Catalytic Wet-Air Oxidation of p-Cresol on Ag/Al2O3−ZrO2 Catalysts

Abstract

Catalytic wet-air oxidation of p-cresol was carried out on Ag/Al2O3−ZrO2 catalysts at 1, 5, 10, and 20 wt % of ZrO2 in a reactor-type batch and 160 °C and 15 bar of oxygen. Al2O3−ZrO2 supports were prepared by the simultaneous hydrolysis of the boehmite and zirconium alkoxide. Ag/Al2O3−ZrO2 catalysts prepared by deposition−precipitation showed higher surface area (202−216 m2/g) and lower Lewis acids sites than the Ag/Al2O3 (161 m2/g) and Ag/ZrO2 (25 m2/g) reference catalysts. FTIR-CO adsorption showed a shift to lower frequencies on Ag/Al2O3−ZrO2 catalyst indicating electron-rich metallic particles. The p-cresol conversion, TOC abatement, and CO2 selectivity were improved when Ag was supported on Al2O3−ZrO2 mixed oxides. A modification of the surface properties of Ag on the Ag/Al2O3−ZrO2 catalysts due to a metal−support interaction leading to a faster oxidation of the adsorbed reactant species is proposed.