CO hydrogenation on group VI metal–ceria catalysts

Abstract

Ceria-supported chromium, molybdenum, and tungsten catalysts were prepared by impregnation. The prepared catalysts were characterized using N2 adsorption, X-ray diffraction (XRD), the temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS) measurements. The catalytic activity in CO hydrogenation was evaluated using a fixed-bed pressurized flow reaction system under the following conditions: 260–300°C, 5.0MPa, GHSV of 5000h−1, and a H2/CO ratio of 1.0–2.0. The effects of ceria support, group VI metals, and catalyst activation methods on C2+ alcohol synthesis were investigated. The use of ceria supports resulted in a decrease in the selectivity for CO2, and in increases in the selectivity for C2+ alcohols and CO conversion. The selectivity for alcohols on the Mo-based catalysts was higher than those on the corresponding Cr or W-based catalysts. A comparison of the methods of activation for the K005Co0620MoCe catalyst demonstrated that sulfidation produced the highest CO conversion and selectivity for C2+ alcohols, as well as the lowest, hydrocarbon selectivity. XPS and H2-TPR measurements show that the mixed metal sulfide phases, e.g., the Co–Mo–S phase, and the thiol group on the catalysts enhanced the formation of C2+ alcohols.