Note: Descriptions are shown in the official language in which they were submitted.
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EX-SITU PRESULPHIDED HYDROCARBON CONVERSION CATALYSTS
This invention relates to a process for preparing
ex-situ sulphided hydrocarbon conversion catalysts,
catalyst compositions resulting therefrom and their use
in hydrocarbon conversion processes.
Many hydrocarbon conversion catalysts, such as
hydrotreating, hydrocracking and tail-gas treating
catalysts, are pyrophoric in their sulphided state. In
the pass, this pyrophoricity has been an obstacle which
prevented the storage of such catalysts in a sulphided
state prior to their use in the respective hydrocarbon
conversion operations. Because of their pyrophoric
nature, they can react exothermically with oxygen when
exposed to the atmosphere, to the extent that a fire
hazard can result. The exothermic reaction occurs
between the metal sulphides and the oxygen, and even if
does not occur to the extent of creating a fire hazard,
it occurs at least to the extent of causing the
generation of noxious fumes, including sulphur dioxide.
It is known to protect such catalysts against attacks
by keeping them under blankets of inert gas or coating
them with oil and keeping them in closed drums.
However, such methods are not only unwieldy, but they
do not afford protection when the catalysts are being
transferred from storage drums into hydroprocessing
~ 25 reactors.
A hydrotreating catalyst may be defined as any
catalyst composition which may be employed to catalyze
the hydrogenation of hydrocarbon feedstocks, and most
particularly to hydrogenate particular components of
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the feedstock, such as sulphur-, nitrogen- and metals-
containing organo-compounds and unsaturates. A hydro-
cracking catalyst may be defined as any catalyst
composition which may be employed to crack large and
complex petroleum derived molecules to attain smaller
molecules with the concomitant addition of hydrogen to
the molecules. A tail gas catalyst may be defined as
any catalyst composition which may be employed to
catalyze the conversion of hazardous effluent gas
streams to less harmful products, and most particularly
to convert oxides of sulphur to hydrogen sulphide which
can be recovered and readily converted to elemental
sulphur. A reduced catalyst may be defined as any
catalyst composition that contains a metal in the
reduced state such as an olefin hydrogenation catalyst.
Such metals are typically reduced with a reducing agent
such as, for example, hydrogen or formic acid. The
metals on these reduced catalysts may be fully reduced
or partially reduced.
Catalyst compositions for hydrogenation catalysts
are well known and several are commercially available.
Typically, the active phase of the catalyst is based on
at least one metal of group VIII, VIB, IVB, IIB or IB
of the periodic table. In general, the hydrogenation
catalysts contain at least one element selected from
Pt, Pd, Ru, Ir, Rh, Os, Fe, Co, Ni, Cu, Mo, W, Ti, Hg,
Ag or Au supported usually on a support such as
alumina, silica, silica-alumina and carbon. Such
reduced catalysts can be classified as spontaneously
combustible substances.
Catalyst compositions for hydrotreating and/or
hydrocracking or tail gas treating are well known and
several are commercially available. Metal oxide
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catalysts which come within this definition include
cobalt-molybdenum, nickel-tungsten, and nickel-
molybdenum supported usually on alumina, silica and
silica-alumina, including zeolite, carriers. Also,
. 5 other transition metal element catalysts may be
employed for these purposes. In general, catalysts
containing at least one element selected from V, Cr, -
Mn, Re, Co, Ni, Cu, Zn, Mo, W, Rh, Ru, Os, Ir, Pd, Pt,
Ag, Au, Cd, Sn, Sb, Bi and Te have been disclosed as
suitable for these purposes.
For maximum effectiveness the metal oxide catalysts
are converted at least in part to metal sulphides. The
metal oxide catalysts can be sulphided in the reactor
by contact at elevated temperatures with hydrogen
sulphide or a sulphur-containing oil or feed stock
("in-situ").
