Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CAT~LYST COMPOSITIONS ~ND TH~IR
USE IN HYDROCARBON CONVERSION PROCESSES
The present invention relates to catalytic compo-
sitions and hydrocarbon conversion processes using them.
Many hydrocarbon conversion processes in the
petroleum industry are carried out using catalyst
compositions based on zeolite Y. The zeolite Y has very
often been subjected to certain stabilising and/or
dealumination process steps during its preparation which
result in its having a reduced unit cell constant (aO)
and an increased silica to alumina molar ratio. These
stabilised zeolites, as well as the as-synthesised
zeolite Y, possess relatively few pores that are larger
than 2 nanometres (nm) in diameter and therefore have a
limited mesopore volume ~a mesopore has a diameter
typically in the range from 2 to 60 nm).
US-A-5 354 452 discloses a process in which ultra-
stable Y zeolites having a silica to alumina molar ratio
of 6 to 20, and superultrastable Y zeolites having a
silica to alumina molar ratio of at least 18 and a unit
~ cell constant (aO~ of 2.420 to 2.448 nm (24.20 to
24.48 A) are subjected to a hydrothermal treatment with
steam at 1000 to 1200 ~F followed by an acid treatment at
140 to 220 ~F. The hydrothermally-treat~d zeolite is
characterised by a unit cell constant (aO) typically in
the range from 2.427 to 2.439 nm (24.27 to 24.39 A), a
secondary pore volume contained in mesopores having a
diameter in the range from 10 to 60 nm ~100 to 600 A) of
0.09 to 0.13 ml/g, and a total pore volume of 0.16 to
0.20 ml/g, whereas the acidified, hydrothermally-treated
zeolite is characterised by a unit cell constant (aO)
typically in the range from 2.405 to 2.418 nm (24.05 to
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24.18 A), a secondary pore volume contained in mesopores
having a diameter in the range from 10 to 60 nm (100 to
600 A) of 0.11 to 0.14 ml/g, and a total pore volume of
0.16 to o. 25 ml/g.
It has now surprisingly been found possible to
prepare catalyst compositions containing certain 'Y-type'
molecular sieves with even higher mesopore volumes which
may advantageously be used in the conversion of hydro-
carbon oils, e.g. by catalytic cracking or hydrocracking,
to produce desirable products in greater yield and
selectivity.
In accordance with the present invention, there is
provided a catalyst composition comprising a molecular
sieve having a structure substantially the same as
zeolite Y, a unit cell constant (aO) less than or equal
to 2.485 nm and a mesopore volume, contained in mesopores
having a diameter in the range from 2 to 60 nm, of at
least 0.05 ml/g, and a binder, wherein the relationship
between the unit cell constant (aO) and the mesopore
volume is defined as follows:
Unit Cell ~on~t~nt (nm) Mesopore Vol1lme (ml/g)
2.485 2 aO > 2.460 2 0.05
2.460 2 aO 2 2.450 2 0.18
2.450 > aO > 2.427 2 0.23
2.427 2 aO 2 0.26
The molecular sieve used in the catalyst compositions
of the invention is defined as having a structure
substantially the same as zeolite Y. This definition is
intended to embrace molecular sieves derived not only
from zeolite Y ~QL ~ but also from modified zeolites Y
in which a proportion of the aluminium ions have been
replaced by other metal ions such as iron, titanium,
gallium, tin, chromium or scandium ions but whose
structures are not significantly different from that of
zeolite Y, as may be determined by X-ray crystallography.
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Examples of suitable iron- and/or titanium-modified
zeolites Y are those disclàsed~in U~ Patents
Nos. 5 176 817 and 5 271 761, and examples of suitable
chromium- and/or tin-modified zeolites Y are tho~e
disclosed in EP-A-321 177.
However, the molecular sieve used in the catalyst
compositions of the invention is preferably derived from
a zeolite Y ~L ~, e.g. as described in Zeolite
Molecular Sieves (~tr~cture, Chemistry and Use) by Donald
W. Breck published by Robert E. Krieger Publishing
Company Inc., 1984; and US Patents Nos. 3 506 400,
3 671 191, 3 808 326, 3 929 672 and 5 242 677.
