Preparation by co-precipitation of Ce–Mn based catalysts for combustion of n-hexane

Abstract

Catalysts for combustion of n-hexane, based on Ce-Mn mixed oxides with different Ce/Mn molar ratios ranging from 0.5 to 2, have been prepared by co-precipitation at constant pH with aging times of 4, 18 and 24 h. XRD patterns of the mixed oxides showed the dominant presence of fluorite-like phase. The surface area of mixed oxides was always higher than their single oxide counterparts and their adsorption isotherm corresponding to type IV depicted a mesoporous surface. TPR profiles of mixed oxides shifted to lower temperatures with increasing content of Ce, revealing a strong metal interaction in composites. Ce-Mn samples exhibited higher activities than the corresponding simple oxides regardless of the aging time. Sample Ce0.67Mn0.33O2 with 24 h of aging time showed the highest performance probably due to the presence of defect sites promoted by the incorporation of MnOx species into CeO2 structure, its highest surface area and best reducibility.