Selective oxidation of methane to benzene over K2MoO4/ZSM-5 catalysts

The conversion of methane into higher hydrocarbons and benzene on K2MoO4/ZSM-5 catalyst has been investigated under non-oxidizing conditions in a fixed bed, continuous flow reactor. The effects of different parameters (space velocity, reduction and calcination temperatures, methane concentration) on the conversion of methane were also examined. The reaction of methane was observed above 923 K. In the initial period, the complete oxidation of methane was the dominant process. After a partial reduction of the catalyst the formation of several hydrocarbons was observed. The main products were benzene, ethylene and ethane. The selectivity to benzene was in the range of 60-70% at 1.2-6.3% methane conversion. The catalyst was found to be active in the dehydrogenation of ethane and in the aromatization of ethylene. Examination of the used catalyst by X-ray photoelectron spectroscopy suggested the formation of Mo,C. The active surface species and the possible mechanism of the reaction are discussed.