Carboxyl‐Decorated UiO‐66 Supporting Pd Nanoparticles for Efficient Room‐Temperature Hydrodeoxygenation of Lignin Derivatives

Abstract Hydrodeoxygenation (HDO) of lignin derivatives at room‐temperature (RT) is still of challenge due to the lack of satisfactory activity reported in previous literature. Here, it is successfully designed a Pd/UiO‐66‐(COOH) 2 catalyst by using UiO‐66‐(COOH) 2 as the support with uncoordinated carboxyl groups. This catalyst, featuring a moderate Pd loading, exhibited exceptional activity in RT HDO of vanillin (VAN, a typical model lignin derivative) to 2‐methoxyl‐4‐methylpheonol (MMP), and >99% VAN conversion with >99% MMP yield is achieved, which is the first metal‐organic framework (MOF)‐based catalyst realizing the goal of RT HDO of lignin derivatives, surpassing previous reports in the literature. Detailed investigations reveal a linear relationship between the amount of uncoordinated carboxyl group and MMP yield. These uncoordinated carboxyl groups accelerate the conversion of intermediate such as vanillyl alcohol (VAL), ultimately leading to a higher yield of MMP over Pd/UiO‐66‐(COOH) 2 catalyst. Furthermore, Pd/UiO‐66‐(COOH) 2 catalyst also exhibits exceptional reusability and excellent substrate generality, highlighting its promising potential for further biomass utilization.