Application of computer modelling to the mechanisms of synthesis of microporous catalytic materials

Abstract

We present results of a study of species present during the hydrothermal synthesis of zeotype materials. We have studied the interactions of typical silica fragments, which condense to form the framework structure, with both solvent (water) and the organic molecules used as structure-directing agents. The hydrophobic nature of the fragments results in the collapse of the fragment structure on solvation, resulting in geometries far removed from their configuration in the crystalline material. The presence of the organic template provides stabilisation for the hydrated fragments, effectively shielding them from the water and allowing them to maintain their open structure. The impact of these results on possible mechanisms of crystallisation is discussed.

References

1. R. M. Barrer, Hydrothermal Chemistry of Zeolites, Academic Press, London, 1982.
2. J. M. Thomas, Angew. Chem. Int. Ed. Engl., 1988, 27, 1673.
3. M. E. Davis, Chemtech, 1994, 22.
4. J. M. Thomas and D. W. Lewis, Z. Phys. Chem., 1996, 197S, 37.
5. C. J. Brinker and G. W. Scherer, Sol–Gel Science, The Physics and Chemistry of Sol-Gel Processing, Academic Press, London, 1989.
6. J. Sauer, Chem. Rev., 1989, 89, 199.
7. L. W. Burggraff and L. P. Davis, in Silanes, Surfaces and Interfaces, ed. D. E. Leyden, Dekker, New York, 1986, p. 157.
8. S. H. Garofalini and G. Martin, J. Phys. Chem., 1994, 98, 1311.
9. F. Rey, G. Sankar, J. M. Thomas, P. A. Barrett, D. W. Lewis, C. R. A. Catlow, S. M. Clark and G. N. Greaves, Chem. Mater., 1995, 7, 1435.
10. J. S. O. Evans, E. J. Francis, D. O'Hare, S. J. Price, S. M. Clark, J. Flaherty, J. Gordon, A. Nield and C. C. Tang, Rev. Sci. Instrum., 1995, 66, 2442.
11. R. J. Francis, S. J. Price, J. S. O. Evans, S. O'Brien, D. O'Hare and S. M. Clark, Chem. Mater., 1996, 8, 2102.
12. G. Sankar, P. A. Wright, S. Natarajan, J. M. Thomas, F. Rey, G. N. Greaves, A. J. Dent, B. R. Dobson, C. A. Ramsdale and R. H. Jones, J. Phys. Chem., 1993, 97, 9550.
13. G. Sankar, J. M. Thomas, F. Rey and G. N. Greaves, J. Chem. Soc., Chem. Commun., 1995, 2549.
14. G. Engelhardt and D. Michel, High-Resolution Solid-state NMR of Silicates and Zeolites, Wiley, New York, 1987.
15. J. El Hage-Al Asswad, N. Dewaele, J. B. Nagy, R. A. Hubert, Z. Gabelica, E. G. Derouane, F. Crea, R. Aiello and A. Nastro, Zeolites, 1988, 8, 221.
16. S. L. Burkett and M. E. Davis, J. Phys. Chem., 1994, 98, 4647.
17. S. L. Burkett and M. E. Davis, Chem. Mater., 1995, 7, 1453.
18. S. L. Burkett and M. E. Davis, Chem. Mater., 1995, 7, 920.
19. W. M. Dokter, H. F. van Garderen, T. P. M. Beelen, R. A. van Santen and W. Bras, Angew. Chem. Int. Ed. Engl., 1995, 34, 73.
20. P. K. Dutta, J. Incl. Phenom. Mol. Recog. Chem., 1995, 21, 215.
21. B. J. Schoeman, J. Sterte and J.-E. Otterstedt, Zeolites, 1994, 14, 110.
22. B. J. Schoeman, J. Sterte and J.-E. Otterstedt, Zeolites, 1994, 14, 208.
23. A. R. Persson, B. J. Schoeman, J. Sterte and J.-E. Otterstedt, Zeolites, 1995, 15, 611.
24. R. A. Jackson and C. R. A. Catlow, Mol. Simul., 1988, 1, 207.
25. R. G. Bell, R. A. Jackson and C. R. A. Catlow, J. Chem. Soc., Chem. Commun., 1990, 782.
26. K.-P. Schroder, J. Sauer, M. Leslie and C. R. A. Catlow, Zeolites, 1992, 12, 20.
27. D. W. Lewis, C. R. A. Catlow, G. Sankar and S. W. Carr, J. Phys. Chem., 1995, 99, 2377.
28. A. R. George, C. R. A. Catlow and J. M. Thomas, Catal. Lett., 1991, 8, 193.
