Thermal Transformation of a Layered Double Hydroxide Pillared with Decavanadate Isopolyanions

V10O286− anions, intercalated by anion-exchange into the interlayer gallery of a Mg–Al layered double hydroxide, undergo chemical transformation and reduction in the valence state when subjected to thermal treatment. XRD and IR analyses indicate that V10O286− breaks up into smaller species at 473 K, which then rearrange to form polymeric vanadate species of the type [–VO3–]nn− at 573–623 K. Concomitant with the disarrangement of the decavanadate anion, reduction of V(V) to V(IV) species takes place even when heat treated under air, as evidenced by ESR analysis. The number of V(IV) species increased steadily from 2.4 × 1018 to 2.2 × 1019 spin g−1 when the temperature of heat treatment rose from 393 to 473 K. Higher temperatures decreased gradually the number of V(IV).