Preparation of Mn/Ce composite oxide catalysts for the wet oxidation of acetic acid and their catalytic activities.

To improve the activity of Mn/Ce composite oxide catalyst in wet oxidation of wastewaters, the effect of the method of preparation of the catalyst was investigated. Acetic acid was used as a pollutant. Among the Mn/Ce catalysts of the same composition prepared by coprecipitation, wet mixing, and impregnation, the one prepared by coprecipitation from a mixed solution of manganese and cerium showed the highest activity. Effects of calcination temperature and atmosphere were also investigated. Oxidizing atmospheres (O2, air) were more effective for activation than neutral or reducing atmospheres (N2, H2). Thus, the most active Mn/Ce catalyst was obtained by coprecipitation followed by calcination under O2 atmosphere at 450°C. The catalyst thus prepared showed activity even higher than that of a homogeneous copper salt catalyst which is known to be most active.