The thermal behaviour of boron substituted ZSM-5 synthesized in the presence of ethylenediamine as an organic template was highlighted for the first time by in situ time-resolved synchrotron powder diffraction in the 25–900 °C temperature range. The evolution of the structural features was followed by full profile Rietveld refinements at up to 730 °C. Above this temperature, a structural breakdown occurs and B-ZSM-5 is converted into a β-cristobalite phase. A continuous increase in unit-cell parameters as a function of temperature is observed both during calcination (between 200 and 500 °C) and afterwards. This behaviour is completely unusual when compared to that assumed by other boron-free MFI-type materials both in their as-synthesized as well as calcined forms. On the basis of all these results, B-ZSM-5 represents the first example of positive thermal expansion in a material with an MFI type topology.

The unusual thermal behaviour of boron-ZSM-5 probed by “in situ” time-resolved synchrotron powder diffraction

LEARDINI, Lara;MARTUCCI, Annalisa;CRUCIANI, Giuseppe
2013

Abstract

The thermal behaviour of boron substituted ZSM-5 synthesized in the presence of ethylenediamine as an organic template was highlighted for the first time by in situ time-resolved synchrotron powder diffraction in the 25–900 °C temperature range. The evolution of the structural features was followed by full profile Rietveld refinements at up to 730 °C. Above this temperature, a structural breakdown occurs and B-ZSM-5 is converted into a β-cristobalite phase. A continuous increase in unit-cell parameters as a function of temperature is observed both during calcination (between 200 and 500 °C) and afterwards. This behaviour is completely unusual when compared to that assumed by other boron-free MFI-type materials both in their as-synthesized as well as calcined forms. On the basis of all these results, B-ZSM-5 represents the first example of positive thermal expansion in a material with an MFI type topology.
2013
Leardini, Lara; Martucci, Annalisa; Cruciani, Giuseppe
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1780099
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 11
  • ???jsp.display-item.citation.isi??? 11
social impact