Bio-oil upgrading over platinum catalysts using in situ generated hydrogen

The liquid phase upgrading of a model bio-oil was studied over a series of supported Pt catalysts. Pt/Al2O3 showed the highest activity for deoxygenation, the oxygen content of the model oil decreasing from an initial value of 41.4 wt% to 2.8 wt% after upgrading. GC-MS analysis of the oil showed it to be highly aromatic. the major components corresponding to alkyl-substituted benzenes and cyclohexanes. CO2 was formed as the major gaseous product, together with lower yields of H-2 and C-1-C-6 hydrocarbons. Based on the product distribution, a reaction scheme is proposed in which light oxygenates predominantly undergo reforming to CO2 and H-2, with C-O bond breaking/hydrogenation (to afford alkanes) as a minor pathway. In a parallel process, aromatics undergo C-O cleavage/hydrogenation, affording benzenes and cyclohexanes. The highly alkylated nature of the products appears to be a consequence of the acidic nature of the reaction medium, favoring the occurrence of aromatic electrophilic substitution reactions. (C) 2009 Elsevier B.V. All rights reserved.