Cerium-loaded MnO x /attapulgite catalyst for the low-temperature NH 3 -selective catalytic reduction

Abstract

Abstract A series of MnO2/attapulgite (ATP) and n(Ce):n(Mn)/ATP (molar ratios) catalysts were prepared and investigated for the selective catalytic reduction of NO by NH3 (NH3-SCR) at low temperature. The results showed that the 7 wt % MnO2/ATP exhibited the best NOx conversion (85% at 300 °C) among all MnO2/ATP catalysts of different mass ratios. The introduction of cerium enhanced the NOx conversion at low temperature, and so Ce–MnOx/ATP can reach the highest NOx conversion (95% at 300 °C). Meanwhile, the as-prepared catalysts were characterized by XRD, TEM, BET, H2-TPR, NH3-TPD, and XPS. It can be deduced from TEM, XRD, and BET, MnOx nanorods in this work mainly existed in the β-MnO2, and cerium highly dispersed on the surface of ATP to form porous structure and thus improved the deNOx performance. Moreover, the study of SO2 tolerance demonstrated that cerium can effectively inhibit SO2 poison. XPS results illustrated that Ce could enhance Mn4+ content on the surface of the catalyst and thus lead to high SCR activity. Therefore Mn(1):Ce(0.25)/ATP was proved to be an excellent catalyst for NH3-SCR.