Of five ceria catalysts prepared for the catalytic wet air oxidation (CWAO) of phenol, the most active was one prepared via a redox reaction in hydrogen peroxide, designated CeO2-A, and the second most active was one prepared via direct calcination of CeCl3·7H2O. The former has 100% phenol (1000 ppm) conversion and 95% COD removal after 2 h at 160 °C. The superior activity of this catalyst was verified by O2-temperature programming desorption, which showed that CeO2-A had the most exchangeable structure O2 (capping O2), and by H2-temperature programming reduction,
which showed that it had the highest H2 consumption (the most H2-reducible Ce species in the catalyst). X-ray diffraction analysis also revealed that CeO2-A had the most structure defects, corresponding to the most exchangeable structure O2 and the highest activity. An induction period, typical of reactions involving free radicals, was observed with all catalysts and this period decreased with more active catalysts and higher reaction temperatures. Used CeO2-A was effectively
regenerated via acetone rinsing without further calcination. The CeO2-A catalyst retained approximately the same activity even after three regenerations, showing that it has good durability.