Experimental and model-based analysis of membrane reactor performance for methane oxidative coupling: Effect of radial heat and mass transfer

Abstract

Performance of the oxidative coupling of methane (OCM) reactions in a porous packed bed membrane reactor (PBMR) was analyzed using a detailed two-dimensional model which considers the mass and heat transfer in both radial and axial directions.In order to investigate the relative effects of diffusion and catalyst activity on the predicted performance of the membrane reactor, the kinetics of two different catalysts, La2O3/CaO and Mn–Na2WO4/SiO2, were implemented in the model. It was observed that the significant overprediction of methane conversion by one-dimensional model, which is sometimes twice of its real value, can be avoided using the two-dimensional model.The mechanisms through which different parameters can be exploited to improve the reactor performance were also studied. It was observed, the selectivity and yield of the desired products in membrane reactor can be significantly improved by tunning the driving force radial for heat transfer and the operating temperature inside the reactor. This is achieved by exploiting a proper set of operating temperature for pre-heating and the surrounding medium temperature. Moreover, exploiting other parameters such as feed flow rate to ensure a proper contact time and effective axial and radial convection heat transfer was also investigated. The results of the experimental investigation of the Mn–Na2WO4/SiO2 catalyst in a membrane reactor, confirmed the precision of the developed model. The reported detailed analysis in this paper enables one to predict the both reaction and thermal performance of the OCM membrane reactor and improve its design characteristics accordingly.