Analysis of equilibrium-limited dehydrogenation and steam reforming in palladium membrane reactors

Abstract

Palladium membrane reactors have the potential to achieve higher conversion as well as larger recovery of purified hydrogen in the steam reforming reaction, even at lower temperatures. However, increasing feed rate resulted in larger deviation from the ideal analytical model assuming plug flow and isothermal conditions. This study developed a computational fluid dynamics (CFD) model, which takes into account the concentration, temperature and velocity distributions due to mass, heat transfer and flow resistances in the membrane reactor. The CFD model clearly showed that large temperature and concentration distributions were formed in both the radial and axial directions, so reducing the reactor performance compared to the ideal reactor. The correctness of the model was verified for the dehydrogenation of cyclohexane in a single tube type as well as a multi-tube type of palladium membrane reactor. Furthermore, the multi-tube model was applicable for simulation of changes in the reactor design such as the membrane dimension. World-leading potentials of palladium membrane reactors in Japan are evaluated by introducing major projects.