Bionic leaf-inspired catalyst bed structure for solar membrane reactor aiming at efficient hydrogen production and separation

Abstract

Membrane reactor technology permits efficient solar thermochemical conversion at low temperatures, but the performance is often limited by concentration polarization. To cope with the hydrogen (H2) concentration polarization in solar membrane reactors, this study proposes a bionic solar membrane reactor (BSMR) inspired by the excellent production-transport management ability of leaves. Designing the structural parameters of the bionic catalyst bed obtains the efficient BSMR, and mechanistically analyzes its reaction and separation performance enhancement. The results show that the BSMR achieves a synergistic reinforcement pattern of ordered H2 separation driving reaction and reaction providing H2 separation pressure at >90° pore block tilt angle, while large porosity differences and small pore block lengths can further amplify this synergy. Currently, the BSMR with pore blocks of 140° tilt angle, 20 mm length and 0.3 low porosity has the optimal performance, which improves methane conversion and hydrogen recovery by 13.4–99.0% and 13.7–99.0%, respectively, relative to the conventional solar membrane reactor under different operating conditions. Also, it is shown that optimal performance enhancement is achieved at high steam-to-methane ratios, low inlet temperatures and high inlet flow rates. In general, the design referring to leaves makes BSMR well inherit the consistently superior performance of leaves, providing new ideas for efficient hydrogen production and separation.