0000000000328649
AUTHOR
Bodo Zibrowius
showing 3 related works from this author
TEMPLATE-FREE AND ALKALI-FREE SYNTHESIZED SILICATES WITH MFI-STRUCTURE -A COMPARATIVE STUDY
1993
ABSTRACT Zeolites and gallosilicates with an MFI-structure which were crystallized from inorganic reaction systems and from alkali-free, tetrapropylammonlumbromide (TPABr) containing systems are compared. The strength, nature and distribution of the acidic sites were determined by FTIR-spectroscopy, TPD, electron microprobing, 29 si, 27 Al and 1 H MAS NMR spectroscopy. The influences of the different trivalent elements as well as the strength, type and distribution of the acidic sites on the catalytic performance of the different MFI-silicates are discussed.
Aspects of the characterization of cloverite by solid-state n.m.r. techniques
1993
Abstract Microporous gallophosphate cloverite has been studied by multinuclear ( 13 C, 19 F, 31 P, 71 Ga) solid-state n.m.r. spectroscopy. An extraordinarily strong quadrupolar coupling is shown to be the reason for a misleading line shape in 71 Ga MAS n.m.r. spectra. Using static 71 Ga n.m.r. spectroscopy, an estimate of the size of this quadrupolar coupling can be obtained. The limitations of the MAS technique for the study of quadrupolar nuclei in sites with very large quadrupolar couplings are addressed.
The synthesis of zeolites from dry powders
1995
Summary ZSM-5 was synthesized by different methods with a gradually decreasing water content ending in a reaction mixture with absolutely dry reagents in form of a powder in the complete absence of a solution phase. Amorphous precursors obtained by drying SiO 2 * Al 2 O 3 gels at 650°C were transformed into zeolites in the presence of dried NH 4 F and TPABr. The reaction products were characterized by XRD, REM, TG/DTA, MAS NMR and Electron Micropobe. Pure ZSM-5 or Silicalite-1 was obtained in all cases. Some water is probably formed as a reaction product, but the maximum water pressure is appreciably below the saturation pressure at the given reaction conditions. To explain the formation of…