Redox Metal–Support Interaction of CoOx/Ti2O3 to Enhance Catalytic Performance for Hydrodeoxygenation of Anisole

Abstract

This study found that the CoO_x/Ti₂O₃ catalyst showed high activity, selectivity, and stability for hydrodeoxygenation (HDO) of anisole to benzene. Due to the reductivity of Ti₂O₃, a redox reaction occurred between Ti₂O₃ and CoO_x, forming cobalt species with a low oxidation state, such as CoO and metallic Co. These cobalt species on Ti₂O₃ enhanced the catalytic performance for the HDO reaction. On the other hand, CoO_x supported on other supports, including TiO₂, Al₂O₃, SiO₂, and active carbon, was in the form of Co₃O₄ and showed only low catalytic activity. H₂-TPR and H₂-TPD experiments demonstrated that CoO_x supported on Ti₂O₃ was easily reduced to metallic Co, which had the ability to activate H₂. CoO_x/Ti₂O₃ and CoO_x/TiO₂ catalysts were deactivated more or less by partial oxidation of the cobalt species during the HDO reaction. The reduction of the partially oxidized cobalt species was promoted by the redox reaction between the cobalt species and Ti₂O₃, and therefore, CoO_x/Ti₂O₃ showed a much longer catalyst life than CoO_x/TiO₂.