Characterization and performance of Pt/SBA-15 for low-temperature SCR of NO by C3H6

Pt supported on mesoporous silica SBA-15 was investigated as a catalyst for low temperature selective catalytic reduction (SCR) of NO by C₃H₆ in the presence of excess oxygen. The prepared catalysts were characterized by means of XRD, BET surface area, TEM, NO-TPD, NO/C₃H₆-TPO, NH₃-TPD, XPS and ²⁷Al MAS NMR. The effects of Pt loading amount, O₂/C₃H₆ concentration, and incorporation of Al into SBA-15 have been studied. It was found that the removal efficiency increased significantly after Pt loading, but an optimal loading amount was observed. In particular, under an atmosphere of 150 ppm NO, 150 ppm C₃H₆, and 18 vol.% O₂, 0.5% Pt/SBA-15 showed remarkably high catalytic performance giving 80.1% NOx reduction and 87.04% C₃H₆ conversion simultaneously at 140°C. The enhanced SCR activity of Pt/SBA-15 is associated with its outstanding oxidation activities of NO to NO₂ and C₃H₆ to CO₂ in low temperature range. The research results also suggested that higher concentration of O₂ and higher concentration of C₃H₆ favored NO removal. The incorporation of Al into SBA-15 improved catalytic performance, which could be ascribed to the enhancement of catalyst surface acidity caused by tetrahedrally coordinated AlO4. Moreover, the catalysts could be easily reused and possessed good stability.