Surface Characterization of Ni-Mg-Al and Co-Mg-Al Hydrotalcites by Inverse Gas Chromatography

Abstract

Carbonate pillared hydrotalcite-like compounds (NixMg3-xAl-LDHs and CoxMg3-xAl-LDHs) with different molar ratios were synthesized through co-precipitation and the samples were characterized by XRD, FTIR and inverse gas chromatography (IGC) techniques. The surface properties were compared and verified by computer simulation. The results indicated that with the increasing content of Ni 2+ in NixMg3-xAl-LDHs, the surface adsorption free energy and dispersive component of the surface energy decreased, while the stability increased gradually, which was contrary to Co 2+ in CoxMg3-xAl-LDHs. Besides, the surface free energy of Ni-Mg-Al hydrotalcites was smaller than Co-Mg-Al hydrotalicites when they were in the same molar ratio and the stability of the former was found to be stronger than the latter.