Optimal reactor design for ethylene production from methane
Résumé
The oxidative coupling of methane (OCM) to ethane and ethylene has been studied for many years as a potential alternative route for the production of valuable hydrocarbons from natural gas in a single step. However, industrial application of OCM is limited by low C2 yields and large production of CO2. Since the OCM reaction is based on catalysts surface and gas phase reactions, the fate of key intermediates like the methyl radicals and the collision probability of these radicals both in the gas phase and with the catalyst surface have a crucial impact on the C2 selectivity. Collision of these radicals in the gas phase leads to primary ethane production while collision with the catalytic surface and/or the reactor walls leads to quenching and the subsequent production of CO2. Barbé et al. have confirmed the beneficial effect of an increased gas phase volume for the C2 selectivity at constant catalytic surface [1]. Their work suggests that a high C2 yield could be reached via adjustment of the reactor geometry, i.e. the gas phase volume to the catalytic surface. In this work, we have compared three different types of reactors with respect to the ratio of the gas phase volume to net catalytic area (V/S ratio), in order to determine the impact of this V/S ratio on the selectivity for a given catalyst, independently of the reactor type.