Process for producing hydrocarbons from a synthesis gas, and catalysts therefor

A method of pre-treating a catalyst support to be used in a catalyst-forming process involving impregnation of the support in neutral or acidic conditions, which method comprises

• admixing an untreated particulate catalyst support selected from the group consisting in Al2O3, titania (TiO2) and magnesia (MgO), with a solution of a precursor of a modifying component selected from the group consisting in Si, Zr, Cu, Zn, Mn, Ba, Co, Ni and La in an impregnation solvent, to form a treatment mixture, with the modifying component being capable, when present in and/or on the catalyst support of suppressing the solubility of the catalyst support in aqueous acid solutions and/or neutral aqueous solutions;
• maintaining the treatment mixture near the boiling point of the impregnation solvent for from 1 minute to 20 hours;
• and
• removing excess solvent or solution under a vacuum of 0.01 to 1 bar(a), to obtain a modifying component-containing modified catalyst support;
• and
• calcining the modifying component-containing catalyst support to decompose organic groups or to form spinel structures with the support, at a temperature from 400° C. to 800° C. and for a period of from 1 minute to 4 hours, to obtain a protected modified catalyst support which is less soluble or more inert in the aqueous acid solutions and/or the neutral aqueous solutions than the untreated catalyst support, with the modifying component being present, in the modified catalyst support particles, on the particle surfaces by being chemically bonded to the particle surfaces, and provided that when the modifying component comprises Co or Zr, the calcination temperature is from 600° C. to 800° C.

A method of forming a catalyst, which method comprises in a first stage or step, dissolving (1.82xy)kg Co(NO3)2.6H2O, where x is the BET pore volume of a protected modified alumina catalyst support obtained by introducing onto and/or into an untreated particulate catalyst support selected from the group consisting in Al2O3, titania (TiO2) and magnesia (MgO), a modifying component which is capable, when present in and/or on the catalyst support, of suppressing the solubility of the catalyst support in aqueous acid solutions and/or neutral aqueous solutions, said modifying component being selected from the group consisting in Si, Zr, Cu, Zn, Mn, Ba, Co, Ni and La, and calcining the resultant modifying component containing catalyst support at a temperature from 400° C. to 800° C. and for a period of from 1 minute to 4 hours, thereby obtaining the protected modified catalyst support which is less soluble or more inert in the aqueous acid solutions and/or the neutral aqueous solutions than the untreated catalyst support, with the modifying component being present, in the modified catalyst support particles, on the particle surfaces by being chemically bonded to the particle surfaces, in mR/g and y is the total mass of the support to be impregnated in kg, in sufficient distilled water such that the final volume of the solution is >xy liter;

• heating this solution to a temperature between 60 and 95° C.;
• adding to this solution the total inventory of y kg support material at atmospheric pressure whilst continuous mixing of the slurry is maintained;
• reducing, with the gradual application of vacuum, under continuous mixing at a temperature between 60 and 95° C., the loss on ignition (L.O.I.) content of the slurry, over 3 or more hours, from >(136.4x)/(1+1.86x) mass % to a state of incipient wetness, with loss on ignition (L.O.I.) being defined as the mass % loss observed during complete calcination or complete decomposition to Co3O4/Al2O3;
• applying, at the state of incipient wetness (L.O.I. of (136.4x)/(1+1.86x)), a vacuum of <20 kpa(a) whilst ensuring that the temperature does not drop below 60° C. under continuous mixing;
• once the state of incipient wetness has been reached, proceeding with vacuum drying in an uninterrupted fashion, at the conditions:
• temperature >60° C., but not higher than 95° C., and a vacuum of <20 kPa(a);
• maintaining vacuum drying under these specific conditions until a L.O.I. <90% of the L.O.I. value at incipient wetness has been reached;
• then effecting direct calcination of this dried material at 200° C. to 300° C.;
• and thereafter in the second stage or step, it is assumed that the BET pore volume of the first stage material is x′ mR/g, and that y′ kg of this material is to be impregnated for a second time, and the following procedure is adopted for proper impregnation:
• using, during this second impregnation, a maximum of (1.82x′y′)kg Co(NO3)2.6H2O, where x′ is the BET pore volume of the first stage calcined material in mR/g, and y′ is the total mass of the first stage calcined material to be impregnated in kg, dissolving the first stage calcined material in sufficient distilled water such that the final volume of the solution is >x′y′ liter;
• heating this solution to a temperature between 60 and 95° C., adding to this solution the final inventory of y′ kg of the first stage calcined material at atmospheric pressure, whilst continuous mixing of the slurry is maintained;
• reducing, with the gradual application of vacuum, under continuous mixing at a temperature between 60 and 95° C., the L.O.I. content of the slurry, over 3 or more hours, to the state of incipient wetness;
• at the stage of incipient wetness, applying a vacuum of <20 kPa(a) whilst simultaneously ensuring that the temperature does not drop below 60° C. under continuous mixing;
• once the stage of incipient wetness has been reached, proceeding with vacuum drying in an uninterrupted fashion, at the conditions:
• temperature >60° C., but not higher than 95° C., and a vacuum of <20 kPa(a);
• maintaining vacuum drying under these specific conditions until a L.O.I. <90% of the L.O.I. value at incipient wetness has been reached;
• then effecting direct calcination of this dried material at 200° C. to 300° C.