Highly Efficient and Stable Ni-Cs/TS-1 Catalyst for Gas-Phase Propylene Epoxidation with H2 and O2

The development of non-noble metal catalysts for gas-phase propylene epoxidation with H2/O2 remains challenging due to their inadequate activity and stability. Herein, we report a Cs+-modified Ni/TS-1 catalyst (9%Ni-Cs/TS-1), which exhibits unprecedented catalytic performance, giving a state-of-the-art PO formation rate of 382.9 gPO·kgcat−1·h−1 with 87.8% selectivity at 200 °C. The catalyst stability was sustainable for 150 h, far surpassing reported Ni-based catalysts. Ni/TS-1 exhibited low catalytic activity. However, the Cs modification significantly enhanced the performance of Ni/TS-1. Furthermore, the intrinsic reason for the enhanced performance was elucidated by multiple techniques such as XPS, N2 physisorption, TEM, 29Si NMR, NH3-TPD-MS, UV–vis, and so on. The findings indicated that the incorporation of Cs+ markedly boosted the reduction of Ni, enhanced Ni0 formation, strengthened Ni-Ti interactions, reduced acid sites to inhibit PO isomerization, improved the dispersion of Ni nanoparticles, reduced particle size, and improved the hydrophobicity of Ni/TS-1 to facilitate propylene adsorption/PO desorption. The 9%Ni-Cs/TS-1 catalyst demonstrated exceptional performance characterized by a low cost, high activity, and long-term stability, offering a viable alternative to Au-based systems.