Nanocomposite MFI-alumina membranes via pore-plugging synthesis: Preparation and morphological characterisation

A specific synthesis protocol, based on zeolite crystallisation within the pores of a host support, the pore-plugging method, has been designed and optimised. A composite membrane has been obtained and its quality evaluated using the separation of adsorbing and non-adsorbing gas mixture.A series of parameters were studied, including the pore size of the support, the composition of the precursor solution and the hydrothermal synthesis temperature program. Accordingly, the membrane quality showed large variations.The material structure was characterised using scanning and transmission electron microscopies. These observations showed a composite organization at the support pore scale, with an architecture very different from conventional supported zeolite films.The final optimisation of the synthesis conditions concluded to a precursor solution containing 2 mol/l of silica, 0.9 mol/l of TPAOH, and the use of an interrupted hydrothermal temperature program, among other parameters. Thanks to this optimisation process, an average increase of one order of magnitude in the separative performance was obtained.