(378t) Modelling Oxygen Permeation across the Membrane of an Alternative Membrane Reactor for Oxidative Coupling of Methane

Oxidative coupling of methane to valuable fuels is currently investigated. Advance reactor concepts are currently been sought alongside high performing catalyst. One of such reactor is the Membrane contactor combining separation and reaction in a single unit. It has the potential of alleviating the kinetic and thermal problems of oxidative coupling of methane (OCM) reactions which is a typical problem of a conventional packed bed reactor. However, conventional membrane reactor still exhibits similar limitations of hotspot generation and trade-off between methane conversion and C₂ (ethane and ethylene) selectivity trade-off, hence, alternative membrane reactor concepts are emerging. One of such concepts is the varying thickness membrane reactor, hinged on the fact that, gradually increasing the membrane thickness along the length of the membrane reactor will minimize the amount of oxygen which can be detrimental for C₂ selectivity. This implies for such reactor, the right proportion and distribution of oxygen into the reaction zone is a key design aspect that can influence the performance of membrane reactors utilized for (OCM). In this study, a detailed kinetic model comprising of 15 catalytic reactions and 39 gas phase reaction is implemented in a membrane reactor. A 2D model taking into account radial dispersion is applied. An oxygen permeation model that distinguishes between the surface reactions at the two solid-gas interfaces of the membrane and the diffusion of oxygen across the membrane is implemented. Various oxygen permeation flux are considered by varying membrane thickness according to a linear, exponential and step change geometries. The importance of these flux profiles on both the performance of the membrane reactor and the oxygen transport limitations across the membrane are highlighted.