1
Claims
1.
A process for the preparation of a catalyst for a Fischer-Tropsch
synthesis reaction, which comprises the following steps:
5
taking an initial porous support material selected from alumina, titania,
zirconia, zeolites, carbonaceous material and mixtures thereof, having an
alkaline earth metal content of less than 1000 ppm;
impregnating the initial support material with a source of cobalt which
contributes an additional alkaline earth metal content of less than 1000 ppm in
10
the final catalyst; and
heat treating the impregnated support material at a temperature of at
least 200˚C to yield a cobalt oxide catalyst;
whereby the final catalyst has an alkaline earth metal content of
less then 2000 ppm.
15
2.
A process as claimed in Claim 1, in which the heat treating step is a
calcination step at a temperature in the range 200 to 600˚C.
3.
20
A process as claimed in Claim 1 or Claim 2, in which, prior to the heat
treating step, the impregnated support material is subjected to a drying step at a
temperature of at least 100˚C.
4.
A process as claimed in any preceding Claim, in which the heat treating
is conducted in a plurality of steps.
25
5.
A process as claimed in any preceding claim, in which the support
material is carbon in a variety of forms including carbon nanofibers and tubes,
and mixtures and reaction products thereof, in any amorphous or
crystallographic form, and optionally modified or mixed with other support
30
material(s) optionally also comprising binders.
2
6.
A process as claimed in any of Claims 1 to 4, in which the support
material is γ-alumina, any transition alumina, α-alumina, boehmite, aluminium
hydroxide or mixtures thereof.
5
7.
A process as claimed in any of Claims 1 to 4 or Claim 6, in which the
support material is alumina and is prepared by the precipitation method or the
alkoxide route.
8.
10
A process as claimed in Claim 6 or Claim 7, in which the support
material is γ-alumina, and is prepared by heating to a temperature in the range
400 to 800˚C.
9.
A process as claimed in any preceding claims, in which the initial
support material has an alkaline earth metal content of less than 500 ppm.
15
10.
A process as claimed in any of Claims 1 to 8, in which the initial support
material has an alkaline earth metal content of between 5 and 1000 ppm,
preferably between 10 and 500 ppm, more preferably between 10 and 200 ppm.
20
11.
A process as claimed in any preceding Claim, in which the alkaline earth
metal is calcium or magnesium.
12.
A process as claimed in any preceding claim, in which a stabiliser is
incorporated into the initial support material.
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13.
A process as claimed in Claim 12, in which the stabiliser is lanthanum.
14.
A process as claimed in any preceding claim, in which the impregnation
step comprises an incipient wetness treatment.
30
3
15.
A process as claimed in Claim 14, in which, in the incipient wetness
treatment, an aqueous solution of a cobalt metal compound is mixed with the
support material until the pores are filled and the impregnated support material
is then dried, prior to calcination.
5
16.
A process as claimed in Claim 15, in which the amount of aqueous
solution used in the impregnation is 0.05-2 times larger than the measured pore
volume of the catalyst support.
10
17.
A process as claimed in any preceding claim, in which the source of
cobalt is selected from cobalt nitrate (Co(NO3)2), cobalt carbonate(s), cobalt
(hexa) amine salt(s) and organic cobalt compounds.
18.
15
A process as claimed in any of Claims 15 to 17, in which the water used
is distilled or de-ionised water.
19.
A process as claimed in any preceding claim, which includes
impregnating or co-impregnating the initial alumina support material with a
promoter.
20
20.
A process as claimed in Claim 19, in which the promoter comprises
platinum or rhenium.
21.
25
A process as claimed in Claim 20, in which the promoter in the oxide
catalyst is platinum and represents between 0.001 and 0.5 wt%, preferably
between 0.01 and 0.1 wt%.
22.
A process as claimed in Claim 20, in which the promoter in the oxide
catalyst is rhenium and represents between 0.01 and 5 wt%, preferably between
30
0.1 and 1.0 wt%.
4
23.
A process as claimed in Claim 20, in which, where the promoter is
rhenium and the source of rhenium is selected from perrhenic acid (HReO4),
ammonium perrhenate, rhenium halide and rhenium carbonyl(s).
5
24.
A process as claimed in any of Claims 14 to 18, in which the
impregnated support material is dried at a temperature in the range of 80 to
120˚C.
25.
10
A process as claimed in any of Claims 19 to 24, in which the steps of
impregnating cobalt and the promoter yield an alkaline earth metal content of
less than 1000 ppm in the cobalt oxide catalyst.
26.
A process as claimed in any of Claims 19 to 25, in which the steps of
impregnating cobalt and the promoter yield an alkaline earth metal content of
15
between 5 and 1000 ppm, preferably between 10 and 500 ppm, more preferably
between 10 and 200 ppm, in the cobalt oxide catalyst.
