Low-temperature SCR activity and SO2 deactivation mechanism of Ce-modified V2O5-WO3/TiO2 catalyst

The promotion effect of ceria modification on the low-temperature activity of V2O5-WO3/TiO2 catalyst was evaluated for the selective catalytic reduction of NO with NH3 (NH3-SCR) The catalytic activity of 1 wt% V2O5-W03/TiO, was significantly enhanced by the addition of 8 wt% ceria, which exhibited a NO conversion above 80% in a broad temperature range 190-450 degrees C. This performance was comparable with 3 wt% V2O5-WO3/TiO2, indicating that the addition of ceria contributed to reducing the usage of toxic vanadia in developing low-temperature SCR catalysts. Moreover, V1CeWTi exhibited approximately 10% decrease in NOx conversion in the presence of 60 ppm SO2. The characterization results indicated that active components of V. W and Ce were well dispersed on TiOx support. The synergetic interaction between Ce and V species by forming V-O-Ce bridges enhanced the reducibility of VCeWTi catalyst and thus improved the low-temperature activity. The sulfur poisoning mechanism was also presented on a basis of the designed TPDC (tetnperature-programmed decomposition) and TPSR (tetnperatureprogrammed surface reaction) experiments. The deposition of (NH4)(2)SO4 on V1CeWTi catalyst was touch smaller compared with that on V1Ti. On the other hand, the oxidation of SO2 to SO3 was significantly promoted on the CeO2-tnodified catalyst, accompanied by the formation of cerium sulfates. Therefore, the deactivation of this catalyst was mainly attributed to the vanishing of the V-Ce interaction and the sulfation of active ceria. (C) 2015 Chinese Materials Research Society. Published by Elsevier GmbH.