Evolution of nickel speciation during ...
Document type :
Article dans une revue scientifique: Article original
DOI :
PMID :
Permalink :
Title :
Evolution of nickel speciation during preparation of Ni-SiO(2) catalysts: effect of the number of chelating ligands in [Ni(en)(x)(H(2)O)(6-2x)](2+) precursor complexes
Author(s) :
Sun, K. Q. [Auteur]
Marceau, Eric [Auteur]
Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181
Che, M. [Auteur]
Marceau, Eric [Auteur]

Unité de Catalyse et Chimie du Solide (UCCS) - UMR 8181
Che, M. [Auteur]
Journal title :
Phys. Chem. Chem. Phys.
Abbreviated title :
Phys. Chem. Chem. Phys.
Pages :
1731-1738
Publication date :
2006-02-28
ISSN :
1463-9076
HAL domain(s) :
Chimie
English abstract : [en]
The evolution of nickel speciation during the successive preparation steps of Ni–SiO2 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 ...
Show more >The evolution of nickel speciation during the successive preparation steps of Ni–SiO2 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(H2O)(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)(H2O)4]2+ (64% of all Ni complexes), [Ni(en)2(H2O)2]2+ (81%) and [Ni(en)3]2+ (61%), respectively. Equilibrium adsorption of [Ni(en)x(H2O)(6−2x)]2+ on SiO2 results in the selective grafting of [Ni(en)(H2O)4]2+ and [Ni(en)2(H2O)2]2+, through the substitution of two labile H2O ligands by two surface SiO− groups. The surface [Ni(en)(H2O)2(SiO)2] complex formed by the grafting of [Ni(en)(H2O)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(H2O)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 Ni2+ ions, which are reduced into small metallic Ni particles with a more homogeneous size distribution, even at higher Ni loading.Show less >
Show more >The evolution of nickel speciation during the successive preparation steps of Ni–SiO2 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(H2O)(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)(H2O)4]2+ (64% of all Ni complexes), [Ni(en)2(H2O)2]2+ (81%) and [Ni(en)3]2+ (61%), respectively. Equilibrium adsorption of [Ni(en)x(H2O)(6−2x)]2+ on SiO2 results in the selective grafting of [Ni(en)(H2O)4]2+ and [Ni(en)2(H2O)2]2+, through the substitution of two labile H2O ligands by two surface SiO− groups. The surface [Ni(en)(H2O)2(SiO)2] complex formed by the grafting of [Ni(en)(H2O)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(H2O)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 Ni2+ ions, which are reduced into small metallic Ni particles with a more homogeneous size distribution, even at higher Ni loading.Show less >
Language :
Anglais
Administrative institution(s) :
Université de Lille
CNRS
Centrale Lille
ENSCL
Univ. Artois
CNRS
Centrale Lille
ENSCL
Univ. Artois
Collections :
Research team(s) :
Matériaux pour la catalyse (MATCAT)
Submission date :
2023-05-30T18:30:06Z