Fischer-tropsch catalysts

Abstract

A method of producing an alumina-supported catalyst for use in a Fischer-Tropsch synthesis reaction, which comprises: calcining an initial γ-alumina support material at a temperature of at least 550° C. to produce a modified alumina support material; impregnating the modified alumina support material with a source cobalt; calcining the impregnated support material at a temperature of 700° C. to 1200° C., and activating the catalyst.

1 . A method of producing an alumina-supported catalyst, which comprises the following steps: 
 a first impregnation step in which an initial alumina support material is impregnated with a source of a 2-valent metal capable of forming a spinel compound with alumina;    a first calcination step in which the impregnated alumina support material is calcined at a temperature of at least 550° C. to produce a modified alumina support material;    a second impregnation step in which the modified alumina support material is impregnated with a source of catalytically active metal; and    a second calcination step in which the impregnated modified support material is calcined at a temperature of at least 150° C.    
   
   
       2 . A method as claimed in  claim 1 , in which the initial alumina support material at least predominantly comprises γ-alumina.  
   
   
       3 . A method as claimed in  claim 1 , in which the impregnated modified support material is calcined at a temperature of up to 600° C.  
   
   
       4 . A method as claimed in  claim 1 , in which the impregnated and calcined modified support has a pore volume measured by nitrogen BET in which at least half the pore volume is constituted by pores larger than 30 nm in diameter.  
   
   
       5 . A method as claimed in  claim 1 , in which the initial alumina support material has a specific surface area in the range 100 to 300 m 2 /g.  
   
   
       6 . A method as claimed in  claim 1 , in which the initial alumina support material comprises essentially spherical particles having a particle size range whereby at least 80 volume % fall in the range 25 to 150 μm.  
   
   
       7 . A method as claimed in  claim 1 , in which the initial alumina support material has a pore volume greater than 0.2 cm 3 /g, preferably greater than 0.4 cm 3 /g.  
   
   
       8 . A method as claimed in  claim 1 , in which the first calcination step is carried out at a temperature in the range 800 to 1200° C.  
   
   
       9 . A method as claimed in  claim 1 , in which the first calcination step is carried out at a temperature in the range 900 to 1200° C.  
   
   
       10 . A method as claimed in  claim 1 , in which the modified alumina support has a surface area of less than 40 m 2 /g.  
   
   
       11 . A method as claimed in  claim 1 , in which the modified alumina support has an ASTM attrition value of less than 20% by weight of fines produced by 5 hours testing.  
   
   
       12 . A method as claimed in  claim 1 , in which the modified alumina support has an ASTM attrition value of less than 8% by weight of fines produced by 5 hours testing.  
   
   
       13 . A method as claimed in  claim 1 , in which the modified alumina support comprises at least 10% by weight of alfa-alumina.  
   
   
       14 . A method as claimed in  claim 1 , in which the source of a 2-valent metal comprises a source of cobalt, zinc, magnesium, manganese, nickel or iron.  
   
   
       15 . A method as claimed in  claim 1 , in which the source of a 2-valent metal does not comprise a source of cobalt.  
   
   
       16 . A method as claimed in  claim 1 , in which the source of a 2-valent metal comprises nickel.  
   
   
       17 . A method as claimed in  claim 1  in which the source of a 2-valent metal comprises nickel in an amount of less than 20 wt % of the final reduced catalyst.  
   
   
       18 . A method as claimed in  claim 1 , in which the source of a 2-valent metal comprises nickel in an amount of less than 8 wt % of the final reduced catalyst.  
   
   
       19 . A method as claimed in  claim 1 , which includes additionally impregnating or co-impregnating the alumina support material with a promoter.  
   
   
       20 . A method as claimed in  claim 19 , in which the promoter comprises platinum or rhenium.  
   
   
       21 . A method as claimed in  claim 20 , in which the promoter is rhenium and the source of rhenium is selected from perrhenic acid (HReO 4 ), ammonium perrhenate, rhenium halide(s) and rhenium carbonyl(s).  
   
   
       22 . A method as claimed in  claim 1 , which includes additionally incorporating a stabiliser into the alumina support material with a stabiliser.  
   
   
       23 . A method as claimed in  claim 22 , in which the stabiliser comprises lanthanum.  
   
   
       24 . A method as claimed in  claim 1 , in which the first impregnation step comprises an incipient wetness treatment in which an aqueous solution of the 2-valent metal compound is mixed with the dry support material until the pores are filled, and the impregnated support is then dried, prior to the first calcining step.  
   
