Hydrodeoxygenation of lignin and its model compounds to hydrocarbon fuels over a bifunctional Ga-doped HZSM-5 supported metal Ru catalyst

Hydrodeoxygenation (HDO) of lignin to value-added biofuels and chemicals has a great significance for the advanced utilization of renewable lignocelluloses and the future biobased economy but is always a big challenge. Herein, a Ga-doped HZSM-5 supported metal Ru catalyst (bifunctional Ru/Ga-HZSM-5) exhibited the excellent HDO performance for converting diphenyl ether (DPE) to produce the only product, i.e., cyclohexane, under extremely mild conditions (180 °C, 1 MPa H 2 and 2 h). The oxygen-containing group in DPE was mainly removed through the cleavage of the C-O ether bond, followed by metal- and acid-catalyzed comprehensive hydrogenation and deoxygenation. Further characterization results confirmed that the doping of Ga remarkably enhanced the interaction between the metal Ru and the support. For the depolymerization of real lignin, Ru/Ga-HZSM-5 could not only significantly improve the total liquid yield of lignin, but also convert the oxygen-containing species into the aliphatic hydrocarbons. • A Ga-doped HZSM-5 supported Ru catalyst with strong interaction was prepared. • Efficient HDO of lignin and its model compounds was achieved over Ru/Ga-HZSM-5. • H 2 rather than solvents provided the main hydrogen source in HDO reaction. • Oxygen-containing functionalities could be removed under very mild conditions. • HDO reaction pathway for DPE over Ru/Ga-HZSM-5 was illustrated.