Transport limitations inside the porous washcoat layer have an important influence in the light-off and overall conversions even in the case of relatively thin layers used in automotive three way catalysts (TWC). The porous structure of the washcoat layer is controlled at two levels: i) at the level of mesoporous structure, which can be determined by the use of specific synthesis techniques (e.g., sol-gel or pore-templating method), and ii) at the level of macroporous structure, which is influenced by the particle size distribution of mesoporous in a slurry that has undergone a specific thermal treatment. This paper investigates the influence of the washcoat structure in the performance of automotive TWC. Furthermore, the article presents a method that allows to quantify the magnitude of the reaction resistance (chemical kinetics), internal mass transfer resistance (washcoat diffusion), and external mass transfer resistance on the TWC conversions. From experimental data gathered at different operating temperatures (from light-off to 1100 K) and applying the developed methodology for resistances quantification, it was found that the internal mass transfer limitations play a major role in the TWC conversions. The main conclusions from this study are: i) the effective diffusivity strongly depends on the washcoat layer structure, which in turn depends on its preparation process; ii) the resistance quantification analysis reveals that the lower effective diffusivity interval is more adequate for the TWC used in the present investigation, which also indicates that the TWC washcoat has a low percentage of macropores; and iii) to decrease the relevance of the internal mass transfer limitation requires an increase in the effective diffusivity and/or a thinner washcoat layer.


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    Titel :

    Influence of the Washcoat Structure in the Performance of Automotive Three Way Catalysts


    Weitere Titelangaben:

    Sae Int. J. Engines


    Beteiligte:
    Santos, Helder (Autor:in) / Pires, João (Autor:in) / Costa, Mário (Autor:in)

    Kongress:

    11th International Conference on Engines & Vehicles ; 2013


    Erschienen in:

    Erscheinungsdatum :

    08.09.2013


    Format / Umfang :

    9 pages




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch


    Schlagwörter :


    Influence of the Washcoat Structure in the Performance of Automotive Three Way Catalysts

    Santos, H. / Pires, J. / Costa, M. et al. | British Library Conference Proceedings | 2013


    Advanced Metallic Three-Way Catalysts with Optimized Washcoat Performance

    Vakkilainen, A. / Torkkell, K. / Harkonen, M. et al. | SAE Technical Papers | 1996


    Advanced metallic three-way catalysts with optimized washcoat performance

    Harkonen,M. / Kivioja,M. / Slotte,T. et al. | Kraftfahrwesen | 1996


    Preparation and study of thermally stable washcoat aluminas for automotive catalysts

    Ismagilov, Z. R. / Shkrabina, R. A. / Koryabkina, N. A. et al. | British Library Conference Proceedings | 1998


    Influence of washcoat distribution on the performance of diesel oxidation catalysts

    Gordiner,S. / De Simone,G. / Mulone,V. et al. | Kraftfahrwesen | 2007