Aging of Cu/SSZ-13 for NH3 SCR in mixed lean condition
Other conference contribution, 2018
Deactivation was observed after all types of aging. However strong differences in deactivation degree exists between aging procedures. Lean aging, for 8h at 800°C, was the most moderate aging tested although it brought about significant activity loss below 250°C. Alternating between long lean periods and short rich periods caused slightly stronger deactivation, which was most significant at 200°C. However, the switching frequency between lean and rich had negligible influence on subsequent activity. As shown in Figure 1, SCR activity after 8h exposure in H2 was outstandingly low. It increased monotonically with temperature to reach a maximum of 58% NO conversion. Further investigation pertaining to the rich treatment was performed. The aging time was reduced to 2h and, for direct comparison, a 32h cycling aging was performed, implying a total rich time of 2h. Both samples were severely impacted over the whole temperature range. It revealed that 2h in rich conditions led to stronger deactivation than 8h in lean and lean/rich conditions, emphasizing the deterioration power of H2. Aging caused by rich conditions was so dominant that additional 30h in lean has negligible influence on SCR below 300°C. However, the long additional exposure to lean conditions lowered significantly the SCR activity between 400 and 500°C.
NH3-SCR
aging
deactivation
Cu-SSZ13
Author
Xavier Auvray
Chemical Process and Reaction Engineering
Ann Grant
Björn Lundberg
Chemical Process and Reaction Engineering
Louise Olsson
Chalmers, Chemistry and Chemical Engineering, Chemical Technology
Tianjin, China,
Subject Categories
Chemical Process Engineering
Other Environmental Engineering
Other Chemical Engineering