CYCLIC POLYOLS - A NEW CLASS OF STRUCTURE-DIRECTING AGENTS - STUDY OFINOSITOL IN THE SYNTHESIS OF FAU-TYPE AND LTA-TYPE ZEOLITES

The use of myo-inositol (cis-1,2,3,5-trans-4,6-cyclohexitol) is studie d in an FAU-type synthesis of composition 10SiO(2):1Al(2)O(3):2.7Na(2) O:yinositol:140H(2)O. For y less than or equal to 3, primarily FAU-typ e materials are obtained with relatively high Si/Al ratios (3.1-3.3), Results of H-1, C-13 and Al-27 liquid-state NMR show that complexation of Al(OH)(4)(-) takes place, which becomes more important at higher i nositol contents. The formation of gmelinite during FAU synthesis coul d be reduced by the addition of small amounts of 15C-5 or gallium. For y=4, instead of FAU, an LTA phase is obtained with a Si/Al ratio of 1 . Contrary to the FAU products, the organic molecule is incorporated i nto the LTA framework and exhibits a clear structure-directing role. T his is ascribed to a stronger interaction of inositol with the Na+ cat ions, Results from Na-23 liquid-state NMR indicate that this interacti on is only feasible after sufficient complexation between inositol and Al has taken place. Possibly, a conformational change of myo-inositol is involved. (C) 1998 Elsevier Science B.V. All rights reserved.