Synergistic Catalysis and Deactivation Analysis of Ru/ZnO/C in Hydrogen-Transfer Reductive Catalytic Fractionation of Poplar Wood

A series of metal oxide promoters were incorporated into the Ru/C catalyst by the impregnation method. Notably, the addition of ZnO demonstrated a pronounced promoting effect on the hydrogen-transfer reductive catalytic fractionation (RCF) of poplar wood. The 1 wt% Ru/ZnO/C catalyst achieved a total phenolic monomer yield of 34.2 %, even surpassing the commercial 5 wt% Ru/C catalyst despite its lower Ru loading. This enhancement stems from the synergistic interaction between ZnO-derived Lewis acid sites and Ru metal nanoparticles. Furthermore, the influences of key parameters such as reaction temperature, catalyst dosage, molar ratio of ZnO to Ru and solvent on the RCF activity were systematically investigated. During recycling process, the Ru/ZnO/C catalyst exhibited gradual deactivation, accompanied by an increased proportion of unsaturated phenolic monomers in the product distribution, indicating a decline in hydrogenation capacity. The deactivation behavior of the Ru/ZnO/C catalyst was characterized using BET, XPS, TEM, and ICP techniques, and tentative regeneration attempts were employed on the spent catalyst.