Aqueous phase hydrodeoxygenation of biomass-derived lignin to its substructure based hydrocarbons and chemicals

Leveraging funded projects from DARPA, NSF, DOE-NREL, and Sun grant-DOT, we have successfully demonstrated novel principles of catalytic upgrading of biomass-derived lignin to biofuels and chemicals. Combinations of noble metal catalysts (e.g. Ru/Al₂O₃, Ru/C, Ru/graphene) in the presence of various acids (e.g. ZnCl₂, AlCl₃ and zeolites, including H⁺-ZSM-5, H⁺-Mordenite, H⁺-Y and Beta- ZSM-5) were tested for hydrodeoxygenation (HDO) activity of the different source of technical lignins (e.g. corn stover, poplar wood, and lodgepole pine). Our results showed generation of hydrocarbon (C₇-C₁₈) derivatives from biomass-derived lignin with high selectivity of C₁₂-C₁₈ cyclic structure hydrocarbons via the cleavage of C–O–C bonds without disrupting the C–C linkages (8–8', 8–5' and 5'–5''/β–O–4') in the lignin structure. The results lead us to believe that reactivity and structural features of technical lignins are key factors of catalyst selection in presence of hydrogen for producing a wide variety of hydrocarbon species (aliphatic and aromatic) that are commonly found in jet fuel blend stocks. In addition, the reactivity of lignin and its interactions with the chemical catalysis systems were studied to reveal the principles of the reaction mechanism, its control and applications.