Low‐Valent Manganese Atoms Stabilized on Ceria for Nitrous Oxide Synthesis
Ivan Surin, Zhenchen Tang, Julian Geiger, Suyash Damir, Henrik Eliasson, Mikhail Agrachev, Frank Krumeich, Sharon Mitchell, Vita A. Kondratenko, Evgenii V. Kondratenko, Gunnar Jeschke, Rolf Erni, Núria López, Javier Pérez‐Ramírez
Abstract
Abstract Nitrous oxide, N 2 O, exhibits unique reactivity in oxidation catalysis, but the high manufacturing costs limit its prospective uses. Direct oxidation of ammonia, NH 3 , to N 2 O can ameliorate this issue but its implementation is thwarted by suboptimal catalyst selectivity and stability, and the lack of established structure–performance relationships. Systematic and controlled material nanostructuring offers an innovative approach for advancement in catalyst design. Herein low‐valent manganese atoms stabilized on ceria, CeO 2 , are discovered as the first stable catalyst for NH 3 oxidation to N 2 O, exhibiting two‐fold higher productivity than the state‐of‐the‐art. Detailed mechanistic, computational and kinetic studies reveal CeO 2 as the mediator of oxygen supply, while undercoordinated manganese species activate O 2 and facilitate N 2 O evolution via NN bond formation between nitroxyl, HNO, intermediates. Synthesis via simple impregnation of a small metal quantity (1 wt%) predominantly generates isolated manganese sites, while full atomic dispersion is achieved upon redispersion of sporadic oxide nanoparticles during reaction, as confirmed by advanced microscopic analysis and electron paramagnetic resonance spectroscopy. Subsequently, manganese speciation is maintained, and no deactivation is observed over 70 h on stream. CeO 2 ‐supported isolated transition metals emerge as a novel class of materials for N 2 O production, encouraging future studies to evaluate their potential in selective catalytic oxidations at large.