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

Abstract

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 N2 adsorption–desorption measurements, X‐ray diffraction, X‐ray photoelectron spectroscopy, H2 temperature‐programmed reduction, H2 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.