Effect of hydration temperature on the structure reconstruction of MgAlY layered materials

This contribution investigates the obtaining of layered double hydroxides (LDHs) modified with different concentrations of yttrium and the effect of the yttrium concentration and temperature during the rehydration of the mixed oxides derived from these solids. Mg₃Al_(1?x)Y_x-LDH (where x = 0.04–0.6) have been prepared using the standard coprecipitation method under low supersaturation conditions. After the calcination of these solids (460 °C, 18 h), the corresponding mixed oxides were obtained. The reconstruction of the layered structure was attempted by rehydration of the mixed oxides under two different conditions: (1) at 25 °C and (2) at 70 °C. All the aforementioned solids have been characterized by chemical analysis, X-ray diffraction, DRIFTS spectra, N₂ adsorption–desorption isotherms, and determination of base sites. Their catalytic activity was tested in cyanoethylation of ethanol with acrylonitrile. The results obtained after the characterization and the catalytic activity tests were compared with those obtained for a standard hydrotalcite Mg₃Al.