THERMAL-CHARACTERISTICS OF A SYNTHETIC HYDROTALCITE-LIKE MATERIAL

The thermal and structural characteristics of a synthetic hydrotalcite-like material are described. Weight losses at 68 and 218-degrees-C are observed, which are attributed to the loss of physisorbed and intercalated water, respectively. The loss of the intercalated water is accompanied by a decrease in the (003) repeat distance from 7.59 to 6.60 A. A broad thermal transition is reported between 270 and 420-degrees-C which results from dehydroxylation of the lattice and decomposition of the charge-balancing carbonate anion. During this decomposition, water and CO2 are evolved simultaneously. The changes in crystal structure of the material which accompany these losses are described. Chemical analysis suggests that both carbonate and bicarbonate species are present within the interlayer region.