Olefin selective ft catalyst composition and preparation thereof

Process for the preparation of a hydrocarbon synthesis catalyst comprising the following steps:

• (a) providing a solution of iron or a suspension of a precipitated, non-calcined iron-containing solid in a solvent in which a precursor of a promoter P1 is present, the promoter P1 comprising one or more element(s) selected from the group of boron, germanium, nitrogen, phosphorus, arsenic, antimony, sulphur, selenium and tellurium,
• (b) removing the solvent from the solution or suspension, and
• (c) subjecting the product of step (b) to a calcination treatment,
• wherein
• the amount of the precursor of promoter P1 is selected so that the one or more element(s) selected from boron, germanium, nitrogen, phosphorus, arsenic, antimony, sulphur, selenium and tellurium is(are) present in an amount of at least 0.02 g/100 g Fe in the catalyst, and
• a precursor of an alkali metal- and/or alkaline-earth metal containing promoter P2 is added before, after or during any of the steps of the process so that promoter P2 is present in the catalyst.

A hydrocarbon synthesis process which is operated in the presence of a catalyst comprising:

• in an unreduced form:
• a) Fe as catalytically active metal,
• b) a first promoter comprising an alkali metal and/or an alkaline-earth metal, the alkali metal and/or alkaline-earth metal being present in a combined amount of 0.1 to 1.0 g/100 g Fe,
• c) a second promoter comprising a metalloid, the metalloid being sulphur, present in an amount of 0.03 to 0.2 g/100 g Fe,
• d) a surface area of 80 m2/g or less, and
• e) a weight ratio of the first promoter to the second promoter of 0.8:1 to 20:1;
• and
• in a reduced form further comprising:
• a chemical bond between the at least one metal of the first promoter and the metalloid of the second promoter, and wherein at least 75 wt. % of the Fe is in the zero oxidation state.

Catalyst obtainable by the following process steps:

• (a) providing a precipitation mixture comprising:
• a precipitated, non-calcined iron-containing solid;
• an aqueous solvent;
• and
• a precursor of a first promoter, the precursor of the first promoter comprising sulphur,
• (b) removing the solvent from the precipitation mixture,
• (c) subjecting the product of step (b) to a calcination treatment, the calcined catalyst comprising an amount of sulphur of at least 0.12 g/100 g Fe, and
• (d) providing a precursor of a second promoter to the calcined catalyst, the second precursor comprising an alkali metal and/or an alkaline-earth metal, the second precursor provided to the calcined catalyst by at least one:
• adding the second precursor to the precipitation mixture and retaining the metal of the second precursor while removing the solvent from the precipitation mixture;
• adding the second precursor to the precipitation mixture after the solvent has been removed;
• and
• adding the second precursor to the calcined catalyst,
• wherein the precursor of the second promoter is provided in amount sufficient to provide in the calcined catalyst a ratio of the metal of the second precursor to the combined amount of the metalloid and/or the non-metal of the first precursor of 0.8:1 to 20:1, and
• (e) reducing the calcined catalyst comprising the precursor of the second promoter, wherein the reduced form of the catalyst comprises a chemical bond between the metal of the second promoter and the sulphur of the first promoter, and wherein at least 75 wt. % of the Fe is in the zero oxidation state.