Title : Solar-driven selective propylene oxidation over size- and core-controlled copper oxide catalysts
Abstract:
The sustainable production of high-value chemical intermediates remains a central challenge in modern catalysis. Propylene oxide and acrolein, critical building blocks in chemical and biochemical manufacturing, are conventionally produced via energy-intensive, high-temperature (>200 °C) processes that rely on fossil-fuel-driven catalysis and suffer from limited selectivity. Solar-driven photocatalysis presents a compelling alternative, enabling selective oxidation under mild conditions without external heating, yet a light-driven route to these oxygenates remains largely underexplored. This study investigates the photocatalytic partial oxidation of propylene over copper oxide-based photocatalysts under simulated solar irradiation (300–2000 nm) in a packed-bed photoreactor. Measurable propylene conversion was achieved, with product analysis confirming propylene oxide and acrolein as primary products and CO₂ as a secondary over-oxidation product. Increasing light intensity enhanced overall conversion while simultaneously influencing product distribution, reflecting a competition between selective and deep oxidation pathways that can be modulated through irradiation conditions.
Mechanistic investigation revealed that catalyst performance is governed by both surface state and light-matter interactions. The nonlinear dependence of activity on irradiation intensity indicates that the reaction is not driven solely by photothermal heating but also involves charge-carrier-mediated photocatalytic processes intrinsic to copper oxide surfaces, whose reversible shifts in oxidation state under illumination play a key role in directing selectivity. Understanding this light-controlled redox behavior offers a design handle for steering selectivity toward the desired oxygenates rather than complete oxidation to CO₂. Collectively, these findings establish copper oxide-based photocatalysts as promising candidates for solar-driven propylene oxidation, offering a scalable pathway toward energy-efficient and sustainable epoxide and oxygenate production.
