A Coating Based Approach to Zeolite Membranes: Hydrogen Separation by MCM-22/Silica Composite Membranes Made Using Layer-by-Layer Deposition

The realization of zeolite membranes in industry has been limited largely because the reproduction of ultra-thin and defect-free zeolite membranes on a large scale is quite challenging. Moreover, any probable methodology such as in-situ or secondary (seeded growth) growth for membrane manufacturing requires considerable time-consuming procedures, especially because of conventional batch-wise hydrothermal growth. Recently, composite zeolite/silica inorganic films with hierarchical structures have been reported .[1-4] These films were physically formed via a one or multiple time spin coatings or castings of nanocrystal suspension and silica precursor mixture. No conventional hydrothermal growth was involved during film manufacturing.

We have also introduced a coating-based strategy, i.e., layer-by-layer deposition, for the preparation of c-oriented MCM-22-zeolite/silica composite films that showed a potential for gas separations and corrosion prevention.[5] MCM-22 layers were deposited in the composite film in such way that they form an array of transport limiting 6 member ring (MR) apertures which allowed the passage of a small molecule like hydrogen across the membrane, while the transport of larger molecules was hindered.

Here we report improvements in the layer-by-layer deposition method which result in membranes with high (larger than 100) H2/N2 selectivity.

References

1. R.A. Farrell, N. Petkov, H. Amenitsch, J.D. Holmes, and M.A. Morris, J. Mater. Chem., 2008. 18(19): p. 2213-2220.

2. N. Petkov, M. Hoelzl, T.H. Metzger, S. Mintova, and T. Bein, J. Phys. Chem. B, 2005. 109(10): p. 4485-4491.

3. N. Petkov, S. Mintova, B. Jean, T.H. Metzger, and T. Bein, Chem. Mater., 2003. 15(11): p. 2240-2246.

4. T. Seo, T. Yoshino, Y. Cho, N. Hata, and T. Kikkawa, Jpn. J. Appl. Phys., Part 1 2007. 46(9A): p. 5742-5746.

5. J. Choi, Z. Lai, S. Ghosh, D.E. Beving, Y. Yan, and M. Tsapatsis, Ind. Eng. Chem. Res., 2007. 46(22): p. 7096-7106.