Role of oxygen species and active phase of CuCeZrOx prepared with bacterial cellulose for toluene catalytic oxidation

Abstract

The present study investigates the active phases and the role of oxygen species in the toluene oxidation process over CuCeZrOx catalysts prepared with bacterial cellulose (BC), and compares them with nitric acid pickling CuCeZrOx-BC(H) and CeZrOx-BC catalysts. The investigation is carried out using in-situ DRIFT, O₂-TPD, H₂-TPR, XRD, and TEM techniques. Our findings suggest that dispersed CuO species on the catalyst surface, Cu-Ce-Zr-O, and Ce-Zr-O solid solutions are active for toluene oxidation over CuCeZrOx-BC, with corresponding activities decreasing successively. The in-situ DRIFT results demonstrate that gaseous oxygen facilitates the chemisorption of toluene on active oxygen species, forming benzoyl oxide species and partially oxidizing the absorbed intermediates to benzyl alcohol at room temperature. Furthermore, lattice oxygen is experimentally found to be involved in the deep oxidation of toluene, and the lattice oxygen present in dispersed CuO species dominates the toluene oxidation process over CuCeZrOx-BC.