   
       25 . A method as claimed in  claim 1 , in which the source of catalytically active metal comprises a source of cobalt.  
   
   
       26 . A method as claimed in  claim 25 , in which the source of cobalt is selected from cobalt nitrate (Co(NO 3 ) 2 ), cobalt acetate(s), cobalt halide(s), cobalt carbonyl(s), cobalt oxalate(s), cobalt phosphate(s), cobalt carbonate(s), cobalt (hexa)amine salt(s) and organic cobalt compounds.  
   
   
       27 . A method as claimed in  claim 1 , in which the second impregnation step comprises an incipient wetness treatment in which an aqueous solution of a cobalt compound and optionally a rhenium compound is mixed with the modified support material until the pores are filled and the impregnated modified support material is then dried, prior to the second calcination step.  
   
   
       28 . A method as claimed in  claim 27 , 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.  
   
   
       29 . A method as claimed in  claim 27 , in which drying is carried out at 80 to 120° C.  
   
   
       30 . A method as claimed in  claim 1 , in which, after the second calcination step, the alumina-supported catalyst material is activated.  
   
   
       31 . A method as claimed in  claim 30 , in which the activation step comprises reduction of a substantial portion of the catalytically active metal compound present to the metal.  
   
   
       32 . A method as claimed in  claim 31 , in which the reduction is carried out by treating the catalyst material with a reducing gas.  
   
   
       33 . A method as claimed in  claim 32 , in which the reducing agent is hydrogen and/or carbon monoxide, optionally mixed with an inert gas.  
   
   
       34 . A method as claimed in any of claims  31 , in which the reduction is carried out at an activation temperature of 250 to 500° C.  
   
   
       35 . A method as claimed in  claim 34 , in which the activation temperature is in the range 300 to 450° C.  
   
   
       36 . A method as claimed in  claim 1 , in which, prior to impregnation, the alumina support has an ASTM attrition value of less than 30% by weight of fines produced by 5 hours testing.  
   
   
       37 . A method as claimed in  claim 36  in which the ASTM value is less than 20%.  
   
   
       38 . An alumina-supported catalyst produced by a method which comprises the following steps: 
 a first impregnation step in which an initial alumina support material is impregnated with a source of a 2-valent metal capable of forming a spinel compound with alumina;    a first calcination step in which the impregnated alumina support material is calcined at a temperature of at least 550° C. to produce a modified alumina support material;    a second impregnation step in which the modified alumina support material is impregnated with a source of catalytically active metal;    and a second calcination step in which the impregnated modified support material is calcined at a temperature of at least 150° C.    
   
   
       39 . A catalyst as claimed in  claim 38 , in which the catalytically active metal and optionally the 2-valent metal are cobalt, and the cobalt content of the catalyst is from 10 to 40% by weight.  
   
   
       40 . A catalyst as claimed in  claim 39 , in which the cobalt content is from 15 to 25% by weight.  
   
   
       41 . A catalyst as claimed in  claim 38 , incorporating less than 3% by weight of a promoter.  
   
   
       42 . A catalyst as claimed in  claim 41 , in which the promoter is rhenium or platinum.  
   
   
       43 . A catalyst as claimed in  claim 38 , in which the initial support material predominantly comprises γ-alumina.  
   
   
       44 . A catalyst as claimed in  claim 43 , in which the γ-alumina is stabilised with a stabilising agent, optionally lanthanum.  
   
   
       45 . A catalyst as claimed in  claim 38 , in which the alumina support material includes a binder.  
   
   
       46 . A catalyst as claimed in  claim 45 , in which the binder represents less than 25% by weight of the catalyst.  
   
   
       47 . A catalyst as claimed in  claim 45 , in which the binder is an alumina-containing binder material.  
   
   
       48 . A catalyst as claimed in  claim 38 , in which the specific surface area of the prepared catalyst, comprising the cobalt on the modified support, is up to 150 m 2 /g.  
   
   
       49 . A catalyst as claimed in  claim 38 , in which the pore volume of the prepared catalyst is from 0.05 to 0.7 cm 3 /g.  
   
   
       50 . A catalyst as claimed in a  claim 38 , in which the pore diameter of the prepared catalyst is at least 10 nm, preferably at least 18 nm.  
   
   
       51 . The use of a catalyst as claimed in  claim 48  in a Fischer-Tropsch synthesis reaction.  
   
   
       52 . A use as claimed in  claim 51 , in which the reaction is carried out in a slurry bubble column reactor.  
   
   
       53 . A use as claimed in  claim 52 , in which H 2  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 H 2  and CO, the catalyst being maintained in suspension in the slurry at least partly by the motion of the gas supplied to the slurry.  
   
