Selective Catalytic Reduction of NO by H-2 over Pt-MnOx/ZrO2-SiO2 Catalyst

Selective catalytic reduction of nitrogen monoxide by hydrogen (H-2-SCR of NO) over platinum catalysts impregnated on zirconia-incorporated silica (ZrO2-SiO2) and manganese oxide (MnOx) was investigated. Pt-MnOx catalyst showed low conversions and low yields of N2O and NO2 at 100-350 degrees C. On the other hand, NO conversions over Pt/ZrO2-SiO2 were very high, but N2O was predominantly produced at 100-150 degrees C and the yield of NO2 increased with temperature at 200-300 degrees C, resulting in poor N-2 yields. Pt-MnOx/ZrO2-SiO2 exhibited a small enhancement in N-2 yield at 100-150 degrees C due to the synergy of MnOx and ZrO2-SiO2. The surface composition and oxidation state of the catalyst components and the acidity of the catalysts were examined. IR spectra of the adsorption of NO and their subsequent reactions with hydrogen on these catalysts were also recorded. The variations of conversion and product yield according to the catalyst components in the H-2-SCR of NO were discussed in relation to their catalytic roles.