Performance of Cu-ZSM-5 in a Coupled Monolith NSR-SCR System for NOx Removal in Lean-Burn Engine Exhaust

• Published in: Topics in catalysis 2016-02, Vol.59 (2-4), p.259-267
• Main Authors: De La Torre, Unai, Pereda-Ayo, Beñat, González-Marcos, José A., Gutiérrez-Ortiz, Miguel A., González-Velasco, Juan R.
• Format: Article
• Language: English
• Subjects: Catalysis; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Original Paper; Pharmacy; Physical Chemistry
• ISSN: 1022-5528; 1572-9028
• DOI: 10.1007/s11244-015-0442-5

The viability of hybrid systems conformed by a combination of Pt–Ba/Al 2 O 3 NSR and Cu-ZSM-5 SCR catalysts is studied with both catalysts over monolithic structures in order to maximize the removal of NO x from lean-burn engines exhaust gases. To optimize performance of these coupled NSR-SCR systems, the NSR catalyst has to work under operational conditions completely different from those optimal when the NSR-only catalyst works, as in the coupled system the intermediate production of ammonia needs to be apparently increased, and then adsorbed in the SCR catalyst (Cu-ZSM-5) which is placed downstream in order to complete elimination of remaining NO x (NO+NO 2 ) selectively to N 2 with minimal amounts of other nitrogen derivates, i.e. N 2 O and NH 3 . The suitable control of operational conditions, specifically H 2 concentration and duration of the rich period, allows establishing the optimal working conditions of the NSR-SCR double system in the practical application, which resulted in temperature around 200 °C and H 2 concentration in excess (3–4 %).