Unveiling and understanding the remarkable enhancement in the catalytic activity by the defect creation in UIO-66 during the catalytic transfer hydrodeoxygenation of vanillin with isopropanol

The catalytic transfer hydrodeoxygenation of vanillin is generally achieved using noble metal-based catalysts. Herein, we report a mechanistic investigation of the catalytic transfer hydrodeoxygenation (CTHDO) of vanillin over a defect-induced UIO-66 MOF. The remarkable enhancement in the CTHDO of vanillin was due to the unique structural features of the defect-induced UIO-66 MOF. The defect creation was confirmed using PXRD, N2-sorption, FT-IR, XPS, HRTEM, dissolution 1H NMR, and quantified by TGA. The linker deficiency created Lewis acid and dynamic Bronsted acid and was confirmed by the NH3-TPD and CD3CN drift FT-IR. The periodic density functional theory calculations were conducted to elucidate the reaction pathway and mechanism. Density function theory, poisoning studies, control reactions, and quantified defect sites elucidate the active sites of the UIO-66def involved in the CTHDO of vanillin with isopropanol. The catalyst was efficiently recycled and retained its activity and structural features after multiple recycles.