Unsaturated hydrocarbons adsorbed on low coordinated Pd surface: A periodic DFT study

SURFACE SCIENCE

卷:604

Article

Belelli, Patricia G.¹  Ferullo, Ricardo M.^1,2  Castellani, Norberto J.¹ 

[1] Univ Nacl Sur, Dept Fis, Grp Mat & Sistemas Catalit, RA-8000 Bahia Blanca, Buenos Aires, Argentina

[2] Univ Nacl Sur, Dept Quim, RA-8000 Bahia Blanca, Buenos Aires, Argentina

关键词: Olefin adsorption;    Pd catalyst;    Stepped surface;    Theoretical approach;    DFT;   

DOI  :  10.1016/j.susc.2009.11.035

来源: Elsevier

【 摘 要 】

In this work, the adsorption of several unsaturated hydrocarbon molecules on a stepped Pd(4 2 2) surface was studied. Using a periodic method based on the Density Functional Theory (DFT) formalism, different adsorption geometries for ethylene, three butene isomers (cis/trans-2-butene and 1-butene), acetylene and 2-butyne were investigated. The results were compared with those obtained for a free defect surface as Pd(1 1 1). The 1-butene is more stable on the free defect surface than on Pd(4 2 2). On the stepped surface, the olefins adsorb tilted towards the step and increases, in almost all the cases, the magnitude of the adsorption energy. Conversely, the 3-fold site is the most stable for the alkynes adsorption on the stepped surface, as it was found on Pd(1 1 1). The analysis of the dipole moment change indicate a charge transfer from the double bond of the olefin to the metallic surface, being higher for the Pd(1 1 1) surface. In case of the alkynes, an important back-donation is produced. Except the alkynes and the 1-butene molecule, the results show the preference of ethylene and cis/trans-2-butene to be adsorbed on the stepped surface. These observations are related with experimental catalytic results. (C) 2009 Elsevier B.V. All rights reserved.

【 授权许可】

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