Fast pyrolysis is emerging as a promising route for the production of liquid fuels from biomass. However, pyrolysis derived bio-oil needs to be upgraded prior to its utilization as a fuel and hydrodeoxygenation (HDO) is an important catalytic step in it. Furfural has been considered as one of the most promising platform molecules directly derived from biomass. The hydrogenation of furfural is one of the most versatile reactions to upgrade furanic components to biofuels. For instance, it can lead to plenty of downstream products, such as tetrahydrofurfuryl alcohol, 2-methyltetrahydro furan, lactones, levulinates, cyclopentanone, or diols. Design of suitable catalysts with high activity and selectivity for the HDO process would require detailed understanding of the underlying catalytic reaction mechanism. Since cobalt alumina-based catalysts have been proposed to be the most effective HDO catalysts, the complete reaction network for HDO of furfural, a representative of furanic compounds present in bio-oil, is elucidated in this study on cobalt alumina surface, using Density Functional Theory calculations. Reaction pathways for the formation of Furfuryl alcohol (FA), Tetrahydrofurfuryl alcohol (THFA), Methyltetrahydrofuran(MTHF), Methylfuran (MF), Cyclopentanol, 1,2 and 1,5 pentane diols, Furan and Pentanes are established. Furan ring opening is facile on cobalt alumina surfaces and our calculations predict pentane formation to be thermodynamically and kinetically favoured in the vapour phase hydrodeoxygenation of furfural on cobalt alumina surfaces.
