Direct electrochemical propylene epoxidation over amorphized perovskite oxide in non-halogenated aqueous electrolyte
摘要
Industrial routes for propylene oxide and propylene glycol production involve either explosive hydrogen peroxide or corrosive chlorine-containing reagents, which produce hazardous halogenated by-products. Direct aqueous electrooxidation is a safe and sustainable alternative that uses water as an oxygen source at a catalytically competent anode. Until now, the direct aqueous route has only been demonstrated on noble metals (Pd, Pt, Au, Ag), which are unstable unless operated in halogenated electrolytes. Here we have developed a noble metal- and halogen-free catalytic system using a cobalt-based perovskite oxide with a Faradaic efficiency of 40% toward propylene oxide and propylene glycol, maintained over 24 h of operation. Kinetic analysis revealed potential-dependent rate-limiting steps involving electrochemical oxygen species generation and thermochemical oxygen transfer to propylene. This work establishes a cost-effective and safe synthetic route with earth-abundant non-noble metal-based catalysts, not only for propylene epoxidation but also for other heterogeneous oxygen-transfer reactions.