Synergistic effect of active metal–acid sites on hydrodeoxygenation of lignin-derived phenolic compounds under mild conditions using Ru/C-HPW catalyst

Hydrodeoxygenation (HDO) is an indispensable reaction in the field of fuel and chemical production, and the synergistic effect of metal–acid sites in the catalyst makes great influence to it. Herein, a bifunctional catalyst of Ru/C combined with phosphotungstic acid (HPW) was employed for the hydrodeoxygenation (HDO) of lignin-derived compounds to make full use of the synergistic effect of active metal–acid sites. HPW possessed a temperature-controlled phase-transfer behavior, which made it dispersed well on the surface of Ru/C catalyst and resulted in a close integration of acid site with metal site. Ru/C-HPW catalyst also owned the advantage of high reaction rate and good recyclability, which exhibited no obvious catalytic activity loss after 5 runs. Lignin-derived phenolic compounds including monomers and dimers enabled to obtain an efficient transformation to cycloalkanes at the temperature of 200 °C. Moreover, a high HDO reaction efficiency of raw lignin-oil was also observed in this study, with the increasing hydrocarbon content from 5.5% to 78.9%. This novel catalytic system can achieve a high HDO efficiency under mild conditions.