Tandem propane dehydrogenation and surface oxidation catalysts for selective propylene synthesis.
basic_science · Level V
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- Record sourced from PubMed, PMID 37498988.
- Also identified by DOI 10.1126/science.adi3416.
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Abstract
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 (H<sub>2</sub>) combustion and PDH with multifunctional ferric vanadate-vanadium oxide (FeVO<sub>4</sub>-VO<i><sub>x</sub></i>) redox catalysts. Well-dispersed VO<i><sub>x</sub></i> supported on aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) provides dehydrogenation sites, and adjacent nanoscale FeVO<sub>4</sub> acts as an oxygen carrier for subsequent H<sub>2</sub> 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 FeVO<sub>4</sub>. Based on catalytic experiments, spectroscopic characterization, and theory calculations, we propose a hydrogen spillover-mediated coupling mechanism. The hydrogen species generated at the VO<i><sub>x</sub></i> sites migrated to adjacent FeVO<sub>4</sub> for combustion, which shifted PDH toward propylene. This mechanism is favored by the proximity between the dehydrogenation and combustion sites.