[Study on the SCR of NO over automobile exhaust catalyst Ag/SAPO-34]

The activity of Ag/SAPO-34 molecular sieve catalyst was investigated, and the selective catalytic reduction (SCR) of NO was studied by in-situ diffuse reflectance FTIR spectroscopy(DRIFTS). The results show that the prepared catalyst had high activity at low temperature and the conversion of NO reduction to N2 was about 70% at 3.6% O2 and 573K-673K of temperature. The catalysis activity rised with the concentration of C3H6 but light decrease with GHSV. Based on in-situ DRIFTS, a reaction mechanism was proposed that NO, propene and oxygen react to form organo-nitro and organo-nitro adsorbed species as key intermediates, then these intermediates were decompose to nitrogen. NO and propene were easily activated in oxygen. Furthermore, the presence of oxygen is necessary to form a series of intermediates.