However, it is advantageous to the user to be
supplied with sulphided catalysts, i.e., metal oxide
catalysts wherein the metal oxides have been converted
to metal sulphides, which can be loaded into a reactor
and brought up to reaction conditions without
additional process steps being needed. These catalysts
provide an economic advantage to the plant operator and
avoid many of the hazards such as flammability and
toxicity, which the plant operator encounters when
using hydrogen sulphide, liquid sulphides,
polysulphides and/or mercaptans to sulphide the
catalysts.
Several methods of presulphurizing metal oxide
catalysts, i.e., converting at least part of the metal
oxides to metal sulphides, are known. Hydrotreating
catalysts have been presulphurized by incorporating
sulphur compounds into a porous catalyst prior to
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hydrotreating a hydrocarbon feedstock. For example,
U.S. Patent Specification No. 4,530,917 discloses a
method of presulphurizing a hydrotreating catalyst with
organic polysulphides. U.S. Patent Specification
No. 4,177,136 discloses a method of presulphurizing a
catalyst by treating the catalyst with elemental
sulphur. Hydrogen is then used as a reducing agent to
convert the elemental sulphur to hydrogen sulphide in
situ. U.S. Patent Specification No. 4,089,930 discloses
the pretreatment of a catalyst with elemental sulphur
in the presence of hydrogen. U.S. Patent Specification
No. 4,943,547 discloses a method of presulphurizing a
hydrotreating catalyst by subliming elemental sulphur
into the pores of the catalyst then heating the
sulphur-catalyst mixture to a temperature above the
melting point of sulphur in the presence of hydrogen.
The catalyst is activated with hydrogen. International
(PCT) patent specification No. W093/02793 discloses a
method of presulphurizing a catalyst where elemental
sulphur is incorporated in a porous catalyst and at the
same time or subsequently treating the catalyst with a
liquid olefinic hydrocarbon.
However, these ex-situ presulphurized catalysts
must be transported to the user or plant operator. In
transportation or shipping, these presulphurized
catalysts are classified as spontaneously combustible
substances which are further classified into two sub-
groups of material, pyrophoric substances or self-
heating substances. Both groups have the same basic
properties of self-heating which may lead to
spontaneous combustion, but differ in the degree of
spontaneous combustion. Pyrophoric substances ignite,
even in small quantities, within five minutes of coming
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into contact with air whereas self-heating substances
ignite in air only when in large quantities and after
long periods of time. US Patent Specifications
Nos. 3,563,912 and 4,177,136 amongst others propose
measures to avoid pyrophoricity of sulphided catalysts
on exposure to air.
Further, some of the prior art ex-situ methods of
presulphurizing supported metal oxide catalysts have
suffered from excessive stripping of sulphur upon
start-up of a hydrotreating reactor in the presence of
a hydrocarbon feedstock. As a result of sulphur
stripping, a decrease in catalyst activity or stability
is observed. Further, the stripping of sulphur can
cause fouling of downstream equipment.
It is an object of the present invention to prepare
an air and/or oxygen stable ex-situ presulphided
catalyst, either fresh or regenerated, which contains
only trace amounts of excess sulphur compounds and
which has an activity that is equivalent to a
conventional in-situ sulphided catalyst.
The present invention provides a catalyst
composition containing sulphided metal particles having
an oxide-containing layer on the surface of said
sulphided metal particles wherein said layer is formed
by contacting the sulphided metal particles with an
oxygen-containing composition, preferably a mixture of
oxygen and at least one inert gas, at a temperature in
the range of from -20 °C to 150 °C and wherein said
catalyst composition has reduced self-heating
characteristics. The resulting ex-situ presulphided
catalyst composition has reduced self-heating
characteristics when compared to sulphided catalysts
which have not been coated, and is ready for use in the
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reactor without additional processing and/or activation
steps.
It has now been found that when the sulphided metal
particles of a hydrocarbon conversion catalyst have an
oxygen-containing protective surface layer, the
catalyst has suppressed self-heating characteristics
when compared to a catalyst without the protective
oxygen-containing layer. Thus, the inventive process
allows the ex-situ presulphided catalysts to be stored,
or transported or shipped in any suitable packaging
such as flow-bins, super-sacks, or sling-bins for
example.
