Catalytic wet air oxidation of high-concentration organic pollutants by upflow packed-bed reactor using a Ru-Ce catalyst derived from a Ru3(CO)12 precursor

Low loading catalysts Ru/gamma-Al2O3 and Ru-Ce/gamma-Al2O3 (Ru: 0.3 wt%) were prepared by thermolysis of Ru-3(CO)(12), which exhibited high activity in Catalytic Wet Air Oxidation (CWAO) of high concentration organic pollutants by upflow packed-bed reactor with initial COD 200 000 mg L-1. XPS results revealed that two new Ru species (Ru-A and Ru-B) were detected due to the chemical interaction between Ru-3(CO)(12) and the active OH groups on the surface of Al2O3 during the process of Ru-3(CO)(12) incomplete decomposition, and the reduction of them can lead to more dispersed metallic phases. The TPR spectrum reveals that the catalyst with addition of Ce produced a strong interaction between Ru and the CeO2-Al2O3 support, which was helpful for the catalytic wet air oxidation. Low loading catalyst Ru-Ce/gamma-Al2O3 reduced in H-2 had the highest activity and the COD removal reached 99.5% above 245 degrees C. The operating parameters investigated included temperature, reactor pressure, gas flow rate and liquid hourly space velocity (LHSV). The results showed that the COD removal is considerably affected by the temperature; when temperature increased around 2-3 degrees C, COD removal was improved about 40% due to the obvious exothermic reaction. The experimental results indicated that the 0.3 wt% Ru-Ce/gamma-Al2O3 catalyst has excellent activity and stability in the CWAO of high concentration organic pollutants in as packed-bed reactor during 100 hours.