Core-shell structure effect on CeO2 and TiO2 supported WO3 for the NH3-SCR process

Abstract

A series of CeTi samples (CeO2/TiO2, TiO2@CeO2, TiO2/CeO2, and CeO2@TiO2) was prepared and modified by tungsten. The 5 %WO3/TiO2@CeO2 (W/Ti@Ce) catalyst exhibited the best NH3-SCR performance (NO conversion and N2 yield above 95 % at 250–500 ºC) due to the synergistic effect of redox ability and acidity. The techniques of XPS, H2-TPR, and NH3-TPD were introduced to reveal the effect of Ce3+ atom contents, redox properties and acidity on catalytic performance. W/Ti@Ce shows good redox ability, which is conducive to the low-temperature selective catalytic reduction (SCR) reaction. NH3-TPD results show that W/Ti@Ce have a large amount of medium- and strong-strength acids, which are conducive to high-temperature SCR reaction. Therefore, the core-shell catalyst has the optimal synergistic effect of redox property and acidity, which is in favor of the excellent NH3-SCR performance. Furthermore, the W/Ti@Ce with a core-shell structure displayed better SO2 resistance due to the stronger interaction between Ce and Ti.