MgCoAl and NiCoAl LDHs synthesized by the hydrothermal urea hydrolysis method: Structural characterization and thermal decomposition

摘要

Layered double hydroxides (LDHs) with Mg/Co/Al and Ni/Co/Al were synthesized for the first time by the urea hydrolysis method. The experimental conditions promoted aluminum rich and crystalline materials. The formation of LDHs was investigated by powder X-ray diffraction (XRD), chemical analysis, solid state nuclear magnetic resonance with magic angle spinning (~(27)Al-MAS-NMR), simultaneous thermogravimetric/differential thermal analysis (TGA/DTA), FTIR spectroscopy, scanning electron microscopy (SEM), and N_2 adsorption-desorption experiments. A single phase corresponding to LDH could be obtained in all the investigated compositions. Thermal calcination of these LDHs at 500 ℃ resulted in the formation of solid solutions in which Al~(3+) was dissolved. All the calcined materials have rock-salt like structures and high surface areas.