The molecular sieve used in the present compositions
has a unit cell constant (aO) less than or equal to (<)
2.485 nm (24.85 A), preferably less than or equal to (S)
2.460 nm (24.60 A), e.g. in the range from 2.427 to
2.485 nm (24.27 to 24.85 A), preferably in the range from
2.427 to 2.460 nm (24.27 to 24.60 A). Advantageously,
the molecular sieve has a unit cell constant (aO) up to
2.440 nm (24.40 A), e.g. in the range from 2.427 to
2.440 nm (24.27 to 24.40 A), or a unit cell constant (aO)
in the range from 2.450 to 2.460 nm (24.50 to 24.60 A).
The mesopore volume of the molecular sieve, as
contained in mesopores having a diameter in the range
from 2 to 60 nm, will vary depending on the unit cell
constant (aO). The relationship between the unit cell
constant (aO) and the mesopore volume is as follows:
U~it Cell Con~t~nt (~m) Mesopore Volllme (ml /g)
2.485 2 aO > 2.460 2 0.05
2.460 2 aO 2 2.450 2 0.18
2.450 > aO > 2.427 2 0.23
2.427 2 aO 2 0.26
The molecular sieve may have a mesopore volume of up
to 0.8 ml/g, e.g. in the range from 0.05, preferably from
0.18, more preferably from 0.23, still more preferably
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from 0.26, advantageously from 0.3 and particularly from
0.4 ml/g, up to 0.6 ml/g, especially up to 0.8 ml/g.
The molecular sieves useful in the present invention
may conveniently be prepared by a hydrothermal treatment
in which a zeolite Y or modified zeolite Y as described
above is contacted hydrothermally with an aqueous
solution having dissolved therein one or more salts,
acids, bases and/or water-soluble organic compounds at a
temperature above the boiling point of the solution at
atmospheric pressure for a period of time sufficient to
provide the zeolite with an increased mesopore volume in
mesopores having a diameter in the range from 2 to 60 nm.
On completion of the hydrothermal treatment, the product
is separated, washed (using deionized water or an acid,
e.g. nitric acid, solution) and recovered. The product
obtained by this treatment will generally have a unit
cell size (unit cell constant) and a silica to alumina
molar ratio similar to those of the starting zeolite.
However, if desired, the product may be subjected to
additional stabilisation and/or dealumination treatments
as are well known in the art in order to change the unit
cell size and/or the silica to alumina molar ratio.
In the preparation of the aqueous hydrothermal
treatment solution, examples of salts which may be used
include ammonium, alkali metal (e.g. sodium and
potassium) and alkaline earth metal salts of strong and
weak, organic and inorganic acids, ~e.g., nitric and
hydrochloric acids); examples of acids which may be used
include strong inorganic acids such as nitric acid and
hydrochloric acid as well as weak organic acids such as
acetic acid and formic acid; examples of bases which may
be used include inorganic bases such as ammonium, alkali
metal and alkaline earth metal hydroxides together with A
organic bases such as quaternary ammonium hydroxides,
amine complexes and pyridinium salts; and examples of
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water-soluble organic compounds which may be used include
C1-C6 alcohols and ethers. The concentration and amount
o~ the aqueous solution contacted with the starting
zeolite is adjusted to provide at least 0.1 part by
weight (pbw) of dissolved solute per part by weight of
zeolite, on a dry weight basis.
The pH of the aqueous hydrothermal treatment solution
may vary between 3 and 10 and depending on the (modified)
zeolite Y to be treated, a high or a low pH may be
preferred. Thus, if the starting zeolite has a unit cell
constant (aO) of from 2.450 to 2.460 nm (2.460 nm 2 aO >
2.450 nm), it is desirable to maintain or adjust the pH
of the solution prior to contact with the zeolite to a
value of 4.5 to 8; if the starting zeolite has a unit
cell constant (aO) of from greater than 2.427 to less
than 2.450 nm (2.450 nm > aO > 2.427 nm), then the pH of
the solution should desirably be maintained or adjusted
to a value of 3 to 8; and if the starting zeolite has a
unit cell constant (aO) less than or equal to 2.427 nm
(2.427 nm 2 aO), then the pH of the solution should
desirably be maintained or adjusted to a value of 3 to 7.
The temperature of the hydrothermal treatment should
be above the atmospheric boiling point of the aqueous
solution. Although temperatures up to 400 ~C can be
used, a temperature in the range from 110 or 115 to
250 ~C is usually satisfactory. Good results can be
obtained using a temperature in the rang~ from 140 to
200 ~C.
