Kinetic Studies on Oxidative Coupling of Methane over Na2WO4-Mn/SiO2 Catalyst
Alamiri, Mohammed Masoud E
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A kinetic study of oxidative coupling of methane over Mn–Na2WO4/SiO2 catalyst was performed in a fixed bed reactor system to investigate the effect of different reaction parameters on the reaction rate and selectivity. Catalyst temperature and the reacting species inlet concentrations were varied. The methane conversion was maintained below 10% to estimate the reaction rate by the differential method. The reaction order for methane conversion rate with respect to oxygen was approximately 0.5 and that is similar to what was reported by other researchers. In contrast, the reaction order with respect to methane was found to be approximately 2; most previous researchers have reported a methane order of unity. The activation energy was also estimated through an Arrhenius analysis and found to be approximately 230 kJ/mol. The kinetics corresponding to the conversion to C2 hydrocarbons and carbon oxides were also determined. It was found that the desired C2 hydrocarbons are maximized by increasing the temperature and the inlet concentration of methane while keeping oxygen concentration at minimum. A systematic analysis of possible mechanisms to explain the reaction orders was conducted. Finally, pore diffusion was checked by calculating Weisz Prater modulus. The result indicated that the effect of diffusion on the system cannot be neglected.