Elucidation of the Cu Redox Cycle Underlying NOx Selective Catalytic Reduction in Cu-SSZ-13

William  Schneider, University of Notre Dame

The Cu-exchanged chabazite catalyst is now a commercially viable solution for the selective catalytic reduction of NOx.  Significant questions remain, however, about the nature of the catalytic active sites and mechanisms.  The answers to such questions are essential to optimizing catalysts for low-temperature applications, to minimize undesirable ammonia oxidation at high temperature, and to minimize the production of the greenhouse gas nitrous oxide.  In this presentation we describe an integrated experimental and computational investigation of these mechanistic questions in well-defined Cu-SSZ-13 catalysts.  Operando x-ray absorption (XAS) experiments provide information about the rates, rate orders, and apparent activation energy of SCR and simultaneously insight into catalyst structure and oxidation state. By combining this information with density functional theory calculations of adsorption, reaction, and activation free energies, we develop a microkinetic model for SCR that accounts for low-temperature SCR activity. We describe prospects for using these results to develop improved catalysts.

Download Presentation: