The Oxidative Coupling of Methane: A Mesoscale Kinetic Model of the Surface and Gas Phase Reaction Network

An open-source program called Mesoflow was used to model the intricate reaction network of the oxidative coupling of methane (OCM). This mesoscale model incorporates both the catalytic and gas phase reactions in addition to the interactions between these two phases, including 39 gas phase reactions, 14 surface reactions, and 32 species. Initially, a Python script was developed to model this reaction network and verify the kinetics. This was compared against Mesoflow’s zero-dimensional dynamic model which checked the accuracy of the Mesoflow program. This preliminary model is kinetically driven. The Python script and the zero-dimensional model matched analytic solutions of simple reactions. Mesoflow’s block catalyst case was then modified to reflect the OCM chemistry. This modified case modeled a batch reactor. The chemistry of this reaction network is very stiff, therefore the SUNDIALS integrator is required. Parameters, such as temperature, volume, and initial concentrations were held constant. Concentrations of key species, such as methane, methyl radicals, and ethylene were calculated as a function of time. With the surface reactions, the yield of valuable products, such as ethylene, was much higher than without. Therefore, a catalyst is required for high yield and selectivity. Over oxidation is also possible. An investigation into the effects of temperature on product selectivity is needed.