0000000000328653
AUTHOR
M. Wallau
TEMPLATE-FREE AND ALKALI-FREE SYNTHESIZED SILICATES WITH MFI-STRUCTURE -A COMPARATIVE STUDY
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.
Intracrystalline Diffusion of Benzene in Ga-Silicate
Abstract The sorption kinetics of benzene in large Ga-MFI crystals was investigated under constant volume- variable pressure conditions. A complete analysis of the uptake curves has been performed using solution of a nonlinear Volterra equation which describes the interaction of uptake process with the apparatus. Within the time scale of uptake measurements (10 3 -10 4 s) the uptake curves were found to be consistent with the solution of the second Fick's law. Corrected diffusion coefficients were found to be essentially independent of loading within the loading range investigated and in contrast to the system benzene-HNaZSM-5 [1,2] their temperature dependence is much stronger.