C-13 SOLID-STATE NMR INVESTIGATION OF TS-1 TS-2 INTERGROWTH STRUCTURES/

TS-1/TS-2 intergrowth structures have been synthesized from hydrogels containing binary mixtures of tetrapropylammonium and tetrabutylammoni um hydroxides (TPAOH/TBAOH). TPA+ cations were shown to be selectively involved in the crystallization process of titanosilicates. These str uctures were interpreted as a layer sequence in which the prevailing i -type stacking was interrupted by sigma-type stacking faults. The latt er were quantified by a probability of occurrence, p, estimated from X -ray diffraction patterns. p was also calculated from C-13 CP/MAS n.m. r. spectra of as-synthesized samples. in the present case, an excellen t agreement was found between the results obtained by both techniques. The corresponding silicalites 1 and 2 have been characterized using S i-29 MAS n.m.r., which has clearly revealed the presence of stacking f aults.