Mordenite acidity: dependence on the silicon/aluminum ratio and the framework aluminum topology. 1. Sample preparation and physicochemical characterization

Autor: Helmut Stach, Ursula Lohse, Bodo Zibrowius, Hans Georg Jerschkewitz, Michael Hunger, Barbara Parlitz, Jochen Jaenchen
Rok vydání: 1992
Předmět:
Zdroj: The Journal of Physical Chemistry. 96:8473-8479
ISSN: 1541-5740
0022-3654
DOI: 10.1021/j100200a050
Popis: A series of dealuminated mordenites (with Si/Alf ratios between 7 and 48) was prepared by acid leaching and characterized by using different physicochemical methods. The A1 content of the framework and the distribution of the tetrahedral and octahedral aluminum were determined by 27Al MAS NMR measurements and chemical analysis. Attempts to quantify the number of SiOH defect groups by '%i MAS NMR measurements (following a procedure given in the literature) failed. The number of silanol groups (and Bransted sites) were determined using 'H MAS NMR investigations. The micro- and mesopore volumes of the samples were derived from measurements of the benzene adsorption isotherms. It was found that low dealumination of the H-mordenites transforms small- into large-port mordenites. The micropore volume diminished again at a high degree of dealumination.
Databáze: OpenAIRE