Influence of calcination on physico-chemical properties and Ficher–Tropsch activity of titanosilicate supported cobalt catalysts with different pore sizes

Abstract

Titanosilicate supports of different pore sizes were synthesized by a surfactant-free templating method. Cobalt was loaded by incipient wetness impregnation on the synthesized supports and commercial γ-Al2O3. The Fischer–Tropsch activities of the catalysts were studied with and without prior calcination in a fixed bed reactor at 220 °C, 1.83 MPa and 2000 mLsyngas/mLcatalyst/h after in situ reduction. XANES analysis of the catalysts revealed that after reduction, a greater fraction of the loaded cobalt had been reduced in the calcined catalyst (74 %) compared to the uncalcined catalyst (58 %). Activity studies revealed that the CO conversion and C5+ selectivities of the catalysts with medium pore titanosilicate supports was higher (80 % conversion, 81–85 % selectivity) than the CO conversion by Co/γ-Al2O3 (77 % conversion, 76 % selectivity). Calcination in air increased the liquid product selectivity of all the catalysts towards the diesel fraction from 21–24 % to 25–32 %.