THE ROLE OF THE TEMPLATE IN DIRECTING THE SI DISTRIBUTION IN SAPO ZEOLITES

X-ray diffraction and Al-27 and Si-29 MAS NMR are used to study the in teraction of the templates (morpholine or TEAOH) with the SAPO-34 fram ework (chabasite structure) and to characterize the distribution of Si in the lattice. The interaction of the template with Si-O-Al bonds su ggests the formation of penta- and hexacoordinated Al. Specific limits of Si contents (x(Si)) determine areas where Si(4A1) species are isol ated (Si(4Al,9P)) or nonisolated (Si(4Al,nP,mSi)) or where Si forms is lands. The two main parameters involved are the upper charge introduce d by the template (b) and the upper x(Si) values (d) derived from topo logy, to have isolated Si, Two main cases of the distribution of Si ar e whether b < d or b > d. The results obtained for SAPO-34 are extende d to any other SAPO.