Gas-Phase Reactions of Copper Oxide Cluster Cations with Ammonia: Selective Catalytic Oxidation to Nitrogen and Water Molecules

Abstract

Reactions of copper oxide cluster cations, Cu O ( n = 3-7; m ≤ 5), with ammonia, NH, are studied at near thermal energies using a guided ion beam tandem mass spectrometer. The single-collision reactions of specific clusters such as CuO, CuO, CuO, CuO, and CuO give rise to the release of HO after NH adsorption efficiently and result in the formation of Cu ONH. These Cu O clusters commonly have Cu average oxidation numbers of 1.0-1.4. On the other hand, the formation of Cu OH, i.e., the release of HNO, is dominantly observed for CuO with a higher Cu oxidation number. Density functional theory calculations are performed for the reaction CuO + NH → CuONH + HO as a typical example of HO release. The calculations show that this reaction occurs almost thermoneutrally, consistent with the experimental observation. Further, our experimental studies indicate that the multiple-collision reactions of CuO and CuO with NH lead to the production of Cu and CuO, respectively. This suggests that the desirable NH oxidation to N and HO proceeds on these clusters.

Stable Compositions and Structures of Copper Oxide Cluster Cations CunOm+ (n = 2–8) Studied by Ion Mobility Mass Spectrometry

“…As a result of CID processes, oxygen-rich and oxygen-equivalent clusters have a tendency to prefer to be dissociated to a variety of oxygen-deficient cluster series, like (Cu 2 O) n /2 + ( n even), Cu n O ( n –1)/2 + ( n odd), and Cu n O ( n +1)/2 + ( n odd), by the loss of oxygen atoms. These results of CID have been also observed by Hirabayashi and Ichihashi . Moreover, the relative intensities of the small stable species were found to be higher under high injection energy because of the fragmentation of larger cluster ions.…”

“…These results of CID have been also observed by Hirabayashi and Ichihashi. 44 Moreover, the relative intensities of the small stable species were found to be higher under high injection energy because of the fragmentation of larger cluster ions. S1).…”

Electron Donation from Cu Atoms to Al Oxide Clusters upon Mixing Revealed by Thermal Desorption Spectrometry

“…12−15 A strong correlation was found between reactivities with NH 3 and the average oxidation states of the Cu atoms in the clusters, where the clusters with average oxidation states of 1−1.5 were reduced by NH 3 . 12 Although the most active oxidation state of Cu, that is, Cu(0) or Cu(I), is still debatable, it is generally accepted that the formation of CuO (consisting of Cu(II)) deactivates the catalyst. 11 In one of our previous studies, we investigated the nature of isolated small Cu oxide clusters: 16 The stable compositions of the small Cu oxide clusters generated at high temperatures by oxidation and the oxidation states of the Cu atoms in the clusters were elucidated.…”

Selective C−O Coupling Hidden in the Thermal Reaction of [Al2CuO5]+ with Methane

“…Also, a series of [Cu n O m ] + clusters ([Cu 6 O 5 ] + , [Cu 8 O 6 ] + , [Cu 9 O 7 ] + , and [Cu 11 O 8 ] + ) are able to oxidize NO to NO 2 . Further, upon reaction with NH 3 , the clusters [Cu 4 O 2 ] + , [Cu 5 O 3 ] + , [Cu 6 O 3 ] + , [Cu 7 O 3 ] + , and [Cu 7 O 4 ] + give rise to the release of H 2 O, whereas [Cu 7 O 5 ] + affords the generation of neutral HNO . In addition, the copper complex [(dppm)Cu 2 (H)] + (dppm=1,1‐bis(diphenylphosphino)‐methane) selectively decomposes formic acid into H 2 and CO 2 , and the structurally more simple copper hydrides [CuH 2 ] − and [Cu 2 H 3 ] − also exhibit versatile reactivities towards a series of small neutral molecules; finally, the [LCuO] + (L=1,10‐phenanthroline) complex reacts with fluoromethanes to give H/O atom transfers .…”

“…[4] Further,u pon reaction with NH 3 ,t he clusters [Cu 4 O 2 ] + ,[ Cu 5 O 3 ] + ,[ Cu 6 O 3 ] + , [Cu 7 O 3 ] + ,a nd [Cu 7 O 4 ] + give rise to the releaseo fH 2 O, whereas [Cu 7 O 5 ] + affords the generation of neutral HNO. [5] In addition, the copper complex[ (dppm)Cu 2 (H)] + (dppm = 1,1-bis(diphenylphosphino)-methane) selectively decomposes formic acid into H 2 and CO 2 , [6] and the structurally more simple copper hydrides [CuH 2 ] À and [Cu 2 H 3 ] À also exhibit versatile reactivities towards as eries of small neutral molecules; [7] finally,t he [LCuO] + Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.…”