Synthesis of heatresistant WO3-CeO2-ZrO2 catalyst and its performance for NH3-SCR of NO in diesel exhaust

A series of oxides (WO3, MoO3, CrO3, MnOx, FeOx and CoOx) supported on homogeneously precipitated CeO2-ZrO2 prepared by incipient wetness impregnation was used as catalyst for the selective catalytic reduction (SCR) of NO in diesel exhaust with NH3. The catalyst was aged in air at 800℃ for 1h and tested in a simulated diesel exhaust containing 0.055% NO, 0.055% NH3, 6% O2, 10% H2O and 10 % CO2, at a space velocity of 90000h-1. The catalyst WO3-CeO2-ZrO2 exhibited high thermal durability. The effects of WO3 loading and Ce/Zr ratio in WO3-CeO2-ZrO2 were examined; 10% WO3 and equimolar composition of Ce-Zr gave it a superior performance for NH3-SCR of NO. The fresh and aged catalyst samples showed a NO conversion above 90% at temperatures 250℃~450℃ and 350℃~500℃, respectively. The catalysts also exhibited the excellent performance for circle and longterm aging.