Design of iron catalysts supported on carbon-silica composites with enhanced catalytic performance in high-temperature Fischer-Tropsch synthesis

A series of iron catalysts supported over carbon-silica composite materials were prepared using fructose via a mild hydrothermal approach. The catalysts exhibited very high surface areas (similar to 300 m(2) g(-1)) and good iron dispersion. Different from conventional silica-supported catalysts, no interaction between iron and silica was observed. Iron moieties were conveniently immobilized onto carbon dispersed over the silica support. A combination of characterization techniques confirmed the presence of iron in the lower oxidation state after calcination in the carbon-silica composites compared to the silica-supported catalysts. The in situ magnetic measurement and in situ XRD were indicative of iron carbide formation during CO activation. Higher carbon content in the carbon-silica composite catalysts favoured the coverage of a higher fraction of the catalyst surface by carbon species and direct interaction of a higher concentration of iron carbide species with the carbon support. The Fischer-Tropsch tests showed enhanced performance of the iron catalysts supported on the carbon-silica composite materials compared to the silica-and pure carbon-supported counterparts.