Comparative Study on Low Temperature Selective Catalytic Oxidation of Ammonia over Transition Metals Supported on TiO2

Four different transition catalysts (V, Cr, Zn, Mo) supported on TiO₂ were prepared by incipient impregnation and their performances of selective catalytic oxidation (SCO) of ammonia(NH₃) were investigated in mixed gas in which 500ppm ammonia was included and the gas hourly space velocity(GHSV) was 35385h^-1. The results shown that 99% ammonia removal efficiency, 19% nitric oxide (NO) conversion and neglectable nitrogen dioxide (NO₂) conversion were obtained at low temperature over Cr/TiO₂. With increasing temperature, the lowest NO and NO₂ conversion were found on Mo/TiO₂. Then comparatively tested Cu/TiO₂ and Cr/TiO₂, much lower NO and NO₂ conversion over Cr/TiO₂ than Cu/TiO₂ was obtained. Various oxygen contents ranging from 0.5% to 5% for the SCO of ammonia were as well as tested and it revealed that oxygen content affected the ammonia removal efficiency, but not as significantly as possible at low temperature, the NO and NO₂ was either not affected by lean oxygen condition at low temperature.