Bio-oil from biomass fast pyrolysis or liquefaction usually consists of phenolic compounds which have high oxygen content compounds (10-50 wt%). Therefore, the oxygen in oil could be removed in the form of water via hydrodeoxygenation (HDO). Catalysts containing W as an active element and Co as a promoter have been used intensively for HDO process. In this present study, unsupported W based sulfide and oxide catalysts were prepared from ammonium tetrathiotungstate (ATTW), ammonium tungstate (ATT) and cobalt nitrate by using a hydrothermal synthesis method involving water, organic solvent and hydrogen. The activity of these catalysts was investigated for hydrodeoxygenation (HDO) of phenolic compounds as the major portion of oxygenated species in bio-oil. In this work, the HDO of phenol was carried out in a batch reactor. The results revealed that HDO of phenol proceeded through two major pathways (hydrogenolysis and hydrogenation) and their products were benzene, cyclohexanone, cyclohexene and cyclohexane. Phenol conversion and product selectivity were strongly dependent on type of promoter and HDO reaction conditions. The CoWS and CoWO catalyst with Co/(W+Co) ratio of 0.50 displayed the highest phenol conversion and the highest selectivity toward cyclohexane, suggesting that the HDO of phenol proceeded through the major pathway of hydrogenation.
