Comprehensive Investigation of the Biomass Derived Furfuryl Alcohol Oligomer Formation over Metal Oxide Catalysts

The conversion of lignocellulosic biomass into fuels has been investigated as a result of increasing demand for petroleum oil and environmental concerns. Furfuryl alcohol (FA), which is produced from furfural derived from a selective dehydration of xylose, is an attractive intermediate chemical for the production of template chemicals, such as levulinic acid and alkyl levulinate and FA polymer (FAP). FAP can be easily produced from FA monomer using strong mineral acid and can produce ordered carbons through the pyrolysis, vapor deposition and carbonization methods. Although mineral acids showed higher conversion of FA with hydrothermal treatment, catalysts should be replaced by heterogeneous solid acid catalysts because of the difficulty of recycling. The feasibility of using metal oxide catalyst (Al₂O₃, ZrO₂, TiO₂, Nb₂O₅, WO₃ and MoO₃), was investigated in the FA oligomerization reaction in the liquid phase under mild experimental conditions, 100^oC and ambient pressure, for 0.5~24 hours. Five dimers (2,2’-Difurylmethane, 2-(2-furylmethyl)-5-methylfuran, Difurfuryl ether, 4-Furfuryl-2-pentenoic acid γ-lactone, 5-Fufuryl-furfuryl alcohol) and two trimmers (2,5-Difurfurylfuran and 2,2’-(Furylmethylene)bis(5-methylfuran)) were observed in GC and GC/MS. A strong C=C and C=O bands observed in the Raman and IR spectra, respectively, provided the formation of a conjugated diene and diketone structure during the reaction. In order to acquire the best yield and selectivity to dimers and trimers, water effect and catalysts loading effect were studied in certain cases correspondingly. The separated FA oligomer solution was concentrated by using distillation under 180^oC. Obtained FA oligomers can be used to produce alternative C9~C15 biofuel with further hydrodeoxygenation (HDO) reaction.