27.
A process as claimed in any preceding claim, in which after the
calcination step, the alumina-supported catalyst material is activated.
20
28.
A process as claimed in Claim 27, in which the activation step comprises
reduction of a substantial portion of the catalytically active metal compound
present to the metal, and is carried out by treating the catalyst material with a
reducing gas, such as hydrogen and/or carbon monoxide, optionally mixed with
25
an inert gas.
29.
A process as claimed in Claim 28, in which the reduction is carried out
at an activation temperature of 250 to 500˚C, preferably in the range of 300 to
450˚C.
30
5
30.
A process as claimed in any preceding claim, in which prior to
impregnating the support with a source of cobalt, the support material is
modified by treatment with a divalent metal which is capable of forming a
spinel, in order to form a spinel with the support material.
5
31.
A process as claimed in any preceding claim, in which the porous
support material is modified by treatment with a divalent metal and prior to the
cobalt impregnation step, the modified support material has a specific surface
area below 80 m2/g, preferably in the range 30 to 70m2/g.
10
32.
A process as claimed in any preceding claim, in which the porous
support material is modified by treatment with a divalent metal and prior to the
cobalt impregnation step, the modified support material has a pore volume
below 0.5 ml/g.
15
33.
A process as claimed in any of Claims 30 to 32, in which the divalent
metal is nickel or zinc or mixtures thereof.
34.
20
A process as claimed in Claim 33, in which the source of nickel is nickel
nitrate, and/or the source of zinc is zinc nitrate.
35.
A process as claimed in Claims 30 to 34, in which the divalent metal is
deployed in one or more impregnation steps using a solvent, yielding from the
impregnation step an alkaline earth metal content of less than 500ppm in the
25
cobalt oxide catalyst.
36.
A process as claimed in Claim 35, in which the divalent metal is
deployed in one or more impregnation steps using a solvent, yielding from the
impregnation step an alkaline earth metal content between 5 and 500 ppm,
30
preferably between 5 and 300 ppm, more preferably between 5 and 100 ppm, in
the cobalt oxide catalyst.
6
37.
A process as claimed in Claim 35 or Claim 36, in which the solvent is
distilled or de-ionised water.
5
38.
A process as claimed in any of Claims 35 to 37, in which the
impregnation step comprises an incipient wetness treatment.
39.
A process as claimed in any of Claims 35 to 37, in which the
impregnation step comprises a precipitation/deposition step.
10
40.
A process as claimed in any of Claims 30 to 40, in which the divalent
metal is incorporated into the material of the support to form a spinel and
thereby a modified support material.
15
41.
A process as claimed in Claim 40, in which the support material is
dispersed as a precursor suspension in a liquid vehicle, a source of a divalent
metal capable of forming a spinel compound with the support precursor is
added to the liquid, and the support material precursor is then formed into
porous solid particles incorporating the divalent metal source, to produce a
20
modified support material.
42.
A process as claimed in Claim 41, in which the solid particles are
produced by spray drying.
25
43.
A process as claimed in any of Claims 30 to 42, in which the support
material incorporating the divalent metal is washed, dried and calcined at up to
600˚C in order to decompose the source of the divalent metal compound to
produce essentially the divalent metal oxide.
7
44.
A process as claimed in Claim 43, in which the modified support
material is subjected to a high temperature calcination at a temperature in the
range 600 to 900˚C to form a spinel compound.
5
45.
A process as claimed in Claim 43 or Claim 44, in which the modified
support material is subjected to a high temperature calcination at a temperature
in the range 900 to 1400˚C, preferably 950 to 1100˚C, in order to strengthen the
material.
10
46.
A process as claimed in any of Claims 38 to 45, in which the process of
forming a modified support material yields an alkaline earth metal content of
less than 1000 ppm in the cobalt oxide catalyst
47.
15
A process as claimed in Claim 46, in which the process of forming a
modified support material yields an alkaline earth metal content of between 10
and 1000 ppm, preferably between 20 and 500 ppm, in the cobalt oxide
catalyst.
48.
20
A catalyst for a Fischer-Tropsch synthesis reaction made in accordance
with a method as claimed in any preceding claim, and comprising a porous
support material, an active cobalt content of 5 to 60 wt% expressed in terms of
weight of the catalyst as a whole, assuming complete reduction of the cobalt to
cobalt metal, and an alkaline earth metal content of less than 1000 ppm.
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49.
A catalyst as claimed in Claim 48, in which the support material is γ-
alumina, which may be modified by the inclusion of an alumina spinel, such as
a nickel alumina spinel.
50.
30
A catalyst as claimed in Claim 48 or 49, further comprising lanthanum
as a stabiliser, and in which the lanthanum content may be up to 3 wt% based
on the weight of the catalyst.
