Effect of support and promoter in Fischer-Tropsch cobalt catalysts

Abstract

The eifect of support (kieselguhr) and promoter (ThO2) in Fischer-Tropsch cobalt catalysts has been investigated using Hz and CO adsorption, X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR) techniques. The extent of reduction is found to be 39% in the presence of kieselguhr due to its migration to the surface of cobalt oxide. Presence of ThO2 increases the extent of reduction to 75% probably restricting the migration of kieselguhr. XPS results show the preferential segregation of Th02 on the surface thus preventing the encapsulation of cobalt oxide by kieselguhr. The CO/Co and H/Co values decrease with decrease in cobalt loadings indicating the possible interaction between cobalt and kieselguhr. During reduction, kieselguhr is found to stabilize Co0 as revealed from TPR studies.