Separation of Organic/Oxygen Mixtures with MCM-48 Silica Mesoporous Tubular Membranes

OSCAR DE LA IGLESIA; MARISA PEDERNERA; REYES MALLADA; JOAQUÍN CORONAS; JESÚS SANTAMARÍA

Seoul ( Korea)

Congreso; International Congress on Membrane Processes 2005 (ICOM 2005); 2005

  The family of mesoporous materials called M41S (MCM-41, MCM-48 and MCM-50) is a subject of growing interest since they were discovered by Mobil researchers in 1992 [1]. These materials are the result of the ordering of micelles formed when a silica and surfactant solution is under proper conditions. In the case of MCM-48, the micelles are ordered in hexagonal arrays, MCM-48 has a three-dimensional cubic structure, with interconnected pores and MCM-50 has an unstable lamellar structure. The main properties of these materials are: i) a very narrow pore size distribution in the mesoporous region, typically between 2 and 4 nm, ii) a high specific surface area (1000-1500 m2/g), iii) a highly ordered structure and iv) an active surface chemistry that allows an easy modification of the properties of these solids. All of them make these materials very attractive for numerous applications such as catalysis, separations, and encapsulation of molecules. An alternative to polymeric membranes for organic separations due to its higher chemical stability are the inorganic membranes, among them zeolite membranes are very good candidates due to their precise pore size distribution and diversity of structures (MFI, MOR, FAU, LTA…). However they are in the microporous range, and are not well suited for separations involving large molecules. The three-dimensional structure of MCM-48 makes this mesoporous material the most appropriate for the synthesis of zeolite-like membranes, since MCM-41 hexagonal channels grow parallel to the support. Although some synthesis of MCM-48 membranes have been carried out over flat supports [2, 3], tubular membranes are more suitable for scale-up because of their higher area to volume ratio. In the present work, mesoporous MCM-48 material has been synthesised either in powder form and also deposited in a tubular porous alumina support. The mesoporous material and membranes were characterised with different techniques: XRD, N2 adsorption, permporometry, SEM, FTIR and individual N2 permeation. Also, the obtained membranes were tested in the gas phase separation of mixtures containing organic compounds.