Effects of titanium silicalite and TiO2 nanocomposites on supported Co-based catalysts for Fischer-Tropsch synthesis

摘要

Titanium silicalite (TS) and TiO2 nanocomposites were prepared by mixing TS and TiO2 with different ratios in ethanol. They were impregnated with 15 wt% Co loading to afford Co-based catalysts. Fischer-Tropsch synthesis (FTS) performance of these TS-TiO2 nanocomposite-supported Co-based catalysts was studied in a fixed-bed tubular reactor. The results reveal that the Co/TS-TiO2 catalysts have better catalytic performance than Co/TS or Co/TiO2 each with a single support, showing the synergistic effect of the binary TS-TiO2 support. Among the TS-TiO2 nanocomposite-supported Co-based catalysts, Co/TS-TiO2-1 presents the highest activity. These catalysts were characterized using N-2 adsorption-desorption measurements, X-ray diffraction, X-ray photoelectron spectroscopy, H-2 temperature-programmed reduction, H-2 temperature-programmed desorption and transmission electron microscopy. It was found that the position of the active component has a significant effect on the catalytic activity. In the TS-TiO2 nanocomposites, cobalt oxides located at the new pores developed between TS and TiO2 can exhibit better catalytic activity. Also, a positive relationship is observed between Co dispersion and FTS catalytic performance for all catalysts. The catalytic activity is improved on increasing the dispersion of Co.