CeO2 Nanoparticle-Loaded MnO2 Nanoflowers for Selective Catalytic Reduction of NOx with NH3 at Low Temperatures

CeO₂ nanoparticle-loaded MnO₂ nanoflowers, prepared by a hydrothermal method followed by an adsorption-calcination technique, were utilized for selective catalytic reduction (SCR) of NO_x with NH₃ at low temperatures. The effects of Ce/Mn ratio and thermal calcination temperature on the NH₃–SCR activity of the CeO₂-MnO₂ nanocomposites were studied comprehensively. The as-prepared CeO₂-MnO₂ 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 NH₃–SCR performance could be ascribed to high surface area, intimate contact, and strong synergistic interaction between CeO₂ nanoparticles and MnO₂ 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 CeO₂-MnO₂ nanocomposites mainly follows the Langmuir–Hinshelwood (L-H) mechanism. Our work provides useful guidance for the development of composite oxide-based low temperature NH₃–SCR catalysts.