The treatment time is inversely related to the
treatment temperature. Thus, at a higher temperature, a
shorter time will be required to effect a given increase
in mesopore volume. The treatment time may vary between
5 minutes and 24 hours but is usually in the range ~rom 2
to 12 hours.
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The duration of the hydrothermal treatment and the
temperature at which it is applied should be such as to
provide a mesopore volume in the final product which is
at least 5~, preferably at least 10%, larger than the
mesopore volume in the starting zeolite.
A preferred molecular sieve to use in the catalyst
composition of the present invention is one prepared by a
process comprising contacting a (modified) zeolite Y as
hereinbefore defined hydrothermally with an aqueous
solution having dissolved therein one or more salts,
acids, bases and/or water-soluble organic compounds at a
temperature above the atmospheric boiling point of the
solution, followed by separation and washing with an acid
solution.
The acid solution may be an aqueous solution of one
or more acids selected from inorganic and organic acids,
e.g. nitric acid, hydrochloric acid, acetic acid, formic
acid and citric acid. Compared to using (deionized)
water, washing with an acid solution has the advantage of
further enhancing the middle distillate selectivity of
the increased mesopore molecular sieve.
As binder in the catalyst compositions of the
invention, it is convenient to use an inorganic oxide or
a mixture of two or more such oxides. The binder may be
amorphous or crystalline. Examples of suitable binders
include alumina, silica, magnesia, titania, zirconia,
silica-alumina, silica-zirconia, silica-boria and
mixtures thereof. A preferred binder to use is alumina,
or alumina in combination with a dispersion of silica-
alumina in an alumina matrix, particularly a matrix of
gamma alumina.
The catalyst composition of the present invention
preferably contains from 1 to 80 ~w (per cent by weight)
of the molecular sieve and from 20 to 99 ~w binder, based
on the total dry weight of molecular sieve and binder.
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More preferably, the catalyst composition contains from
10 to 70 ~w of the molecular sieve and from 30 to 90 ~w
binder, in particular from 20 to 50 ~w of the molecular
sieve and from 50 to 80 ~w binder, based on the total dry
weight of molecular sieve and binder.
Depending on the application o~ the present catalyst
compositions (e.g. in hydrocracking), they may further
comprise at least one hydrogenation component. Examples
of hydrogenation components useful in the present
invention include Group 6B (e.g. molybdenum and tungsten)
and Group 8 metals (e.g. cobalt, nickel, iridium,
platinum and palladium), their oxides and sulphides. The
catalyst composition preferably contains at least two
hydrogenation components, e.g. a molybdenum and/or
tungsten component in combination with a cobalt and/or
nickel component. Particularly preferred combinations
are nickel/tungsten and nickel/molybdenum. Very
advantageous results are obtained when the metals are
used in the sulphide form.
The catalyst composition may contain up to 50 parts
by weight o~ hydroyenation component, calculated as metal
per lO0 parts by weight of total catalyst composition.
For example, the catalyst composition may contain from 2
to 40, more preferably from 5 to 25 and especially from
10 to 20, parts by weight of Group 6 metal(s) and/or from
0.05 to 10, more preferably from 0.5 to 8 and advantage-
ously from 2 to 6, parts by weight of Group 8 metal(s),
calculated as metal per 100 parts by weight of total
catalyst composition.
The present catalyst compositions may be prepared in
accordance with techniques conventional in the art.
A convenient method for preparing a catalyst
composition for use in cracking comprises mixing binder
material with water to ~orm a slurry or sol, adjusting
the pH of the slurry or sol as appropriate and then
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adding a powdered molecular sieve as defined above
together with additional water to obtain a slurry or sol
with a desired solids concentration. The slurry or sol
is then spray-dried. The spray-dried particles thus
formed may be used directly or may be calcined prior to
use.
One method for preparing a catalyst composition for
use in hydrocracking comprises mulling a molecular sieve
as defined above and binder in the presence of water and
optionally a peptising agent, extruding the resulting
mixture into pellets and calcining the pellets. The
pellets thus obtained are then impregnated with one or
more solutions of Group 6B and/or Group 8 metal salts and
again calcined.
Alternatively, the molecular sieve and binder may be
co-mulled in the presence of one or more solutions of
Group 6B and/or Group 8 metal salts and optionally a
peptising agent, and the mixture so formed extruded into
pellets. The pellets may then be calcined.
