Abstract: Pillared anionic clays or layered double hydroxides were prepared by means of hydrothermal ion exchange reaction of [Zn₂Al(OH) ₆]NO₃· x H₂O (ZnAl NO₃) with [GaW₁₁ O₃₉ M(H₂O)]^7- (abbreviated as GaW₁₁ M, M=Mn²⁺ , Co^{+2 or Ni2+). The layered compounds were characterized by means of XRD, IR, elemental analysis and DTA. The X-ray diffraction and IR spectra show that the new anionic clays synthesized are layered compounds with the gallery heights of 0.99-1.00 nm and the Keggin structure tungstogallic heteropolyanions almost completely replace the interlayer NO₃-, entering the layer and retain their Keggin structure. The DTA gives a thermostability order of ZnAl GaW₁₁ Ni >ZnAl-GaW₁₁ Co>ZnAl-GaW₁₁ Mn>ZnAl-NO₃. The ctalytic tests showed that the new pillared compounds have higher catalytic activities in the cyclooxidation reaction of maleic acid.}

Key words: Heteropolyanion, Intercalation, Pillared clay, Epoxidation