Synthesis And Structure Differences Of Hydrotalcites And Intercalation And Assembly Of Organic Anion-pillared Hydrotalcite

Hydrotalcite are a sort of layered anionic clays with acid properties, basic properties, micropore structure, memory effect and interlayer anionic exchangeability and adjustability. For the reason, it is also a kind of new important catalytic and functional material. The molar rations of different metal atoms in hydrotalcite affect it's functions and properties greatly. So we synthesis three kinds of hydrotalcite and study their structure differences. Recently, the research work of organic anion pillared hydrotalcite assembled by anion exchange method using hydrotalcite as a precursor is proceeding, and we also do the same work using MgFe hydrotalcite.Three series of carbonate pillared MgFe, CoFe, CoAl hydrotalcites with different adding M2+/M3+ molar rations are synthesized by coprecipitation. XRD, IR and TG-DTA are used in search of the composition and structure of the products.The results of the XRD measurement certify that the hydrotalcites have nice crystal forms and high purity. Cell parameters of all these hydrotalcites change regularly.It can be seen from the TG-DTA curves MgFe hydrotalcite has two endothermic decomposition stages but CoFe has only one. The thermal stability of MgFe hydrotalcite is higer than CoFe hydrotalcite. All hydrotalcites will lose weight in decomposition stage and different samples exhibit different rates of weight loss.The results of IR analysis tell us it is Co32- the that has been intercalated between the double layers of hydrotalcite-structure. There are peaks reflecting M-0 vibration in hydrotalcites in all of the IR spectra of the tested samples.They both show that the synthesis of hydrotalcites is successful. And IR also tell us the structure differences of different samples. Organic anion pillared MgFe hydrotalcite are assembled by anion exchange method with MgFe hydrotalcite being theprecursor. The samples were analyzed by XRD,IR and TG-DTA. The results showed that by controlling the pH of the ion-exchange medium, organic anions can replace carbonate ions in the interlayeres.