H2O and/or SO2 Tolerance of Cu-Mn/SAPO-34 Catalyst for NO Reduction with NH3 at Low Temperature

A series of molecular sieve catalysts (Cu–Mn/SAPO-34) with different loadings of Cu and Mn components were prepared by the impregnation method. The deNO x activity of the catalyst was investigated during the selective catalytic reduction (SCR) of NO with NH 3 in the temperature range of 120 °C to 330 °C, including the effects of H 2O vapors and SO 2. In order to understand the poisoning mechanism by the injection of H 2O and/or SO 2 into the feeding gas, the characteristics of the fresh and spent catalyst were identified by means of Brunner？Emmet？Teller (BET), X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM) and Thermal Gravity- Differential Thermal Gravity (TG-DTG). The conversion of NO by the catalyst can achieve at 72% under the reaction temperature of 120 °C, while the value reached more than 90% under the temperature between 180 °C and 330 °C. The deNO x activity test shows that the H 2O has a reversible negative effect on NO conversion, which is mainly due to the competitive adsorption of H 2O and NH 3 on Lewis acid sites. When the reaction temperature increases to 300 °C, the poisoning effect of H 2O can be negligible. The poisoning effect of SO 2 on deNO x activity is dependent on the reaction temperature. At low temperature, the poisoning effect of SO 2 is permanent with no recovery of deNO x activity after the elimination of SO 2. The formation of (NH4) 2SO 4, which results in the plug of active sites and a decrease of surface area, and the competitive adsorption of SO 2 and NO should be responsible for the loss of deNO x activity over Cu/SAPO-34. View Full-Tex