Structure-activity relationships in NH3-SCR over Cu/SSZ-13 as probed by reaction kinetics and EPR

Charles  Peden, Pacific Northwest National Laboratory

ORAL PRESENTATION:

Selective catalytic reduction (SCR) of NOx with ammonia using metal-exchanged molecular sieves with a Chabazite (CHA) structure has recently been commercialized on diesel vehicles [1-3]. Catalysts with outstanding SCR performance (activity, hydrothermal stability, etc.) include the aluminosilicate zeolite, SSZ-13, with ion-exchanged Cu. Apart from the commercial success, detailed catalyst structures, reaction mechanisms, and structure-activity relationships are still lacking. In the current study, we use Electron Paramagnetic Resonance (EPR), a technique ideally suited for studying Cu2+ exchanged zeolites, to study hydrated Cu-SSZ-13 catalysts at various Cu loadings in order to gain further insights into their locations. Also, NH3-SCR and NH3 oxidation kinetics are investigated over these catalysts at high space velocity conditions for the development of structure-activity relationships.

1. Kwak, J.H., Tonkyn, R.G., Kim, D.H., Szanyi, J., Peden, C.H.F.  J. Catal. 275, 187 (2010).
2. Fickel, D.W., Lobo, R.F. J. Phys. Chem. C 114, 1633 (2010).
3. Schmieg, S.J., Oh, S.H., Kim, C.H., Brown, D.W., Lee, J.H., Peden, C.H.F., Kim, D.H. Catal. Today 184, 252 (2012).

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