Differences Between Individual ZSM‐5 Crystals in Forming Hollow Single Crystals and Mesopores During Base Leaching |
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| Authors: | Daniel Fodor Dr. Frank Krumeich Dr. Roland Hauert Prof. Jeroen A. van Bokhoven |
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| Affiliation: | 1. ETH Zurich, Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, Vladimir‐Prelog‐Weg 1, 8093 Zurich (Switzerland);2. ETH Zurich, Department of Chemistry and Applied Biosciences, Laboratory of Inorganic Chemistry, Vladimir‐Prelog‐Weg 1, 8093 Zurich (Switzerland);3. Empa, Swiss Federal Laboratories for Materials Science and Technology, überlandstrasse 129, 8600 Dübendorf (Switzerland);4. Paul Scherrer Insitute, 5232 Villigen (Switzerland) |
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| 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 27Al MAS NMR after the base leaching of nano‐sized ZSM‐5. |
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| Keywords: | aluminum base leaching desilication ZSM‐5 zeolites |
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