Effect of support and cobalt precursors on the activity of Co/AlPO 4 catalysts in Fischer–Tropsch synthesis

Abstract

Cobalt supported on amorphous aluminum phosphate (Co/AlPO 4) catalysts were prepared by the impregnation method using three different cobalt precursors such as cobalt nitrate, acetate and chloride to elucidate the activity of Fischer–Tropsch synthesis. The use of AlPO 4 as a support for cobalt-based catalysts exhibits better catalytic performance during FTS reaction than the corresponding Co/Al 2O 3 catalyst. TPR results also suggest that the reducibility of the catalysts varies with the nature of cobalt precursors employed during the impregnation on AlPO 4 support. The Co/AlPO 4 catalyst prepared from cobalt nitrate shows higher CO conversion and C 8+ selectivity than the others due to the facile formation of homogeneous cobalt particles with proper electronic characters and high reducibility. Interestingly, all Co/AlPO 4 showed a growth of filamentous carbon initiated from the large mobile cobalt particles during the reaction. The differences in catalytic properties of Co/AlPO 4 are mainly attributed to the cobalt particle size, reducibility with different electronic states of metallic cobalt, pore diameter of AlPO 4 and formation of filamentous carbon.