Abstract
A methodology based on reoxidation at 298 K with O2(5%)/He pulses followed by quantitative TPO runs allowed us to study the redox state reached by CeO2 and Ln3+ -containing ceria‐based mixed oxide samples Ln3+:La3+ or Y3+) after their reduction in a flow of hydrogen. The temperature range covered in the reduction treatments was from 623 up to 1223 K. During the severe reduction treatments hexagonal sesquioxide phases segregate from all the samples. The reduction temperature at which segregation occurs follows the trend La/Ce < Y/Ce < CeO2. The TPO and H2-TPD traces of reduced samples which showed evidence of segregation in XRD exhibit characteristic features which can also be used as an indication of this effect. The discussion is focussed on the overall and detailed understanding of the reoxidation process and on the analysis of the H2-TPD profiles.
Similar content being viewed by others
References
H. Inaba and H. Tagawa, Solid State Ionics 83 (1996) 1.
S. Bernal, G. Blanco, G. Cifredo, J.A. Pérez Omil, J.M. Pintado and J.M. Rodríguez-Izquierdo, J. Alloys Comp. 250 (1997) 449.
M. Ozawa, M. Kimura and A. Isogai, J. Mater. Sci. 26 (1991) 4818.
N. Miyoshi, S. Matsumoto, M. Ozawa and M. Kimura, SAE paper no. 891870, Society of Automotive Engineers, Dearborn, MI (1989).
S. Matsumoto, N. Miyoshi, T. Kanazawa, M. Kimura and M. Ozawa, Catalytic Science and Technology, Vol. 1, eds. S. Yoshida, N. Tabezawa and T. Ono (Kodansha/VCH, Tokyo/New York, 1991) p. 335.
T. Kirchner, A. Dounerstag, A. König and G. Eigenberger, Preprints of CAPOC4, Brussels, April 9-11, 1997, Stud. Surf. Sci. Catal., to be published.
G. Blanco, Dr. thesis, University of Cadiz (1997).
V. Perrichon, A. Laachir, G. Bergeret, R. Fréty, L. Tournayan and O. Touret, J. Chem. Soc. Faraday Trans. 90 (1994) 773.
A. Laachir, V. Perrichon, A. Badri, J. Lamotte, E. Catherine, J.C. Lavalley, J. El Fallah, L. Hilaire, F. Le Normand, E. Quéméré, G.N. Sauvion and O. Touret, J. Chem. Soc. Faraday Trans. 87 (1991) 1601.
R.D. Shannon, Acta Crystal. A 32 (1976) 751.
B.G. Hyde, D.J.M. Bevan and L. Eyring, Proc. Roy. Soc. A 259 (1966) 70.
L. Eyring, in: Handbook on the Physics and Chemistry of the Rare Earths, eds. K.A. Gschneidner and L. Eyring (North-Holland, Amsterdam, 1979) chapter 27, p. 337.
R.P. Turcotte, J.M. Warmkessel, R.J.D. Tilley and L. Eyring, J. Solid State Chem. 3 (1971) 265.
U. Lott, H. Rickert and C. Keller, J. Inorg. Nucl. Chem. 31 (1969) 3427.
S. Bernal, G. Blanco, J.J. Calvino, G.A. Cifredo, J.A. Pérez-Omil, J.M. Pintado and A. Varo, Stud. Surf. Sci. Catal. 82 (1994) 507.
R. Wallenberg, R. Withers, D.J.M. Bevan, J.G. Thompson, P. Barlow and B.G. Hyde, J. Less. Comm. Met. 156 (1989) 1.
R.L. Withers, R. Wallenberg, D.J.M. Bevan, J.G. Thompson and B.G. Hyde, J. Less Comm. Met. 156 (1989) 17.
D.J.M. Bevan, W.W. Baker, T.C. Parks and R.L. Martin, in: Rare Earth Research III, ed. L. Eyring (Gordon and Breach, London, 1965) p. 441.
N. Gabbitas, J.G. Thompson, R.L. Withers and A.D. Rae, J. Solid State Chem. 115 (1995) 23.
S. El Houte and O.T. Sörensen, Internal Report Riso-M-2495, Risö National Laboratory, Roskilde, Denmark (1985).
G. Blanco, J.J. Calvino, C. López-Cartes, J.A. Pérez-Omil, J.M. Pintado and J.M. Rodríguez-Izquierdo, Inst. Phys. Conf. Ser. 153 (1997) 387.
S. Bernal, F.J. Botana, J.J. Calvino, G.A. Cifredo, J.A. Pérez-Omil and J.M. Pintado, Catal. Today 23 (1995) 219.
J.A. Pérez-Omil, Dr. thesis, University of Cadiz (1994).
S. Bernal, J.J. Calvino, G.A. Cifredo, J.M. Rodríguez-Izquierdo, V. Perrichon and A. Laachir, J. Catal. 137 (1992) 1.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bernal, S., Blanco, G., Cauqui, M.A. et al. Influence of reduction treatment on the structural and redox behaviour of ceria, La/Ce and Y/Ce mixed oxides. Catalysis Letters 53, 51–57 (1998). https://doi.org/10.1023/A:1019005922456
Issue Date:
DOI: https://doi.org/10.1023/A:1019005922456