DETERIORATION OF CANAA-TYPE ZEOLITES BY HYDROTHERMAL TREATMENT AND UNDER THE CONDITIONS OF HYDROCARBON SEPARATION PROCESSES

Citation
R. Seidel et B. Staudte, DETERIORATION OF CANAA-TYPE ZEOLITES BY HYDROTHERMAL TREATMENT AND UNDER THE CONDITIONS OF HYDROCARBON SEPARATION PROCESSES, Zeolites, 13(5), 1993, pp. 348-356
Citations number
34
Categorie Soggetti
Chemistry Physical
Journal title
ISSN journal
01442449
Volume
13
Issue
5
Year of publication
1993
Pages
348 - 356
Database
ISI
SICI code
0144-2449(1993)13:5<348:DOCZBH>2.0.ZU;2-4
Abstract
The dynamic adsorption properties of CaNaA-type zeolites are deteriora ted after being exposed to the conditions of the hydrocarbon separatio n process for a long period. The static adsorption properties and the structural parameters are slightly changed, but the diffusivity of ads orbed molecules is hindered drastically due to the origin of a surface barrier. There are coke depositions predominantly in the surface laye r of the zeolite crystals. The coke formation depends on the working t ime, the composition of the mineral oil fraction, and the way the sepa ration process is driven. We find the same microdynamical picture bein g valid for the behavior of molecular sieves after the separation proc ess as well as after a hydrothermal treatment: the origin of a surface barrier. But the nature of these barriers is completely different.