Controlled hydrodeoxygenation of lignin-derived anisole over supported Pt on UiO-66 based-catalysts through defect engineering approach

Abstract

Herein, we report a series of Platinum (Pt) phase loading on the highly porous channels of the metal-organic framework (MOF) introduces open Lewis acid sites through a defective-effect, which are crucial for selective hydrodeoxygenation (HDO) process of anisole. Thereby, UiO-66 (University of Oslo) based-supports were synthesized by a microwave-assisted solvothermal method using isophthalic acid (IPA) as a mixed linker at different concentrations. The total amount of acid sites in the defective UiO-66 samples was 1.5–2.5 times higher than that of pristine UiO-66, with the corresponding linker deficiency increasing to 1.94 as the concentration of the mixed linker was increased to 30% in the starting material. Consequently, the 3Pt/defective UiO-66 catalysts achieved better catalytic performance for the anisole HDO process, with a turn-over frequency (TOF) value of the Pt site being 2–3 times higher than that of the pristine 3Pt/UiO-66. Notably, the reaction pathway shifted from producing cyclohexane to producing benzene through the demethoxylation of anisole. This resulted in an increase in the TOF value based on the benzene yield by over 10 times as the defective linker content increased from 0 to 20%. The catalytic stability was also investigated using a series of Pt/defective UiO-66 catalysts.