| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 47081 | Applied Catalysis B: Environmental | 2010 | 7 Pages |
The influence of H+ and Na+ co-cations on the formation of Cu species and on NO reduction activity of Cu/ZSM-5 catalyst is investigated. 3.5Cu/0.6NaZSM-5 catalyst was significantly more active for NOx reduction with NH3 compared with 2.6Cu/HZSM-5. Catalyst characterization indicated that, the type of co-cations present in the catalyst tailors copper species redox properties, NO2 formation rate and acidity of the catalyst. Copper species in NaZSM-5, is relatively easily reducible than when present in HZSM-5. UV–vis and FTIR characterization showed the presence of a higher amount of Cu+ species in 3.5Cu/0.6NaZSM-5 compared to 2.6Cu/HZSM-5. The easily reducible copper along with Cu+ species in 3.5Cu/0.6NaZSM-5 seems to activate oxygen which reacts with NO to form NO2. The Na+ co-cations can further capture the thus produced NO2 to form intermediate surface nitrite/nitrate species, which improves the NOx conversion. The acidity measured by NH3-TPD and FTIR is needed for SCR, but not crucial for NOx conversion.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Influence of cations in the zeolite on NOx reduction by NH3 over Cu/ZSM-5 studied. ▶ Cu/0.6NaZSM-5 is more active for NOx reduction with NH3 compared with Cu/HZSM-5. ▶ Na+ cations tailor the Cu+/Cu2+ active species. ▶ Na+ cation also enhances intermediate nitrogen oxides formation. ▶ Higher amount of active Cu+ species in Cu/NaZSM-5 leads to higher activity.
