Hostname: page-component-586b7cd67f-g8jcs Total loading time: 0 Render date: 2024-11-28T10:48:25.283Z Has data issue: false hasContentIssue false
  • English
  • Français

Neutron and Raman Spectroscopes of 134 and 134a Hydrofluorocarbons Encaged in Na-X Zeolite

Published online by Cambridge University Press:  22 February 2011

T. J. Udovic ,
J. M. Nicol ,
R. R. Cavanagh ,
J. J. Rush ,
M. K. Crawford ,
C. P. Grey  and
D. R. Corbin
T. J. Udovic
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
J. M. Nicol
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
R. R. Cavanagh
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
J. J. Rush
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
M. K. Crawford
Affiliation:
E. I. Du Pont de Nemours and Company, Experimental Station, Wilmington, DE 19880
C. P. Grey
Affiliation:
E. I. Du Pont de Nemours and Company, Experimental Station, Wilmington, DE 19880
D. R. Corbin
Affiliation:
E. I. Du Pont de Nemours and Company, Experimental Station, Wilmington, DE 19880
Get access

Abstract

Inelastic neutron scattering methods were used in conjunction with Raman spectroscopy to probe the vibrational density of states of the hydrofluorocarbons (HFCs) 134 (HF2C-CF2H) and 134a (F3C-CFH2) adsorbed in the cages of dehydrated Na-X zeolite. A comparison of the vibrational spectra of the encaged HFC species with those of their gas-phase analogs indicates that the HFCs adsorb nondissociatively at room temperature and are most likely associated with Na cations in the supercages at the SIII sites. Guest-host interactions are manifested by adsorption-induced perturbations of the gas-phase torsional and C-H stretching vibrations and the presence of additional features presumably due to low-energy whole-molecule vibrations and adsorbate-coupled zeolite framework vibrations. Moreover, although the 134 trans conformer is favored by 5 kJ/mole in the gas phase at 300 K, the gauche conformer seems to be more prevalent in the zeolite at this temperature and below. This suggests that a sizeable fraction of the Na-X adsorption sites provides a stabilizing configuration for the otherwise higher-energy gauche conformation, perhaps due to hydrogen-bonding interactions with the zeolite framework.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 376: Symposium BB – Neutron Scattering in Materials Science , 1994 , 751
Copyright
Copyright © Materials Research Society 1995

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1 Corbin, D. R. and Grey, C. P., (DuPont) unpublished data.Google Scholar
2 Breck, D. W., Zeolite Molecular Sieves, John Wiley and Sons, New York (1974).Google Scholar
3 Jacobs, W. P. J. H., van Wolput, J. H. M. C., van Santen, R. A., and Jobic, H., Zeolites 14, 117 (1994).Google Scholar
4 Klaboe, P. and Nielsen, J. R., J. Chem. Phys. 32, 899 (1960).Google Scholar
5 Kalasinsky, V. F., Anjaria, H. V., and Little, T. S., J. Phys. Chem. 86, 1351 (1982).Google Scholar
6 Danti, A. and Wood, J. L., J. Chem. Phys. 30, 582 (1959).Google Scholar
7 Crawford, M. K. and Corbin, D. R., (DuPont) unpublished data.Google Scholar