A mid/low-temperature solar-driven integrated membrane reactor for the dehydrogenation of propane – A thermodynamic assessment

Solar thermochemical conversion is an effective method for solar energy storage, and propane dehydrogenation is one popular technology to generate propylene and hydrogen, while the high temperature required in the reaction limits its efficiency and utilization. In this research, a solar–driven hydrogen permeation membrane reactor system for propane dehydrogenation is proposed for efficiently generating pure hydrogen and propylene in a mild temperature range, which can decrease the heat loss and increase the conversion rate, thereby converting low–grade solar thermal energy into high–grade chemical energy. Using the method of numerical simulation, the thermodynamic, kinetic, and environmental performances of the system are analyzed at different temperatures (250–500 °C) and H2 permeate pressures (10–5–10–2 bar). The C3H8 conversion rate, C3H6 selectivity, and C3H6 yield can achieve 99.2%, 99.1%, and 98.3% at 400 °C, 10–5 bar with the assistance of hydrogen separation. The first–law thermodynamic efficiency, solar–to–fuel efficiency, and exergy efficiency of the system are calculated to be 93.1%, 33.6%, and 73.4% (400 °C, 10–4 bar), respectively. The annual standard coal savings and carbon dioxide reduction rates are calculated to be 279.8 kg/(m2·year) and 685.5 kg/(m2·year) (400 °C, 10–5 bar). This study demonstrates the feasibility of a solar collector integrated with a membrane reactor for efficient solar energy storage via C3H8 dehydrogenation and provides guidance for further experimental research.