Elucidating the origin and nature of SCR-onset conversion inflections over commercial Cu-chabazite SCR catalysts via spatiotemporal measurements and modeling

William  Partridge, Oak Ridge National Laboratory

Elucidating the origin and nature of SCR-onset conversion inflections over commercial Cu-chabazite SCR catalysts via spatiotemporal measurements and modeling

William Partridge,^a,* Neal Currier,^b Saurabh Joshi^b

^aOak Ridge National Laboratory, Knoxville, 37932, USA

^bCummins Inc, Columbus, 47201, USA

*Corresponding author: partridgwp@ornl.gov

 

By measuring inside Cu-SCR catalyst, we observe conversion inflections (CI) that occur at SCR onset.  Such CI is commonly observed in the effluent of Fe-SCR catalysts due to surface NH₃ coverage building beyond an optimum value, and corresponding models have been developed that include dependence on various active sites [1-3].  Because Cu-SCR catalysts are less sensitive to NH₃ inhibition and CI is not observed in their effluent, this phenomenon has not been studied to a significant extent for Cu-SCR catalysts. However, via SpaciMS measurements we observe CI in the front zone of Cu-SCR catalysts where gas-phase NH₃ and NO_x are high [4], and which diminishes with progressive conversion.  Through measurements and modeling we illustrate the CI phenomenon, compare it with Fe-CI theory and demonstrate the impact on catalyst design, modeling and control.  This is particularly relevant to development and commercialization of non-EGR engine-catalyst systems. 

References

1. Tronconi, et al., Catal. Today 2005, 105, 529-536.
2. Grossale, et al., Top. Catal. 2009, 52, 1837-1841.
3. Colombo, et al., Appl. Catal. B 2012, 111-112, 106-118.
4. P. Partridge, et al., 2015 CLEERS Workshop, http://cleers.org/workshops/workshop2015/index.php?presentation=1.