CeO 2 Nanoparticle-Loaded MnO 2 Nanoflowers for Selective Catalytic Reduction of NO x with NH 3 at Low Temperatures.

CeO 2 nanoparticle-loaded MnO 2 nanoflowers, prepared by a hydrothermal method followed by an adsorption-calcination technique, were utilized for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures. The effects of Ce/Mn ratio and thermal calcination temperature on the NH 3 -SCR activity of the CeO 2 -MnO 2 nanocomposites were studied comprehensively. The as-prepared CeO 2 -MnO 2 catalysts show high NO x reduction efficiency in the temperature range of 150-300 °C, with a complete NO x conversion at 200 °C for the optimal sample. The excellent NH 3 -SCR performance could be ascribed to high surface area, intimate contact, and strong synergistic interaction between CeO 2 nanoparticles and MnO 2 nanoflowers of the well-designed composite catalyst. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) characterizations evidence that the SCR reaction on the surface of the CeO 2 -MnO 2 nanocomposites mainly follows the Langmuir-Hinshelwood (L-H) mechanism. Our work provides useful guidance for the development of composite oxide-based low temperature NH 3 -SCR catalysts.