MULTINUCLEAR MAGNETIC-RESONANCE CHARACTERIZATION OF VARIOUS ALUMINOSILICATE GELS IN THE PRESENCE OF TETRAALKYLAMMONIUM IONS

Four gels of initial compositions 8 TAABr:Al2O3:90 SiO2:1,000 H2O (gel I), 8 TAAOH:Al2O3:90 SiO2: 1,000 H2O (gel II), 2 TAAOH:Al2O3:200 H2O (gel III), and 8 TAABr:4.5 Na2O:Al2O3:90 SiO2: 1,000 H2O (gel IV) were prepared and dried at 363 K (TAA = tetramethyl, tetraethyl, tetraprop yl, and tetrabutylammonium). The dried gels were characterized by C-13 , Al-27, and Si-29 n.m.r. and the calcined gels by Xe-129 n.m.r. of ad sorbed xenon. The Al atoms are very well dispersed in a tetrahedral fo rm of the get structure in gel II, rather well dispersed in gel IV, an d partially dispersed in gel I. In gels I and IV, large and medium siz e cavities contained aggregated (crystalline) TAABr and less aggregate d species. Only gel II is able to disperse the TAA ions in monomeric f orms where they ate countercations to gel negative charges. The monome ric TAA species could play a direct role in zeolite synthesis.