Relay activation H2 over Pd/MnOx-VC for efficient aqueous-phase hydrogenation of concentrated 5-hydroxymethylfurfural to 2,5-bis(hydroxymethyl)tetrahydrofuran under low temperatures

The selective hydrogenation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF) under mild conditions holds great significance for sustainable chemical production. However, this process remains hindered by challenges such as the instability of HMF in aqueous media and the insufficient efficiency of H 2 activation. Herein, a Pd catalyst supported on oxygen-vacancy–enriched MnO x -VC (Pd/MnO x -VC) is developed, featuring highly dispersed Pd/PdO heterostructures with abundant Pd–O–Mn interfacial active sites. Notably, Pd/MnO x -VC offered a high BHMTHF formation rates of 366.5 mol BHMTHF ·mol Pd −1 ·h −1 in water under mild conditions. Moreover, the catalyst was able to efficiently convert both purified and crude HMF at high concentrations (≥ 10 wt%), achieving BHMTHF yields exceeding 90 % in either batch or continuous-flow reactor under low temperatures (30–60 °C), underscoring its potential for industrial application. Mechanistic studies revealed that the relay activation of H 2 over Pd nanoparticles and adjacent Pd–O–Mn sites generates polarized H δ⁺ –H δ⁻ pairs, which primarily contributed to the outstanding activity of Pd/MnO x -VC. This work highlights the importance of interfacial site engineering in designing high-performance catalysts for HMF hydrogenation.