ABSTRACT
Cu, Ni, CuO and NiO catalysts, prepared by wet impregnation with urea and supported on γ-Al2O3, CeO2, and Al2O3-CeO2, were evaluated for Catalytic Wet Air Oxidation (CWAO) of phenol in a batch reactor under a milder condition (120 °C and 10 bar O2). The synthesized samples, at their calcined and/or their reduced form, were characterized by XRD, H2-TPR, N2 adsorption-desorption, SEM-EDS and DR-UV-Vis to explain the differences observed in their catalytic activity towards the studied reaction. The influence of the support on the efficiency of CWAO of phenol at 120 °C and 10 bar of pure oxygen has been examined and compared over nickel and copper species. The SEM-EDS results reveal that the spherical crystalline Cu and Ni were successfully deposited on the surface of γ-Al2O3, CeO2, Al2O3-CeO2 within 16-90 nm and that they were highly homogeneously dispersed. It was found that catalysts prepared from impregnation solutions of Cu(NO3)2·3H2O and Ni(NO3)2·6H2O with urea addition had different textural characteristics and degrees of dispersion of Cu and Ni species. The urea addition in the traditional wet impregnation method was essential to improve the reducibility and degree of dispersion in Ni, and to a lesser extent, in Cu. According to the characterization analysis of H2-TPR and UV-VIS RD a structure-activity relationship can be determined. The chemical oxygen demand (COD) and GC analyses confirmed the effect of calcined and reduced species for Cu and Ni applied to the catalytic oxidation of phenol, showing their significant impact in the final performance of the catalyst.
ABSTRACT
Destruction of methyl tert-butyl ether (MTBE) in liquid phase and in a batch reactor was studied using ruthenium catalysts over alumina support, modified with different cerium loadings. Ce loading increment causes an increase in the particle size from 1.26 nm to 2.3 nm, enhancing the MTBE oxidation (at 150 °C), and the selectivity toward CO2. The high catalytic activity of Ru/ACe10 is attributed to the species Ce4+-O2--M that could favor the oxygen transfer between the catalyst surface and the adsorbed species by a redox mechanism. Thus, CeOx plays an important role in both enhancing the affinity between MTBE and catalyst during MTBE adsorption and promoting the catalytic activity for MTBE oxidation.
Subject(s)
Methyl Ethers/analysis , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/analysis , Bioreactors , Carbon Dioxide/chemistry , Cerium/chemistry , Oxidation-Reduction , WaterABSTRACT
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