29. R. Shah, M. C. Payne and J. D. Gale, Science, 1996, 271, 1395.
30. S. R. Blaszkowski and R. A. Van Santen, J. Am. Chem. Soc., 1996, 118, 5152.
31. P. E. Sinclair and C. R. A. Catlow, J. Chem. Soc., Faraday Trans., 1996, 92, 2099.
32. C. M. Freeman, D. W. Lewis, T. V. Harris, A. K. Cheetham, N. J. Henson, P. A. Cox, A. M. Gorman, S. M. Levine, J. M. Newsam, E. Hernandez and C. R. A. Catlow, in Computer Aided Materials Design: Applications in Agrochemical, Materials and Pharmaceuticals, ed. C. H. Reynolds, M. K. Holloway and H. K. Cox, ACS, Washington DC, 1995, p. 326.
33. D. W. Lewis, C. M. Freeman and C. R. A. Catlow, J. Phys. Chem., 1995, 99, 11194.
34. R. G. Bell, D. W. Lewis, P. Voigt, C. M. Freeman, J. M. Thomas and C. R. A. Catlow, Stud. Surf. Sci. Catal., 1994, 84, 2075.
35. P. A. Cox, A. P. Stevens, L. Banting and A. M. Gorman, Stud. Surf. Sci. Catal., 1994, 84, 2115.
36. T. V. Harris and S. I. Zones, Stud. Surf. Sci. Catal., 1994, 84, 29.
37. S. I. Zones, Y. Nakagawa, L. T. Yuen and T. V. Harris, J. Am. Chem. Soc., 1996, 118, 7558.
38. R. M. Barrer and P. J. Denny, J. Chem. Soc., 1961, 971.
39. H. Gies and B. Marler, Zeolites, 1992, 12, 42.
40. M. E. Davis and R. F. Lobo, Chem. Mater., 1992, 4, 759.
41. P. A. Wright, R. H. Jones, S. Natarajan, R. G. Bell, J. Chem, M. B. Hursthouse and J. M. Thomas, J. Chem. Soc., Chem. Commun., 1993, 644.
42. A. P. Stevens, A. H. Gorman, C. M. Freeman and P. A. Cox, J. Chem. Soc., Faraday Trans., 1996, 92, 2065.
43. C. M. Freeman, C. R. A. Catlow, J. M. Thomas and S. Brode, Chem. Phys. Lett., 1991, 186, 137.
44. R. E. Boyett, A. P. Stevens, M. G. Ford and P. A. Cox, Zeolites, 1996, 17, 508.
45. M. G. Uytterhoeven and R. A. Schoonheydt, Microporous Mater., 1994, 3, 265.
46. P. Norby, A. N. Christensen and J. C. Hanson, Stud. Surf. Sci. Catal., 1994, 84, 179.
47. D. W. Lewis, C. R. A. Catlow and J. M. Thomas, Chem. Mater., 1996, 8, 1112.
48. R. A. Lewis and P. M. Dean, Proc. R. Soc. London (Biol), 1989, 236, 125.
49. R. S. Bohacek and C. J. McMartin, J. Am. Chem. Soc., 1994, 116, 5560.
50. R. S. Bohacek and C. McMartin, in ref. 32, p. 82.
51. T. I. Oprea, C. M. W. Ho and G. R. Marshall, in ref. 32, p. 65.
52. D. W. Lewis, D. J. Willock, C. R. A. Catlow, J. M. Thomas and G. J. Hutchings, Nature (London), 1996, 382, 604.
53. D. J. Willock, D. W. Lewis, C. R. A. Catlow, G. J. Hutchings and J. M. Thomas, J. Mol. Catal. A, 1997, 119, 415.
54. C. R. A. Catlow, A. R. George and C. M. Freeman, J. Chem. Soc., Chem. Commun., 1996, 1311.
55. C. Pereira and C. R. A. Catlow, in preparation; see also C. Pereira, PhD Thesis, University of London, 1997.
56. O. Regev, Y. Cohen, E. Kehat and Y. Talmon, Zeolites, 1994, 14, 314.
57. A. T. Hagler, S. Lifson and P. Dauber, J. Am. Chem. Soc., 1979, 101, 5122.
58. J.-R. Hill and J. Sauer, J. Phys. Chem., 1994, 98, 1238.
59. Discover, Molecular Simulations Inc., San Diego, CA, 1995.
60. InsightII, Molecular Simulations Inc., San Diego, CA, 1996.
61. M. L. Connolly, J. Appl. Crystallogr., 1983, 548.
62. L. B. McCusker, Mater. Sci. Forum, 1993, 133–136, 423.
63. C. R. A. Catlow, D. S. Coombes, C. M. Freeman and A. R. George, in preparation.
64. N. J. Henson, A. K. Cheetham, A. Redondo, S. M. Levine and J. M. Newsam, Stud. Surf. Sci. Catal., 1994, 84, 2059.
65. F. Lefebvre, M. Sacerdote-Peronnet and B. F. Mentzen, CR Acad. Sci. Paris, Ser. 2, 1993, 316, 1549.
66. S. Merlino, E. Galli and A. Alberti, Tschermaks Mineral. Petrogr. Mitt., 1975, 22, 117.
67. M. M. Helmkamp and M. E. Davis, Annu. Rev. Mater. Sci., 1995, 25, 161.