The present invention further provides a process for
converting a hydrocarbonaceous feedstock into lower
boiling materials which comprises contacting the
feedstock at elevated temperature with a catalyst
composition according to the invention.
The hydrocarbonaceous feedstocks useful in the
present process can vary within a wide boiling range.
They include lighter fractions such as kerosine fractions
as well as heavier fractions such as gas oils, coker gas
oils, vacuum gas oils, deasphalted oils, long and short
residues, catalytically cracked cycle oils, thermally or
catalytically cracked gas oils, and syncrudes, optionally
originating from tar sands, shale oils, residue upgrading
processes or biomass. Combinations of various hydro-
carbon oils may also be employed. The feedstock will
generally comprise hydrocarbons having a boiling point of
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at least 330 ~C. In a preferred embodiment of the
invention, at least 50 ~w of the feedstock has a boiling
point above 370 ~C. The feedstock may have a 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. It
i8 possible and may sometimes be desirable to subject
part or all of the feedstock to a pre-treatment, for
example, hydrodenitrogenation, hydrodesulphurisation or
hydrodemetallisation, methods for which are known in the
art.
If the process is carried out under catalytic
cracking conditions (i.e. in the absence of added
hydrogen), the process is conveniently carried out in an
upwardly or downwardly moving catalyst bed, e.g. in the
manner of conventional Thermofor Catalytic Cracking (TCC)
or Fluidised Catalytic Cracking (FCC) processes. The
process conditions are preferably a reaction temperature
in the range from 400 to 900 ~C, more preferably from 450
to 800 ~C and especially from 500 to 650 ~C; a total
pressure of from 1 x 105 to 1 x 1o6 Pa (1 to 10 bar), in
particular from 1 x 105 to 7.5 x 105 Pa (1 to 7.5 bar); a
catalyst composition/feedstock weight ratio (kg/kg) in
the range from 5 to 150, especially 20 to 100; and a
contact time between catalyst composition and feedstock
of from 0.1 to 10 seconds, advantageously from 1 to 6
seconds.
However, the process according to the present
invention is preferably carried out under hydrogenating
conditions, i.e. under catalytic hydrocracking
conditions, e.g. residue hydrocracking conditions.
Thus, the reaction temperature is preferably in the
range from 250 to 500 ~C, more preferably from 300 to
450 ~C and especially from 350 to 450 ~C.
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The total pressure is preferably in the range from
5 x 106 to 3 x 107 Pa (50 to 300 bar), more preferably
from 7.5 x 106 to 2.5 x 107 Pa (75 to 250 bar) and even
more preferably from 1 x 107 to 2 x 107 Pa (100 to
200 bar).
The hydrogen partial pressure is preferably in the
range from 2.5 x 106 to 2.5 x 107 Pa (25 to 250 bar),
more preferably from 5 x 106 to 2 x 107 Pa (50 to
200 bar) and still more preferably from 6 x 106 to
1.8 x 107 Pa (60 to 180 bar).
A space velocity in the range from 0.05 to 10 kg
feedstock per litre catalyst composition per hour
(kg.l~1.h~l) is conveniently used. Preferably the space
velocity is in the range from 0.1 to 8, particularly from
0.1 to 5, kg.l~1.h~1. Furthermore, total gas rates
(gas/feed ratios) in the range from 100 to 5000 Nl/kg are
conveniently employed. Preferably, the total gas rate
employed is in the range from 250 to 2500 Nl/kg.
The present invention will be further understood from
the following illustrative examples in which the unit
cell constant (aO) was determined according to standard
test method ASTM D 3942-80, the relative crystallinity
(%) was determined by comparing X-ray crystallography
data for the increased mesopore zeolite Y with that for a
standard corresponding zeolite Y of the prior art, and
the surface properties (i.e. surface area (m2/g) and
mesopore volume (ml/g)) were determined using nitrogen
adsorption at 77 ~K (-196 ~C).