For the purpose of definition, the term "sulphided
metal particles" refers to metal oxide particles which
have been converted to the sulphide form. Further, the
term "metal(s)" includes metal oxides) in partially
reduced form. The term "presulphurized catalyst(s)"
refers to catalysts wherein part of the metals are in
the oxide form, and part of the metals may have been
converted to the sulphide form. Presulphurized
catalysts typically contain additional sulphur
compounds which facilitate the sulphiding of the
remaining metal oxides during the startup process. The
term "presulphided catalyst(s)" refers to catalysts
wherein the majority of the metal oxides have been
converted to metal sulphides.
In the present invention, a hydrocarbon conversion
catalyst containing sulphided metal particles is
contacted with an oxygen-containing compound at a
temperature in the range of from -20 °C to 150 °C,
preferably from -20 °C to 50 °C, and more preferably
from 0 °C to 35 °C. Upon contact, the surface of the
sulphided metal particles is coated with the oxygen-
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containing compound. For the purpose of definition, the
surface of the sulphided metal particles include the
external surface of the catalyst as well as the
internal pore surfaces of the catalyst. The word
"coating" or "coated" does not rule out some reaction
leading to passivation of the catalyst surfaces.
When applied to sulphided catalysts, the treatment
with an oxygen-containing compound provides a catalyst
with suppressed self-heating characteristics without
substantially compromising sulphur retention or
activity. The sulphided catalysts can be catalysts
sulphided by an in-situ presulphiding method or an ex-
situ presulphiding or presulphurizing method. The
sulphided catalysts can be fresh or oxy-regenerated.
For example, the oxygen-containing compound can be
coated on any of the sulphur-containing catalysts such
as disclosed in U.S. Patent Specification
Nos. 4,530,917; 4,177,136; 4,089,930; 5,153,163;
5,139,983; 5,169,819; 4,943,547 and in PCT patent
specification No. W093/02793. The oxygen-containing
compound can also be coated on a reduced hydrogenation
catalyst such as disclosed in U.S. Patent Specification
No. 5,032,565.
In the present invention, the sulphided catalyst is
contacted with an oxygen-containing compound at a
temperature and for a time effective to cause the
catalysts to exhibit suppressed self-heating properties
compared to catalysts without treatment with the
oxygen-containing compound. In general, the reaction
conditions should be such that an effective protective
layer is formed, but such that the metal sulphide
particles are not substantially oxidized.
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The mechanism by which the oxygen-containing
compound suppresses self-heating characteristics of the
sulphur-incorporated catalyst when contacted is not
known and will be referenced herein as "reaction" or
"reacts" for lack of better terminology. The suppressed
self-heating result can be readily determined without
undue experimentation by measuring the exothermic onset
temperatures.
Generally, the ex-situ presulphided catalysts of
the present invention have enhanced resistance to
sulphur stripping during activation in a hydrotreating
and/or hydrocracking reactor in the presence of a
hydrocarbon feedstock. The potential for sulphur
stripping is less than that for a presulphurized
catalyst since in the presulphurized catalyst, the bulk
of the sulphur has already reacted with the metal oxide
particles and is bound in the form of metal sulphide
particles. The enhanced resistance to sulphur stripping
can readily be determined using one of several methods.
For example, the sulphur retention of presulphurized
catalysts and presulphided catalysts can be compared by
Soxhlet Extraction of the catalysts followed by sulphur
analysis of the liquid extract.
The underlying teaching of the prior art is that
unless special measures are taken, exposure of
sulphided catalysts to air is to be avoided because of
their pyrophoric nature and the loss of activity
resulting from oxidation. It has now been found that
under controlled conditions a normally pyrophoric
sulphided catalyst can be passivated by exposure to an
oxygen-containing composition such as air, such that a
substantially non-pyrophoric catalyst results without a
significant loss of activity.
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For the present invention suitably a presulphided
catalyst is contacted with an oxygen-containing
composition for a sufficient time such that the oxygen-
containing composition impregnates (or reacts) with the
catalyst and provides an ex-situ presulphided catalyst
that is less spontaneously combustible but not sub-
stantially lower in activity than one not contacted
with an oxygen-containing composition. This time can be
assessed readily by the skilled person in the art by
routine measures.
