Raman scattering of MnOx-CeOx composite catalysts: structural aspects and laser-heating effects

Composite MnOx-CeOx catalysts (Mn-at: Ce-at = 1) synthesized via the redox and coprecipitation routes were comparatively characterized by micro-Raman spectroscopy using a laser irradiation power ranging between 0.6 and 4.2 mW. A quasi-molecular dispersion of the oxide species determines a major and irreversible structural rearrangement of the redox MnOx-CeOx system because of severe heating effects for laser power in excess of 0.6 mW. The X-ray diffraction data of samples calcined in the range of 673-1273 K confirm that the micro-Raman characterization of the composite MnOx-CeOx systems requires an adequate minimization of the irradiation power to prevent the strong sintering and restructuring phenomena due to laser-heating effects. Copyright (c) 2011 John Wiley & Sons, Ltd.