A novel dual layer SCR catalyst with a broad temperature window for the control of NOx emission from diesel bus

• Configuration A showed an excellent SCR performance in a broad temperature window.
• The SCR performance of Configuration A was much better than those of B and C.
• The SCR performance mainly depended on the distribution of NH3 consumed.
• The relationship between the SCR performance and the configuration was discovered.

In this work, a high temperature SCR catalyst (i.e., Fe–Ti spinel) and a low temperature SCR catalyst (i.e., Mn–Fe spinel) were combined to widen the operating temperature window of the SCR reaction. As the Fe–Ti spinel layer was placed upstream of the Mn–Fe spinel layer, both Fe–Ti spinel and Mn–Fe spinel displayed their strong points at their appropriate temperatures for the SCR reaction. Therefore, the dual layer catalyst showed excellent SCR activity and N2 selectivity at a broad temperature window even in the presence of H2O, which was much better than the performance of other combination modes.

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