The unusual thermal behaviour of boron-ZSM-5 probed by %26quot;in situ%26quot; time-resolved synchrotron powder diffraction

作者：Leardini Lara^*; Martucci Annalisa; Cruciani Giuseppe

来源：Microporous and Mesoporous Materials, 2013, 173: 6-14.

DOI：10.1016/j.micromeso.2013.01.036

• B-ZSM-5
• Thermal behaviour
• Rietveld refinement
• In situ X-ray powder diffraction

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 degrees C temperature range. The evolution of the structural features was followed by full profile Rietveld refinements at up to 730 degrees C. Above this temperature, a structural breakdown occurs and B-ZSM-5 is converted into a beta-cristobalite phase. A continuous increase in unit-cell parameters as a function of temperature is observed both during calcination (between 200 and 500 degrees 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.

• 出版日期2013-6