Abstract
Flow reactor experiments and X-ray photoelectron spectroscopy (XPS) measurements were used to investigate the importance of platinum oxide formation on Pt/BaO/Al2O3 NO x storage catalysts during reactions conditions. The reaction studied was NO(g) + 1/2 O2(g) ⇔ NO2(g). During NO2 exposure of the catalyst the NO2 dissociation rate decreased during the reaction. This activity decrease with time was also studied with XPS and it was found to be due to platinum oxide formation. The influence of sulphur exposure conditions on the performance of the NO x storage catalysts was studied by exposing the samples to lean and/or rich gas mixtures, simulating the conditions in a mixed lean application, containing SO2. The main results show that all samples are sensitive to sulphur and that the deactivation proceeds faster when SO2 is present in the feed under rich conditions than under lean or continuous SO2 exposure. Additionally, the influence of the noble metals present in the catalysts was investigated regarding sulphur sensitivity and it was found that a combination of platinum and rhodium seems to be preferable to retain high performance of the catalyst under SO2 exposure and subsequent regeneration. Finally, the behaviour of micro-fabricated model NO x storage catalysts was studied as a function of temperature and gas composition with area-resolved XPS. These model catalysts consisted of a thin film of Pt deposited on one-half of a BaCO3 pellet. It was found that the combination of SO2 and O2 resulted in migration of Pt on the BaCO3 support up to one mm away from the Pt/BaCO3 interface.
Similar content being viewed by others
References
N. Miyoshi, S. Matsumoto, K. Katoh, N. Takahashi, K. Yokota and K. Kasahara, SAE Technical Paper Series, No. 950809 (1995).
N. Takahashi, H. Shinjoh, T. Iijima, T. Suzuki, K. Yamazaki, K. Yokota, S. Tateishi and K. Kasahara, Catal. Today 27 (1996) (63).
Fridell E., Skoglundh M., Johansson S., Westerberg B., Törncrona A. and Smedler G. (1998). Stud. Surf. Sci. Catal. 116: 537
Fridell E., Skoglundh M., Westerberg B., Johansson S. and Smedler G. (1999). J. Catal 183: 196
L. Olsson and E. Fridell, J. Catal. 210 (2002) 340.
H. Shinjoh, N. Isomura, H. Sobukawa and M. Sugiura, Stud. Surf. Sci. Catal. 116 (1998) 83.
C. -H. Lee and Y. -W. Chen, Ind. Eng. Chem. Res. 37 (1998) 1260.
H. Yoshida, Y. Yazawa and T. Hattori, Catal. Today, 87 (2003) 19.
A. Amberntsson, B. Westerberg, P. Engström, E. Fridell and M. Skoglundh, Stud. Surf. Sci. Catal. 13 (1999) 317.
E. Fridell, H. Persson, L. Olsson, B. Westerberg, A. Amberntsson and M. Skoglundh, Top. Catal. 16–17 (2001) 133.
A. Amberntsson, M. Skoglundh, M. Jonsson and E. Fridell, Catal. Today 73 (2002) 279.
L. Olsson, H. Persson, E. Fridell, M. Skoglundh and B. Andersson, J. Phys. Chem. B 105 (2001) 6895.
S. Matsumoto, CATTECH 4 (2000) 102.
J. Dawody, M. Skoglundh, E. Fridell, J. Mol. Catal. A, 209 (2004) 215.
A. Amberntsson, M. Skoglundh, S. Ljungström and E. Fridell, J. Catal. 217 (2003) 253.
A.W. Grant, A. Amberntsson, and E. Fridell, in manuscript.
C. Sedlmair, K. Seshan, A. Jentys and J. Lercher, Catal. Today 75 (2002) 413.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Fridell, E., Amberntsson, A., Olsson, L. et al. Platinum oxidation and sulphur deactivation in NO x storage catalysts. Topics in Catalysis 30, 143–146 (2004). https://doi.org/10.1023/B:TOCA.0000029742.53316.3c
Issue Date:
DOI: https://doi.org/10.1023/B:TOCA.0000029742.53316.3c