Sorbate Rearrangement and Cation Migration in HFC-134 Loaded NaY Zeolite: a Temperature Dependent Synchrotron Powder Diffraction Study
The HFC-134/NaY binding has been monitored by temperature dependent X-ray powder diffraction. Diffraction patterns were obtained as a function of different loading levels to investigate the rearrangement of the cations and of the HFC-134 molecules, in the temperature range 100-230 K. In situ real-time data were collected using a Translating Imaging Plate System (TIPS) at the NSLS (USA). Rietveld structure refinements were performed for the HFC-134 (32 molecules per unit cell [m/uc = molecules per unit cell] or 4 molecules per supercage [m/sc = molecules per supercage]) using data collected from 100 to 230 K. A phase transition is observed at about 180 K (A to B phase transition) where a disordering of the HFC-134 molecule takes place and modification of its surrounding due to Na+ migrations is observed. These results are preliminary and the experiment with the 32 m/uc should be repeated in order to assess whether the observed effect is reproducible.
Yvonne Andersson, Eric J. Mittemeijer and Udo Welzel
A.F. Gualtieri et al., "Sorbate Rearrangement and Cation Migration in HFC-134 Loaded NaY Zeolite: a Temperature Dependent Synchrotron Powder Diffraction Study", Materials Science Forum, Vols. 443-444, pp. 295-298, 2004