Abstract
Low-temperature active Ag/Al2O3 and high-temperature active Fe-BEA zeolite were combined and tested for H2-assisted NH3-selective catalytic reduction (SCR) of NO x . The catalysts were either washcoated onto separate monoliths that were placed up- or downstream of each other (dual-brick layout) or washcoated on top of each other in a sandwiched layout (dual-layer). Our results showed that it is highly preferred to have Ag/Al2O3 as the upstream or outer layer catalyst. Fe-BEA showed a high NH3 oxidation giving an NH3 deficit over the Ag/Al2O3. Ag/Al2O3 formed NO2 which enhanced the activity over Fe-BEA through the “fast”-SCR reaction when Fe-BEA was placed downstream or as inner layer. When no H2, which is needed for the SCR reaction over Ag/Al2O3, was added, the dual-layer layout was preferred. The shorter diffusion distance between the layers is a probable explanation.
Original language | English |
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Journal | Topics in Catalysis |
Volume | 56 |
Issue number | 1-8 |
Pages (from-to) | 14-18 |
ISSN | 1022-5528 |
DOIs | |
Publication status | Published - 2013 |
Keywords
- Ag/Al2O3
- Fe-BEA
- Monoliths
- H2
- NH3
- SCR