The impact of Fe/Mn loads on the surface property of rare earth mineral

Abstract

After using the mixed acid system to modify the surface of rare earth minerals, two transition metals (Fe and Mn) are loaded on the surface of the rare earth minerals by hydrothermal method to improve the NH3-SCR (Selective catalytic reduction) activity. In this paper, a variety of characterization means like SEM, XRD, BET, XPS, H2-TPR (Temperature-programmed reduction), NH3-TPD (Temperature-programmed desorption) and NO-TPD are used to study and analyze the surface properties of rare earth minerals before and after loading transition metals. Its catalytic performance was further measured in a simulated flue gas installation. The results show that the active elements on the surface of rare earth minerals after loading transition metals are mainly oxides. The specific surface area of rare earth minerals is effectively improved, the crystallinity of the active material is reduced, and the element distribution is more uniform. In addition, a composite structure of Fe-Ce and Mn-Ce is formed on the surface of rare earth minerals, and the oxygen vacancies and adsorption sites on the surface of the minerals are significantly improved. The NOX conversion rate for Fe-loaded mineral catalysts reached 89.1% at 300 ℃. The NOX conversion rate for Mn-loaded mineral catalysts reached 92.3% at 250 ℃. Generally speaking, the NH3-SCR activity of rare earth mineral can be improved by loading transition metals (Fe and Mn).