Effect of incorporation manner of Zr on the Co/SBA-15 catalyst for the Fischer–Tropsch synthesis

Abstract

The effect of incorporation manner of Zr on the textural properties, surface physicochemical properties, reduction degree and catalytic performance of Co/SBA-15 catalyst for the Fischer–Tropsch synthesis (FTS) was investigated. The catalysts were prepared by sequential impregnation, co-impregnation and in-situ synthesis method, respectively. The loading amount of Co and Zr remained constant in all catalysts with 15wt.% and 5wt.%, respectively. The catalysts were characterized by N2 adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), temperature-programmed reduction (H2-TPR) and evaluated for the FTS. It was revealed that the Co3O4 was considered as the main surface cobalt phase, and the BET surface area and pore size were decreased regardless of the incorporation manner. The reduction degree of cobalt species increased from 80% (Co/SBA-15) to 90% (Co/Zr/SBA-15) and 85% (CoZr/SBA-15) with the addition of Zr, except for the Co/Zr-SBA-15 catalyst (74%). The catalyst prepared by sequential impregnation method (Co/Zr/SBA-15) showed the highest selectivity of long-chain hydrocarbons (C12–C22, 53%) with the chain growth probability α up to 0.84, which could be attributed to the highest reducibility of cobalt species.