Example 1
(i) Preparation of a molecular sieve with increased
mesopore volume
A very ultrastable zeolite Y (WSY) having a silica
to alumina molar ratio of 7.4, a unit cell constant (aO)
of 2.433 nm (24.33 A), a surface area of 691 m2/g and a
mesopore volume of 0.177 ml/g was added to an aqueous 4N
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solution of ammonium nitrate (NH4NO3) in an amount such
that, on a dry weight basis, the ratio of the number of
grams of ammonium nitrate to the number of grams of
zeolite Y was 1.5. The resulting slurry was placed in a
2 litre stirred autoclave and the slurry was heated at
150 ~C for 12 hours. After cooling, the contents of the
autoclave were filtered to yield a molecular sieve having
a structure substantially the same as zeolite Y which,
after 2 three-hour washes at 93 ~C with a nitric acid
solution (2 milli-equlvalents (meq) hydrogen ions (H+)
per gram of zeolite) and drying at 110 ~C, was found to
have a silica to alumina molar ratio of 13.2, a unit cell
constant (aO) of 2.429 nm (24.29 ~), a relati~e
crystallinity of 87%, a surface area of 756 m~/g and a
mesopore volume of 0.322 ml/g.
(ii) Preparation of a catalyst composition
To a mixture consisting of a molecular sieve prepared
as described in ~i) above (5 g), amorphous 55/45 silica-
alumina (104 g) and high microporosity precipitated
alumina (50 g) was added water (145 g) and acetic acid
(96%, 4 g). The mixture was first mulled and was then
extruded, following the addition of an extrusion aid,
into pellets of cylindrical shape. The pellets were
dried for 2 hours at 120 ~C and subsequently calcined for
2 hours at 530 ~C. The pellets so obtained had a
circular end surface diameter of 1.6 mm and a water pore
~olume of 0.72 ml/g. The pellets comprLsed 4 %w of the
molecular sieve and 96 %w binder (66 %w silica-alumina
and 30 %w alumina), on a dry weight basis.
10.07 g of an aqueous solution of nickel nitrate
(14 %w nickel) and 16.83 g of an aqueous solution of
ammonium metatungstate (39.8 %w tungsten) were combined
and the resulting nickel/tungsten solution was diluted
with water (18 g) and homogenised. 25.0 g of the pellets
were impregnated with the homogenised nickel/tungsten
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solution, dried for 1 hour at 120 ~C and finally calcined
for 2 hours at 500 ~C. The pellets contained 3.9 ~w
nickel and 18.9 %w tungsten, based on total composition.
Example 2
(i) Preparation of a molecular sieve with increased
mesopore volume
A very ultrastable zeolite Y (WSY) having a silica
to alumina molar ratio of 8.4, a unit cell constant (aO)
of 2.434 nm (24.34 ~), a surface area of 72/ m2/g and a
mesopore volume of 0.180 ml/g was added to an aqueous 4N
solution of ammonium nitrate (NH4NO3) in an amount such
that, on a dry weight basis, the ratio of the number of
grams of ammonium nitrate to the number of grams of
zeolite Y was 1.5. The resulting slurry was placed in a
2 litre stirred autoclave and the slurry was heated at
200 ~C for 6 hours. After cooling, the contents of the
autoclave were filtered to yield a molecular sieve having
a structure substantially the same as zeolite Y which,
after 2 three-hour washes at 93 ~C with a nitric acid
solution (2 milli-equivalents (meq) hydrogen ions (H+)
per gram of zeolite) and drying at 110 ~C, was found to
have a silica to alumina molar ratio of 10.0, a unit cell
constant (aO) of 2.427 nm (24.27 A), a relative
crystallinity of 71~, a surface area of 605 m2/g and a
mesopore volume of 0.423 ml/g.
(ii) Preparation of a catalyst composition
In the manner described in Example l(ii), a molecular
sieve prepared as described in (i) above (5 g) was
combined with amorphous 55/45 silica-alumina (82 g) and
high microporosity precipitated alumina (40 g) to form
cylindrically-shaped pellets which, after drying and r
calcination, had a circular end surface diameter of
1.2 mm and-a water pore volume of 0.717 ml/g. The
pellets comprised 5 %w of the molecular sieve and 95 %w
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binder (65 %w silica-alumina and 30 96W alumina), on a dry
weight basis.
8.34 g of an aqueous solution of nickel nitrate
(14.1 ~w nickel) and 8.29 g of an aqueous solution of
J 5 ammonium metatungstate (67.3 %w tungsten) were combined
and the resulting nickel/tungsten solution was diluted
with water (7.2 g) and homogenised. 25.0 g of the
pellets were impregnated with the homogenised
nickel/tungsten solution, dried for 1 hour at 120 ~C and
finally calcined for 2 hours at 500 ~C. The pellets
contained 3.9 %w nickel and 18.9 ~w tungsten, based on
total composition.
