Lewis acid-base modulation for efficient CO2 oxidative propane dehydrogenation: A case study of a La-modified binuclear Feoxo site

Abstract

CO2 oxidative propane dehydrogenation to propylene (CO2-ODH) is promising for propylene production and CO2 utilization. Developing an efficient bifunctional CO2-ODH site capable of activating C–H and C=O bonds with inhibited C–C scission capacity remains a challenge. This work describes a La-modified binuclear Feoxo (La-Feoxo) site stabilized on a silicalite-1 support; it achieves 32.7% propane conversion (1.72 times higher than the direct propane dehydrogenation [PDH] counterpart) with 83.2% propylene selectivity. The promising CO2-ODH performance, attributed to the appropriate FeOx dispersion and La modification, balances the acid-base property, which helps stabilize key HCOO∗ intermediates toward enhanced CO2-assisted H removal efficiency. The inferior CO2-ODH performance of isolated Feiso and clustered Fe4O6 was rationalized by insufficient CO2 activation and huge dry reforming contribution, respectively. We propose H2 dissociative binding energy and O∗ binding energy as descriptors for the acid-base strength and catalytic CO2 dissociation capacity in that they predict the CO2-ODH and extent of propane dry reforming.