DOPING OF CeO2 IN V2O5-TiO2 CATALYST FOR LOW-TEMPERATURE SELECTIVE CATALYTIC REDUCTION OF NITROGEN OXIDE BY AMMONIA

Abstract

This research investigated the selective catalytic reduction of NO by NH3 over V2O5-CeO2/TiO2 catalyst at low temperature. Formation of nitrogen oxide from the ammonia oxidation reaction and SCR reaction was also investigated. Titanium dioxide support was prepared by a sol-gel method. Then vanadium and cerium were deposited via an incipient wetness impregnation method. The amounts of vanadium and cerium in the catalyst ranged from 1 to 7%wt and 5 to 30%wt, respectively. The catalysts were characterized by N2 physisorption, ICP-OES, XRD and NH3-TPD techniques. The testing of SCR activity of the catalyst was carried out in a tubular reactor at a temperature in the range of 120-450oC. From the result, the catalyst containing 5 %wt. V2O5, 30 %wt. CeO2 showed superior SCR activity at low temperature and reached the highest activity at 250oC. The addition of CeO2 increased the specific surface area and the total acid site of catalyst, resulting in high catalytic activity. The extent of ammonia oxidation increased as the reaction temperature and the vanadium content in catalysts increased. Addition of cerium to catalyst inhibited ammonia oxidation reaction and retained the SCR activity at high temperature. Furthermore, the addition of cerium oxide to the V2O5-TiO2 catalyst yielded SCR catalysts an excellent resist to water vapor and sulfur dioxide under our test conditions.