Example 3
(i) Preparation of a molecular sieve with increased
mesopore volume
A very ultrastable zeolite Y ~WSY) having a silica
to alumina molar ratio of 7.4, a unit cell collstant (aO)
of 2.433 nm (24.33 A), a surface area of 691 m2/g and a
mesopore volume of 0.177 ml/g was added to an aqueous 4N
solution of ammonium nitrate (NH4NO3) in an amount such
that, on a dry weight basis, the ratio of the number of
grams of ammonium nitrate to the number of grams of
zeolite Y was 1.5. The resulting slurry was placed in a
2 litre stirred autoclave and the slurry was heated at
180 ~C for 12 hours. ~fter cooling, the contents of the
autoclave weré filtered to yield a molecular sieve having
a structure substantially the same as zeolite Y which,
after 2 three-hour washes at 93 ~C with a nitric acid
solution (2 milli-equivalents (meq) hydrogen ions (H+)
per gram of zeolite) and drying at 110 ~C, was found to
have a silica to alumina molar ratio of 10.2, a unit cell
constant (aO) of 2.428 nm (24.28 A), a relative
crystallinity of 57%, a surface area of 519 m2/g and a
mesopore volume of 0.458 ml/g.
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(ii) Preparation of a catalyst composition
In the manner described in Example l~ii), a molecular
sieve prepared as described in ~i) above (7 g) was
combined with amorphous 55/45 silica-alumina (125 g) and
high microporosity precipitated alumina (60 g) to form
cylindrically-shaped pellets which, after drying and
calcination, had a circular end surface diameter of
1.6 mm and a water pore volume of 0.792 ml/g. The
pellets comprised 4 %w of the molecular sieve and 96 %w
binder (66 ~w silica-alumina and 30 %w alumina), on a dry
weight basis.
13.12 g of an aqueous solution of nickel nitrate
(14.1 %w nickel) and 12.94 g of an aqueous solution of
ammonium metatungstate (67.3 %w tungsten) were combined
and the resulting nickel/tungsten solution was diluted
with water (13.69 g) and homogenised. 32.53 g of the
pellets were impregnated with the homogenised
nickel/tungsten solution, dried for 1 hour at 120 ~C and
finally calcined for 2 hours at 500 ~C. The pellets
contained 3.9 %w nickel and 18.9 %w tungsten, based on
total composition.
Example 4
Hydrocracking experiment
Each of the catalyst compositions of Examples 1 to 3
was assessed for middle distillates selectivity in a
hydrocracking performance test. The test involved
contacting a hydrocarbonaceous feedstock, (a hydrotreated
heavy vacuum gas oil) with the catalyst compositions
(pre-sulphided in conventional manner) in a once-through
operation under the following operating conditions: a
space velocity of 1.5 kg gas oil per litre catalyst
composition per hour (kg.l~l.h~1), a hydrogen sulphide
partial pressure of 5.5 x 105 Pa (5.5 bar), an ammonia
partial pressure of 7.5 x 103 Pa (0.075 bar), a total
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pressure of 14 x 106 Pa (140 bar) and a gas/feed ratio of
1500 Nl/kg.
The hydrotreated heavy vacuum gas oil had the
following properties:
Carbon content : 86.5 %w
Hydrogen content : 13.4 %w
Sulphur content : 0.007 %w
Nitrogen content : 16.1 ppmw
Density (~0/4) : O.8493 g/ml
Kinematic viscosity at 100 ~C : 8.81 I[un2/s (cS)
Initial boiling point : 345 ~C
10 %w boiling point : 402 ~C
20 %w boiling point : 423 ~C
30 %w boiling point : 441 ~C
40 %w boiling point : 456 ~C
50 %w boiling point : 472 ~C
60 %w boiling point : 490 ~C
70 %w boiling point : 508 ~C
80 96w boiling point : 532 ~C
90 96w boiling point : 564 ~C
Final boiling point : 741 ~C
The performance of each catalyst composition was
assessed at 65 %w net conversion of feed components
boiling above 370 ~C. The selectivities for middle
distillates (i.e. the fraction boiling in the temperature
range from 150 to 3~0 ~C) shown by the catalyst
compositions of Examples 1 to 3 are given in Table I
following.
