Modulating Chemical Environments of Metal–Organic Framework-Supported Molybdenum(VI) Catalysts for Insights into the Structure–Activity Relationship in Cyclohexene Epoxidation

• DOI: 10.1021/jacs.1c12421
• Publication Date: 2022-02-18T21:44:25Z
• Authors: Yongwei Chen; Sol Ahn; Mohammad Rasel Mian; Xingjie Wang; Qing Ma; Florencia A. Son; Lifeng Yang; Kaikai Ma; Xuan Zhang; Justin M. Notestein; Omar K. Farha
• Keywords: X-ray absorption spectroscopy

Solid supports are crucial in heterogeneous catalysis due to their profound effects on catalytic activity and selectivity. However, elucidating the specific arising from such remains challenging. We selected a series of metal-organic frameworks (MOFs) with 8-connected Zr6 nodes as deposit molybdenum(VI) onto study pore environment topology resulting Mo-supported catalysts. As characterized by X-ray absorption spectroscopy (XAS) single-crystal diffraction (SCXRD), we modulated chemical environments deposited Mo species. For Mo-NU-1000, species monodentately bound were anchored microporous c-pore, but for Mo-NU-1008 they mesopore Mo-NU-1008. Both monodentate bidentate modes found Mo-NU-1200. Cyclohexene epoxidation H2O2 was probed evaluate support effect unveil structure-activity relationships. SCXRD XAS studies demonstrated atomically precise structural differences binding motifs over course cyclohexene epoxidation. No apparent change observed whereas mode Mo-NU-1200 evolved new between two adjacent oxygen atoms node. This work demonstrates great advantage using MOF constructing catalysts an active relationships reactions.