Synthesis and characterization of lanthanide-incorporated FSM-16 type mesoporous silica

摘要

Noble FSM-16 type mesoporous silicas incorporating lanthanides (Ln = La, Ce, Pr) have been successfully synthesized by a modified sheet folding process of kanemite-CTAB system. For comparison, Ln-loaded FSM-16 was prepared by a simple impregnation method. The local structure of Ln species and pore structure were investigated by XRD, diffuse reflectance UV absorption, XAFS and N_2 adsorption measurement. The impregnation causes the deposition of Ln species on the pore walls and thus decreases the pore size and pore volume. By contrast, Ln-incorporated FSM-16 exhibited mesoporosity comparable to the pristine FSM-16. XAFS analysis indicated that Ln species showed tetrahedral coordination and the Ln-O atomic distance was smaller than that of bulk oxide such as La_2O_3, CeO_2 and Pr_2O_3. The pore structure of Ln-FSM-16 and local structure of lanthanide were thermostable up to 800 deg C.