Direct propylene epoxidation on stabilized partially oxidized copper

Direct epoxidation of propylene using molecular oxygen remains as one of the holy grails in catalysis. While silver-based catalysts are highly effective for ethylene and butadiene epoxidation, their performance toward propylene oxide has remained lackluster for almost a century. Copper-based catalysts have been explored, but they rapidly deactivate. We demonstrate that a mixed-oxide Cu–Ga delafossite catalyst exhibits high performance and stability for propylene epoxidation. Operando multimodal characterization reveal the stabilization of metastable partially oxidized copper centers on the delafossite, without altering its structure. Combined experimental and theoretical work indicate that Cu⁺ sites generate and stabilize reactive peroxides that react to form propylene oxide. These findings underscore the potential of tailored mixed-oxide catalysts as robust platforms for selective partial oxidation reactions.