.times.10.sup.5 Pa (4.7 bar) 
and a total pressure of 14.times.10.sup.6 Pa (140 bar). 
______________________________________ 
The heavy gas oil used had the following properties 
______________________________________ 
Carbon content 86.69% w 
Hydrogen content 13.35% w 
Nitrogen (N) content 19 ppmw 
Added n-Decylamine 12.3 g/kg 
(equivalent to 
1100 ppmw N) 
Total nitrogen (N) content 1119 ppmw 
Density (15/4 C) 0.8789 g/ml 
Density (70/4 C) 0.8447 g/ml 
Molar weight 433 g 
Initial boiling point 349.degree. C. 
50% w boiling point 461.degree. C. 
Final boiling point 620.degree. C. 
Fraction boiling below 370.degree. C. 2.0% w 
Fraction boiling above 540.degree. C. 13.3% w 
______________________________________ 
Hydrocracking performance was assessed at conversion levels between 45 and 
100% w net conversion of feed components boiling above 370.degree. C. The 
results obtained at 65% w net conversion of feed components boiling above 
370.degree. C. are shown in Table I below. 
Comparative Example A' 
The test procedure of Example 2 was repeated except that a bottom catalyst 
bed comprising 10 ml of the catalyst composition of Comparative Example A 
(hereinafter referred to as Catalyst A) diluted with 10 ml of 0.1 mm SiC 
particles was used. Hydrocracking performance was assessed at conversion 
levels between 45 and 100% w net conversion of feed components boiling 
above 370.degree. C. The results obtained at 65% w net conversion of feed 
components boiling above 370.degree. C. are presented in Table I below. 
TABLE I 
______________________________________ 
Catalyst System 
C-424/Cat. A 
C-424/Cat. 1 
______________________________________ 
Temp. (.degree. C.) at 65% w net 
371.5 368.5 
conversion 
Product Selectivities 
(% w on feed) 
Gas (C.sub.1 -C.sub.3) 0.8 0.9 
(C.sub.4) 2.7 3.1 
Naphtha 34 34 
(C.sub.5 -- 150.degree. C.) 
Kerosine 36 37 
(150-250.degree. C.) 
Gas Oil 26.5 25 
(250-370.degree. C.) 
Iso/Normal ratio of 2.4 2.7 
butanes 
______________________________________ 
It will be observed from Table I that whilst Catalyst 1 (prepared by the 
process of the present invention) and comparative Catalyst A both produced 
the same high yields of middle distillates with very little C.sub.1 
-C.sub.3 gaseous by-product, this was achieved at a lower temperature 
using Catalyst 1 (368.5.degree. C.) than Catalyst A (371.5.degree. C.). 
Thus, Catalyst 1 demonstrates increased activity without any loss in 
middle distillate selectivity relative to Catalyst A. Furthermore, whilst 
the iso/normal ratio for butanes only is quoted which is higher for 
Catalyst 1 than Catalyst A, a similar outcome would be expected for the 
other products. The higher the iso/normal ratio, the better the quality of 
the product. 
EXAMPLE 3 
Pellets comprising 10% w zeolite beta, 50% w VUSY zeolite and 40% w alumina 
were prepared following the procedure of Example 1 ii)a) above. 
10.79 g of an aqueous solution of Pt(NH.sub.3).sub.4 (NO.sub.3).sub.2 
(2.99% w platinum) and 0.98 g of an aqueous solution of Pd/NH.sub.3).sub.4 
(NO.sub.3).sub.2 (6.56% w palladium) were combined and the resulting 
mixture was diluted with water to 24.9 ml and then homogenised. 31.84 g 
pellets were impregnated with the homogenised mixture, and then 
dried/calcined in air in a tube rotating at 10 rpm under the following 
heating regime: heating to 180.degree. C. at 15.degree. C. per minute; 
maintaining the temperature at 180.degree. C. for 10 minutes; heating to 
300.degree. C. at 30.degree. C. per minute; maintaining at 300.degree. C. 
for 15 minutes. 
The resulting pellets contained a metals loading of 1% w platinum and 0.2% 
w palladium (hydrogenation components) based on total composition. 
EXAMPLE 4 
The hydrocracking performance of the catalyst composition of Example 3 
(hereinafter referred to a Catalyst 2) was assessed in a wax hydrocracking 
simulation test. The testing was carried out in once-through microflow 
equipment which had been loaded with a catalyst bed comprising 10 ml 
Catalyst 2 diluted with 10 ml of 0.1 mm SiC particles. The catalyst bed 
was reduced with hydrogen prior to testing. 
The test involved the contact of a hydrocarbonaceous feedstock (a 
Fischer-Tropsch wax) with the catalyst bed in a once-through operation 
under the following process conditions: a space velocity of 1.15 kg wax 
per liter catalyst per hour (kg. 1.sup.-1.h.sup.-1), a hydrogen gas/heavy 
gas oil ratio of 750 Nl/kg, and a total pressure of 4.times.10.sup.6 Pa 
(40 bar). 
______________________________________ 
The heavy gas oil used had the following properties 
______________________________________ 
Carbon content 85.35% w 
Hydrogen content 14.62% w 
Sulphur (S) content &lt;10 ppmw 
Density (125/4 C) 0.7437 g/ml 
Kinetic viscosity (@ 100.degree. C.) 3.9 mm.sup.2 /s (3.9 cSt) 
Initial boiling point 65.degree. C. 
50% w boiling point 442.degree. C. 
Final boiling point 700.degree. C. 
Fraction boiling below 370.degree. C. 20.6% w 
Fraction boiling above 540.degree. C. 19.1% w 
______________________________________ 
Hydrocracking performance was assessed at conversion levels between 35 and 
80% w net conversion of feed components boiling above 370.degree. C. The 
results obtained at 60% w net conversion of feed components boiling above 
370.degree. C. are shown in Table II below. 
TABLE II 
______________________________________ 
Catalyst System 
Catalyst 2 
______________________________________ 
Temp. (.degree. C.) at 65% w net conversion 
241 
Product Selectivities 
(% w on feed) 
Gas (C.sub.1 -C.sub.3) 0.5 
(C.sub.4) 2.1 
Naphtha (C.sub.5 -- 140.degree. C.) 19 
Kerosine (140-220.degree. C.) 24 
Gas Oil (220-370.degree. C.) 54 
Iso/Normal ratio of butanes 3.6 
______________________________________ 
It will be observed from Table II that Catalyst 2 (prepared by the process 
of the present invention) produced high yields of middle distillates with 
very little C.sub.1 -C.sub.3 gaseous by-product, and a high iso/normal 
ratio for butanes.