Accelerated Zeolite Defect Healing Suppresses Oxygen-Containing Species Trapping for Tandem Propene Epoxidation

Abstract Selective oxidation of chemical feedstocks with in situ-generated H2O2 offers a sustainable route to high-value oxygenates, yet such tandem catalysis is often fundamentally limited by the trapping of oxygen-containing species, including H2O2-derived intermediates and oxygenated products in zeolite microenvironments, where they undergo nonproductive decomposition and side reactions. Herein, we overcome this limitation by accelerating titanosilicalite hydroxyl defect healing through intensified nucleation and subsequent accelerated crystal growth. The resulting defect-healed microenvironment facilitates the transport of in situ-generated H2O2 between bifunctional active sites while suppressing its nonproductive decomposition to H2O. Moreover, it accelerates product propylene oxide (PO) desorption by weakening hydrogen bond interactions between PO and hydroxyl defects, thereby suppressing ring-opening and overoxidation side reactions. Consequently, the defect-healed Au/TS-1 catalyst exhibits a 1.8-fold enhancement in the PO formation rate and a 2.1-fold increase in Au-based productivity. This defect-healing strategy is broadly applicable to titanosilicates, aluminosilicates, and pure-silica zeolites and can be readily extended to a 10 L scale process, delivering reductions of 21% in production cost and 54% in carbon emissions compared with conventional TS-1 synthesis. Overall, this work establishes a sustainable, scalable, and cost-effective route for zeolite defect healing and provides a general strategy to overcome the long-standing transport-decomposition trade-off in tandem catalysis with in situ-generated H2O2.