Selective breaking of C−O bonds in hydrodeoxygenation of 4-methylphenol over CoMoS/ZrO₂

CoMoS/ZrO₂ catalysts with different Co-Mo atomic ratios (0.25, 0.30, 0.35, 0.40 and 0.45) and Co-Mo loading amounts (2.35%, 4.36%, 7.48% and 10.79%) were prepared by incipient wetness impregnation. These catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (H₂-TPR), nitrogen adsorption/desorption and X-ray photoelectron spectroscopy (XPS). 4-methylphenol was used as model compound for hydrodeoxygenation reaction. The result showed that when the atomic ratio of Co-Mo (Co/Co + Mo) was 0.30 and the Mo loading amount was 4.36%, the highest hydrogenation activity was observed. The conversion of 4-methylphenol was up to 99.86% and the selectivity of main product toluene reached to 87.85%. The formation of CoMoO₄ was unfavourable to the formation of toluene. An appropriate interaction between Co-Mo and ZrO₂ was required.