Kinetic modeling of oxidative coupling of methane over Mn/Na2WO4/SiO2 catalyst

A comprehensive kinetic model for oxidative coupling of methane (OCM) on Mn/Na2WO4/SiO2 catalyst was developed based on a microcatalytic reactor data. The methane conversion and ethylene, ethane, carbon monoxide and carbon dioxide selectivities were obtained in a wide range of operating conditions including 750 < T < 875 deg C, 4 < CH4/O2 < 7.5 and space time between 30 and 160 kg * s/m3 at P = 657 mmHg. The reaction networks of five kinetic models with appropriate rate equation type were compared together. The kinetics rates parameters of each reaction network were estimated using genetic algorithm optimization method. After comparing the reaction networks, the reaction network presented by Stansch et al. was found to best represent the OCM reaction network and was further used in this work. This kinetic network considers both catalytic and gas-phase as well as primary and consecutive reaction steps to predict the performance of the OCM. Comparing the experimental and predicted data showed that presented model has a reasonable fit between the experimental data and the predicted values with average absolute relative deviation of +/- 9.1%.