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Table I
Catalyst Middle distillates
composition selectivity at
of Example 65%w net
conversion (%w/w)
1 70.5
2 72.S
3 72.5
As can be seen from Table I above, the catalyst
compositions of Examples 1 to 3 according to the
invention show high middle distillate selectivity.
Example 5
(i) Preparation of a molecular sieve with increased
mesopore volume
A very ultrastable zeolite Y (WSY) having a silica
to alumina molar ratio of 7.9, a unit cell constant (aO)
of 2.431 nm (24.31 A), a surface area of 550 m2/g and a
mesopore volume of 0.141 ml/g was added to an aqueous 4N
solution of ammonium nitrate (NH4NO3) in an amount such
that, on a dry weight basis, the ratio of the number of
grams of ammonium nitrate to the number of grams of
zeolite Y was 1.5. The resulting slurry was placed in a
2 litre stirred autoclave and the slurry was heated to
200 ~C for 6 hours. After cooling, the contents of the
autoclave were filtered to yield a molecular sieve having
a structure substantially the same as zeolite Y which,
after 2 three-hour washes at 93 ~C with de-mineralized
water and drying at 110 ~C, was found to have a silica to
alumina molar ratio of 8.5, a unit cell constant (aO) of
2.432 nm (24.32 ~), a relative crystallinity of 69%, a
surface area of 481 m2/g and a mesopore volume of
0.41 ml/g.
CA 02214331 1997-08-29
W096l27438 PCTi~l ''v~915
(ii) Preparation of a catalyst composition
In the manner described in Example llii), a molecular
sieve prepared as described in ~i) above (22.3 g) was
combined with high microporosity precipitated alumina
(llO.0 g) to form cylindrically-shaped pellets which,
after drying and calcination, had a circular end surface
diameter of l.6 mm and a water pore volume of 0.642 ml/g.
The pellets comprised 20 ~w of the molecular sieve and
80 %w alumina binder, on a dry weight basis.
8.92 g of an aqueous solution of nickel nitrate
(13.9 %w nickel) and 7.85 g of an aqueous solution of
ammonium metatungstate (67.3 %w tungsten) were combined
and the resulting nickel/tungsten solution was diluted
with water (6.6 g) and homogenised. 22.76 g of the
pellets were impregnated with the homogenised nickel/-
tungsten solution, dried for l hour at 120 ~C and finally
calcined for 2 hours at 500 ~C. The pellets contained
4.0 %w nickel and 17.0 ~w tungsten, based on total
composition.
Example 6
Hydrocracking experiment
The catalyst composition of Example 5, which is a
catalyst composition according to the present invention,
was assessed for middle distillates selectivity in a
hydrocracking performance test. The test involved
contacting a hydrocarbonaceous feedstock (a hydrotreated
heavy vacuum gas oil) with the catalyst.composition of
Example 5 (pre-sulphided in conventional manner) in a
once-through operation under the following operating
conditions: a space velocity of l.5 kg gas oil per litre
catalyst composition per hour (kg.l~l.h~l), a hydrogen
sulphide partial pressure of 5.5 x 105 Pa (5.5 bar), an
ammonia partial pressure of l.65 x 104 Pa (0.165 bar), a
total pressure of 14 x 106 Pa (140 bar) and a gas/feed
ratio of 1500 Nl/kg.
CA 022l433l l997-08-29
W 096/27438 PCTAEP96/00915
- 18 -
The hydrotreated heavy vacuum gas oil had the
following properties:
Carbon content : 86. 7 %W
Hydrogen content : 13.3 %W
Sulphur content : 0. 007 %W
Nitrogen content : 19.0 ppmw
Density (70/4) : 0.8447 g/ml
Initial boiling point : 349 ~C
10 %w boiling point : 390 ~C
20 %w boiling point : 410 ~C
30 %w boiling point : 427 ~C
40 %w boiling point : 444 ~C
50 %W boiling point : 461 ~C
60 %w boiling point : 478 ~C
70 %w boiling point : 498 ~C
80 %w boiling point : 523 ~C
90 %w boiling point : 554 ~C
Final boiling point : 620 ~C
The performance of the catalyst composition was
assessed at 65 %w net conversion of feed components
boiling above 370 ~C. The selectivity for middle
distillates (i.e. the fraction boiling in the temperature
range from 150 to 370 ~C) shown by the catalyst
composition of Example 5 was found to be high at
69.0 %w/w.
