Tandem propane dehydrogenation and surface oxidation catalysts for selective propylene synthesis

Direct propane dehydrogenation (PDH) to propylene is a desirable commercial reaction but is highly endothermic and severely limited by thermodynamic equilibrium. Routes that oxidatively remove hydrogen as water have safety and cost challenges. We coupled chemical looping-selective hydrogen (H₂) combustion and PDH with multifunctional ferric vanadate-vanadium oxide (FeVO₄-VO_x) redox catalysts. Well-dispersed VO_x supported on aluminum oxide (Al₂O₃) provides dehydrogenation sites, and adjacent nanoscale FeVO₄ acts as an oxygen carrier for subsequent H₂ combustion. We achieved an integral performance of 81.3% propylene selectivity at 42.7% propane conversion at 550°C for 200 chemical looping cycles for the reoxidization of FeVO₄. Based on catalytic experiments, spectroscopic characterization, and theory calculations, we propose a hydrogen spillover-mediated coupling mechanism. The hydrogen species generated at the VO_x sites migrated to adjacent FeVO₄ for combustion, which shifted PDH toward propylene. This mechanism is favored by the proximity between the dehydrogenation and combustion sites.