Unsupported Ni-Mo Composite Oxide Catalysts Prepared by Sol-gel Method for Hydrodeoxygenation

Unsupported Ni-Mo composite oxide catalysts were successfully prepared by the sol-gel method with citric acid as a complex agent. The catalysts were characterized using N₂ adsorption-desorption, X-ray diffraction (XRD) and temperature programmed desorption (NH₃-TPD). The effects of Mo/Ni molar ratio and reaction temperature on the hydrodeoxygenation activity of the catalysts were investigated emphatically using acetic acid and phenol as probe compounds. The results showed that the catalysts prepared by the sol-gel method can possess higher specific surface area and the double mesoporous structure. The β-NiMoO₃ phase determined by XRD was existed in the catalysts. For Mo/Ni molar ratios between 0.0 ~ 0.8, the pore volume, the specific surface area, the medium strong acidity and hydrodeoxygenation activity of the catalyst are not monotonically increasing functions of Mo/Ni ratio. The catalyst with Mo/Ni ratio of 0.6 exhibited the highest hydrodeoxygenation activity. At 0.3MPa, the deoxygenation percentage of the phenol was 99.0% at 210°C and 99.9% at 270°C for the acetic acid, respectively.