cogelled xerogel catalysts; tailored morphology; nucleation; metal dispersion; hydrodechlorination
Abstract :
[en] The study of the influence of synthesis operating variables (nature and concentration of complexing silane, palladium percentage, temperatures of gelling, aging and vacuum drying of xerogels, molar ratio between the complexing silane and palladium, molar concentration of ammonia solution, and use of tetramethylammonium hydroxide as base instead of NH3) allows improving metal dispersion in Pd/SiO2 cogelled xerogel catalysts. The use of 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) or 3-(2-aminoethylamino)propyltriethoxysilane (EDAES) to complex palladium in an ethanolic solution containing tetraethoxy si lane (TEOS) and an ammonia solution of 0.54 mol/l allows obtaining a Pd/SiO2 xerogel catalyst with a mean metal particle diameter of 2.4 nm located inside silica particles. Indeed, complexes Pd(EDA(E)S)(x)(n+) induce a nucleation mechanism because of their higher reactivity compared to the network-reagent (TEOS). Although metal particles are located inside the silica particles, their complete accessibility, via the micropore network, has been shown. 1,2-dichloroethane hydrodechlorination over Pd/SiO2 catalysts mainly produces ethane and the specific hydrodechlorination rate per gram of palladium increases proportionally with palladium dispersion. Hydrodechlorination over Pd/SiO2 cogelled xerogel catalysts is a structure insensitive reaction with regard to the ensemble size concept. (C) 2004 Elsevier B.V. All rights reserved.
Disciplines :
Chemical engineering Materials science & engineering
Author, co-author :
Lambert, Stéphanie ; Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Génie catalytique - Département de chimie appliquée
Polard, Jean-François; Université de Liège - ULiège > Département de chimie appliquée
Pirard, Jean-Paul ; Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Génie catalytique
Heinrichs, Benoît ; Université de Liège - ULiège > Département de chimie appliquée > Ingén. des nanomatériaux, des matér. divisés et des interf.
Language :
English
Title :
Improvement of metal dispersion in Pd/SiO2 cogelled xerogel catalysts for 1,2-dichloroethane hydrodechlorination
Publication date :
2004
Journal title :
Applied Catalysis B: Environmental
ISSN :
0926-3373
eISSN :
1873-3883
Publisher :
Elsevier Science Bv, Amsterdam, Netherlands
Volume :
50
Pages :
127-140
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
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