Thermodynamic Analysis of Direct Partial Oxidation of Methane to Benzene

فاقد چكيده

Recent reports on methane aromatisation have shown that the partial oxidation of methane to benzene can be made to proceed at about 1000 K, but it is limited by thermodynamic equilibrium and the eventual deactivation of any catalyst by coking. In order to identify the most favourable operating conditions for the direct partial oxidation of methane to benzene thermodynamic aspects of the reaction system have been analysed. The present contribution examines the equilibrium compositions of products from direct partial oxidation of methane to benzene. The study was conducted over a temperature range of 500-1500K, pressure range of 0.1-5 MPa, CH4/O2 ratio of 2-20. CHEMKIN software is used for thermodynamic equilibrium calculations using the Gibbs free energy minimisation method. It has been found that from the thermodynamic viewpoint the reforming products, H2, H2O, CO and CO2, are the major compounds at temperatures around 1000 K, while benzene is produced mostly at temperatures above 1200 K. It is shown that pressure inhibits methane conversion, benzene selectivity and the molar ratio of C6H6/(C2+C3) at equilibrium. The feed CH4/O2 ratio has an important role in the conversion of methane to hydrocarbons, C6H6, C2 and C3. While methane conversion decreases with increasing CH4/O2 ratio, benzene selectivity and the C6H6/(C2+C3) equilibrium molar ratio are enhanced.