Typically the contact temperature is in the range
of from -20 °C to 150 °C, preferably from -20 °C to
50 °C, and preferably from 0 °C to 35 °C. Typically the
oxygen-containing compound will be in gaseous form when
contacting the catalyst. The oxygen partial pressure
will typically be in the range of from 0.01 psia
(0.07 kPa) to 100 psia (689 kPa), preferably from
0.1 psia (0.7 kPa) to 50 psia (345 kPa), and more
preferably from 1 psia (7 kPa) to 10 psia (69 kPa). The
contact temperature will vary depending on the
temperature, the oxygen partial pressure and the nature
of the oxygen-containing composition. For example, when
the oxygen-containing composition is air, the process
temperature should preferably be less than 45 °C.
Suitable contact times will depend on temperature
and the oxygen partial pressures, with higher
temperatures requiring shorter times and lower oxygen
partial pressures requiring longer times. The time
required can also depend on the nature of the catalyst.
In general a suitable contact time will be in the range
of from 10 seconds to 24 hours, preferably from
10 seconds to 5 hours, more preferably to 1 hour,
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although longer times, for example up to 200 hours, can
also be used.
When the oxygen-containing composition is in
gaseous form when contacted with the sulphided
catalyst, the gas flowrate over the catalyst is
suitably in the range of from 0.1 to 100 1/hr,
preferably from 0.5 to 70 1/hr, more preferably from ~
to 60 1/hr.
Preferably the oxygen-containing compound is
ZO sufficiently flowable or sublimable to give a
sufficient contact with the metal oxide catalyst. An
oxygen-containing composition which is gaseous at the
contact temperature is more preferred for ease of
handling. Preferably the oxygen-containing composition
is a mixture of oxygen and at least one inert gas, for
example nitrogen, argon, helium, neon or mixtures
thereof. It is preferred that the oxygen-containing
composition is selected from the group consisting of
air, carbon dioxide, aldehydes, ketones, ethers,
alcohols, vitamin E, water and mixtures thereof, with
air being particularly preferred. It should be
understood that if the oxygen-containing composition
utilized is "wet" such as, for example, if water is
used in the liquid or vapour form, or if the resulting
ex-situ presulphided catalyst is exposed to moisture
prior to being loaded in the reactor, the catalyst must
be dried prior to use in the reactor, as it is known
that moisture can be detrimental to catalyst
performance. The catalyst can be dried using any
conventional means, such as for example, by drying in
air or nitrogen.
The minimum amounts of oxygen-containing
composition to be used should be such that upon contact
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with the catalyst, a catalyst is obtained with a
protective oxygen-containing layer. The maximum amounts
of oxygen-containing composition used are determined
primarily by the contact temperature, i.e., when low
contact temperatures are used, more oxygen-containing
composition is required to accomplish the objective of
putting a protective layer on the catalyst than when
high contact temperatures are used. By way of example,
a catalyst which has not been subjected to sufficient
amounts of oxygen-containing composition to coat the
catalyst with a protective layer will not exhibit
reduced self-heating characteristics, as can be
determined using a standard self-heating test, such as
that outlined in the International Maritime Dangerous
Goods (IMDG) Regulations Class 4 Division 5.1. A
catalyst which has been subjected to so much oxygen-
containing composition that the catalyst is
substantially oxidized as opposed to having a
protective layer of oxygen will exhibit extremely poor
activity, i.e., at least fifteen percent less than that
of a conventional sulphided catalyst, when placed in a
reactor.
In preferred operation the ex-situ presulphided
catalyst of the instant invention is loaded into a
hydrotreating and/or hydrocracking reactor or tail gas
reactor and hydrogen flow is started to the reactor and
the reactor is heated up to operating (hydrotreating
and/or hydrocracking or tail gas treating) conditions.
In the hydrotreating and/or hydrocracking process, a
. 30 hydrocarbon feedstock flow can be started simultane-
ously with the hydrogen or later.
