Preparation and characterization of rare earth-containing layered double hydroxides

Novel Layered Double Hydroxide (LDH) phases containing Rare Earth Elements (Ce3+ and Eu3+) have been prepared by ion exchange method using Ln(dipic)33− complexes as guest anions ([C7H3NO4]2−=dipic ligand). Intercalation of Ce3+ and more generally of rare earth cations in the opened structure of LDH displays many interests for applications as catalysts or catalyst precursors and materials with luminescence properties. The influence of various experimental conditions were investigated for the optimisation of the intercalation reaction, including the host layer composition and charge density and other synthesis parameters such as temperature, pressure, reagent concentration, and reaction time. Moreover, the adsorption isotherm of Na3[Ce(dipic)3] on Zn2Al-LDH was recorded in order to study the ion-exchange process. The different products were characterized using ICP, XRD, FTIR, TG and UV solid. The results confirmed the intercalation of [Ce(dipic)3]3− anions and the preparation of Ce-containing LDHs. The interlayer spacing of [Ce(dipic)3]3− containing ZnAl LDH was 1.24 nm, in agreement with the mean size of the complex (0.9 nm) and a slanted orientation between the layers. This study was extended to the intercalation of [Eu(dipic)3]3− complexes and preliminary results on luminescence properties have been recorded. Hereafter, rare-earth element will be noted (REE).