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Thermal Deterioration Mechanism of Pt/Rh Three-way Catalysts
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Abstract
To clarify the thermal deterioration mechanism of three-way catalysts quantitatively, we investigated the relationship between the catalytic performance and the catalyst characteristics for thermally aged Pt/Rh catalysts.
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1.
Experimentally, the HC oxidation reaction, which occurs on the surface of Pt/Rh particles on catalysts, is approximated by a first-order reaction of HC concentration with a constant activation energy.
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2.
The relationship between the Pt mean diameter D and the HC 50% conversion temperature T50 is described by the following equation;
where E and kB are the activation energy of the reaction and the Boltzman constant, respectively. -
3.
The sintering rate of Pt particles on the three-way catalysts was found to depend on the aging temperature(T) of catalyst and the concentration of oxygen in the gas phase([O2]). The relationship among Pt particle mean diameter(D), T, [O2] and time(t) is expressed by the following equation.
where A and x are constants for the given reaction. -
4.
The relationship between the Pt particle mean diameter D and the oxygen storage capacity(OSC) of typical three-way catalyst is expressed as;
where α is the constant.
It may be stressed that the deactivation of HC conversion and the decrease in OSC of the Pt/Rh three-way catalyst strongly depend on the sintering of the Pt particles.
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Authors
- Shin'ichi Matsunaga - Toyota Central Research & Development Labs. co. Inc.
- Koji Yokota - Toyota Central Research & Development Labs. co. Inc.
- Shi-aki Hyodo - Toyota Central Research & Development Labs. co. Inc.
- Tadashi Suzuki - Toyota Central Research & Development Labs. co. Inc.
- Hideo Sobukawa - Toyota Central Research & Development Labs. co. Inc.
Topic
Citation
Matsunaga, S., Yokota, K., Hyodo, S., Suzuki, T. et al., "Thermal Deterioration Mechanism of Pt/Rh Three-way Catalysts," SAE Technical Paper 982706, 1998, https://doi.org/10.4271/982706.Also In
References
- Muraki, H. Sobukawa, H. Kimura, M. Isogai, A. “The Effect of Palladium on the Performance of Three-Way Catalyst” SAE Paper 900610 Detroit, MI 1990
- Muraki, H. Yokota, K. Fujitani, Y. Appl. Catal. 48 93 1989
- Konomi, I. 3 6 2 2 2 3 6 2 2