The process of the present invention is further
applicable to sulphided spent catalysts which have been
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oxy-regenerated. After a conventional oxy-regeneration
process, an oxy-regenerated catalyst may be pre-
sulphided as would fresh catalyst in any conventional
manner.
The present invention is also intended to encompass -
a method for stabilizing (reducing the self-heating
characteristics) of a sulphided supported metal
catalyst, particularly a Group VIB and/or Group VIII
metal catalyst by contacting the catalyst with an
oxygen-containing composition at a temperature and time
sufficient to impregnate the catalyst with a protective
oxygen-containing layer.
In applying the oxygen-containing composition to
the catalyst, the oxygen-containing composition can be
added in batches and mixed or added continuously, for
example, by proportionally flowing the desired compound
over a fixed bed of catalyst.
The inventive process is particularly suitable for
application to hydrotreating and/or hydrocracking or
tail gas treating catalysts. These catalysts typically
comprise Group VIB and/or Group VIII metals supported
on porous supports such as alumina, silica, silica-
alumina, and zeolite. The materials are well defined
in the art and can be prepared by techniques described
therein, such as in U.S. patent specification
No. 4,530,911, and U.S. patent specification
No. 4,520,128. Preferred hydrotreating and/or hydro-
cracking or tail gas treating catalysts will contain a
group VIB metal selected from molybdenum, tungsten and
mixtures thereof and a Group VIII metal selected from
nickel, cobalt and mixtures thereof supported on
alumina. Versatile hydrotreating and/or hydrocracking
catalysts which show good activity under various
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reactor conditions are alumina-supported nickel-
molybdenum and cobalt-molybdenum catalysts. Phosphorous
is sometimes added as a promoter. A versatile tail gas
treating catalyst which shows good activity under
various reactor conditions is an alumina-supported
cobalt-molybdenum catalyst.
With respect to hydrotreating catalysts which are
specifically designated for hydrodenitrification
operations, such as alumina-supported nickel-molybdenum
catalysts, the presulphided catalysts of the present
invention which have a protective oxygen-containing
layer have activities approximately equal to the
activities of presulphurized or conventionally
sulphided catalysts which do not have a protective
oxygen-containing layer. The ability to avoid
instantaneous combusting provides the present
presulphided catalysts with a significant commercial
advantage. The ex-situ method of this invention allows
the hydrotreating, hydrocracking and/or tail gas
treating reactors to be started up more quickly and
consistently compared with conventionally sulphided
catalysts by eliminating the in-situ presulphiding
step.
Thus, the present invention relates to an improved
process for starting up a hydrotreating and/or hydro-
cracking reactor, which comprises loading the ex-situ
presulphided catalyst of the present invention into the
reactor and heating the reactor to operating conditions
in the presence of hydrogen and optionally a hydro-
carbon feedstock. The invention is also an improved
hydrotreating and/or hydrocracking process which
w comprises contacting at hydrotreating and/or hydro-
cracking conditions a hydrocarbon feedstock and
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hydrogen with the ex-situ presulphided catalyst of the
present invention which has been heated to hydro-
treating and/or hydrocracking temperature in the
presence of hydrogen and optionally a hydrocarbon
feedstock.
Thus, the present invention further provides a
process for converting a hydrocarbonaceous feedstock
which comprises contacting the feedstock with hydrogen
at elevated temperature in the presence of a catalyst
composition according to the invention.
Hydrotreating conditions comprise temperatures in
the range of from 100 °C to 425 °C, and pressures above
40 atmospheres (4052 kPa). The total pressure will
typically be in the range of from 400 to 2500 psig
(2758 to 17237 kPa). The hydrogen partial pressure will
typically be in the range of from 200 to 2200 psig
(1379 to 15169 kPa). The hydrogen feed rate will
typically be in the range of from about 200 to about
10000 standard cubic feet per barrel ("SCF/BBL"). The
feedstock rate will typically have a liquid hourly
space velocity ("LHSV") in the range of from O.I to 15.
