Highly efficient degradation of high-loaded phenol over Ru–Cu/Al2O3 catalyst at mild conditions

Abstract

Ru–M/Al₂O₃ (M = Cu, Fe, Co, Ni, Mn, Zn, Ag, La and Ce) catalysts were prepared using the co-impregnation method and assessed for catalytic wet oxidation of highly concentrated phenol under mild conditions. The results showed that the Ru–5Cu/Al₂O₃ (the loading of Cu was 5 wt%) catalyst, especially, had the highest catalytic activity in degradation of phenol with chemical oxygen demand (COD) removal achieved at 95.8% after a 2 h reaction at 130 °C, 0.8 MPa oxygen pressure and an initial COD concentration of 23 000 mg L⁻¹ (the concentration of phenol was about 10 g L⁻¹). In order to confirm the structure and properties of Ru-based catalysts, the samples were characterized by BET, TG-DSC, XRD, XPS, TPR and TEM techniques. In addition, the influence of different parameters on phenol degradation efficiency was examined and the reaction kinetics were investigated. Hence, the Ru–5Cu/Al₂O₃ catalyst showing the highest activity might be owing to a synergetic effect between the Ru and Cu species and good dispersion of Ru. The main cause of Ru–5Cu/Al₂O₃ deactivation was the coke deposit covered active sites, but it was easily regenerated by calcination.