Synthesis and thermal analysis of indium-based hydrotalcites of formula Mg6In2(CO3)(OH)16•4H2O

Insight into the unique structure of layered double hydroxides (LDHs) has been obtained using a combination of X-ray diffraction and thermal analysis. Indium containing hydrotalcites of formula Mg4In2(CO3)(OH)(12)center dot 4H(2)O (2:1 In-LDH) through to Mg8In2(CO3)(OH)(18)center dot 4H(2)O (4:1 In-LDH) with variation in the Mg:In ratio have been successfully synthesised. The d(003) spacing varied from 7.83 for the 2:1 LDH to 8.15 for the 3:1 indium containing LDH. Distinct mass loss steps attributed to dehydration, dehydroxylation and decarbonation are observed for the indium containing hydrotalcite. Dehydration occurs over the temperature range ambient to 205 A degrees C. Dehydroxylation takes place in a series of steps over the 238-277 A degrees C temperature range. Decarbonation occurs between 763 and 795 A degrees C. The dehydroxylation and decarbonation steps depend upon the Mg:In ratio. The formation of indium containing hydrotalcites and their thermal activation provides a method for the synthesis of indium oxide-based catalysts.