The influence of the cationic ratio on the incorporation of Ti4+ in the brucite-like sheets of layered double hydroxides

The incorporation of the tetravalent Ti4+ cations into layered double hydroxide (LDH) type materials was studied as a function of the cationic ratio in the brucite-like sheets. Therefore, Zn-Ti-LDHs with different cationic ratio were prepared by the coprecipitation method at constant pH. The X-ray diffraction patterns revealed that only for the cationic ratio of 3, the characteristic layered structure was formed. The presence and the symmetry of the interlayer carbonate anions were investigated with FTIR-PAS spectroscopy. The UV-DR shows the octahedral environment of the Ti4+ cations in the brucite-like sheets. Following the same synthesis procedure, a reference sample containing Zn2+ and Al3+ (cationic ratio of 3) was synthesized. The Zn-Al- and Zn-Ti-LDHs textural features were investigated with N-2 adsorption at 77 K and scanning electron microscopy. Incorporation of Ti4+ cations in the brucite-like sheets of LDHs lead to a material with much smaller particles, therefore more interparticle porosity and higher volume of N-2 adsorbed at high relative pressures was observed. (C) 2007 Elsevier Inc. All rights reserved.