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Oxygen availability in mixed cerium/praseodymium oxides and the effect of noble metals

Published online by Cambridge University Press:  03 March 2011

A.D. Logan  and
M. Shelef
A.D. Logan
Affiliation:
Chemical Engineering Department, Ford Research Laboratory, P.O. Box 2053, Dearborn, Michigan 48121-2053
M. Shelef
Affiliation:
Chemical Engineering Department, Ford Research Laboratory, P.O. Box 2053, Dearborn, Michigan 48121-2053
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Abstract

Oxyreduction studies of mixed Ce/Pr oxides have been carried out. Temperature-programmed desorption (TPD), temperature-programmed reduction (TPR), and temperature-programmed oxidation (TPO) were used to study the uptake and release of the oxygen. Large amounts of oxygen, exceeding those in ceria, are accessible in the mixed metal oxides at moderate temperatures. The addition of small amounts of noble metals to the mixed oxides shifts the accessibility of the “stored” oxygen to still lower temperatures with the effect of Pd being more pronounced than that of Pt. In a sample containing 45 mol % ceria and 55 mol % praseodymia, a small addition of Pd (0.24 mol %) was found to lower the reduction temperature by more than 100 °C. The addition of Pt had a lesser effect. Similarly, in pure praseodymia (Pr6O11) Pd influences the reduction much more strongly than Pt. In the mixed samples, whether doped with a noble metal or not, the whole oxyreduction effect can be accounted for by the change in oxidation state of the praseodymium ions solely. This notwithstanding, the reduction of the mixed oxides, without noble metals or doped by Pt, is more facile than that of praseodymia. Only the incorporation of Pd makes the reduction of praseodymia proceed at a temperature below that registered for a mixed ceriapraseodymia sample.

Type
Articles
Information
Journal of Materials Research , Volume 9 , Issue 2 , February 1994 , pp. 468 - 475
Copyright
Copyright © Materials Research Society 1994

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References

1.Gandhi, H.S., Piken, A.G., Shelef, M., and Delosh, R.G., SAE 760201, 55-66 (1976).Google Scholar
2.Kummer, J.T., Prog. Energy Combust. Sci. 6, 177–199 (1980).CrossRefGoogle Scholar
3.Schlatter, J. C. and Mitchell, P.J., Ind. Eng. Chem., Prod. Res. Dev. 19, 288–293 (1980).CrossRefGoogle Scholar
4.Kim, G., Ind. Eng. Chem., Prod. Res. Dev. 21, 267–274 (1982).CrossRefGoogle Scholar
5.Yao, H.C. and Yao, Y.F. Yu, J. Catal. 86, 254–265 (1984).CrossRefGoogle Scholar
6.Sass, A. S., Kuznetsov, A. V., Shvets, V. A., Savel'eva, G. A., Popova, N. M., and Kazanskii, V.B., Kinet. Katal. 26, 1411–1416 (1985).Google Scholar
7.Su, E. C. and Rothschild, W. G., J. Catal. 99, 506–510 (1986).CrossRefGoogle Scholar
8.Shyu, J. Z., Weber, W. H., and Gandhi, H. S., J. Phys. Chem. 92, 4964–4970 (1988).CrossRefGoogle Scholar
9.Ozawa, M. and Kimura, M., J. Mater. Sci. Lett. 9, 291–293 (1990).CrossRefGoogle Scholar
10.Oh, S.E., J. Catal. 124, 477–487 (1990).CrossRefGoogle Scholar
11.Oh, S.E. and Eickel, C.C., J. Catal. 128, 526–536 (1991).CrossRefGoogle Scholar
12.Cho, B.K., Shanks, B.H., and Bailey, J.E., J. Catal. 155, 486–499 (1989).CrossRefGoogle Scholar
13.Miki, T., Ogawa, T., Haneda, M., Kakuta, N., Ueno, A., Tateishi, S., Matsuura, S., and Sato, M., J. Phys. Chem. 94, 6464–6467 (1990).CrossRefGoogle Scholar
14.Cho, B. K., J. Catal. 131, 74–87 (1991).CrossRefGoogle Scholar
15.Jones, J. A. and Blue, G.D., J. Spacecraft 25, 202–208 (1988).CrossRefGoogle Scholar
16.Mullhaupt, J.T., U.S. Patent 3 980763 (1976).Google Scholar
17. Japan Kokai Tokkyo Koho JP Nos.: 63-240947, 63-104651, 63-84636, 63-77545, 62-282640, 61-293550, and 61-197038.Google Scholar
18.Kitaguchi, S., Tsuchiya, K., and Ohata, T., Japan Kokai Tokkyo Koho JP No. 03–196841.Google Scholar
19.Liu, X., Yang, Y., and Zhang, J., Appl. Catal. 71, 167–184 (1991).CrossRefGoogle Scholar
20.Bevan, D.J.M., J. Inorg. Nucl. Chem. 1, 49–59 (1955).CrossRefGoogle Scholar
21.Harrison, B., Dilwell, A. F., and Hallett, C., Plat. Met. Rev. 32, 73 (1988).CrossRefGoogle Scholar
22.Mitchell, M.D. and Vannice, M.A., Ind. Eng. Chem. Fund. 23, 88 (1984).CrossRefGoogle Scholar
23.Binary Alloy Phase Diagrams (American Society for Metals, Metals Park, OH, 1986).Google Scholar
24.Gartsman, K.G., Kartenko, N.F., Melekh, B.T., Nikitin, S.V., Smirnov, I. A., Filin, Yu. N., Sharenkova, N. V., Shunaev, A. T., Khel'mer, B. Yu, and Ovsyannikov, F. M., Fiz. Tverd. Tela (Leningrad) [Sov. Phys. Solid State] 32, 1868–1870 (1990).Google Scholar