Abstract
In situ FT-IR spectroscopy coupled with mass spectrometry have been used to study the mechanism of nitrates formation and reduction over a common Pt–Rh/Ba/Al2O3 NO x storage catalyst, compared with a different alumina-based compound.
The experimental device used consists of a transmission reactor cell (having a very small dead volume) dedicated to the evolution of surface species, and of a mass spectrometer combined with a FT-IR micro-cell for gas analysis, allowing time resolved analysis in stationary and transient conditions.
At the first time the nitration properties of the catalysts under a lean flow have been studied in the appropriate temperature window (473–673 K). The dynamics of nitrates formation has been pointed out, as well as the different coordination sites on the compounds surface. Then the catalysts have been alternatively exposed to rich and lean flows very close to the real exhaust composition. This has allowed the identification of reduction pathway, active sites, intermediate species and by-products for NO X -trap reaction. In particular, we have differentiated the role of the support and of the noble metal in the mechanism, as well as of isocyanate adspecies and ammonia among the detected species. The very high NO X storage properties and the selectivity (near 100%) in nitrogen of the newly designed catalyst have been pointed out.
Similar content being viewed by others
References
K. Kato, H. Nohira, K. Nakanishi, S. Iguchi, T. Kihara and H. Muraki, Eur. Patent application 0573672 A1 (1993), to Toyota.
N. Myioshi, S. Matsumoto, K. Katoh, T. Tanaka, K. Harada, N. Takahashi, K. Yokota, M. Sugiura and K. Kasahara, SAE Technical papers series No 950809 (1995).
Lesage T., Verrier C., Bazin P., Saussey J. and Daturi M. (2003). Phys. Chem. Chem. Phys. 5: 4435
Macleod N. and Lambert R.M. (2002). Appl. Catal. B 35: 269
Binet C., Jadi A. and Lavalley J.-C. (1989). J. Chim. Phys. 86: 451
Chi Y. and Chuang S.S.C. (2000). J. Phys. Chem. B 104: 4673
Nakagawa I. and Walter J.L. (1969). J. Chem. Phys. 51: 1389
Hadjiivanov K. (2000). Catal. Rev.-Sci. Eng. 42: 71
Westerberg B. and Fridell E. (2001). J. Mol. Catal. A 165: 249
Coronado J.M and Anderson J.A. (1999). J. Mol. Catal. A 138: 83
Bates J.B. and Boyd G.E. (1973). Appl. Spectrosc. 27: 204
Laane J. and Ohlsen J.R. (1980). Prog. Inorg. Chem. 27: 465
Schraml-Marth M., Wokaun A. and Baiker A. (1992). J. Catal. 138: 306
Hess C. and Lunsford J.H. (2002). J. Phys. Chem. B 106: 6358
Broqvist P., Panas I., Fridell E. and Persson H. (2002). J. Phys. Chem. B 106: 137
Bion N., Saussey J., Hedouin C., Seguelong T. and Daturi M. (2001). Phys. Chem. Chem. Phys. 3: 4811
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Lesage, T., Verrier, C., Bazin, P. et al. Comparison between a Pt–Rh/Ba/Al2O3 and a newly formulated NO X -trap catalysts under alternate lean–rich flows. Topics in Catalysis 30, 31–36 (2004). https://doi.org/10.1023/B:TOCA.0000029724.42807.e0
Issue Date:
DOI: https://doi.org/10.1023/B:TOCA.0000029724.42807.e0