Hydrodeoxygenation of Phenol over Sulfided CoMo Catalysts Supported on a Mixed Al₂O₃-TiO₂ Oxide

In this work, the effect of the mixed Al₂O₃-TiO₂ oxide (Al/Ti=2, named AT2) support on the support-metal interaction in oxide state, its influence on MoS₂ dispersion and its impact on the hydrodeoxygenation of phenol reaction was studied. In contrast with CoMo/Al₂O₃ catalysts, the use of Al₂O₃-TiO₂ as support tuned favorably the support-metal interaction, increasing the availability of easily reducible CoO_X and MoO_X species with octahedral coordination, which are recognized as precursors of the active phase. The lower support-metal interaction strength caused a decrease in the dispersion of MoS₂ phase. Even so, the sulfided CoMo/AT2 catalyst reached 85% higher catalytic activity in the hydrodeoxygenation of phenol than CoMo/Al₂O₃. These increases were explained in terms of the formation of a higher amount of active CoMoS phase, and it is consistent with the increased availability of cobalt promoter for the decoration of MoS₂ edges. CoMo/AT2 catalyst was more resistant to inhibition by CS₂ than CoMo/Al₂O₃ in direct deoxygenation route and hydrodeoxygenation of phenol.