8
51.
A catalyst as claimed in any of Claims 48 to 50, in which the cobalt
content is 10 to 30 wt%.
5
52.
A catalyst as claimed in any of Claims 48 to 51, further comprising
rhenium as a promoter, and in which the promoter content may be 0.01 to 5
wt% based on the weight of the catalyst.
53.
10
A catalyst as claimed in any of Claims 48 to 52, having a pore volume of
at least 0.2ml/g, and/or a specific surface area of at least 20 m2/g.
54.
A process for the production of hydrocarbons which comprises
subjecting H2 and CO gases to a Fischer-Tropsch synthesis reaction in a reactor
in the presence of a supported Co-based catalyst, in which make-up synthesis
15
gas comprising H2 and CO is introduced to the synthesis reaction and the makeup synthesis gas contains less than 100 ppb of an alkaline earth metal or alkali
metal.
55.
20
A process as claimed in Claim 54, in which the make-up synthesis gas
contains between 0.1 and 100 ppb, preferably between 0.5 and 50, more
preferably between 0.5 and 20 ppb, of an alkaline earth metal or alkali metal.
56.
A process as claimed in Claim 54 or Claim 55, in which the alkaline
earth metal is calcium, and/or the alkali metal is sodium.
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57.
A process as claimed in any of Claims 54 to 56, in which the make-up
synthesis gas is passed through a guard bed of materials arranged to absorb
components of alkali and alkaline earth metals from the synthesis gas stream,
before the synthesis gas is subjected to a Fischer-Tropsch synthesis reaction.
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9
58.
A process as claimed in Claim 57, in which the guard bed is comprised
of metal oxides.
59.
5
A process as claimed in Claim 58, in which the metal oxide is selected
from alumina, silica, silica-alumina or zeolites.
60.
A process as claimed in Claim 58, in which the metal oxide is selected
from magnesium or zinc oxide.
10
61.
A process as claimed in Claim 57, in which the guard bed material is
selected from activated carbon or carbon nano fibres or tubes.
62.
A process as claimed in Claim 58, in which the guard bed material is
formed from spent or deactivated catalysts supported on metal oxide materials.
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63.
A process as claimed in Claim 62, in which the metal oxide materials are
alumina-containing supports.
64.
20
A process as claimed in any one of Claims 57 to 63, in which the guard
bed materials have a high specific surface area.
65.
A process as claimed in Claim 64, in which the specific surface area is
above 75m2/g, preferably above 150m2/g.
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66.
A process as claimed in any one of Claims 57 to 65, in which the guard
bed materials have a porosity above 0.15 cm3/g, preferably above 0.3 cm3/g.
67.
A process as claimed in any of Claims 54 to 66, in which the reaction is
a three-phase reaction in which the reactants are gaseous, the product is at least
30
partially liquid and the catalyst is solid, and in which the reaction is carried out
in a slurry bubble column reactor.
10
68.
A process as claimed in Claim 67, in which the H2 and CO are supplied
to a slurry in the reactor, the slurry comprising the catalyst in suspension in a
liquid including the reaction products of the H2 and CO, the catalyst being
5
maintained in suspension in the slurry at least partly by the motion of the gas
supplied to the slurry.
69.
A process as claimed in Claim 68, in which the reaction temperature is
in the range 190 - 250˚C preferably, in the range 200 - 230˚C, and the reaction
10
pressure is in the range 10 - 60 bar, preferably, the range 15 - 30 bar.
70.
A process as claimed in any of Claims 54 to 69, in which the H2/CO
ratio of the gases supplied to the Fischer-Tropsch synthesis reactor is in the
range 1.1 to 2.2, preferably, in the range 1.5 to 1.95.
15
71.
A process as claimed in any of Claims 54 to 70, in which the superficial
gas velocity in the reactor is in the range 5 to 60 cm/s, preferably, in the range
20 to 40 cm/s.
20
72.
A process as claimed in any of Claims 54 to 71, in which the product of
the Fischer-Tropsch synthesis reaction is subsequently subjected to postprocessing, which may comprise de-waxing and/or hydro-isomerisation and/or
hydro-cracking.
25
73.
A process as claimed in any one of Claims 54 to 72, in which the
catalyst comprises a porous support material, an active cobalt content of 5 to 60
wt% expressed in terms of weight of the catalyst as a whole, assuming
complete reduction of the cobalt to cobalt metal, and an alkaline earth metal
content of less than 1000 ppm.
30
11
74.
A process as claimed in Claim 73, in which the support material is γ-
alumina, which may be modified by the inclusion of an alumina spinel, such as
a nickel alumina spinel.
5
75.
