Dispersion and reduction behavior of CuO/α-Fe2O3 systems

(Note: The full text of this document is currently only available in the PDF Version )

Lin Dong, Zheng Liu, Yuhai Hu, Bin Xu and Yi Chen


Abstract

The dispersion and reduction behaviors of CuO/α-Fe2O3 samples have been studied by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) and temperature programmed reduction (TPR). XRD and XPS results show that the dispersion capacity of CuO on α-Fe2O3 is about 13.7 Cu2+ nm-2 (α-Fe2O3). At low copper loading, highly dispersed surface copper oxide is the main species, and crystalline CuO evidently appears after the Cu loading exceeds the dispersion capacity. For Cu XPS spectra, the intensity ratio of satellite peaks (Isat) to the principal peaks (Ipp) shows that the highly dispersed Cu2+ ions simultaneously exist as tetrahedrally and octahedrally coordinated states in the low Cu loading samples, and the octahedrally coordinated surface Cu species is the predominant species in high Cu loading samples, which is in basic agreement with the prediction of the incorporation model proposed previously (Y. Chen and L. F. Zhang, Catal. Lett., 1992, 12, 51). The BET surface area of α-Fe2O3 support in all the samples remains constant, indicating that the calcination process has not induced an evident change to the surface of α-Fe2O3 support. TPR results indicate that the reduction peaks at about 473 and 493 K correspond to the reduction of the octahedrally and tetrahedrally coordinated surface copper oxide species, respectively, and the reduction peak at about 563 K is ascribed to the reduction of crystalline CuO. In addition, the influence of the different calcination temperatures on the interaction between CuO and α-Fe2O3 has also been investigated by XRD, TPR and XPS, and the results show that the calcination temperature can affect the extent of interaction, and a new compound, CuFe2O4, formed as the CuO/α-Fe2O3 sample was calcined at 1123 K.


References

  1. C. L. Thomas, Catalytic Processes and Proven Catalysts, Academic Press, New York, 1976, p. 198 Search PubMed.
  2. L. Hodges, Environmental Pollution, Holt, Rinehart and Winston, New York, 1972 Search PubMed.
  3. R. Behara, Appl. Catal., 1985, 16, 15 CrossRef.
  4. B. Strohmeier, D. E. Leiden, R. S. Field and D. M. Hercules, J. Catal., 1985, 94, 514 CrossRef CAS.
  5. G. Ertl, R. Hierl, H. Knozinger, N. Thiele and H. P. Urbach, Appl. Surf. Sci., 1980, 5, 49 CAS.
  6. R. Hierl, H. Knozinger and H. P. Urbach, J. Catal., 1981, 69, 475 CrossRef CAS.
  7. M. Barber, P. K. Sharpe and J. C. Vickerman, J. Catal., 1976, 41, 240 CAS.
  8. H. Lumbeck and J. Voitlander, J. Catal., 1969, 132, 117 CrossRef.
  9. R. M. Friedman, J. J. Freeman and F. W. Lytle, J. Catal., 1978, 55, 10 CrossRef CAS.
  10. M. Shelef, M. A. Z. Wheeler and H. C. Yao, Surf. Sci., 1975, 47, 697 CrossRef CAS.
  11. F. E. Massoth, Adv. Catal., 1978, 27, 265 CAS.
  12. S. F. Tikhov, V. A. Sadykov, G. N. Kryukova, E. A. Paukshtis, V. V. Popovskii, T. G. Starostina, G. V. Kharlamov, V. F. Anufrienko, V. F. Poluboyarov, V. A. Razdobarov, N. N. Bulgakov and A. V. Kalinkin, J. Catal., 1992, 134, 506 CrossRef CAS.
  13. M. Lo. Jacono, A. Cimino and M. Inversi, J. Catal., 1982, 76, 320 CrossRef; W. P. Dow and T. J. Huang, J. Catal., 1996, 160, 155, 171 CrossRef CAS.
  14. Th. Simons, E. Vrheijen, Ph. A. Batist and G. C. A. Schuit, Adv. Chem. Ser., 1968, no. 76, vol. 2, 261 Search PubMed.
  15. K. Weissermet and H. J. Arpe, Industrial Organic Chemistry, Verlag Chemie, Weinheim, 1978, p. 297 Search PubMed.
  16. K. Weissermel and H. J. Arpe, Industrial Organic Chemistry, Verlag Chemie, Weinheim, 1978, p. 36 Search PubMed.
  17. S. R. Morrison, The Chemical Physics of Surfaces, Plenum, New York, 1977, p. 361 Search PubMed.
  18. M. Niwa, M. Sano, H. Yamada and Y. Murakami, J. Catal., 1995, 151, 285 CrossRef CAS; H. Yamada, M. Niwa and Y. Murakami, Appl. Catal., A, 1993, 96, 113 CrossRef CAS.
  19. L. Dong, K. Chen and Y. Chen, J. Solid State Chem., 1997, 129, 30 CrossRef CAS.
  20. Y. C. Xie and Y. Q. Tang, Adv. Catal., 1990, 37, 1 CAS.
  21. P. Mikusik, T. Juska, J. Novakova, L. Kubelkova and B. Wichterlova, J. Chem. Soc., Faraday Trans. 1, 1981, 77(5), 1179 RSC.
  22. G. C. Bond, J. P. Zurita and S. Flamerz, Appl. Catal., 1986, 27, 353 CrossRef CAS.
  23. M. Wu and D. M. Hercules, J. Phys. Chem., 1979, 83(15), 2003 CrossRef CAS.
  24. L. Dong and Y. Chen, J. Chem. Soc., Faraday Trans., 1996, 92(22), 4589 RSC.
  25. D. C. Frost, A. Ishitani and C. A. McDowell, Mol. Phys., 1972, 24, 861 CAS.
  26. A. F. Wells, Structural Inorganic Chemistry, Oxford University Press, 1984, p. 539 Search PubMed.
  27. M. Niwa, H. Yamada and Y. Murakami, J. Catal., 1992, 134, 331 CrossRef CAS.
  28. Powder diffraction file, Sets 25–26, published by the JCPDS, printed in USA International Centre for Diffraction Data, 1601 Park Lane, Swarthmore, Pennsylvania 19801, USA, 1984, P101, no. 25–283 Search PubMed.
Click here to see how this site uses Cookies. View our privacy policy here.