SOLID-STATE NMR-STUDIES OF THE HIGH-SILICA ZEOLITE THETA-1

In the following study, the diethylamine template present in as-synthesized high-silica Theta-1 is used as a probe molecule. The high-silica form of Theta-1 is characterized by high-resolution 13C and 29Si MAS n.m.r. The 13C spectra are interpreted as showing the presence of both neutral and protonated template molecules. These observations are discussed in terms of the possible presence of silanol defect sites/residual hydroxyl ions and their spatial distribution. The 29Si n.m.r results are consistent with the template molecule occupying the 10-T channels only, and the spin-lattice relaxation behavior of both the 13C and 29Si spins is interpreted in terms of restricted motions of the template molecules. Changes in the 29Si n.m.r. spectra on calcination indicate the possibility of a minor framework rearrangement. © 1990 Butterworth-Heinemann.