Development of Fe Fischer–Tropsch catalysts for slurry bubble column reactors

The effect of two binder systems — a silica-based system and a silica–kaolin–clay–phosphate-based system — on a doubly promoted Fischer–Tropsch (FT) synthesis iron catalyst (100Fe/5Cu/4.2K) was studied. The catalysts were prepared by coprecipitation, followed by binder addition and spray drying at 270°C in a 1 m diameter, 2 m tall spray dryer. The binder silica content was varied from 0 to 20 wt.%. A catalyst with 12 wt.% binder silica was found to have the highest attrition resistance. The FT activity and selectivity of this catalyst are better than a Ruhrchemie catalyst at 270°C and 1.48 MPa. The addition of precipitated silica or kaolin to catalysts containing 10–12 wt.% binder silica decreases attrition resistance and increases methane selectivity. Based on the experience gained, a catalyst has been successfully spray dried in 500 g quantity. This catalyst showed 95% CO conversion over 125 h of testing at 270°C, 1.48 MPa, and 2 NL/g-cat/h and had less than 4% methane selectivity. Its attrition resistance was one of the highest among the catalysts tested.