Roles of Acid Sites on Pt/H-ZSM5 Catalyst in Catalytic Oxidation of Diesel soot

Pt/H-ZSMS and Pt/Al2O3 with similar surface Pt particle sizes and chemical states were prepared by incipient wetness impregnation as catalysts for soot oxidation. Pt/H-ZSMS exhibits obviously higher activities in both O-2 and NO + O-2 than Pt/Al2O3. On the basis of the results obtained with in situ DRIFT and other structural and surface property characterizations, the high catalytic activity of Pt/H-ZSMS is currently attributed to two main factors. First, the acidic H-ZSMS support inhibits NO2 adsorption on the catalyst, leading to a preferential adsorption of NO2 on the surface of soot and providing more chances for NO2-soot reactions. Second, the strong acid sites on the surface of Pt/H-ZSMS can participate in the catalytic formation and decomposition of surface oxygenated complexes. Consequently, a high achieved on the Pt/H-ZSMS catalyst.