Variation of Catalyst Structure and Catalytic Activity During Catalyst Preparation for Catalytic Ozonation of Heavy Oil Produced Water

Ni, Cu, and Ni-Cu metal oxides supported on granular activated carbon (GAC) were synthesized and used in catalytic ozonation of heavy oil produced water. The effect of preparation conditions on their catalyst composition, catalyst structure, and catalytic activity was investigated. The catalyst structure was characterized by X-ray power diffraction (XRD). The results revealed that the Ni-Cu/GAC has the highest catalytic activity, followed by Cu/GAC and Ni/GAC. Metal oxide loading rate depended on impregnation process, whereas dispersion of metal oxides was controlled by calcination process. The XRD analysis showed that the principal active phase was Cu2O for Cu/GAC and NiCu/GAC catalyst and NiO for Ni/GAC catalyst. The most active plane was Cu2O(200) and then followed by Cu2O(110) and Cu2O(111) for Cu-supported catalysts. Higher calcination temperature and time favored the generation of Cu2O but increased the crystalline diameter. It also suggested that promoting the generation of NiO and Cu2O phase and reducing the crystalline diameter could improve the catalytic activity. During Ni-Cu/GAC preparation, existence of Ni(NO3)(2) could accelerate the adsorption of Cu(NO3)(2), promoting the generation of Cu2O, and improve the dispersion of Cu2O phase.