Comparison of Cu/BEA, Cu/SSZ-13 and Cu/SAPO-34 for ammonia-SCR reactions
Artikel i vetenskaplig tidskrift, 2015

In this study, the ammonia-SCR process was investigated using 2.5 wt.% Cu/BEA, 2.6 wt.% Cu/SAPO-34 and 3.1 wt.% Cu/SSZ-13. Several reactions such as NO oxidation, ammonia oxidation, standard SCR, fast SCR and NO2 SCR were studied to understand the effect of zeolite type. It was found that the small-pore zeolites/silicoaluminophosphates with CHA structure (Cu/SAPO-34 and Cu/SSZ-13) exhibited higher SCR activity at 150°C and lower selectivity toward N2O formation during standard SCR conditions than Cu/BEA. However, formation of ammonium nitrate species during fast SCR conditions at 150°C occurred over Cu/CHA catalysts, which resulted in a gradual decrease of the NOx conversion. Such blocking was also observed over Cu/BEA, albeit to a minor extent. The ammonium nitrate formation and its decomposition temperature regimes resulted in that the Cu/BEA was catalytically more active at lower temperature than either Cu/SAPO-34 or Cu/SSZ-13 during fast SCR conditions. Additionally, our results show that the ammonium nitrate species were more stable on the small-pore zeolites than on Cu/BEA. Comparing the two Cu/CHA catalysts, Cu/SAPO-34 and Cu/SSZ-13, it was found that ammonia oxidation at high temperatures and ammonia SCR at 150°C was higher on Cu/SAPO-34. Further, TPR experiments showed that Cu in Cu/SAPO-34 is more easily reduced compared to Cu/SSZ-13. This can facilitate the redox processes and can thereby be a reason for the higher activity at 150°C for Cu/SAPO-34. In addition, Cu/SAPO-34 forms less N2O and this might be a result of the formation of more stable ammonium nitrates. To conclude, the choice of the type of zeolite/silicoaluminophosphates affects the activity and selectivity of the different steps in the SCR process.







Kirsten Leistner

Kompetenscentrum katalys

Chalmers, Kemi och kemiteknik, Kemiteknik

Oana Mihai

Chalmers, Kemi och kemiteknik, Kemiteknik

Kompetenscentrum katalys

Kurnia Wijayanti

Chalmers, Kemi och kemiteknik, Kemiteknik

Kompetenscentrum katalys

A. Kumar

Cummins Inc.

K. Kamasamudram

Cummins Inc.

N. W. Currier

Cummins Inc.

Aleksey Yezerets

Cummins Inc.

Louise Olsson

Chalmers, Kemi och kemiteknik, Kemiteknik

Kompetenscentrum katalys

Catalysis Today

0920-5861 (ISSN)

Vol. 258 49-55

Grundläggande mekanismer för deaktivering av NOx-lagringskatalysatorer vid användning av biobränsle

Vetenskapsrådet (VR) (2011-4860), 2012-01-01 -- 2016-12-31.




Kemiska processer



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