Computational Insights into the Mechanism of the Selective Catalytic Reduction of NOx: Fe- Versus Cu-Doped Zeolite Catalysts

We computationally investigate the mechanism of the reduction half-cycle of the selective catalytic reduction (SCR) of nitrogen oxides with ammonia. We compare both Fe- and Cu-doped zeolite catalysts and aim at exploring all accessible reaction pathways. From our calculations, a comprehensive picture emerges that unifies sev- eral previous mechanistic proposals. We find that both for Fe and for Cu catalysts, different reaction pathways are feasible, but some of the possible reaction pathways differ in these two cases. Our computational results provide a basis for the inter- pretation of in situ spectroscopic investigations that can possibly distinguish the different mechanistic pathways.