Ethylene Adsorption on the Pt-Cu Bimetallic Catalysts. Density Functional Theory Cluster Study Научная публикация
Журнал |
Surface Science
ISSN: 0039-6028 |
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Вых. Данные | Год: 2005, Том: 583, Номер: 1, Страницы: 46-59 Страниц : 14 DOI: 10.1016/j.susc.2005.03.021 | ||||
Ключевые слова | 1,2-Dichloroethane dechlorination, Adsorption, DFT, DOS, Ethylene, Pt-Cu catalysts, Vibrations of adsorbed ethylene | ||||
Авторы |
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Организации |
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Информация о финансировании (2)
1 | United States Department of Energy | DE-AC03-76SF00098 |
2 | United States Department of Energy | DE-FG02-95ER14539 |
Реферат:
The adsorption of ethylene on Cu12Pt2 clusters has been studied within the density functional theory (DFT) approach to understand the high ethylene selectivity of Cu-rich Pt–Cu catalyst particles in the reaction of hydrogen-assisted 1,2-dichloroethane dechlorination. The structural parameters for Cu12Pt2 clusters with D4h, D2d, and C3v symmetry have been calculated. The relative stability of the isomeric Cu12Pt2 clusters follows the order: C3v > D2d > D4h. Each isomer has an active site for ethylene adsorption that consists of a single Pt atom surrounded by Cu atoms. The interaction of ethylene with the active site yields a π-C2H4 adsorption complex. The strongest π-C2H4 complex forms with the cluster of C3v symmetry; the bonding energy, ΔEπ(C2H4), is −15.6 kcal mol−1. The bonding energies for the π-C2H4 complex with Cu14 and Pt14 clusters are −6.5 and −18.8 kcal mol−1, respectively.
The addition of Pt to Cu modifies the valence spd-band of the cluster as compared to a Cu14 cluster. The DOS near the Fermi level increases when C2H4 adsorbs on the Cu12Pt2 cluster. As well, the center of the d-band shifts toward lower binding energies. Ethylene adsorption also induces a number of states below the d-band. These states correspond to those of gas-phase C2H4.
The vibrational frequencies of C2H4 adsorbed on the clusters of D4h and C3v symmetry have been calculated. The phonon vibrations occur below 250 cm−1. The intense bands around 200 cm−1 are attributed to stretching vibrations of the Pt–Cu bonds normal to the cluster surface. The stretching vibrations of the Pt–C bonds depend on the local structure of the active site: νs(Pt–C) = 268 cm−1 and νas(Pt–C) = 357 cm−1 for the cluster of the D4h symmetry; νs(Pt–C) = 335 cm−1 and νas(Pt–C) = 397 cm−1 for the cluster of the C3v symmetry. Bands in the range of 800–3100 cm−1 are attributed to vibrations of the adsorbed C2H4 molecule. The signature frequencies of the π-C2H4 adsorption complex are the δs(CH2) deformation vibration at ∼1200 cm−1 and the ν(C–C) stretching vibration at ∼1500 cm−1. These vibration are absent for di-σ-C2H4 adsorption complexes.
Библиографическая ссылка:
Avdeev V.I.
, Kovalchuk V.I.
, Zhidomirov G.M.
, d’Itri J.L.
Ethylene Adsorption on the Pt-Cu Bimetallic Catalysts. Density Functional Theory Cluster Study
Surface Science. 2005. V.583. N1. P.46-59. DOI: 10.1016/j.susc.2005.03.021 WOS Scopus РИНЦ
Ethylene Adsorption on the Pt-Cu Bimetallic Catalysts. Density Functional Theory Cluster Study
Surface Science. 2005. V.583. N1. P.46-59. DOI: 10.1016/j.susc.2005.03.021 WOS Scopus РИНЦ
Даты:
Поступила в редакцию: | 17 дек. 2004 г. |
Принята к публикации: | 14 мар. 2005 г. |
Опубликована online: | 31 мар. 2005 г. |
Опубликована в печати: | 20 мая 2005 г. |
Идентификаторы БД:
Web of science | WOS:000229423500008 |
Scopus | 2-s2.0-18544390833 |
РИНЦ | 13490351 |
Chemical Abstracts | 2005:411265 |
Chemical Abstracts (print) | 143:104006 |
OpenAlex | W1974732736 |