CPL - Chalmers Publication Library
| Utbildning | Forskning | Styrkeområden | Om Chalmers | In English In English Ej inloggad.

Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13

Kirsten Leistner (Institutionen för kemi och kemiteknik, Kemisk reaktionsteknik ; Kompetenscentrum katalys (KCK)) ; Kunpeng Xie (Institutionen för kemi och kemiteknik, Kemisk reaktionsteknik ; Kompetenscentrum katalys (KCK)) ; A. Kumar ; K. Kamasamudram ; Louise Olsson (Institutionen för kemi och kemiteknik, Kemisk reaktionsteknik ; Kompetenscentrum katalys (KCK))
Catalysis Letters (1011-372X). Vol. 147 (2017), 8, p. 1882-1890.
[Artikel, refereegranskad vetenskaplig]

The purpose of this study is to attribute NH 3 -TPD peaks observed over Cu/SSZ-13 catalysts to different catalytic sites. This is done by comparing a large number of copper loadings, especially below 40% ion exchange, to be able to see effects relevant to sites in both 6-membered and 8-membered rings. We found that intermediate (200–300 °C) and high (400–500 °C) temperature NH 3 -TPD peaks followed similar trends to the copper species in 6-membered and 8-membered rings respectively, as seen by H 2 -TPR and NO-DRIFTS. Thus we propose that these two TPD peaks represent ammonia stored on H and Cu sites in 6 and 8-membered rings, respectively. This assignment is further supported by the finding that the intermediate and high temperature NH 3 -TPD peaks of samples with different Si/Al ratios also follow the same trend. Moreover, we observe that the activation energy for ammonia oxidation is significantly lower for Cu in 6MR compared to Cu in 8MR rings. Graphical Abstract: [Figure not available: see fulltext.].

Nyckelord: Chabazite , Copper loading , Cu/SSZ-13 , Large cages , NH adsorption 3 , Si/Al ratio , Six-membered rings



Denna post skapades 2017-08-21. Senast ändrad 2017-09-14.
CPL Pubid: 251307

 

Läs direkt!

Lokal fulltext (fritt tillgänglig)

Länk till annan sajt (kan kräva inloggning)