Activity and SO2 resistance of amorphous CeaTiOx catalysts for the selective catalytic reduction of NO with NH3: in situ DRIFT studies

A series of CeaTiOx catalysts with different Ce/Ti molar ratios was prepared by a sol-gel method and used for selective catalytic reaction (SCR) of NO with NH3. The NO conversion values confirmed that the Ce0.3TiOx catalyst showed a much higher activity at low temperature, and the catalyst exhibited 100% NO conversion in the broad temperature range of 200-350 degrees C and nearly 100% N-2 selectivity. The catalysts were characterized by the BET surface area, XRD, XPS, NH3-TPD and H-2-TPR. These results demonstrated that the excellent catalytic performance of the complete amorphous Ce0.3TiOx catalyst was associated with the strong interactions between Ce and Ti, the higher BET surface area, abundant acid sites, and greater presence of Ce3+ and chemisorbed oxygen. In situ DRIFTS was used for studies of the reaction mechanism and SO2 resistance. The results indicate that the L-H reaction pathway can be hindered in the presence of SO2 at low temperature (< 200 degrees C), however the reaction mainly via the E-R reaction pathway at high temperature (> 200 degrees C) led to a satisfactory SO2 resistance.