Preparation and hydrodeoxygenation properties of CoMo/ZrO₂-Al₂O₃ catalysts

A series of ZrO₂-Al₂O₃ mixed oxides with different ZrO₂ contents were prepared by using ZrOCl₂·6H₂O and Al₂(SO₄)₃ as raw materials through ultrasonic coprecipitation method. CoMo/ZrO₂-Al₂O₃ catalysts with 6.0% cobalt and 16.0% molybdenum loading were prepared by impregnation method. The BET， XRD， H₂-TPR and NH₃-TPD characterization results showed that the ZrO₂-Al₂O₃ mixed oxide support had high surface area, large pore volume and pore diameter. The surface area of the ZrO₂-Al₂O₃ mixed oxide support decreased with the increase of ZrO₂ content in the mixed oxides. The active component of CoMo/ZrO₂-Al₂O₃ catalyst was highly dispersed over the ZrO₂-Al₂O₃ and the amount of the loaded CoMo was closed to the monolayer dispersion threshold. Compared to the CoMo supported on the single alumina or zirconia catalysts, the surface of the CoMo/ZrO₂-Al₂O₃ catalyst had stronger reduction ability and more active acid sites, which led to its higher catalytic activity and benzene selectivity in the hydrodeoxygenation of phenol.