Fischer-Tropsch synthesis over TiO2 supported cobalt catalyst: Effect of TiO2 crystal phase and metal ion loading

Five kinds of cobalt-loaded TiO2 (Co/TiO2) catalysts, which were prepared from TiO2 samples with different crystal phase and specific surface area by an impregnation method, were studied for Fischer-Tropsch (FT) synthesis with the stirred slurry phase tank reactor. Co/TiO2 catalysts prepared from TiO2 with more than 15% of rutile phase exhibited about four times higher CO conversion rate than those from pure anatase TiO2 did. We further examined eleven kinds of metal ion as the additives of the TiO2 support. Co/TiO2 catalysts loaded with alkali earth elements showed high CO conversion rate, while Mn- and V-loaded catalysts showed high C5+ selectivity and low CH4 selectivity. Among the prepared catalysts, Co/TiO2 loaded with small amount (0.8 wt%) of Ca ions showed the highest CO conversion rate and site-time yield of C5+ products, which were 1.7 and 1.9 times higher than those over the bare Co/TiO2 catalyst. The activity of Co/TiO2 catalysts proportionally increased with increasing the surface area of cobalt metal, showing that the reaction would be structure-insensitive and depend on the number of the exposed Co metal sites on the catalyst surface. (c) 2013 Elsevier B.V. All rights reserved.