Effect of sulfidation temperature on CoO–MoO3/γ-Al2O3 catalyst for sulfur-resistant methanation

Abstract

The effect of sulfidation temperature on the catalytic activity of CoO–MoO3/γ-Al2O3 catalyst toward sulfur-resistant methanation was studied. The prepared catalysts were characterized by N2-physisorption (BET), Temperature-programmed sulfidation (TPS), X-ray diffraction (XRD), Raman spectroscopy (RS), and Transmission electron microscope (TEM). The combined results of TPS, XRD, and RS indicated that CoMoO4 species in CoO–MoO3/γ-Al2O3 catalyst would be sulfided when the sulfidation temperature was at or higher than 300 °C. The catalyst sulfided at 400 °C exhibited the highest catalytic activity because there were the most CoMoS structures in the catalyst. When the sulfidation temperature was higher than 400 °C, the catalytic activity decreased with increasing sulfidation temperature. This decline was primarily caused by the formation of Co9S8 and MoS2 crystals. The CoMoS(II) formation did not favor the catalytic activity, because the formation of this species resulted in the occurrence of Co9S8 and crystalline MoS2 in catalysts.