   
       54 . A process for the production of hydrocarbons which comprise subjecting H 2  and CO gases to a Fischer-Tropsch synthesis reaction in a reactor in the presence of a catalyst as claimed in  claim 38 .  
   
   
       55 . A process as claimed in  claim 54 , 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.  
   
   
       56 . A process as claimed in  claim 55 , in which the reaction is carried out in a slurry bubble column reactor.  
   
   
       57 . A process as claimed in  claim 56 , in which the H 2  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 H 2  and CO, the catalyst being maintained in suspension in the slurry at least partly by the motion of the gas supplied to the slurry.  
   
   
       58 . A process as claimed in  claim 54 , in which the reaction temperature is in the range 190-250° C.  
   
   
       59 . A process as claimed in  claim 58 , in which the reaction temperature is in the range 200-230° C.  
   
   
       60 . A process as claimed in any  claim 54 , in which the reaction pressure is in the range 10-60 bar.  
   
   
       61 . A process as claimed in  claim 60 , in which the reaction pressure is in the range 15 to 30 bar.  
   
   
       62 . A process as claimed in  claim 54 , in which the H 2 /CO ratio of the gases supplied to the Fischer-Tropsch synthesis reactor is in the range 1.1 to 2.2.  
   
   
       63 . A process as claimed in  claim 62 , in which the H 2 /CO ratio is in the range 1.5 to 1.95.  
   
   
       64 . A process as claimed in  claim 54 , in which the superficial gas velocity in the reactor is in the range 5 to 60 cm/s.  
   
   
       65 . A process as claimed in  claim 64  in which the superficial gas velocity is in the range 20 to 40 cm/s.  
   
   
       66 . A process as claimed in  claim 54 , in which the product of the Fischer-Tropsch synthesis reaction is subsequently subjected to post-processing.  
   
   
       67 . A process as claimed in  claim 66  in which the post-processing is selected from de-waxing, hydro-isomerisation, hydro-cracking and combinations of these.  
   
   
       68 . A method for the production of an alumina support for a catalyst, which comprises impregnating an initial alumina support material with a source of a 2-valent metal capable of forming a spinel compound with alumina, and calcining the impregnated alumina at a temperature of at least 550° C.  
   
   
       69 . A method as claimed in  claim 68 , in which the initial alumina support material at least predominantly comprises γ-alumina.  
   
   
       70 . A method as claimed in  claim 68 , in which the initial alumina support material has a specific surface area in the range 100 to 300 m 2 /g.  
   
   
       71 . A method as claimed in  claim 68 , in which the initial alumina support material comprises agglomerated essentially spherical particles having a particle size range whereby at least 80% fall in the range 30 to 120 μm.  
   
   
       72 . A method as claimed in  claim 68 , in which the initial alumina support material has a pore volume greater than 0.2 cm 3 /g, preferably greater than 0.4 cm 3 /g.  
   
   
       73 . A method as claimed in  claim 68 , in which the impregnated alumina support material is calcined at a temperature in the range 800 to 1200° C.  
   
   
       74 . A method as claimed in  claim 68 , in which the source of a 2-valent metal comprises a source of cobalt, zinc or magnesium.  
   
   
       75 . A method as claimed in  claim 68 , which includes additionally impregnating the alumina support material with a promoter.  
   
   
       76 . A method as claimed in  claim 75 , in which in which the promoter comprises platinum or rhenium.  
   
   
       77 . A method as claimed in  claim 76 , in which the promoter is rhenium and the source of rhenium is selected from perrhenic acid (HReO 4 ), ammonium perrhenate, rhenium halide(s) and rhenium carbonyl(s).  
   
   
       78 . A method as claimed in  claim 77 , in which the source of the 2-valent metal compound is cobalt nitrate and the rhenium compound is perrhenic acid.  
   
   
       79 . A method as claimed in  claim 68 , which includes additionally impregnating the alumina support material with a stabiliser.  
   
   
       80 . A method as claimed in  claim 79 , in which the stabiliser comprises lanthanum.  
   
   
       81 . A method as claimed in anyone of  claim 68 , in which the first impregnation step comprises an incipient wetness treatment in which an aqueous solution of the 2-valent metal compound and optionally a rhenium compound is mixed with the dry support material until the pores are filled, and the impregnated support is then dried, prior to the second calcining step.  
   
   
       82 . A method as claimed in  claim 68 , 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.  
   
   
       83 . A method as claimed in  claim 81 , in which the drying is carried out at 80 to 120° C.