129Xe NMR study of ZSM-5 type zeolites Effect of cationic sites |
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| Institution: | 1. Institute of Materials, China Academy of Engineering Physics, P.O. Box 9071-12, Mianyang 621907, China;2. Max Planck Institute for Intelligent Systems, Heisenbergstr.3, 70569 Stuttgart, Germany;1. Bruker-Biospin, 15 Fortune Drive, Billerica, MA 01730, USA;2. Communications and Power Industries, 811 Hansen Way, Palo Alto, CA 94304, USA;3. Bruker-Biospin, Silberstreifen 4, 76287 Rheinstetten, Germany;1. Graz University of Technology, Institute of Materials Science, Joining and Forming, Research Group of Tools & Forming, Inffeldgasse 11/I, 8010, Graz, Austria;2. Ghent University, Department of Materials, Textiles and Chemical Engineering, Research Group Sustainable Materials Science, Technologiepark 46, 9052, Ghent, Belgium |
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| Abstract: | A comprehensive 129Xe NMR spectroscopy study on H-ZSM-5 zeolites having different aluminum contents and on cation-exchanged ZSM-5 zeolites is reported. The parent H-ZSM-5 zeolites were ion-exchanged with Group I–III metal ions ( K, Ca, Sr, Ba, Al, La) to varying degrees. The chemical shift of adsorbed 129Xe is seen to be a function of the pentasil structure of ZSM-5, of the number of free Brønsted acid sites and of the number of metal cations in the framework. Differences in the chemical shift of 129Xe are seen between cations due to their different polarizing forces against xenon. The amount of cations has also an effect on the δxe-xe term in Fraissard's equation that may be caused by changes in the diffusional characteristics of Xe atoms in the ZSM-5 framework. |
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