Synthesis and characterization of cubic mesoporous neodymium-containing silica

The cubic neodymium-modified MCM-48 molecular sieves were synthesized via a hydrothermal method using cethyltrimethylammonium bromide as template. The X-ray diffraction and TEM indicate a well-ordered cubic mesoporous structure was obtained 'when the Nd/Si molar ration was less than 0.05. With the increase of Nd/Si molar ration, the increase of unit cell parameters and the change of FT-IR provide powerful evidences for the incorporation of neodymium in the framework of mesoporous molecular sieves. Nitrogen adsorption-desorption suggests the BET surface area is 1195 m(2).g(-1) and that the average pore diameter is 3.6 nm. Diffuse reflectance UV-Visible (UV-Vis) spectroscopy confirms the presence of neodymium in the octahedral position. X-ray photoelectron spectroscopy (XPS) studies further reveal that most of neodymium is trivalent in the framework of mesoporous molecular sieves.