Hydrodeoxygenation of phenol and biomass fast pyrolysis oil (bio-oil) over Ni/WO₃-ZrO₂ catalyst

The hydrodeoxygenation of pure phenol in hexane solution and of catalytic biomass fast pyrolysis oil (bio-oil) over 10 %Ni/ZrO₂ and 10 %Ni/WO₃-ZrO₂ catalysts was investigated in the present study, at relatively mild conditions (ca. 50−250 °C, 30 bar H₂) in a continuous flow high-pressure fixed bed reactor. The catalysts were characterized for their structural, porosity, redox and acidic/basic properties which were used to rationalize the observed catalytic performance. The 10 %Ni/ZrO₂ catalyst was very active and selective towards cyclohexanol in the phenol HDO experiments (100 % conversion and selectivity at 110 °C) but the enhanced acidity offered by the addition WO₃ in ZrO₂ was necessary to succeed a complete hydrodeoxygenation of phenol to cyclohexane at the low temperature of 150 °C with the 10 %Ni/WO₃-ZrO₂ catalyst. This catalyst was also proven very active in the hydrodeoxygenation of the catalytic bio-oil which consisted of mono-aromatics (i.e. alkyl-benzenes) and PAHs (mainly naphthalenes and indenes), and fewer oxygenated compounds (i.e. alkyl-phenols and benzofurans), providing a product oil containing mainly alkyl-cycloalkanes and fewer alkyl-benzenes, at the mild conditions of 210 °C and 30 bar H₂.