Alkali Metal-Promoted Au/TS-1 Bifunctional Catalyst for Highly Efficient and Stable Gas-Phase Propylene Epoxidation with H2 and O2 via In Situ-Generated H2O2

Developing effective catalysts for the epoxidation of propylene with H2 and O2 holds significant scientific and industrial significance. This study synthesized a series of Au/TS-1 catalysts modified with alkali metals (Na+, Cs+) and carefully examined their impact on gas-phase propylene epoxidation, with particular attention to the role of anions. The optimal Au–CsC(1:10)/TS-1 catalyst (Cs2CO3 modified, Au/Cs molar ratio = 1:10) achieves a propylene conversion of 16.8%, a PO selectivity of 88.5%, an H2 efficiency of 40.8%, a record PO formation rate of 383.9 gpo·kgcat−1·h−1, and unprecedented long term stability (>380 h without deactivation). To the best of our knowledge, no previous study has simultaneously achieved such balanced and outstanding performance across all these key indicators. Comprehensive characterization reveals that Cs+ modification suppresses side reactions and coke formation, increases microporosity, tunes surface acid–base properties and hydrophobicity, restricts Au particle size, and stabilizes both Au0 and tetra coordinated Ti sites, thereby inhibiting H2O2 decomposition and PO isomerization while greatly enhancing reaction efficiency. This holistic advancement represents a significant leap forward for Au based catalysts in gas phase propylene epoxidation, offering both a theoretical foundation and practical guidance for the development of high performance epoxidation catalysts.