Influence of desorption conditions before gas separation studies in nanocomposite MFI–alumina membranes

The gas permeation and separation performance of polycrystalline MFI-type zeolite membranes is strongly dependent on the number and type of intercrystalline pores in its structure. Herein we show that the role of such domains is affected by how a membrane is pre-treated before use to remove adsorbed species (e.g. moisture and organics). This ‘pre-treatment’ step appears to be crucial not only to obtain reliable permeation data, but also to improve the membrane separation performance in practical applications. We illustrate this idea by using a collection of tubular nanocomposite MFI–alumina membranes showing different quality for the separation of n-butane/H2 mixtures and submitted to different pre-treatment protocols. The influence of each protocol on the final separation performance of the membranes depends on their quality, namely on the density of intercrystalline defects or non-zeolite pores in their structure. Moreover the quality of the support affects the final membrane performance

Nanocomposite MFI – ceramic hollow fibres: prospects for CO2 separation

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Synthesis and characterization of nanocomposite MFI-alumina hollow fibres: application to CO2 capture

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Synthèse et caractérisation de fibres creuses nanocomposites MFI-alumine

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Nanocomposite MFI - Ceramic hollow fibres: Prospects for CO2 separation

Alshebani, A. Pera-Titus, M. Landrivon, E. Schiestel, Th. Miachon, S. Dalmon, J. -A. 4th International Zeolite Membrane Meeting JUL 22-25, 2007 Zaragoza, SPAIN Sp. Iss. SIThe membrane surface/module volume ratio is one of the main criteria in designing separation units. This parameter can be increased by one order of magnitude when dropping the membrane tube diameter from the cm to the mm scale. Alumina hollow fibres have been used as supports and submitted to pore-plugging MFI zeolite synthesis. Ail alumina-MFI nanocomposite structure, showing no surface film. has been obtained, as observed by SEM and EDX analysis and confirmed by high temperature variation of H-2 and N-2 permeances. Maxwell-Stefan modeling provides ail equivalent thickness lower than 1 mu m. The membrane quality has been assessed by gas separation of n-butane/H-2. A first application to CO2/H-2 separation has been achieved, reaching separation factors close to 10. Such a system. based oil cheap symmetric supports, could lead to an important decrease in module costs for gas separation applications. (C) 2008 Elsevier Inc. All rights reserved

Nanocomposite MFI−alumina membranes: high-flux hollow fibers for CO2 capture from internal combustion vehicles

The transport field accounts for about 35% of CO2 emissions in France, while energy production only involves 16% of the emissions. The strong contribution of transport to the CO2 emission pattern in France is mainly ascribed to the great development of the nuclear field as energy vector. Therefore, in order to meet Kyoto targets, CO2 emissions in vehicles should be drastically reduced in France in the forthcoming decades. To this aim, taking into account a scenario where thermal engines will keep their supremacy as the main propulsion technology at short and mid terms, in addition to increasing more and more energy efficiency, a possibility to reduce drastically CO2 emissions from transport could involve direct CO2 capture and in situ storage from exhaust gases. In this study, we propose the use of high-flux nanocomposite MFI−alumina hollow-fiber membranes recently developed in our laboratory for direct CO2 capture from mobile sources. A critical discussion is provided about the technico-economical feasibility (i.e., CO2 recovery, CO2 purity in the permeate, module volume, energy overcomsumption, and autonomy) of a membrane-based unit for CO2 capture and liquefaction in the special case of heavy vehicles (over 3500 kg) using conventional diesel propulsion standards

On a membrane-based process for CO2 capture from internal combustion vehicles

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On a membrane-based process for CO2 capture from internal combustion vehicles

High-flux MFI-alumina hollow fibers with a negligible amt. of intercryst. defects and selective to CO2 at room temp. were successfully prepd. using the pore-plugging approach. Unlike film-like membranes, the nanocomposite architecture of these materials, involving a very low effective thickness, allows higher permeances. Although the sepn. factors obtained remain still low and need therefore further optimization, the high fluxes obtained on these materials make them promising to embark on an application for in situ CO2 capture in mobile sources. In addn., the use of hollow fibers instead of conventional tubular membranes might allow a redn. about 1 order of magnitude of the sepn. unit vol

Synthesis and characterization of nanocomposite MCM-41 ('LUS') ceramic membranes

Hamad, B. Alshebani, A. Pera-Titus, M. Wang, S. Torres, M. Albela, B. Bonneviot, L. Miachon, S. Dalmon, J. -A. 4th International Zeolite Membrane Meeting JUL 22-25, 2007 Zaragoza, SPAIN Sp. Iss. SIA new type of nanocomposite membranes, MCM-41 ('LUS')-based material networks grown into porous ceramic membrane support walls (alumina and zirconia), were prepared. Physical characterization (low-angle XRD, TPD, SEM-EDX) confirm the sole presence of the LUS mesostructure (BJH pore size approximate to 3.2 nm), and in a high enough amount to plug the pores of the tubular supports. Single gas hydrodynamic characterization shows that the contribution of defects (i.e. viscous flux) is negligible or comparable to reference mesoporous commercial membranes (5 nm pore size gamma-alumina), but with a considerably enhanced permeance for gases and water, as well as, a single pore size. When compared to literature results on similar organized mesoporous membranes, this work shows even greater improvements. (C) 2008 Elsevier Inc. All rights reserved