Effect of cobalt and its adding sequence on the catalytic performance of MoO3/Al2O3 toward sulfur-resistant methanation

The effect of promoter cobalt and the sequences of adding cobalt and molybdenum precursors on the performance of sulfur-resistant methanation were investigated. All these samples were prepared by impregnation method and characterized by N2-adsorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR) and laser Raman spectroscopy (LRS). The conversions of CO for Mo-Co/Al, Co-Mo/Al and CoMo/Al catalysts were 59.7%, 54.3% and 53.9%, respectively. Among these catalysts, the Mo-Co/Al catalyst prepared stepwisely by impregnating Mo precursor firstly showed the best catalytic performance. Meanwhile, the conversions of CO were 48.9% for Mo/Al catalyst and 10.5% for Co/Al catalyst. The addition of cobalt species could improve the catalytic activity of Mo/Al catalyst. The N2-adsorption results showed that Co-Mo/Al catalyst had the smallest specific surface area among these catalysts. CoMoO4 species in CoMo/Al catalyst were detected with XRD, TPR and LRS. Moreover, crystal MoS2 which was reported to be less active than amorphous MoS2 was found in both Co-Mo/Al and CoMo/Al catalysts. Mo-Co/Al catalyst showed the best catalytic performance as it had an appropriate surface structure, i.e., no crystal MoS2 and very little CoMoO4 species.

Graphical AbstractIt is found that the addition of Co into MoO3/Al2O3 catalyst can improve the catalytic activity. Mo-Co/Al catalyst exhibits higher activity than Co-Mo/Al in methanation reaction.Figure optionsDownload as PowerPoint slide