(678h) Enhanced Aromatic Selectivity during Deoxygenation of Phenolic Model Compounds over Bifunctional Catalysts

Phenolic compounds are produced either from fast pyrolysis of lignocellulosic biomass to produce biooils or from depolymerization of woody or grass lignins. To efficiently convert lignin to meet the specifications of either transportation fuels or aromatic chemical precursors, catalytic upgrading via hydrodeoxygenation (HDO) is a necessary step. Among the diversity of phenolic compounds present in either biooil or depolymerized lignin, guaiacol is often used as a model compound, since it includes both phenolic (Ph−OH) and methoxy (−OCH) groups, representing a large number of oxygen containing components in these sources. In the present work, various bifunctional catalysts with metal and acidic sites were synthesized and evaluated for guaiacol HDO performance with the target of maximizing aromatic hydrocarbon selectivity. It was found that under optimum operating conditions, guaiacol is fully deoxygenated with stable conversion and selectivity profiles over bifunctional catalysts, leading to a maximum aromatic hydrocarbon yield of ~35%. Full deoxygenation of phenolic compounds to aromatic hydrocarbons with enhanced selectivity is demonstrated with bimetallic catalysts supported on mesoporous silicates with tunable acidity. The results have both fundamental and practical implications for designing catalysts and processes for selective deoxygenation of phenolic compounds in either biooil or depolymerized lignin mixtures.