Thermal decomposition of hydrotalcites. An infrared and nuclear magnetic resonance spectroscopic study

• DOI: 10.1039/ft9928802233
• Publication Date: 2004-04-15T12:29:37Z
• Authors: Fernando Rey; Vicente Fornés; José M. Rojo
• Keywords: Hydrotalcite; Thermogravimetric analysis

Calcined hydrotalcites have been used extensively as catalysts for base-catalysed reactions. The calcination procedure in critical determining the behaviour of final material. characteristics hydrotalcite, following different stages calcination, studied by means thermogravimetric (TG), X-ray diffraction (XRD), IR, 1H and 27Al NMR techniques. We shown that dehydroxylation begins within layers then a second stage occurs between adjacent layers, causing collapse structure. This process is accompanied change from octahedral to tetrahedral coordination aluminium. Decarbonation leads formation micropores radius <1.75 nm. Dehydroxylation decarbonation are reversible processes, their rates depend on temperature.