Metal-support interactions revisited by theoretical calculations: The influence of organic ligands for preparing Ni/SiO₂ catalysts

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• 作者：Diego Valencia^a ; ^b ; ^{dvalencia@comunidad.unam.mx" class="auth_mail} ; Laura Pe&ntilde ; a^b ; V&iacute ; ctor Hugo Uc^c ; Isidoro Garc&iacute ; a-Cruz^a ; ^{igarcia@imp.mx" class="auth_mail}
• 关键词：Heterogeneous catalysts ; Chelating agents ; Support ; Hydrogen bond ; DFT ; ONIOM
• 刊名：Applied Catalysis A: General
• 出版年：5 April, 2014
• 年：2014
• 卷：475
• 期：Complete
• 页码：134-139
• 全文大小：1269 K

文摘

We performed a theoretical study of the interaction between Ni-containing compounds and amorphous SiO₂ support, which have been used for preparing supported catalysts. The aim of this work is to understand the effect of the chemical structure of the metal species and its interaction with the support during the preparation of heterogeneous catalysts. The metal-support interactions were revisited for a series of Ni-containing compounds with different ligands adsorbed on SiO₂. We studied some of most commonly used ligands for preparing Ni/SiO₂ catalysts such as ethylenediamine, citric acid and EDTA. Replacement of the first atom of the ligand bound to Ni by the -OH surface group of the support was modeled using the ONIOM combined quantum mechanics/molecular mechanics (QM/MM) approach. The adsorption geometry and the Gibbs energy are clearly related to the ligand structure. We also noted the stabilization of the adsorbed compounds through cooperative hydrogen bonds with the -OH moiety adjacent surface group present on SiO₂. We point out the importance of the ligand structure in the metal-support interactions. These results can be useful to understand the metal- and ligand-support interactions during the preparation of supported catalysts.