SYNTHESES, CHARACTERIZATION AND CATALYTIC REACTIVITIES OF HETEROPOLYANION-PILLARED CLAY OF ANIONS OF ZN-AL TYPE

Mono-substituted Keggin ions PW11O39Cr(H2O)(4-), PW11TiO405- and PW11V O404- were intercalated between the layers of the clay of anions of Zn -Al type using the ion exchange method to obtain a new type of pillare d layered microporous materials ZnAl-PW11Cr, ZnAl-PW11Ti and ZnAl-PW11 V with basal spacing (1.48+/-0.02) nm. On the basis of the MAS NMR res ults of Al-27 and P-31, a steric pillared layered structure model of o rientation localization of (PWVO404-)-V-11 in the orientation in which the C-2 axis of PW11VO404- perpendicular to the host layer. It has be en found that this kind of pillared layered microporous materials poss ess a higher catalytic activity for the esterification of acetic acid with n-butanol than I-I-type molecular sieves.