A process as claimed in Claim 73 or Claim 74, in which the catalyst
further comprises lanthanum as a stabiliser, and in which the lanthanum content
may be up to 3 wt% based on the weight of the catalyst.
76.
10
A process as claimed in any of Claims 73 to 75, in which the cobalt
content in the catalyst is 10 to 30 wt%.
77.
A process as claimed in any of Claims 73 to 76, in which the catalyst
further comprises rhenium as a promoter, and in which the promoter content
may be 0.01 to 5 wt% based on the weight of the catalyst.
15
78.
A process as claimed in any of Claims 73 to 77, in which the catalyst has
a pore volume of at least 0.2ml/g, and/or a specific surface area of at least 20
m2/g.
20
79.
A process for the production of hydrocarbons which comprises
subjecting H2 and CO gases to a Fischer-Tropsch synthesis reaction in a reactor
in the presence of a catalyst made by a process according to any of Claims 1 to
47.
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80.
A process as claimed in Claim 79, in which make-up synthesis gas
comprising H2 and CO is introduced to the synthesis reaction and the make-up
synthesis gas contains less than 100 ppb of an alkaline earth metal or alkali
metal.
30
81.
A process as claimed in Claim 79 or Claim 80, in which the make-up
synthesis gas contains between 0.1 and 100 ppb, preferably between 0.5 and 50,
12
more preferably between 0.5 and 20 ppb, of an alkaline earth metal or alkali
metal.
82.
5
A process as claimed in Claim 80 or Claim 81, in which the alkaline
earth metal is calcium, and/or the alkali metal is sodium.
83.
A process as claimed in any of Claims 80 to 82, in which the make-up
synthesis gas is passed through a guard bed of materials arranged to absorb
components of alkali and alkaline earth metals from the synthesis gas stream,
10
before the synthesis gas is subjected to a Fischer-Tropsch synthesis reaction.
84.
A process as claimed in any of Claim 79 to 83, in which the reaction is a
three-phase reaction in which the reactants are gaseous, the product is at least
partially liquid and the catalyst is solid, and in which the reaction is carried out
15
in a slurry bubble column reactor.
85.
A process as claimed in Claim 84, in which the H2 and CO are supplied
to a slurry in the reactor, the slurry comprising the catalyst in suspension in a
liquid including the reaction products of the H2 and CO, the catalyst being
20
maintained in suspension in the slurry at least partly by the motion of the gas
supplied to the slurry.
86.
A process as claimed in Claim 85, in which the reaction temperature is
in the range 190 - 250˚C preferably, in the range 200 - 230˚C, and the reaction
25
pressure is in the range 10 - 60 bar, preferably, the range 15 - 30 bar.
87.
A process as claimed in any of Claims 79 to 86, in which the H2/CO
ration of the gases supplied to the Fischer-Tropsch synthesis reactor is in the
range 1.1 to 2.2, preferably, in the range 1.5 to 1.95.
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13
88.
A process as claimed in any of Claims 79 to 87, in which the superficial
gas velocity in the reactor is in the range 5 to 60 cm/s, preferably, in the range
20 to 40 cm/s.
5
89.
A process as claimed in any of Claims 79 to 88, in which the product of
the Fischer-Tropsch synthesis reaction is subsequently subjected to postprocessing, which may comprise de-waxing and/or hydro-isomerisation and/or
hydro-cracking.
10
90.
A process as claimed in any one of Claims 54 to 89, in which the content
of alkaline earth metal or alkali metal in the synthesis gas is controlled by using
feed containing low concentrations of alkaline earth metals and/or alkali metals.
91.
15
A process as claimed in Claim 90, in which water or steam are
introduced or reintroduced as reactants in the production of the synthesis gas,
wherein such reactants are cleaned using one or more process selected from
distillation, filtration, water softening, reverse osmosis, ultra-filtration,
molecular stripping, de-ionisation, and carbon treatment.
20
92.
A process as claimed in any one of Claims 54 to 91, in which the lining
of reactors, tubing and equipment exposed to process streams in the production,
transport and Fischer-Tropsch conversion of the synthesis gas is made of
materials resistant to giving off alkaline earth metals or alkali metals.
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93.
A process as claimed in Claim 92, in which the lining is a refractory or
ceramic lining.
94.
A process as claimed in any one of Claims 54 to 93, in which surfaces
of reactors, catalysts, tubing or other equipment exposed to process streams
30
involved in production and transport of synthesis gas and its conversion to
hydrocarbons in a hydrocarbon-producing plant are cleaned by removing alkali
14
or alkaline earth metal substances from such surfaces before start-up of
hydrocarbon production.
95.
5
A process as claimed in any one of Claims 54 to 94, in which steam or
water is used for cleaning of said surfaces.