Mechanisms of Hydrodeoxygenation Biomass-Derived Lignin to Its Substructure Based Hydrocarbons in Aqueous Phase

The experimental evidence showed that generation of lignin substructure based 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.  While promising, these experimental results point to need for a more fundamental understanding of deploymerization and hydrodeoxygenation reactions that will lead to the development of catalysts suitable for industrial applications. Thus, hydrodeoxygenation of lignin model compounds over the combinations of noble metal catalysts (e.g. Ru/Al₂O₃) and solid acids (e.g. zeolites) in aqueous phase was investigated using density functional theory-based ab initio molecular dynamics simulations. The impetus of this work is to use targeted fundamentals to hone the aqueous phase catalysis of depolymerized reactive lignin from biomass-derived lignin into aliphatic, aromatic and cyclic hydrocarbons.