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Oxidative addition of dihydrogen as the key step of the active center formation in the HDS sulfide bimetallic catalysts: Ab initio MO/MP2 studyстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Zakharov I.I., Startsev A.N., Zhidomirov G.M., Parmon V.N.
- Журнал: Journal of Molecular Catalysis A: Chemical
- Том: 137
- Номер: 1-3
- Год издания: 1999
- Издательство: Elsevier BV
- Местоположение издательства: Netherlands
- Первая страница: 101
- Последняя страница: 111
- DOI: 10.1016/S1381-1169(98)00106-X
- Аннотация: The electronic structure of Ni in the sulfide bimetallic species (SBMS), which is the active component of the sulfide HDS catalysts, is studied with the ab initio molecular orbital calculations. In the previous paper [I.I. Zakharov, A.N. Startsev, G.M. Zhidomirov, J. Mol. Catal. 119 (1997) 437], we have shown that the d8 Ni(II) electronic state in the SBMS composition cannot be active in lIDS reaction because of the lack of possibility to coordinate S-containing molecule. Therefore, this paper deals with the study of the possibility to stabilize d6 electron configuration with the formal Ni(IV) oxidation state. With this in mind, the reaction of oxidative addition of dihydrogen to square-planar complex Ni(II)Cl2(PH3)2 has been studied, which allowed to predict a stabilization of the octahedral complex Ni(IV)H2Cl2(PH3)2 with d6 configuration. This allows us to assume a possibility of an oxidative adsorption of dihydrogen to the Ni atom entering the SBMS composition. Ab initio calculations have shown that such type of oxidative addition is thermodynamically favorable resulting in stabilization of the Ni(IV) d6 electronic state. Consequently, the dihydrogen molecule is assumed to dissociate on the Ni atom resulting in the formation of ’surface’ H(s) and ’occluded’ H(o) hydrogen, which is located under the Ni atom in the center of the trigonal sulfur prism. The structure of the active centers is optimized and the stretching modes of the hydrogen atoms are calculated, which appear to be close to the literature data. The H2S adsorption on the active center was also investigated and it was shown that the hydrogen disulfide molecule benefits to stabilization of the active Ni(IV) d6 state. The conclusion is drawn that the deciding factor in the formation of the active centers of sulfide HDS catalysts is the ’occluded’ hydrogen.
- Добавил в систему: Жидомиров Георгий Михайлович