Mixed matrix materials comprising of zeolites incorporated in suitable matrix are promising as future membrane material with high permselectivity. However, they suffer from the drawback of low productivity due to increase in membrane thickness by incorporation of zeolites. Nanocomposite membranes consisting of thin zeolite layers (~2 nm) represent a material which combines high selectivity without increasing the membrane thickness due to very small thickness of layers.

In this talk, the fabrication and properties of composite membranes containing ~50-100 nm thick MCM-22 crystals[1] will be presented and compared with nanocomposites containing 2.5 nm exfoliated MCM-22 layers[2,3]. MCM-22 composites were prepared by depositing alternate layers of a matrix phase and oriented MCM-22 crystals and, for a certain appropriately selected matrix, they exhibit high hydrogen/nitrogen and carbon dioxide/nitrogen selectivities. Nanocomposites were prepared by swelling MCM-22(P) layers by surfactant intercalation and employing melt-processing techniques to separate the layers[3]. A major challenge during nanocomposite processing, layered structure preservation[4], was successfully addressed as revealed by Small Angle X-Ray Scattering and Transmission Electron Miocroscopy[3]. The potential use of the nanocomposite films as easily processable, high-flux, high-selectivity gas separation membranes will be discussed.

[1] Leonowicz, M. E.; Lawton, J. A.; Lawton, S. L.; Rubin, M. K., Science, 1994, 264, 1910-13.

[2] Choi, J.; Lai, Z.; Ghosh, S.; Beving, D. E.; Yan, Y.; Tsapatsis, M., Industrial & Engineering Chemistry Research, 2007, 46, 7096-7106.

[3] Maheshwari, S.; Jordan, E.; Kumar, S.; Bates, F. S.; Penn, R. L.; Shantz, D. F.; Tsapatsis, M., Journal of the American Chemical Society, 2008, 130, 1507-1516.

[4] Choi, S.; Coronas, J.; Jordan, E.; Oh, W.; Nair, S.; Onorato, F.; Shantz, D. F.; Tsapatsis, M., Angewandte Chemie International Edition, 2007, 47, 3, 552-555.