MODELING OF OXIDATIVE COUPLING OF METHANE TO ETHYLENE WITH CHEMICAL EQUILIBRIA

Abstract

Chemical Equilibrium models were constructed for Oxidative Coupling of Methane reaction (OCM) with three catalysts, i.e. Mn/Na2WO4/SiO2, La2O3/CaO and PbO/Al2O3. The models were verified under operating temperatures of 650-900oC and methane to oxygen feed ratio 3-10. The compositions of methane, ethane, ethylene, hydrogen, water and carbon oxides in the effluent of each model were compared with the corresponding experiments. The suitable equilibrium model for both Mn/Na2WO4/SiO2 and PbO/Al2O3 was the trio-equilibrium reaction model, consisting of OCM and oxidative dehydrogenation model, combustion model, and hydrocracking model. While, the duo-equilibrium reaction model, containing OCM and oxidative dehydrogenation model, and combustion model, was appropriate for La2O3/CaO catalyst. The accuracy of all equilibrium models could be improved by specifying the desired ethane yield. In addition, based on the reactor performance, i.e. conversion, and yields, the limitation of the manipulated equilibrium models was evaluated within the operating temperatures and the methane to oxygen ratio above. Finally, the equilibrium models, especially the duo-equilibrium model, could be employed to predict the reactor performance containing other OCM catalysts.