Catalyst deactivation by carbon formation during CO hydrogenation to hydrocarbons on mesoporous Co3O4

Abstract

Mesoporous cobalt oxide (Co3O4) was prepared through the template-replicating method by using the templating material of KIT-6, and its catalytic activity for CO hydrogenation to hydrocarbons by the Fischer-Tropsch (FT) synthesis was investigated and compared with that of precipitated Co3O4. The mesoporous Co3O4 showed an enhanced catalytic activity at initial reaction stage by an increased mass-transfer rate of heavier hydrocarbons in large regular pore structures above 6 nm in size and high metallic surface area of cobalt. Different deactivation phenomena were observed during the FT reaction due to collapse of the pore structure and carbon deposition such as formation of graphitic whisker carbon on mesoporous Co3O4 and encapsulation of amorphous carbon on precipitated Co3O4. The different catalytic performance and deactivation behavior of the two Co3O4 catalysts were mainly due to the variation of surface morphologies and the types of coke formed.