Mechanism and Kinetics Study on Low-Temperature NH₃-SCR Over Manganese–Cerium Composite Oxide Catalysts

Abstract

Titanium dioxide-supported manganese oxide and cerium oxide noted as MnO x /TiO2, CeO2/TiO2, and MnO x –CeO2/TiO2 were prepared by sol–gel method and their low-temperature (<200 °C) catalytic activity toward selective catalytic reduction (SCR) of NO with NH3 were evaluated. The MnO x –CeO2/TiO2 catalyst exhibited optimal low-temperature performance that is nearly 98% of NO was abated below 200 °C. That is because MnO x /TiO2 combined with CeO2 improves redox ability and surface acidity of the catalyst, mainly due to the incorporation of Mn atoms into bulk CeO2 that creates active Mn–O–Ce structures. In situ Fourier transform infrared (FTIR) spectroscopy suggested that the coordinated NH3 on Lewis acid sites were favored to react with NO and the NH3-SCR over MnO x –CeO2/TiO2 catalyst mainly followed the E–R mechanism at 200 °C. Furthermore, the reaction rate constant and apparent activation energy of the NH3-SCR reaction on the MnO x –CeO2/TiO2 catalyst confirmed the promotional effects of Ce addition on the activity of Mn-based catalyst.

Titanium–silicon ferrierites and their delaminated forms modified with copper as effective catalysts for low-temperature NH3-SCR

“…Development of the effective NH 3 -SCR catalyst operating at low temperatures could enable retrofitting of the installations of flue gases treatment resulting in increased efficiency of flue gases purification and reduction operation costs. The catalysts containing copper, 10 manganese 11 and iron 12 were reported to operate in the low-temperature range. The very promising results of low-temperature NH 3 -SCR were obtained for zeolites modified with copper.…”

Thulium oxides supported on MnCeTiOX catalysts for low-temperature NH3-SCR of NOX

“…The outstanding perfprmance of many metal oxides have facilitated them to be applied as promoters. Manganese oxide has labile lattice oxygens and multivalent Mn species [3][4][5]. Meanwhile, manganese oxides have the advantages of being environmentally friendly, abundant in resources and low in cost [6].…”

Experimental and kinetic modeling study for N2O formation of NH3-SCR over commercial Cu-zeolite catalyst

“…Selective catalytic reduction (SCR) of NOx by NH 3 is currently the most effective technology used for reducing NOx through selective reactions on the catalytic surface between NOx and adsorbed NH 3 . [1][2][3][4][5] The SCR of NOx with NH 3 has been studied extensively on various catalysts. [6][7][8][9][10][11][12][13] Ciardelli et al 6 studied the reactivity of NH 3 -SCR over a commercial V 2 O 5 -WO 3 /TiO 2 catalyst in a wide range of conditions and identified the reaction network at the different operating conditions.…”