A novel approach to the modeling of dual-layer ammonia slip catalysts
Massimo Colombo, Laboratory of Applied Themodynamics, Aristotle University
A novel approach to the modeling of dual-layer ammonia slip catalysts
Massimo Colombo (a,b), Grigorios Koltsakis (a)
Isabella Nova (b), Enrico Tronconi (b)
Ioannis Koutoufaris (c)
(a) Laboratory of Applied Themodynamics, Aristotle University Thessaloniki, Greece
email: grigoris@auth.gr
(b) LCCP, Dipartimento di Energia, Politecnico di Milano, P.zza L. da Vinci 32,
20133 Milano, Italy
email: enrico.tronconi@mail.polimi.it
(c) Exothermia SA, Thessaloniki, Greece
email: ioannis.koutoufaris@exothermia.com
The challenge to attain minimal ammonia breakthrough, providing at the same time high NOx reduction efficiency, in NH3/urea SCR automotive systems can be addressed employing in the after-treatment line an Ammonia Slip Catalyst (ASC) downstream from the SCR converter. The use of double layer systems for ASC looks particularly attractive for a configuration where a PGM catalytic layer lies beneath an SCR coating [1]. In fact, while the noble metal layer ensures very high activity in the ammonia oxidation, with such a double layer configuration the NH3 oxidation products have to back diffuse and thus can further react with ammonia across the SCR layer.
The modelling of such systems would in principle require the coupling of reaction and diffusion in both catalytic layers. In addition to this demanding approach, we use a simplified one, where only surface reaction is assumed to occur in the very active PGM layer, while diffusion and reaction in the SCR layer are still fully described. The two approaches are comparatively discussed and the simulation results are used to analyze the performance aspects of a dual layer ASC configuration.
[1] A. Scheuer, M. Votsmeier, J. Gieshoff, A. Drochner, H. Vogel, 6th International Conference on Environmental Catalysis, ICEC 2010 ? 12-15 September 2010 ? Beijing ? China, ? Design of Dual Layer Catalysts for NH3 Oxidation in Automotive Exhaust ? Oral Presentation
Download oral presentation: 