Effect of catalyst confinement and pore size on Fischer-Tropsch synthesis over cobalt supported on carbon nanotubes

Abstract

This paper studies the impact of structure of cobalt catalysts supported on carbon nanotubes (CNT) on the activity and product selectivity of Fischer-Tropsch synthesis (FTS) reaction. Three types of CNT with average pore sizes of 5, 11, and 17 nm were used as the supports. The catalysts were prepared by selectively impregnating cobalt nanoparticles either inside or outside CNT. The TPR results indicated that the catalyst with Co particles inside CNT was easier to be reduced than those outside CNT, and the reducibility of cobalt oxide particles inside the CNT decreased with the cobalt oxide particle size increasing. The activity of the catalyst with Co inside CNT was higher than that of catalysts with Co particles outside CNT. Smaller CNT pore size also appears to enhance the catalyst reduction and FTS activity due to the little interaction between cobalt oxide with carbon and the enhanced electron shift on the non-planar carbon tube surface.