Computational fluid dynamics study on concentration polarization phenomena in silica membrane reactor during methanol steam reforming

In this study, the concentration polarization phenomena occurring during methanol steam reforming carried out in a silica membrane reactor were theoretically investigated using a computational fluid dynamic tool. To our best knowledge, there are no computational fluid dynamics studies applied to the investigation of the concentration polarization phenomena in silica membrane reactors. Therefore, this study represents a first step in analyzing theoretically this phenomenon in such reactors. After developing a two-dimensional model and solving their governing equations by numerical method, the validation of the theoretical results have been carried out by using experimental data published in previous works. The simulation results showed that operational conditions such as temperature, pressure, feed flow rate, and H2O/CH3OH molar ratio are effective on the concentration polarization. Moreover, the impact of the velocity profile on the concentration polarization module in the silica membrane reactor of this work was theoretically discussed. In this regard, increasing temperature and pressure from 470 to 570 K, and from 2 to 10 bar, respectively, better performance in terms of methanol conversion (from 50% to 98%, and from 88% to 91%, respectively) and H2 recovery (from 20% to 21.5%, and from 20% to 22.5%, respectively) were reached, even though it determined a more evident concentration polarization effect. This study pointed out how higher pressures determined a significant increase of the concentration polarization factor, which was responsible for the plateau trend of both conversion and hydrogen recovery above 6 bar.