Enhanced Low Temperature NO Reduction Performance via MnOx-Fe2O3/Vermiculite Monolithic Honeycomb Catalysts

Selective catalytic reduction of NOx by ammonia (NH3-SCR) was the most efficient and economic technology for De-NOx applications. Therefore, a series of MnOx/vermiculite (VMT) and MnOx-Fe2O3/VMT catalysts were prepared by an impregnation method for the selective catalytic reduction (SCR) of nitrogen oxides (NOx). The MnOx-Fe2O3/VMT catalysts provided an excellent NO conversion of 96.5% at 200 degrees C with a gas hourly space velocity (GHSV) of 30,000 h(-1) and an NO concentration of 500 ppm. X-ray photoelectron spectroscopy results indicated that the Mn and Fe oxides of the MnOx-Fe2O3/VMT catalyst were mainly composed of MnO2 and Fe2O3. However, the MnO2 and Fe2O3 components were well dispersed because no discernible MnO2 and Fe2O3 phases were observed in X-ray powder diffraction spectra. Corresponding MnOx-Fe2O3/VMT monolithic honeycomb catalysts (MHCs) were prepared by an extrusion method, and the MHCs achieved excellent SCR activity at low temperature, with an NO conversion greater than 98.6% at 150 degrees C and a GHSV of 4000 h(-1). In particular, the MnOx-Fe2O3/VMT MHCs provided a good SCR activity at room temperature (20 degrees C), with an NO conversion of 62.2% (GHSV = 1000 h(-1)). In addition, the NO reduction performance of the MnOx-Fe2O3/VMT MHCs also demonstrated an excellent SO2 resistance.