SYNTHESIS, CHARACTERIZATION AND CATALYSIS OF PILLARED ANION CLAY .6. STRUCTURE, PROPERTY AND OXIDIZING ACTIVITY OF ZN2AL-SIW11 AND ZN2AL-SIW(11)Z

The compounds pillared by heteropolyanion, Zn2Al-SiW11 and Zn2Al-SiW(1 1)Z (Z= Co2+, Cu2+ and Ni2+), were synthesized. The results of XRD, IR , TG-DTA and Al-27 and Si-29 MAS NMR studies indicated that they were pillared layered compounds with gallery height 0.99 nm. Layers have si gnificant effect on heteropolyanions in gallery and on the symmetry of Si-O tetrahedron. The order of their thermal decomposition temperatur e was found as follows: Zn2Al-SiW11Ni (347 degrees C) > Zn(2)Ai-SiW11C o (341 degrees C) > Zn2Al-SiW11 Cu (335 degrees C) > Zn2Al-SiW11(329 d egrees C) > Zn2Al-NO3(290 degrees C). In boiling aqueous solution, the stable pH range of these compounds is 3.6-7.5. And their BET adsorpti on isotherm and the pore size distribution curve were determined. It w as found that this kind of microporous catalyst had high activity and selectivity for the oxidation of benzaldehyde to benzoic acid using H2 O2 as oxidant in liquid-solid biphase system.