Phenol Hydrodeoxygenation over a Reduced and Sulfided NiMo/γ-Al₂O₃ Catalyst

Phenol hydrodeoxygenation over a commercial NiMo/γ-Al₂O₃ catalyst in a reduced and sulfided form was investigated. Crushed particles (0.165–0.315 mm) were employed to determine the intrinsic reaction kinetics in either case. The internal diffusion phenomena within the catalytic particle of commercial dimensions and forms were also studied, and the phenol effective diffusion coefficient and effectiveness factor for both forms of the catalyst were determined. The sulfided form was active to phenol conversion at higher temperatures in comparison to the reduced form. As indicated from the data acquired by phenol, cyclohexanol, and benzene hydrotreatment experiments, phenol hydrodeoxygenation over the reduced and sulfided NiMo/γ-Al₂O₃ catalyst follows both parallel pathways: the direct deoxygenation (DDO) and the stepwise hydrogenation (HYD). The stepwise hydrogenation (HYD) pathway is favored under the tested conditions. In the presence of the reduced catalyst, cyclohexanol and cyclohexane are the main products and the selectivity toward cyclohexanol is high at low temperatures. In the presence of the sulfided catalyst, cyclohexane was the main hydrotreatment product together with a small amount of benzene.