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Science in China Series B: Chemistry

, Volume 44, Issue 3, pp 283–293 | Cite as

Investigation on the mechanism and applications of the reaction Cl2+2HBr=2HCl+Br2

  • Heming Xiao
  • Zunyao Wang
  • Jijun Xiao
  • Zhaoxu Chen
Article

Abstract

The mechanism of reaction Cl2+2HBr=2HCl+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-centred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, respectively) of two bimolecular elementary reactions Cl2+HBr→HCl+BrCl and BrCl+HBr→HCl+Br2 is smaller than the dissociation energy of Cl2, HBr and BrCl, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engineering process of recycling Br2 from HBr. Gaseous Cl2 directly reacts with HBr gas, which produces gaseous mixtures containing Br2, and liquid Br2 and HCl are obtained by cooling the mixtures and further separated by absorption with CCl4. The recovery percentage of Br2 is more than 96%, and the Cl2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.

Keywords

chlorine bromine hydride bromine density functional theory reaction mechanism recycling process 

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References

  1. 1.
    Goldfinger, P., Noyes, R. M., Wen, W. Y., The gas phase chlorine plus hydrogen bromide reaction, A bimolecular reaction of diatomic molecules, J. Am. Chem. Soc., 1969, 91: 4003–4004.CrossRefGoogle Scholar
  2. 2.
    Wen, W. Y., Noyes, R. M., Reactions of halogens with hydrogen halides studies in the Cl2+HBr system, Int. J. Chem. Ki-net., 1974, 6(1): 29–37.CrossRefGoogle Scholar
  3. 3.
    Baer, M., Collinear quantum mechanical treatment of the heavy-light-heavy mass combination: Cl+HBr→HCl+Br, J. Chem. Phys., 1975, 62(1): 305–307.CrossRefGoogle Scholar
  4. 4.
    Garrett, B. C., Abusalbi, N., Koun, D. J., Test of variational transition state theory and the least-action approximation for multidimensional tunneling probabilities against accurate quantal rate constants for a collinear reaction involving tunneling into an excited state, J. Chem. Phys., 1985, 83(5): 2252–2258.CrossRefGoogle Scholar
  5. 5.
    Bian, W. S., Ju, G. Z., Deng, C. H., Studies on the reactions Cl+HBr, Cl+DBr, Br+HI and Br+DI with the variaional transition-state theory, Chinese J. Chem. Phys., 1993, 16(6): 496–502.Google Scholar
  6. 6.
    Cohen, M. J., Willetts, A., Handy, N. C., Reaction rates of HBr+Cl=Br+HCl using semiclassical transition state theory, Chem. Phys. Lett., 1994, 223: 459–464.CrossRefGoogle Scholar
  7. 7.
    Last, I., Baer, M., Three-dimensional DIM-3C potential energy surfaces for the reactions H+XY and X+HY(X,Y=F, Cl, Br, I), J. Chem. Phys., 1984, 80(7): 3246–3252.CrossRefGoogle Scholar
  8. 8.
    Yasushi, O., Ohgi, T., Osamu, K.,Ab initio MO study of structure and stability of heteronuclear trihalide anions X2Y- (X, Y=Cl, Br, or I) in the gas phase and in solution, Theochem., 1998, 429: 187–196.CrossRefGoogle Scholar
  9. 9.
    Liu, Z. H., Recycling bromine directly from synthesized aromatic bromide, Dye Industry, 1991, 28(2): 15–17.Google Scholar
  10. 10.
    Schubert, P., Mahajan, S., Recover bromine on site, Chemistry Technology, 1993, 23(4): 37–41.Google Scholar
  11. 11.
    Wang, Z. Y., Xiao, H. M., The comparative investigation of the structure and property of halogen and halide with density function theory methods, J. Molecular Science, 2000, 16(4): 267–272.Google Scholar
  12. 12.
    Wan, Z. Y., Chen, Z. X., Xiao, H. M. et al., A study on the mechanism of the reaction F2+2HCl→2HF+Cl2 using density functional theory, Acta Chimica Sinica, 2000, 58(3): 267–272.Google Scholar
  13. 13.
    Becke, A. D., Density-functional thermochemistry, III. The role of exact exchange, J. Chem. Phys., 1993, 98: 5648–5652.CrossRefGoogle Scholar
  14. 14.
    Lee, C., Yang, W., Parr, R. G., Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density, Phys. Rev., 1988, B37: 785–789.Google Scholar
  15. 15.
    Frisch, M. J., Trucks, G. W., Schlegel, H. B. et al., Gaussian 98, Pittsburgh PA: Gaussian, Inc., 1998.Google Scholar
  16. 16.
    Hahre, W. J., Radom, L., Schleyer, P. V. R. et al.,Ab Initio Molecular Orbital Theory, New York: Wiley, 1986.Google Scholar
  17. 17.
    Simons, J., Jorgensen, P., Taylor, H. et al., Walking on potential energy surfaces, J. Phys. Chem., 1983, 87: 2745–2747.CrossRefGoogle Scholar
  18. 18.
    Cerjan, C. J., Miller, W. H., On finding transition states, J. Chem. Phys., 1981, 75: 2800–2804.CrossRefGoogle Scholar
  19. 19.
    Bannerjee, A., Adams, N., Simons, J. et al., Search for stationary points on surfaces, J. Phys. Chem., 1985, 89: 52–56.CrossRefGoogle Scholar
  20. 20.
    Wan, Z. Y., Studies on the Mechanisms of the Reactions of Halogen and Halogen and of Halogen and Hydrogen Halogen with Density Funtional Theory (DFT), Ph. D. Thesis, Nanjing University of Science and Technology, Nanjing, 2000.Google Scholar
  21. 21.
    Tianjin Chemical Institute, Handbook of Inorganic Salt Industry, Beijing: Chemical Industry Press, 1979.Google Scholar
  22. 22.
    Yang, C. S., Wan, Z. Y., Xiao, H. M., Studies on new technology for recycling bromine with CCl4 extraction, J. Nanjing Univ. Sci. & Tech., 1999, 27(5): 35–37.Google Scholar

Copyright information

© Science in China Press 2001

Authors and Affiliations

  • Heming Xiao
    • 1
  • Zunyao Wang
    • 1
    • 2
  • Jijun Xiao
    • 1
  • Zhaoxu Chen
    • 1
  1. 1.Department of ChemistryNanjing University of Science and TechnologyNanjingChina
  2. 2.Department of Chemical EngineeringYancheng Institute of TechnologyYanchengChina

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