Promotional effect of Ce on the SCR of NO with NH3 at low temperature over MnO (x) supported by nitric acid-modified activated carbon

Different amounts of Mn and Ce oxides were loaded onto nitric acid-modified activated carbon (ACN) by wet impregnation. The series of catalysts were employed for the selective catalytic reduction of NO (x) by NH3 at temperatures between 100 and 250 A degrees C. Cerium-modified catalysts exhibited higher de-NO (x) performance than those modified with Mn/ACN, even with the same total loadings. The precursor solution with a molar ratio for Ce/(Mn + Ce) of 0.4 exhibited the highest catalytic activity. Enhanced resistance to SO2 and H2O and better stability were observed for 10%Mn-Ce(0.4)/ACN relative to 10%Mn/ACN. The catalysts were further characterized by N-2 physisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H-2-TPR), and temperature-programmed desorption of ammonia (NH3-TPD). The N-2 physisorption and XRD results suggested that co-doping Ce with Mn increased the surface area and promoted the dispersion of Mn-Ce binary metal oxides. H-2-TPR the NH3-TPD results demonstrated that the interaction between manganese oxide and cerium oxide species enhanced the redox and surface acidity of 10%Mn-Ce(0.4)/ACN.