Selective Oxidation of Ammonia by Co-adsorbed Oxygen on Iridium Surfaces: Formation of N2O

Abstract

Temperature programmed desorption is used to investigate ammonia oxidation by pre-adsorbed oxygen on planar Ir(210) and faceted Ir(210) with different facet sizes. Evidence is found for formation of N 2 O from both surfaces, which is the first observation of N 2 O production in catalytic ammonia oxidation under UHV conditions (\1 9 10 -9 Torr). The selectivity of the reaction to N 2 , N 2 O and NO can be tuned by oxygen pre-coverage, surface structure, and facet size. The reaction exhibits strong structure sensitivity on faceted Ir(210) versus planar Ir(210) and moderate size effects on faceted Ir(210) for average facet sizes of 5-14 nm. Graphical Abstract

Cascade NH3 Oxidation and N2O Decomposition via Bifunctional Co and Cu Catalysts

“…The nitrogen selectivity increases with the adsorption of NO x and N 2 O x species, as the oxidation of NH 3 is inhibited due to the reduced concentration of surface-active O. These results are consistent with studies on Ir-based and Au-based catalysts. Karatok et al reported that disordered surface atomic O can selectively catalyze N–H bond cleavage, yielding mainly N 2 products, while the O/Ag(111) surface with higher oxygen coverage shows higher selectivity for N 2 O than N 2 .…”