Synthesis and Thermal Stability of Oxalate-intercalated Hydrotalcites

Oxalate anions pillared layered double hydroxides(LDHs) were synthesized by in-situ synthetic method and direct ion-exchange reaction in aqueous solution using nitrate-containing LDH as precursors,and were characterized by XRD,IR and DTA.The thermal stabilities of synthesized samples were studied.Results show that the pillared products can be prepared using both methods,but the sample prepared by in situ synthetic method has higher crystallity and better layered structure than that of the sample prepared by direct anion exchange method.Results from DTA studies indicate that the thermal stabilities of the oxalate-intercalated Mg2Al-LDHs are higher than that of the Zn2Al-LDHs,and the thermal stabilities of the pillared products are slightly decreased with the NO3-ions replaced by the organo-anions.Less thermal stability differences are observed for the prepared samples via the two different methods.8figs.,14refs.