Catalytic wet air oxidation of phenol with pelletized ruthenium catalysts

The pelletized ruthenium catalysts were prepared by impregnation of different pelletized supports: CeO2 and ZrO2-CeO2. Their mechanical strength, specific surface area, pore size distribution and adsorption capacity for phenol were studied. Catalytic wet air oxidation of phenol with pelletized catalyst of Ru/ZrO2-CeO2 was performed in a continuous packed-bubble column reactor. The fresh and used Ru/ZrO2-CeO2 catalysts were compared. It shows that introduction of ZrO2 into Ru/CeO2 increased the mechanical strength, specific surface area and adsorption capacity of pelletized catalyst. In the experiment of wet air oxidation of phenol with Ru/ZrO2-CeO2 for 100 h, phenol and TOC removal stabilized around 100 and 96%, respectively. The concentrations of intermediates were low. The leaching concentrations of active species during the reaction were also low. After reaction, the textures, morphologies, microcosmic crystal pattern of catalyst and oxidation state of catalytic active phase of zirconium, cerium, ruthenium and oxygen did not change much, but the carbonaceous deposits on the surface of used catalyst were observed, and they would be fully oxidized at about 300 °C. The pelletized catalyst of Ru/ZrO2-CeO2 possesses the possibility of practical use.