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Mesopores in USY Zeolites II
Author(s) -
Lutz Wolfgang,
Enke Dirk,
Einicke WolfDietrich,
Täschner Dirk,
Kurzhals Rolf
Publication year - 2012
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201200294
Subject(s) - mesoporous material , microporous material , zeolite , alkali metal , sorption , ion exchange , inorganic chemistry , ion , potassium , chemistry , materials science , sodium , aluminium , chemical engineering , catalysis , adsorption , organic chemistry , engineering
Microporous zeolites Na‐Y and K‐Y were converted into the NaNH 4 ‐Y and KNH 4 ‐Y modifications by ion exchange being active in dealumination. Removal of framework aluminium and silicon is accompanied by formation of secondary mesopores. Internal mesopores are formed in the centre of zeolite crystals and external pores at their surface. Formation of mesopores changes the sorption behaviour.Residual alkali metal cations as Na + or K + stabilise, however, the framework ≡Si‐O‐Al≡ bonds. Because of inhomogeneous distribution of sodium ions, in NaNH 4 ‐Y less internal but more external mesopores are formed. Potassium ions of KNH 4 ‐Y are more homogeneous distributed over the framework why a more balanced formation of secondary pores takes place.