Catalytic Deoxygenation of Bio-Oil Model Compounds over Acid-Base Bifunctional Catalysts...

摘要

Fast pyrolytic conversion of biomass into bio-oil provides a potential pathway for producing hydrocarbon fuels from renewable resources. However, bio-oil produced in this manner has a high oxygen content leading to low energy density, instability, and corrosivity. Acid and base catalysts have been examined for their efficacy in oxygen removal during biomass fast pyrolysis, since they can catalyze C-O and C-C bond cleavage through dehydration, decarboxylation, and decarboxylation reactions. Herein, the authors describe the catalytic deoxygenation of eight carbohydrate-derived bio-oil model compounds using a fixed bed reactor employing silica-aluminas and zirconias as well as an acid-base bifunctional catalyst prepared by acid treatment of a natural mineral, serpentine (approximate composition: Mg3Si2O5(OH)4) (Table 1). Characterization of the serpentine catalyst revealed that the number of acidic and basic sites increased after the acid treatment largely due to an increase in surface area. However, stronger acid sites were also introduced by the formation of bridged hydroxyl groups between a Si atom and a heteroatom. In comparison with the physical mixtures, the bifunctional catalyst had a higher activity for aldol condensation (Figure 1).