An Electrocatalytic/Heterogeneous Catalytic Cascade for Selective Production of Propylene Oxide via Anodic H ₂ O ₂ Generation

Propylene oxide, a key intermediate with wide applications in the plastics industry, is still mainly produced by energy-intensive and environmentally non-sustainable processes. Electrochemically assisted epoxidation of propylene is emerging as a sustainable and atom-efficient method for highly selective synthesis of propylene oxide. Here, we introduce a cascade strategy that combines anodic H₂O₂ generation with propylene epoxidation at a porous layer of immobilized titanium silicate (TS-1). A ZnWO₄ electrocatalyst was developed for efficient anodic H₂O₂ generation. To maximize local reactant concentrations, we designed an integrated TS-1-immobilized gas diffusion layer, which facilitates rapid propylene transport to the triple-phase boundaries, while preventing TS-1 loss and avoiding separation issues common in solution-phase heterogeneous catalytic systems. Furthermore, an acetonitrile-bicarbonate containing electrolyte system was optimized to facilitate direct utilization of H₂O₂ for propylene epoxidation, leading to 98% H₂O₂ utilization efficiency and over 97% selectivity for propylene oxide. This work offers a safer and greener alternative for propylene oxide production and broadens the application of electrochemically generated H₂O₂ from water oxidation for selective oxygenation reactions.