0000000000016653
AUTHOR
A. Tissler
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.
Control of catalytic properties of ZSM-5 made by fast and template- free synthesis.
Abstract The fast template-free synthesis of ZSM-5 was accomplished in both static and stirred autoclaves employing sodiumwaterglass.silica hydrogel and pyrogenic silicas as silica sources. Highly pure crystalline ZSM-5 was obtained in the sodiumwaterglass reaction system in the stirred autoclaves without seeds within 3 hours. Addition of 2% (w/w) of seeds reduced the reaction time to 2 hours. The catalytic activity and shape selectivity of the H-ZSM-5, tested by the disproportionation of ethylbenzene, was found to be largely controlled by the synthesis parameters and by the posttreatments. The homogeneous aluminum distribution across the crystals achieved by this synthetis route resulted i…
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.