Preparation of MnO₂/γ-Al₂O₃ catalysts modified by CeO₂ and its catalytic oxidation of p-nitrophenol wastewater under microwave

A series of MnO₂/γ-Al₂O₃ catalysts modified by different amount of CeO₂ were pre-pared by one-step impregnation-calcinations' process, the optimal combination were calcined at different temperature of 350, 500, 700°C, by the time, XRD was used to identify their crystallites. The effect of the catalysts on degradation of the refractory p-Nitrophenol was investigated in a trickle bed reactor in microwave oven. The results showed that the crystal forms of catalysts calcinated at 350, 500°C were amorphous, and 700°C was Mn₂O₃. The highest removal rate of PNP was 92.9%, while the catalyst 15g with the CeO₂ content was 4% and TOC of PNP was 3000mg/L, pH6, and its dropping rate was 3ml/min under 800W power of microwave. Addition of inhibitor on free radical(tert-butyl alcohol) showed that the oxidation process maybe followed the free radical reaction mechanism.