Ceria added Sb-V2O5/TiO2 catalysts for low temperature NH3 SCR: Physico-chemical properties and catalytic activity

Abstract

A systematic investigation of the effect of ceria loading over Sb-V2O5/TiO2 catalysts was carried out for the selective catalytic reduction (SCR) of NOx by NH3. The various ceria loaded Sb-V2O5/TiO2 catalysts were prepared by deposition precipitation and impregnation methods. Addition of 10% ceria to Sb-V2O5/TiO2 catalyst significantly enhanced the NOx conversion at wide temperature range of 220–500°C. The 10% ceria loaded Sb-V2O5/TiO2 catalyst showed superior N2 selectivity (>95%) throughout the reaction temperatures. The physicochemical characteristics of the obtained catalysts were thoroughly characterized by BET surface area, X-ray diffractometry (XRD), temperature programmed desorption (TPD) of NO, SO2 and NH3, H2- temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The XRD results indicated the active components of antimony and vanadia were homogeneously dispersed over CeO2/TiO2. It was found that the addition of 10% ceria to Sb-V2O5/TiO2 could enhance the total acidity and redox properties of the catalyst, which lead to show higher NOx conversions at wide temperature window. In XPS studies, increase in intensity of the chemisorbed mobile oxygen peak was observed for ceria loaded catalysts. In particular, the DRIFT spectra of ceria loaded Sb-V2O5/TiO2 catalysts showed abundant Brønsted acid sites at 1436 and 1673cm−1 band, which are responsible for high NOx conversion. Furthermore, the results of NO and SO2 TPD of 10% ceria loaded Sb-V2O5/TiO2 catalyst showed enhancement of NO adsorption and SO2 inhibition properties, which is thought to play a significant role in long term stability of the catalyst during SO2 on–off study for 38h at 240°C.