Microkinetics of methane oxidative coupling

Abstract

A detailed microkinetic model for methane oxidative coupling has been developed including so-called catalyst descriptors. The reaction network contains 39 elementary steps describing the gas-phase reactions and 14 catalytic reactions. The model has been implemented in a one-dimensional heterogeneous reactor model, which accounts for the interactions between the species in the gas phase and inside the catalyst pores. Based on the proposed reaction mechanism, catalyst descriptors of methane oxidative coupling have been identified and incorporated into the microkinetic model through the use of Polanyi relationships for the reaction families of catalytic reactions encountered in the reaction network. The application of catalyst descriptors for two catalysts, Li/MgO and Sn/Li/MgO, has been used as an example to illustrate the model performance. The simulations are consistent with the experimental results over a broad range of operating conditions. This is a first validation of the description of experimental data on a family of catalysts with a single kinetic model including catalyst descriptors that can capture the trends in productivity and selectivity on different catalysts. This microkinetic model with catalyst descriptors can be used as an effective tool to extract knowledge from high-throughput experiments of methane oxidative coupling.