Crystalline, microporous zirconium silicates with MEL structure
- National Chemical Lab., Pune (India)
The isomorphous substitution of Si{sup 4+} by Ti{sup 4+} and Sn{sup 4+} in the silicalite-2 (ZSM-11, MEL) framework has been the subject of some recent reports. The possibility of substituting silicon by zirconium in the framework of ZSM-5 (MFI) by hydrothermal synthesis has been reported but not really substantiated by experimental evidence. In earlier attempts, based on the unit cell volume expansion of about 21 {Angstrom}{sup 3} of the MFI structure, it was presumed that only 0.6 Zr atom per unit cell of MFI could be incorporated. In this communication, the authors report for the first time the synthesis of crystalline and microporous Al-free zirconium silicates with MEL structure. The presence of zirconium in the MEL framework is elucidated by X-ray diffraction (XRD), framework FTIR spectroscopy, diffuse reflectance UV-visible (DR UV-Vis) spectroscopy, and catalytic activity in the hydroxylation of phenol, using hydrogen peroxide as oxidant. The acid sites of all samples are determined by pyridine adsorption studies. 21 refs., 5 refs., 2 tabs.
- OSTI ID:
- 501862
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 163; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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