Bulletin of the Korean Chemical Society

Korean Chemical Society (대한화학회)
권호 표지
DOI QR코드

DOI QR Code

Remarkable Structure Relaxation of Zeolite Windows in Rb₃- and K₃-A Crystal Structures of $M_3nA_{9-x}H_xSi_{12}Al_{12}O_{48}$ where M-Rb or K and x=1 or 0

  • Published : 1995.10.20
Download PDF
⟨ Previous Next ⟩

Abstract

Four crystal structures of M3-A (M3Na9-xHx-A, M=Rb or K and x=1 or 0), Rb3Na8H-A(a=12.228(1) Å and R1=0.046), Rb3Na9-A (a=12.258(3) Å and R1=0.058), K3Na8H-A (a=12.257(3) Å and R1=0.048) and K3Na9-A (a=12.257(3) Å and R1=0.052), have been determined by single crystal x-ray diffraction technique in the cubic space group Pm3^m at 21 ℃. In all structures, each unit cell contained three M+ ions all located at one crystallographically distinct position on 8-rings. Rb+ ions are 3.12 and 3.21 Å away respectively from O(1) and O(2) oxygens, about 0.40 Å away from the centers of the 8-rings, and K+ ions are 2.87 and 2.81 Å apart from the corresponding oxygens. These distances are the shortest ones among those previously found for the corresoponding ones. Eight 6-rings per unit cell are occupied by eight Na+ ions, each with a distance of 2.31 Å to three O(3) oxygens. The twelfth cation per unit cell is found as Na+ opposite 4-ring in the large cavities of M3Na9-A and assumed to be H+ for M3Na8H-A. With these noble non-framework cationic arrangements, larger M+ ions preferably on all larger 8-rings and the compact Na+ ions on all 6-rings, the bond angles in the 8-rings of M3-A, 145.1 and 161.0 respectively for (Si,Al)-O(1)-(Si,Al) and (Si,Al)-O(2)-(Si,Al), turned out to be remarkably stable and smaller, by more than 12 to 17°, than the corresponding angles found in the crystal structures of zeolites A with high concentration of M+ ions. It is to achieve these remarkably relaxed 8-rings, the main windows for the passage of gas molecules, with simultaneously maximized cavity volumes that M3-A have been selected as one of the efficient zeolite A systems for gas encapsulation.

Keywords

References

  1. Zeolite Molecular Sieves: Structure, Chemistry, and Uses Breck, D. W.
  2. Chem. Tech. v.1 Fraenkel, D.
  3. Trans. Faraday Soc. v.67 Barrer, R. M.;Vaughan, D. E. W.
  4. Innovation in Zeolite Material Science Vansant, E. F.;Grobet, P. J.(et al.)(Eds.)
  5. Surface Science v.14 Barrer, R. M.;Vaughan, D. E. W.
  6. Argon, Helium, and the Rare Gases v.1 Cook, G. A.
  7. J. Phys. Chem. Solids v.32 Barrer, R. M.;Vaughan, D. E. W.
  8. Trans. Faraday Soc. v.63 Barrer, R. M.;Vaughan, D. E. W.
  9. ibid v.59 Barrer, R. M.;Gibbons, R. M.
  10. ibid v.61 Barrer, R. M.;Gibbons, R. M.
  11. J. Am. Chem. Soc. v.99 Fraenkel, D.;Shabtai, J.
  12. J. Chem. Soc. Faraday Trans. I v.77 Fraenkel, D.
  13. J. Chem. Soc. Chem. Commun. Fraenkel, D.;Ittah, B.;Levy, M.
  14. J. Phys. Chem. v.96 Yoon, J. H.;Heo, N. H.
  15. Hwahak Konghak v.29 Heo, N. H.;Rho, B. R.;Kim, D. H.;Kim, J. T.
  16. ibid v.29 Kim, D. H.;Heo, N. H.;Kim, J. T.
  17. Bull. Kor. Chem. Soc. v.14 Kwon, J. H.;Cho, K. H.;Kim, H. W.;Suh, S. H.;Heo, N. H.
  18. ME Thesis Kwon, J. H.
  19. Hwahak Konghak v.32 Kim, D. H.;Heo, N. H.;Kim, J. T.
  20. The nomenclature refers to the contents of the Pm3m unit cell: e.g., $Na_{12}-A represents Na_{12}Si_{12}Al_{12}O_{48} and Rb_3Na_8H-A represents Rb_3Na_8HSi_{12}Al_{12}O_48$
  21. Bull. Kor. Chem. Soc. v.15 Cho, K. H.;Kwon, J. H.;Kim, H. W.;Park, C. S.;Heo, N. H.
  22. Phys. Chem. v.98 Heo, N. H.;Cho, K. H.;Kim, J. T.;Seff, K. J.
  23. J. Am. Chem. Soc. v.99 Firror, R. L.;Seff, K.
  24. J. Phys. Chem. v.79 Leung P. C. W.;Kunz, K. B.;Maxwell, I. E.;Seff, K.
  25. Handbook of Chemistry and Physics; Chemical rubber Co., Cleveland, OH 64th ed.
  26. Acta Cryst. v.B25 Shannon, R. D.;Prewitt, C. T.
  27. The Proceedings of 72nd Annual Meeting of Korean Chemical Society Jeong, H. K.;Kim J. S.;No, K. T.
  28. J. Crystal Growth v.8 Charnell, J. F.
  29. J. Am. Chem. Soc. v.100 Cruz, W. V.;Leung, P. C. W.;Seff, K.
  30. J. Phys. Cham. v.88 Mellum, M. D.;Seff, K.
  31. Internaational Tables for X-ray Crystallography v.Ⅵ Birmingham
  32. Calculations were preformed with Structure Determination Systme, Molen Enraf-Nonius
  33. J. Phys. Chem. v.89 Blackwell, C. S.;Pluth, J. J.;Smith, J. V.
  34. Acta Crystallogr. Sect. A v.24 Doyle, P. A.;Turner, P. S.
  35. Reference 31
  36. Acta Crystallogr. v.18 Cromer, D. T.
  37. Reference 31
  38. J. Phys. Chem. v.77 Yanagida, R. Y.;Amaro, A. A.;Seff, K.
  39. J. Am. Chem. Soc. v.109 Heo, N. H.;Seff, K.