Abstract
Model Pd automotive three‐way catalysts were prepared with high‐surface‐area Zr‐rich ceria–zirconia powders as support materials, aged for 12 h at 1050°C under redox conditions simulating automotive exhaust gases, and characterized by a combination of techniques including oxygen storage capacity (OSC) measurements. Differences in OSC amongst aged catalysts made with materials of similar ceria–zirconia compositions, but produced by different processes, were weakly correlated with differences in support surface area. Evidence of encapsulation of Pd particles was found in most of the aged catalysts. The promotional effect of zirconia on ceria reducibility, well known from previous temperature‐programmed H2 reduction studies, was apparent in Ce 3d core‐level spectra from X‐ray photoelectron spectroscopy measurements, which showed that both X‐ray‐induced and H2 reduction become increasingly facile with increasing zirconia content. A slight Ce enrichment at the surface of the fresh catalysts made with the more Zr‐rich powders was found to increase upon aging.
Similar content being viewed by others
References
G.J. Bartley et al., Paper No. 930076, Society of Automotive Engineers, Warrendale, PA (1993).
B.H. Engler et al., Paper No. 930738, Society of Automotive Engineers, Warrendale, PA (1993).
J.C. Summers, J.J. White and W.B. Williamson, Paper No. 890794, Society of Automotive Engineers, Warrendale, PA (1989).
J.S. Hepburn et al., Paper No. 941058, Society of Automotive Engineers, Warrendale, PA (1994).
J.-P. Cuif et al., Paper No. 970463, Society of Automotive Engineers, Warrendale, PA (1997).
H.-W. Jen, G.W. Graham, W. Chun, R.W. McCabe, J.-P. Cuif, S.E. Deutsch and O. Touret, Catal. Today 50 (1999) 309.
JCPDS files: 17-923 (tetragonal ZrO2), 37-1484 (monoclinic ZrO2), 34-394 (CeO2).
S. Meriani and G. Spinolo, Powder Diffraction 2 (1987) 255.
G.W. Graham, H.-W. Jen, W. Chun and R.W. McCabe, J. Catal. 182 (1999) 228.
M. Shelef, L.P. Haack, R.E. Soltis, J.E. de Vries and E.M. Logothetis, J. Catal. 137 (1992) 114.
P.W. Park and J.S. Ledford, Langmuir 12 (1996) 1794.
A. Trovarelli, F. Zamar, J. Llorca, C. de Leitenburg, G. Dolcetti and J.T. Kiss, J. Catal. 169 (1997) 490.
A. Galtayries, R. Sporken, J. Riga, G. Blanchard and R. Caudano, J. Electron Spectrosc. Relat. Phenom. 88-91 (1998) 951.
Y. Gao, G.S. Herman, S. Thevuthasan, C.H.F. Peden and S.A. Chambers, J. Vac. Sci. Technol. A 17 (1999) 961.
P. Andersen, private communication.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Graham, G., Jen, H., McCabe, R. et al. Characterization of model automotive exhaust catalysts: Pd on Zr‐rich ceria–zirconia supports. Catalysis Letters 67, 99–105 (2000). https://doi.org/10.1023/A:1019086026110
Issue Date:
DOI: https://doi.org/10.1023/A:1019086026110