Influence of ZrO2 Loading on SBA-15-Supported Cobalt Catalysts for Fischer−Tropsch Synthesis

Abstract

The effect of ZrO2 loading on SBA-15-supported cobalt Fischer−Tropsch catalysts was investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), NH3-temperature-programmed desorption (TPD), and CO hydrogenation. Zirconia was first impregnated into SBA-15 to produce Zr-modified SBA-15 supports, following impregnation of Co. The final catalysts contained Zr content from 0 to 20 wt %. It was found that the promotion of ZrO2 increased the cobalt dispersion, but the Co−Si interaction was gradually replaced by the Co−Zr interaction, which led to a decrease in the reduction degree (<400 °C) of cobalt species. As a result, both CO conversion and C5+ selectivity showed a maximum with appropriate ZrO2 content. Furthermore, C5−C11 hydrocarbon selectivity increased with the rise of ZrO2 content.