Hierarchical porous silica membranes with dispersed Pt nanoparticles
Résumé
Multifunctional silica membranes with a hierarchical porosity and containing dispersed Pt nanoparticles were prepared by an original one pot microwave-assisted sol-gel route. These membranes exhibit three porosity levels: interconnected micropores (<2 nm) in silica walls, isolated ordered mesopores (similar to 4 nm), and isolated macropores (similar to 70 nm). They were directly coated on tubular macropotous alumina supports without any intermediate mesoporous layer contrary to conventional membrane architectures. The isolated macropores and mesopores enable to increase the membrane permeability whereas the interconnected microporosity defines the rnembrane cut-off The catalytic Pt nanoparticles (similar to 4 nm) mainly hosted in the mesoporous volume. are stabilised against undesirable agglomeration under working conditions. A first series of multifunctional membranes were prepared, in which preferential adsorption of hydrocarbon gases and efficient propene oxidation were evidenced. In order to avoid any possible interconnection between macropores, several strategies were investigated, which prevented sot infiltration in the macroporous support during the deposition process. These original multifunctional membranes are potentially attractive for gas separation and catalytic reactor applications. (C) 2009 Elsevier Inc. All rights reserved.