We report the results of an in-situ synchrotron X-ray powderdiffra ction study–performedusing silicone oil as‘‘non-penetrating’’ pressure transmitting medium– of the elastic behavior of three zeolites with MFI-type framework: the natural zeolite mutinaite and two silicalites (labeledAandB) synthesized under different conditions. While in mutinaite no symmetry change is observed as a function of pressure, a phase transition from monoclinic (P21/n) to orthorhombic (Pnma) symmetry occurs at about 1.0GPa in the silicalite samples. This phase transition is irreversible upon decompression. The second order bulk moduli of silicalite A and silicalite B, calculated after the fulfillment of thephase transition, are: K0=18.2(2)and K0=14.3 (2)GPa, respectively. These values make silicalite the most compressible zeolite among those up to now studied in silicone oil. The structural deformations induced by HP in silicalite A were investigated by means of complete Rietveld structural refinements, before and after the phase transition,at Pamb and 0.9GPa,respectively.The elastic behaviors of thethree MFI- type zeolites here investigated were compared with those of Na-ZSM-5 and H-ZSM-5, studied in similar experimental conditions: the two silicalites–which are the phases with the highestSi/Al ratios and hence the lowest extraframework contents–show the highest compressibility. On the contrary, the most rigid material is mutinaite, which has a very complex extraframework composition characterized by a high number of cations and wate rmolecules.

ELASTIC BEHAVIOR OF MFI-TYPE ZEOLITES: 3- COMPRESSIBILITY OF SILICALITE AND MUTINAITE / Quartieri, S.; Arletti, R.; Vezzalini, Maria Giovanna; Di Renzo, F.; Dmitriev, V.. - In: JOURNAL OF SOLID STATE CHEMISTRY. - ISSN 0022-4596. - STAMPA. - 191:(2012), pp. 201-212. [10.1016/j.jssc.2012.03.039]

ELASTIC BEHAVIOR OF MFI-TYPE ZEOLITES: 3- COMPRESSIBILITY OF SILICALITE AND MUTINAITE

R. Arletti;VEZZALINI, Maria Giovanna;
2012

Abstract

We report the results of an in-situ synchrotron X-ray powderdiffra ction study–performedusing silicone oil as‘‘non-penetrating’’ pressure transmitting medium– of the elastic behavior of three zeolites with MFI-type framework: the natural zeolite mutinaite and two silicalites (labeledAandB) synthesized under different conditions. While in mutinaite no symmetry change is observed as a function of pressure, a phase transition from monoclinic (P21/n) to orthorhombic (Pnma) symmetry occurs at about 1.0GPa in the silicalite samples. This phase transition is irreversible upon decompression. The second order bulk moduli of silicalite A and silicalite B, calculated after the fulfillment of thephase transition, are: K0=18.2(2)and K0=14.3 (2)GPa, respectively. These values make silicalite the most compressible zeolite among those up to now studied in silicone oil. The structural deformations induced by HP in silicalite A were investigated by means of complete Rietveld structural refinements, before and after the phase transition,at Pamb and 0.9GPa,respectively.The elastic behaviors of thethree MFI- type zeolites here investigated were compared with those of Na-ZSM-5 and H-ZSM-5, studied in similar experimental conditions: the two silicalites–which are the phases with the highestSi/Al ratios and hence the lowest extraframework contents–show the highest compressibility. On the contrary, the most rigid material is mutinaite, which has a very complex extraframework composition characterized by a high number of cations and wate rmolecules.
2012
191
201
212
ELASTIC BEHAVIOR OF MFI-TYPE ZEOLITES: 3- COMPRESSIBILITY OF SILICALITE AND MUTINAITE / Quartieri, S.; Arletti, R.; Vezzalini, Maria Giovanna; Di Renzo, F.; Dmitriev, V.. - In: JOURNAL OF SOLID STATE CHEMISTRY. - ISSN 0022-4596. - STAMPA. - 191:(2012), pp. 201-212. [10.1016/j.jssc.2012.03.039]
Quartieri, S.; Arletti, R.; Vezzalini, Maria Giovanna; Di Renzo, F.; Dmitriev, V.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/736658
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