Search for: All records

Direct conversion of methane into ethylene through the oxidative coupling of methane (OCM) is a technically important reaction. However, conventional co-fed fixed-bed OCM reactors still face serious challenges in conversion and selectivity. In this paper, we apply a finite element model to simulate OCM reaction in a plug-flow CO₂/O₂transport membrane (CTM) reactor with a directly captured CO₂and O₂mixture as a soft oxidizer. The CTM is made of three phases: molten carbonate, 20% Sm-doped CeO₂, and LiNiO₂. The membrane parameters are first validated by CO₂/O₂flux data obtained from CTM experiments. The OCM reaction is then simulated along the length of tubular plug-flow reactors filled with a La₂O₃-CaO-modified CeO₂catalyst bed, while a mixture of CO₂/O₂is gradually added through the wall of the tubular membrane. A 12-step OCM kinetic mechanism is considered in the model for the catalyst bed and validated by data obtained from a co-fed fixed-bed reactor. The modeled results indicate a much-improved OCM performance by membrane reactor in terms of C₂-yield and CH₄conversion rate over the state-of-the-art, co-fed, fixed-bed reactor. The model further reveals that improved performance is fundamentally rooted in the gradual methane conversion with CO₂/O₂offered by the plug-flow membrane reactor.