Study On Mo₂C Based Catalysts In Sulfur-resistant Methanation

On behalf of clean and high-efficiency fossil resource,the SNG has been drawn increase attention in public,whose production could effectively relieve the shortage of natural gas and reduce the pressure of environmental pollution.Since methanation plays a pivotal role in the SNG production from coal,it is necessary to increase the capacity during the methanation process.In details,how to research and improve the catalytic performance should be the primary mission The Mo catalysts have great performance in the sulfur-resistant methanation,and the Mo₂C-based catalysts have shown the excellent activity for hydrogenation reactions because of their attractive physical and chemical properties.In this study,Mo₂C-based catalysts have been prepared by calcination of the mixed complex,which contained the AHM and HMT,it studied the catalytic performance in methanation and the structure-activity of molybdenum carbide catalysts.The Mo₂C/Al₂O₃ catalysts were evaluated for methantion,and the effect of Mo₂C loading,the H₂S content of feed gas,and the addition of Co was investigated.The results showed that 15%Mo₂C/Al₂O₃ catalysts had best catalytic performance over Mo₂C/Al₂O₃ catalysts with different loading of Mo₂C.When the concentration of H₂S increased up to 1500ppm,the Mo carbides on the surface could been gradual sulfidation caused the formation of MoS_2,further increase of the H₂S content could lead to the increase of sulfide degree resulting into Mo₇S₈,which had methanation activity.However,the textural properties of catalysts were destroyed as cobalt was added into catalysts,and the Co₃Mo₃C and CoMoO₄ were found on the catalysts,which might be responsible for the decrease of catalytic performance.Mo₂C/ZrO₂ catalysts prepared by co-precipitation achieved greatest activity compared with those catalysts prepared by impregnation.As the bath temperature was raised up to 80?C,the catalysts showed the batter catalytic activity and stability as the weak acid site increased and the content of ZrMo₂O₈ decreased.Mo₂C catalysts supported by m-ZrO₂ and t-ZrO₂ were both studied in sulfur-resistant methanation,the m-ZrO₂ catalysts had better activity with larger BET surface and more Mo₂C density on the surface,while catalysts supported by the t-ZrO₂ would resulting into the formation of coke.