Effects of calcination temperature on the properties of unsupported Ni-Mo-Al₂O₃ catalysts for hydrodeoxygenation

The un-supported Ni-Mo-Al₂O₃ catalysts were prepared using the thermal decomposition method with nitrate hexahydrate and ammonium paramolybdate as precursors. The evaluation of hydrodeoxygenation activity of the catalysts was conducted in a continuous flow fixed-bed reactor, using the acetic acid and the phenol as probe compound. The catalysts were characterized using specific surface area (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrdmeter (EDS). The effects of calcination temperature on the catalyst crystalline structure, element relative content and activity were investigated emphatically. The results show that the surface area of the catalysts increases and the crystallization degree of catalysts were improved with increasing the calcination temperature. The Ni/Mo/Al radio on surface of the catalysts calcined at 550℃ was optimal, and the catalyst exhibited the highest hydrodeoxygenation activity, and the deoxygenation percentage of the acetic acid was 96.0% at 250℃, 0.4MPa and the deoxygenationa percentage of the phenol was 96.8% at 200℃, 0.3MPa.