Hydrocracking conditions comprise temperatures in
the range of from 300 °C to 500 °C, pressures above
90 atmospheres (4052 kPa). The total pressure will
typically be in the range of from 400 to 3000 psig
(2758 to 20684 kPa). The hydrogen partial pressure will
typically be in the range of from 300 to 2600 psig
(2068 to 17926 kPa). The hydrogen feed rate will
typically be in the range of from 1000 to 10,000
standard cubic feet per barrel ("SCF/BBL"). The
feedstock rate will typically have a liquid hourly
space velocity ("LHSV") in the range of from 0.1 to 15.
First stage hydrocrackers, which carry out considerable
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hydrotreating of the feedstock may operate at higher
temperatures than hydrotreaters and at lower
temperatures than second stage hydrocrackers.
The hydrocarbonaceous feedstocks to be hydrotreated
or hydrocracked 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 oil, 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 hydrocarbon oils may also be employed.
Tail gas treatment reactors typically operate at
temperatures in the range of from 200 °C to 900 °C and
at atmospheric pressure (101 kPa). About 0.5-5o vol. of
the tail gas fed to the reactor will comprise hydrogen.
Standard gaseous hourly space velocities of the tail
gas through the reactor will be in the range of from
500 to 10,000 hr-1. There are several ways the subject
catalysts can be started up in a tail gas treatment
reactor. Claus unit feed or tail gas can be used to
start up the subject catalysts. Supplemental hydrogen,
as required, may be provided by a gas burner operating
at a substoichiometric ratio in order to produce
hydrogen.
The invention will be described by the following
Examples.
Examples
The catalysts used in the following Examples and
Comparative Example were subjected to the following
sulphiding procedure.
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A 24.5 gram sample of the catalyst was loaded into
a testing unit having a set pressure of sulphiding gas
(5% H2S/95% H2) of 1 psig (7 kPa). A sulphiding gas
flow rate of 1 litre/minute was then started over the
catalyst, which was heated to 204 °C and held for
2 hours, then heated to 316 °C for 1 hour and finally
heated to 371 °C for 2 hours, after which it was cooled
to 25 °C in the sulphiding gas flow.
In order to establish the activity of a con-
ventionally sulphided catalyst, the above sulphided
catalyst was immediately tested according to the test
procedure outlined below. The test results were used
for comparison with the catalysts prepared in the
examples below.
Example 1 (Dry Air)
C-424 Ni/M/P, 1/16" (1.6 mm) trilobe, sulphided
hydrotreating catalyst, available from Criterion
Catalyst Company L.P., was coated with an oxygen-
containing compound according to the procedure set
forth below.
A 24.5 gram sample of the above sulphided catalyst
was placed in a reactor tube 5/8" (15.9 mm) inside
diameter. The catalyst was then exposed to dry air (dew
point approximately -68 °C ) for 1 hour at 25 °C and an
air flow rate of 60 normal litres/hour. During this
process, the temperature of the catalyst bed was
monitored using a mufti-point thermocouple. Upon
exposure to air, an exotherm was observed, with the top
portions of the bed reaching approximately 40 °C. After
about 15 minutes of air flow, the catalyst returned to
its starting temperature. The air flow was continued
for another 45 minutes after which the catalyst testing
procedure set forth below was carried out. The results
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of the catalyst testing are presented in Table 1 below.
As can be seen in Table I below, the catalyst had
equivalent activity to a conventionally sulphided
catalyst. The catalyst is thus distinguished from
oxidized sulphided catalysts which are known to lose
considerable activity on oxidation.
Example 2 (Nitrogen + Dry Air for 4 Hours)
C-424 Ni/M/P, 1/16" (1.6 mm) trilobe, sulphided
hydrotreating catalyst, available from Criterion
Catalyst Company L.P., was coated with an oxygen-
containing compound according to the procedure set
forth below.
