Environmentally-friendly tourmaline modified CeMnFeOx catalysts for low-temperature selective catalytic reduction of NOx with NH3

Abstract The tourmaline/manganese-iron-cerium-oxide composites prepared by the hydrothermal method was investigated for NOx removal in simulated flue gas. The microstructure of the catalyst has been characterized by X-ray diffractometer (XRD), temperature-programmed reductions (TPR) and X-ray photoelectron spectra (XPS). The incorporation of tourmaline could remarkably enhance the activity of tourmaline/Mn-Fe-Ce catalyst at low temperature. H2-TPR results indicated that H2 adsorption amount decreased after the incorporation of tourmaline. The XPS results revealed that the incorporation of tourmaline could enhanced the contents of high valence Oα (Oα/O) in the composite catalysts, which is favorable for oxidation process of elemental manganese. Overall, the catalytic performance of tourmaline/Mn-Fe-Ce was closely related to the addition of tourmaline. When the addition of tourmaline was 2%, the composite catalyst showed the best catalytic performance: The NOx conversion of the composite catalyst is 100% at 170–230 °C. Moreover, the denitrification mechanism of composites was studied. The addition of tourmaline improved the catalytic process, and stable bidentate nitrate species was activated at low temperature during the denitrification reaction. As a mineral material, tourmaline has excellent far-infrared properties and spontaneous polarization properties, which can significantly improve the denitration performance of the catalyst. The use of mineral materials as raw materials to prepare denitration catalysts provides new ideas for future research.