Dual layer automotive ammonia oxidation catalysts: Experiments and computer simulation

作者：Scheuer A; Hauptmann W; Drochner A; Gieshoff J; Vogel H; Votsmeier M^*

来源：Applied Catalysis B: Environmental , 2012, 111: 445-455.

DOI：10.1016/j.apcatb.2011.10.032

• Catalysis
• Automotive
• Dual layer
• Ammonia oxidation
• Platinum

Today, platinum based ammonia oxidation catalysts are applied in automotive exhaust systems to avoid ammonia slip from the SCR catalyst. In this paper we present a dual layer catalyst design with an additional SCR layer on top of the Pt/Al2O3 layer. Laboratory experiments show that the additional SCR layer significantly reduces NO formation, improves N-2 selectivity but also reduces the overall NH3 conversion. %26lt;br%26gt;A mechanistically based kinetic model for NH3 oxidation on platinum is presented. The model is parameterised using experiments with a single layer Pt/Al2O3 catalyst and well describes the NH3 conversion and the selectivities for the products N-2, N2O and NO. Additionally NO oxidation to NO2 is included in the model. %26lt;br%26gt;Based on the mechanistic model for the platinum layer and a previously published model for the SCR layer, a 2-D model of the dual layer catalyst is set up. This model takes into account the diffusion and reaction in the two washcoat layers of one monolith channel. The 2-D model reproduces the experimental data well, with the mechanisms for the two layers parameterised in separate experiments and no additional parameters adjusted for the dual layer model. %26lt;br%26gt;Finally, the model is used to study the effect of some design parameters such as catalyst size, NO oxidation capacity of the Pt-layer and the thickness or diffusion coefficient of the SCR layer.

• 出版日期2012-1-12