¹⁹F/²³Na Cross polarization NMR study of hydrofluorocarbon–zeolite binding on zeolite NaY

Abstract

¹⁹F/²³Na Cross polarization (CP) MAS NMR experiments of various asymmetric hydrofluorocarbons (HFCs) such as CF₃CFH₂ (HFC-134a) and CF₂HCFH₂ (HFC-143) adsorbed on zeolite NaY, demonstrate that the hydrogen-containing groups are bound more strongly to the zeolite framework, in the order CF₃<<CF₂H<CFH₂; the results help explain the preferential binding of CF₂HCF₂H (HFC-134) over HFC-134a, and hence the effectiveness of basic zeolites in the separation of HFC-134/134a gas mixtures.

References

1. L. E. Manzer, Science, 1990, 249, 31; G. Webb and J. Winfield, Chem. Br., 1992, 28, 996; L. E. Manzer and V. N. M. Rao, Adv. Catal., 1993, 39, 329.
2. D. R. Corbin and B. A. Mahler, U.S. Pat. 5600040 (July 17, 1995).
3. C. P. Grey and D. R. Corbin, J. Phys. Chem., 1995, 99, 16 821.
4. C. P. Grey, F. I. Poshni, A. F. Gualtieri, P. Norby, J. C. Hanson and D. R. Corbin, J. Am. Chem. Soc., 1997, 119, 1981.
5. M. Mehring, Principles of High Resolution NMR in Solids, 2nd edn., 1983, Springer-Verlag, New York.
6. T. H. Walter, G. L. Turner and E. Oldfield, J. Magn. Reson., 1988, 76, 106.
7. A. J. Vega, J. Magn. Reson., 1992, 96, 50.
8. K. K. Irikura and R. R. Cavanagh, personal communication.
9. T. J. Udovic, J. M. Nicol, R. R. Cavanagh, J. J. Rush, M. K. Crawford, C. P. Grey and D. R. Corbin, Mater. Res. Soc. Symp. Proc., 1995, 376, 751.