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Catalytic Wet Peroxide Oxidation of Phenol Over CaO-CuO-CeO2 Mixed Oxide

Hoang Thi Huong Hue, Pham Anh Son, and Nguyen Van Quang

CaO-CuO-CeO2 materials with different contents of CaO and CuO are fabricated by the sol-gel method and used as the catalysts for the complete decomposition of phenol with hydrogen peroxide. The prepared solids are characterized by various techniques such as X-ray diffraction (XRD), thermal analysis (TG/DTA), scanning electron microscopy (SEM), temperature-programmed reduction (H2-TPR), Raman Spectroscopy, and X-ray photoelectron spectroscopy (XPS). The relationship between catalytic activity and properties of materials is carefully investigated. The XPS results confirm the existence of copper species in the bivalent form, while the H2-TPR elucidates the three existence states of copper species in sample, namely amorphous, crystalline CuO and copper ions participating the crystal lattice of CeO2 to form solid solution. The results show that the optimum concentrations of CuO and CaO mixed oxide are 15 mol% and 7.5 mol% in order to obtain single CeO2 phase possessing higher catalytic activity. The gel aging and calcination conditions also significantly impact the surface morphology and the activity of the formed solids. Under the optimum fabrication conditions of catalyst, the highest phenol conversion is 96%. It was proven that the modification of CeO2 by both copper and calcium generates the large amount of oxygen vacancies, which positively effect on the catalytic activity.