Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Here we show that copper substitution in perovskite-type barium strontium cobalt copper oxide (BSCC) membranes confers extremely high oxygen fluxes well beyond the state of art, reaching 27.5 ml cm−2 min−1at 950 °C. A key feature of BSCC is the formation of a mixed matrix catalyst-perovskite membrane caused by the segregation of copper, leading to the formation of an intergranular network of copper-rich oxide between perovskite grains. BSCC membranes delivered pressure normalised oxygen flux (i.e. permeance) of up to 86 times higher, above pressure difference of 18 kPa, as compared to best perovskite membrane, BBSC, due to the catalytic effect of segregated copper oxide. Unlike conventional dual-phase membranes which contain ion and electron conducting phases, this work shows for the first time perovskite-type membranes consisting of a mixed matrix of oxygen ion/electron conducting (perovskite) and catalytic (copper oxide) phases, thus paving the way to the development of high performance membranes for oxygen separation from air for clean energy applications. © 2016 Elsevier B.V.
ISSN: 0376-7388

hal-01683219
https://hal.univ-antilles.fr/hal-01683219
DOI : 10.1016/j.memsci.2016.12.035

Éditeur(s) : HAL CCSD Royal Society of Chemistry
Résumé : International audience
A versatile sol-gel route has been developed for the preparation of hierarchical porous silica membrane material with highly dispersed platinum nanoparticles (Pt-NPs). The outstanding feature of the "one pot" synthesis developed in this work lies in the successful preparation of a stable complex suspension made of silica sol, multi-scale porogens and Pt nanoparticles. The multi-scale porogens were based on non-ionic triblock copolymers and aqueous latex suspension to create mesopores and macropores, respectively, with finely tuned pore size and organization. For further functionalization of the membranes, Pt nanoparticles of about 4 nm in diameter were prepared by irradiating with microwaves (MW) the Pt precursors added in the starting suspension. This original path is suggested to enable a pre-organization of Pt nanoparticles in the ordered mesoporous structure. The suspensions were then deposited as thin films on either dense or macroporous supports, and further thermally treated at 450°C to remove the porogen units. Hierarchical porous layers composed of micropores (<2 nm), ordered mesopores (∼4 nm) and macropores (∼70 nm) with or without Pt were prepared and characterized. The resulting membranes are foreseen to exhibit great potential as multifunctional membranes for gas separation coupled with catalytic reaction. © The Royal Society of Chemistry 2008.
ISSN: 0959-9428

hal-01680586
https://hal.univ-antilles.fr/hal-01680586
DOI : 10.1039/b807029f

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Abstract View references (38)Silicalite-1 (S-1) and ZSM-5 membranes prepared by secondary growth on tubular ceramic supports were tested using a pervaporation set up for the desalination of aqueous solutions containing NaCl in concentrations corresponding to brackish (0.3-1wt%), sea (3.5wt%) and brine (7.5-15wt%) water. ZSM-5 membranes delivered higher water fluxes when compared with S-1 membranes due to enhanced hydrophilicity of the Al-rich zeolite structure leading to fluxes as high as 11.5kgm -2h -1 for 0.3wt% NaCl feed solutions at 75°C. At higher salt concentration the water flux decreased alongside with the salt rejection rate, however the hydrophilic ZMS-5 membrane became more susceptible to performance loss, particularly at high temperatures. Detailed stability experiments carried out for up to 560h showed the dissolution of both S-1 and ZSM-5 top layers. This was attributed to the combined effects of ion exchange and water dissolution mechanisms. Interesting though, the MFI structure zeolite was still observed on the XRD patterns whilst EDX depth profile showed the presence of silica up to 30μm depth into the support. These results suggest the formation/infiltration of a compact amorphous phase in the substrate, derived from the aggregation of the dissolved silicate species and possibly together with the arrangement of MFI nano-slabs during the desalination tests. Despite generating lower water fluxes, the S-1 membrane exhibited relatively high robustness under the long term testing conditions which included temperature cycling, delivering salt rejections from initial >99% to <80% at the end of the testing period (560h). © 2012 Elsevier B.V.
ISSN: 0376-7388

hal-01683201
https://hal.univ-antilles.fr/hal-01683201
DOI : 10.1016/j.memsci.2012.05.074