Electrospray ionization (ESI) can produce a wide range of gas‐phase uranyl (UO22+) complexes for tandem mass spectrometry studies of intrinsic structure and reactivity. We describe here the formation and collision‐induced dissociation (CID) of [UO2(NO3)3]−and [UO2(NO3)2(O2)]−. Multiple‐stage CID experiments reveal that the complexes dissociate in reactions that involve elimination of O2, NO2, or NO3, and subsequent reactions of interesting uranyl‐oxo product ions with (neutral) H2O and/or O2were investigated. Density functional theory (DFT) calculations reproduce experimental results and show that dissociation of nitrate ligands, with ejection of neutral NO2, is favored for both [UO2(NO3)3]−and [UO2(NO3)2(O2)]−. DFT calculations also suggest that H2O adducts to products such as [UO2(O)(NO3)]−spontaneously rearrange to create dihydroxides and that addition of O2is favored over addition of H2O to formally U(V) species.
Tandem catalysis couples multiple reactions and promises to improve chemical processing, but precise spatiotemporal control over reactive intermediates remains elusive. We used atomic layer deposition to grow In2O3over Pt/Al2O3, and this nanostructure kinetically couples the domains through surface hydrogen atom transfer, resulting in propane dehydrogenation (PDH) to propylene by platinum, then selective hydrogen combustion by In2O3, without excessive hydrocarbon combustion. Other nanostructures, including platinum on In2O3or platinum mixed with In2O3, favor propane combustion because they cannot organize the reactions sequentially. The net effect is rapid and stable oxidative dehydrogenation of propane at high per-pass yields exceeding the PDH equilibrium. Tandem catalysis using this nanoscale overcoating geometry is validated as an opportunity for highly selective catalytic performance in a grand challenge reaction.
more » « less- Award ID(s):
- 1647722
- NSF-PAR ID:
- 10217925
- Publisher / Repository:
- American Association for the Advancement of Science (AAAS)
- Date Published:
- Journal Name:
- Science
- Volume:
- 371
- Issue:
- 6535
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- p. 1257-1260
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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