Rare Earth Metal (La, Ce, Nd, Eu) Doped Cu/Zr-PILC Catalysts for the Efficient NH3-SCR at Low Temperature

Abstract

ABSTRACT A series of RE-3Cu/Zr-PILC (RE = La, Ce, Nd, Eu) catalysts were prepared via an impregnation method and activities for NH3-SCR were evaluated. The physicochemical properties of each catalyst were explored using XRD, BET, H2-TPR, NH3-TPD, XPS and in-situ DRIFTS techniques. The doping of RE had enhanced the NH3-SCR efficiency of 3Cu/Zr-PILC. Among them, the 6Ce-3Cu/Zr-PILC sample demonstrated exceptional performance, achieving NO conversion rates exceeding 90% within the temperature range of 250–350°C. Moreover, it reached its peak NO conversion rate of 96.3% at 300°C while maintaining an impressive resistance to SO2. According to the results of TPR, TPD and XPS analysis, the modification of RE (especially Ce) enhanced the redox properties, the surface acidity, the atomic ratio of Cu2+/Cu+ and the amount of surface chemisorbed oxygen in the 3Cu/Zr-PILC samples, all of these are favorable for the NH3-SCR reaction. Furthermore, in-situ DRIFTS analysis reveals that the NH3-SCR reaction of RE-3Cu/Zr-PILC samples at low temperatures is governed by the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms, with the L-H mechanism being the predominant factor.