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Sun KQ, Marceau E, Che M. Evolution of nickel speciation during preparation of Ni–SiO2 catalysts: effect of the number of chelating ligands in [Ni(en)x(H2O)6–2x]2+ precursor complexes. Phys Chem Chem Phys 2006; 8:1731-8. [PMID: 16633658 DOI: 10.1039/b513319j] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The evolution of nickel speciation during the successive preparation steps of Ni-SiO(2) catalysts is studied by UV-Vis-NIR, FT-IR, DTG, TPR and TEM. The study focuses on the effect of the number of chelating ligands in the precursor complexes [Ni(en)(x)(H(2)O)((6-2x))](2+) (en = ethylenediamine, x = 1, 2, 3) on the adsorption on silica, and on nickel speciation after thermal treatment. When the en:Ni ratio in solution increases from 1 to 3, the most abundant complex is [Ni(en)(H(2)O)(4)](2+) (64% of all Ni complexes), [Ni(en)(2)(H(2)O)(2)](2+) (81%) and [Ni(en)(3)](2+) (61%), respectively. Equilibrium adsorption of [Ni(en)(x)(H(2)O)((6-2x))](2+) on SiO(2) results in the selective grafting of [Ni(en)(H(2)O)(4)](2+) and [Ni(en)(2)(H(2)O)(2)](2+), through the substitution of two labile H(2)O ligands by two surface SiO(-) groups. The surface [Ni(en)(H(2)O)(2)(SiO)(2)] complex formed by the grafting of [Ni(en)(H(2)O)(4)](2+) onto silica tends to transform into NiO and nickel phyllosilicate after calcination, which consequently leads to large and heterogeneously distributed metallic Ni particles upon reduction. In contrast, [Ni(en)(2)(SiO)(2)], resulting from the grafting of [Ni(en)(2)(H(2)O)(2)](2+) onto silica, no longer has aqua ligands able to react with other nickel complexes or silicium-containing species. Calcination transforms these complexes into isolated Ni(2+) ions, which are reduced into small metallic Ni particles with a more homogeneous size distribution, even at higher Ni loading.
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Affiliation(s)
- Ke-Qiang Sun
- Laboratoire de Réactivité de Surface (UMR 7609-CNRS), Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, France
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Vivier V, Aguey F, Fournier J, Lambert JF, Bedioui F, Che M. Spectroscopic and Electrochemical Study of the Adsorption of [Co(en)2Cl2]Cl on γ-Alumina: Influence of the Alumina Ligand on Co(III)/(II) Redox Potential. J Phys Chem B 2005; 110:900-6. [PMID: 16471621 DOI: 10.1021/jp058224x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
UV-visible and Raman spectroscopies as well as electrochemical techniques have been used to characterize cis- and trans-[Co(III)(en)2Cl2]Cl (en=ethylenediamine) complexes and the gamma-alumina-supported cis-Co((III)) complex. It is shown that the electrochemical reduction of these complexes occurs according to a multistage mechanism involving two electrochemical steps, with the formation of a dimer that was characterized by UV-visible spectroscopy (intervalence band at 670 nm). The apparent standard redox potential for each step has been determined, and experimental results reveal that cis and trans complexes present similar electrochemical characteristics. It is also shown that the deposition of trans-[Co(III)(en)2Cl2]+ on gamma-alumina leads to an inner-sphere complex (ISC) in a cis configuration in which Cl- ligands are substituted by OH or O- surface groups of alumina. These changes in the coordination sphere of the complex induce a substantial decrease of its apparent redox potential since it is -0.63 V/SCE (saturated calomel electrode) for the gamma-alumina-supported cis-Co(III) complex, whereas values of -0.17 and -0.35 V/SCE were determined in dimethyl sulfoxide (DMSO) for the trans and cis precursor complexes, respectively.
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Affiliation(s)
- Vincent Vivier
- Laboratoire de Réactivité de Surface, UMR 7609-CNRS, Université Pierre & Marie Curie, 4 place Jussieu, Casier 178, 75252 Paris Cedex 05, France.
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Malka K, Aubard J, Delamar M, Vivier V, Che M, Louis C. Electron Transfer at the Gas−Solid Interface: Reaction of Gas-Phase MoCl5 with Vanadium Oxide Supported on Silica. J Phys Chem B 2003. [DOI: 10.1021/jp022258c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Karen Malka
- Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France, Institut de Topologie et Dynamique des Systèmes (ITODYS), UMR CNRS 7086, Université Paris VII-Denis Diderot, 1 rue Guy de la Brosse, 75251 Paris Cedex 05, France, and Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
| | - Jean Aubard
- Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France, Institut de Topologie et Dynamique des Systèmes (ITODYS), UMR CNRS 7086, Université Paris VII-Denis Diderot, 1 rue Guy de la Brosse, 75251 Paris Cedex 05, France, and Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
| | - Michel Delamar
- Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France, Institut de Topologie et Dynamique des Systèmes (ITODYS), UMR CNRS 7086, Université Paris VII-Denis Diderot, 1 rue Guy de la Brosse, 75251 Paris Cedex 05, France, and Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
| | - Vincent Vivier
- Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France, Institut de Topologie et Dynamique des Systèmes (ITODYS), UMR CNRS 7086, Université Paris VII-Denis Diderot, 1 rue Guy de la Brosse, 75251 Paris Cedex 05, France, and Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
| | - Michel Che
- Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France, Institut de Topologie et Dynamique des Systèmes (ITODYS), UMR CNRS 7086, Université Paris VII-Denis Diderot, 1 rue Guy de la Brosse, 75251 Paris Cedex 05, France, and Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
| | - Catherine Louis
- Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France, Institut de Topologie et Dynamique des Systèmes (ITODYS), UMR CNRS 7086, Université Paris VII-Denis Diderot, 1 rue Guy de la Brosse, 75251 Paris Cedex 05, France, and Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
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Garrot JM, Lepetit C, Che M, Chaquin P. Modeling of the Tridentate Amorphous Silica Ligand. J Phys Chem A 2001. [DOI: 10.1021/jp011329p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jean-Michel Garrot
- Laboratoire de Réactivité de Surface, UMR 7609 CNRS, Université Pierre et Marie Curie, Tour 54-55, 2ème étage, 4, Place Jussieu, 75252 Paris Cedex 05, France
| | - Christine Lepetit
- Laboratoire de Réactivité de Surface, UMR 7609 CNRS, Université Pierre et Marie Curie, Tour 54-55, 2ème étage, 4, Place Jussieu, 75252 Paris Cedex 05, France
| | - Michel Che
- Laboratoire de Réactivité de Surface, UMR 7609 CNRS, Université Pierre et Marie Curie, Tour 54-55, 2ème étage, 4, Place Jussieu, 75252 Paris Cedex 05, France
| | - Patrick Chaquin
- Laboratoire de Chimie Théorique, UMR 7616 CNRS, Université P. et M. Curie, Tour 22-23, 1er étage, 4, Place Jussieu, 75252 Paris Cedex 05, France
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Kermarec M, Decarreau A, Che M, Carriat J. Identification of supported phases produced in the preparation of silica-supported Ni catalysts by competitive cationic exchange. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s0167-2991(06)81840-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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