Activity Self-Optimization Steered by Dynamically Evolved Fe 3+ @Fe 2+ Double-Center on Fe 2 O 3 Catalyst for NH 3 -SCR.

Identification of the active centers dynamically stable under the reaction condition is of paramount importance but challenging because of the limited knowledge of steady-state chemistry on catalysts at the atomic level. Herein, focusing on the Fe 2 O 3 catalyst for the selective catalytic reduction of NO with NH 3 (NH 3 -SCR) as a model system, we reveal quantitatively the self-evolving Fe 3+ @Fe 2+ (∼1:1) double-centers under the in-situ condition by the first-principles microkinetic simulations, which enables the accurate prediction of the optimal industry operating temperature (590 K). The cooperation of this double-center achieves the self-optimization of catalytic activity and rationalizes the intrinsic origin of Fe 2 O 3 catalyzing NH 3 -SCR at middle-high temperatures instead of high temperatures. Our findings demonstrate the atomic-level self-evolution of active sites and the dynamically adjusted activity variation of the catalyst under the in-situ condition during the reaction process and provide insights into the reaction mechanism and catalyst optimization.