H2 co-feeding within oxygen permeable membrane reactor boosts OPDH selectivity: Modeling local chemical equilibrium coupled with chemical reaction kinetics

Abstract

Oxidative propane dehydrogenation (OPDH) represents a promising alternative route for propylene production but remains challenged by selectivity loss due to propylene over-oxidation. Herein, we propose H₂ co-feeding in an oxygen permeable membrane reactor (OPMR) to maintain high propylene selectivity while enhancing propane conversion. The mechanisms of H₂ include: (i) continuously diluting propylene to suppress kinetics; (ii) selectively oxidizing H₂ to consume excess oxygen; and (iii) synergistically mitigating over-oxidation with a uniform oxygen supply. This work develops a multi-mechanism coupled model integrating oxygen transport, local chemical equilibrium for H₂ selective oxidation, and detailed propane dehydrogenation kinetics. The model combines the conventional oxygen transport framework with the local chemical equilibrium of H₂ selective oxidation to describe the coupled transport and reaction processes in the OPMR. The model’s accuracy and applicability are validated by experiments at various oxygen addition rates under industrial H₂ co-feeding conditions. Under optimized operating conditions, the proposed OPMR achieves a propylene selectivity of 91.05%, comparable to the industrial selectivity benchmark of 91.02%, together with a propane conversion of 37.46%, exceeding the industrial conversion benchmark by 1.81 %age points. This integrated strategy effectively balances over-oxidation suppression with enhanced reaction efficiency, providing an efficient and economically viable pathway toward the industrial implementation of OPDH.