Facile synthesis of Pd@MOF catalyst and its application for highly selective catalytic reduction of biomass-derived compounds towards tunable products

High selective reduction of biomass-derived compounds is still challenging especially under mild reaction con-ditions using heterogeneous catalysis. Here, we reported a one-step synthesis method that successfully prepared highly dispersed Pd species immobilized on NH2-MIL-125 (Ti) frameworks which were named Pd@MOF and used as a highly efficient hydrodeoxygenation catalyst for the reduction of vanillin to 2-methoxy-4-methyl phenol in excellent yield with an atm of H2 pressure at room temperature. Pd(PPh3)4 was dispersed in a sol-vent containing the MOFs precursors. Among them, the PPh3 ligand could be oxidized to remove and Pd particles in situ doped in MOFs framework during the solvothermal process. Compare to immersed-Pd/MOF and Pd-MOF, Pd@MOF has higher catalytic efficiency because the smaller Pd particles encapsulated in MOFs inhibit Pd over oxidation. Moreover, the different reduction products could be obtained selectively by tuning reaction time, and the catalyst realized to catalyze the highly effective transformation of a variety of biomass-derived compounds.

Automated summary

In this study, highly dispersed Pd species were successfully immobilized on NH2-MIL-125 (Ti) frameworks through a one-step synthesis method, forming Pd@MOF. The Pd@MOF catalyst showed high efficiency in the hydrodeoxygenation reaction of vanillin to 2-methoxy-4-methyl phenol at room temperature under 1 atm of H2 pressure. The smaller Pd particles encapsulated in MOFs inhibited Pd over oxidation and allowed for the selective production of different reduction products by tuning the reaction time. This catalyst also exhibited high effectiveness in the transformation of various biomass-derived compounds.