A 24.5 gram sample of the C-424 catalyst was placed
in a reactor tube and then sulphided as in the above
procedure. Instead of cooling the catalyst in
sulphiding gas, it was purged with nitrogen during the
cooling, at a rate of approximately 60 normal
litres/hour nitrogen flow. After the sample cooled to
approximately 25 °C, the sample was exposed to a 1:1
mixture of dry air and nitrogen at a total flow rate of
1 litre per hour for four hours. Thereafter, the
nitrogen flow was stopped and the air flow was
increased to 1 litre per hour. The air flow was
continued for seventeen hours. The catalyst was then
evaluated using the catalyst testing procedure set
forth below. The results of the catalyst testing are
presented in Table 1 below. As can be seen in Table I
below, the nitrogen purge and air exposure did not
affect the activity of the catalyst compared with a
conventionally sulphided catalyst.
Example 3 (Dry Air for 1 Week)
- C-424 Ni/M/P, 1/16" (1.6 mm) trilobe, sulphided
hydrotreating catalyst, available from Criterion
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Catalyst Company L.P., was coated with an oxygen-
containing compound according to the procedure set
forth below.
A 24.5 gram sample sulphided as above and air
exposed as in Example 1 was purged with dry air for an
additional 170 hours. The sample was then tested
according the catalyst testing procedure outlined
below. The results of the catalyst testing are
presented in Table 1 below. As can be seen in Table I
below, the catalyst again has an activity equivalent to
that of a conventionally sulphided catalyst. This
example demonstrates that the catalyst activity can be
preserved even after extended air exposure.
Comparative Example (Base Case - No Coating)
A sulphided hydrotreating catalyst as described in
Example 1 above was subjected to the essentially the
same presulphiding procedure set forth above, but the
catalyst was not impregnated with an oxygen-containing
compound. The catalyst was then subjected to the
catalyst testing procedure set forth below. The results
of the activity testing are presented in Table 1 below.
Example 4 (Wet Air + Nitrogen Drying for 4 Hours)
C-424 Ni/M/P, 1/16" (1.6 mm) trilobe, sulphided
hydrotreating catalyst, available from Criterion
Catalyst Company L.P., was coated with an oxygen-
containing compound according to the procedure set
forth below.
A sample of the above sulphided catalyst was
passivated for 1 hour in dry air as in Example 1. The
sample was then exposed to water-saturated air at 25 °C
for one hour. After the air exposure, a nitrogen flow
of 60 normal litres per hour was started over the
catalyst bed, which was heated to 200 °C and held at
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that temperature for four hours. Following the drying
procedure, the catalyst was cooled to 25 °C, and the
. activity was evaluated using the procedure set forth
below. The results of the activity testing are
. 5 presented in Table 1 below.
Catalyst Testing Procedure
The reactor containing the catalyst (approximately
30 cc) is first pressurized to 1100 psig (7584 kPa)
with pure hydrogen after which a hydrogen flow of
95 litres/hour is established. The catalyst is then
heated to 204 °C at which point the hydrocarbon feed
flow of approximately 60 cc/hour is started. The test
feed used for the examples has the characteristics
listed in Table 2. After feed introduction, the
temperature of the reactor is raised to 332 °C. The
total duration of the test, defined as the period from
the time the reactor reaches 332 °C until the end of
the final measurement period, is held constant at
approximately 65 hours. During the last 16 hours of the
test, the reactor product is collected and analyzed for
sulphur and nitrogen content, and the hydrogen content
is determined. Rate constants are calculated assuming
first order HDN and hydrogenation, and 1.5 order HDS.
CA 02279968 1999-08-OS
WO 98/34728 PCT/EP98I00722
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Table 1
RELATIVE
ACTIVITY
HDS HDN HYDRO
Example 1 1.01 1.01 0.99
Example 2 0.97 1.01 1.00
Example 3 1.00 0.88 1.02
Comparative Example 1.00 1.00 1.00
Example 9 0.97 0.96 1.02
Table 2
Feed Analysis
Sulphur 2.32 wto
Nitrogen 826 ppm
Hydrogen 9.28 wt%
Carbon 87,77 wts
Oxygen .306 wt~
Simulated Distillation,
ASTM D2887:
IBP = 330
F
Wts Overhead Temp (F)
10 525
20 567
30 587
40 600
50 612
60 628
70 650
80 671
90 701
FBP 952
