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Differences Between Individual ZSM‐5 Crystals in Forming Hollow Single Crystals and Mesopores During Base Leaching
Author(s) -
Fodor Daniel,
Krumeich Frank,
Hauert Roland,
van Bokhoven Jeroen A.
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201406182
Subject(s) - materials science , leaching (pedology) , mesoporous material , base (topology) , zsm 5 , chemical engineering , crystallography , mineralogy , zeolite , chemistry , environmental science , soil science , organic chemistry , mathematics , engineering , catalysis , soil water , mathematical analysis
Abstract After base treatment of ZSM‐5 crystals below 100 nm in size, TEM shows hollow single crystals with a 10 nm shell. SEM images confirm that the shell is well‐ preserved even after prolonged treatment. Determination of the Si/Al ratios with AAS and XPS in combination with argon sputtering reveals aluminum zoning of the parent zeolite, and the total pore volume increases in the first two hours of base treatment. In corresponding TEM images, the amount of hollow crystals are observed to increase during the first two hours of base treatment, and intact crystals are visible even after 10 h of leaching; these observations indicate different dissolution rates between individual crystals. TEM of large, commercially available ZSM‐5 crystals shows inhomogeneous distribution of mesopores among different crystals, which points to the existence of structural differences between individual crystals. Only tetrahedrally coordinated aluminum is detected with 27 Al MAS NMR after the base leaching of nano‐sized ZSM‐5.