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Title: Generation and reactivity of putative support systems, Ce-Al neutral binary oxide nanoclusters: CO oxidation and C–H bond activation

Abstract

Both ceria (CeO{sub 2}) and alumina (Al{sub 2}O{sub 3}) are very important catalyst support materials. Neutral binary oxide nanoclusters (NBONCs), Ce{sub x}Al{sub y}O{sub z}, are generated and detected in the gas phase and their reactivity with carbon monoxide (CO) and butane (C{sub 4}H{sub 10}) is studied. The very active species CeAlO{sub 4}{sup •} can react with CO and butane via O atom transfer (OAT) and H atom transfer (HAT), respectively. Other Ce{sub x}Al{sub y}O{sub z} NBONCs do not show reactivities toward CO and C{sub 4}H{sub 10}. The structures, as well as the reactivities, of Ce{sub x}Al{sub y}O{sub z} NBONCs are studied theoretically employing density functional theory (DFT) calculations. The ground state CeAlO{sub 4}{sup •} NBONC possesses a kite-shaped structure with an O{sub t}CeO{sub b}O{sub b}AlO{sub t} configuration (O{sub t}, terminal oxygen; O{sub b}, bridging oxygen). An unpaired electron is localized on the O{sub t} atom of the AlO{sub t} moiety rather than the CeO{sub t} moiety: this O{sub t} centered radical moiety plays a very important role for the reactivity of the CeAlO{sub 4}{sup •} NBONC. The reactivities of Ce{sub 2}O{sub 4}, CeAlO{sub 4}{sup •}, and Al{sub 2}O{sub 4} toward CO are compared, emphasizing the importance of a spin-localized terminalmore » oxygen for these reactions. Intramolecular charge distributions do not appear to play a role in the reactivities of these neutral clusters, but could be important for charged isoelectronic BONCs. DFT studies show that the reaction of CeAlO{sub 4}{sup •} with C{sub 4}H{sub 10} to form the CeAlO{sub 4}H•C{sub 4}H{sub 9}{sup •} encounter complex is barrierless. While HAT processes have been previously characterized for cationic and anionic oxide clusters, the reported study is the first observation of a HAT process supported by a ground state neutral oxide cluster. Mechanisms for catalytic oxidation of CO over surfaces of Al{sub x}O{sub y}/M{sub m}O{sub n} or M{sub m}O{sub n}/Al{sub x}O{sub y} materials are proposed consistent with the presented experimental and theoretical results.« less

Authors:
;
Publication Date:
OSTI Identifier:
22251385
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 139; Journal Issue: 19; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 77 NANOSCIENCE AND NANOTECHNOLOGY; 2-METHYLPROPANE; ALUMINIUM OXIDES; ATOMS; BUTANE; CARBON MONOXIDE; CATALYST SUPPORTS; CERIUM OXIDES; CHARGE DISTRIBUTION; DENSITY FUNCTIONAL METHOD; GROUND STATES; NANOSTRUCTURES; OXIDATION; OXYGEN; REACTIVITY

Citation Formats

Wang, Zhe-Chen, Yin, Shi, and Bernstein, Elliot R., E-mail: erb@lamar.colostate.edu. Generation and reactivity of putative support systems, Ce-Al neutral binary oxide nanoclusters: CO oxidation and C–H bond activation. United States: N. p., 2013. Web. doi:10.1063/1.4830406.
Wang, Zhe-Chen, Yin, Shi, & Bernstein, Elliot R., E-mail: erb@lamar.colostate.edu. Generation and reactivity of putative support systems, Ce-Al neutral binary oxide nanoclusters: CO oxidation and C–H bond activation. United States. https://doi.org/10.1063/1.4830406
Wang, Zhe-Chen, Yin, Shi, and Bernstein, Elliot R., E-mail: erb@lamar.colostate.edu. 2013. "Generation and reactivity of putative support systems, Ce-Al neutral binary oxide nanoclusters: CO oxidation and C–H bond activation". United States. https://doi.org/10.1063/1.4830406.
@article{osti_22251385,
title = {Generation and reactivity of putative support systems, Ce-Al neutral binary oxide nanoclusters: CO oxidation and C–H bond activation},
author = {Wang, Zhe-Chen and Yin, Shi and Bernstein, Elliot R., E-mail: erb@lamar.colostate.edu},
abstractNote = {Both ceria (CeO{sub 2}) and alumina (Al{sub 2}O{sub 3}) are very important catalyst support materials. Neutral binary oxide nanoclusters (NBONCs), Ce{sub x}Al{sub y}O{sub z}, are generated and detected in the gas phase and their reactivity with carbon monoxide (CO) and butane (C{sub 4}H{sub 10}) is studied. The very active species CeAlO{sub 4}{sup •} can react with CO and butane via O atom transfer (OAT) and H atom transfer (HAT), respectively. Other Ce{sub x}Al{sub y}O{sub z} NBONCs do not show reactivities toward CO and C{sub 4}H{sub 10}. The structures, as well as the reactivities, of Ce{sub x}Al{sub y}O{sub z} NBONCs are studied theoretically employing density functional theory (DFT) calculations. The ground state CeAlO{sub 4}{sup •} NBONC possesses a kite-shaped structure with an O{sub t}CeO{sub b}O{sub b}AlO{sub t} configuration (O{sub t}, terminal oxygen; O{sub b}, bridging oxygen). An unpaired electron is localized on the O{sub t} atom of the AlO{sub t} moiety rather than the CeO{sub t} moiety: this O{sub t} centered radical moiety plays a very important role for the reactivity of the CeAlO{sub 4}{sup •} NBONC. The reactivities of Ce{sub 2}O{sub 4}, CeAlO{sub 4}{sup •}, and Al{sub 2}O{sub 4} toward CO are compared, emphasizing the importance of a spin-localized terminal oxygen for these reactions. Intramolecular charge distributions do not appear to play a role in the reactivities of these neutral clusters, but could be important for charged isoelectronic BONCs. DFT studies show that the reaction of CeAlO{sub 4}{sup •} with C{sub 4}H{sub 10} to form the CeAlO{sub 4}H•C{sub 4}H{sub 9}{sup •} encounter complex is barrierless. While HAT processes have been previously characterized for cationic and anionic oxide clusters, the reported study is the first observation of a HAT process supported by a ground state neutral oxide cluster. Mechanisms for catalytic oxidation of CO over surfaces of Al{sub x}O{sub y}/M{sub m}O{sub n} or M{sub m}O{sub n}/Al{sub x}O{sub y} materials are proposed consistent with the presented experimental and theoretical results.},
doi = {10.1063/1.4830406},
url = {https://www.osti.gov/biblio/22251385}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 19,
volume = 139,
place = {United States},
year = {Thu Nov 21 00:00:00 EST 2013},
month = {Thu Nov 21 00:00:00 EST 2013}
}