329419 Formation of Uniform CHA Zeolite Layers

Eunjoo Kim1, Wanxi Cai1, Hionsuck Baik2 and Jungkyu Choi1, (1)Chemical and Biological Engineering, Korea University, Seoul, South Korea, (2)Seoul Center, Korea Basic Science Institute, Seoul, South Korea

All-silica CHA zeolites[1] hold promise to separate CO2 from other molecules (e.g., N2 in the post-combustion process) through their molecular sieving. In particular, the pore size of CHA zeolites (0.370 nm × 0.417 nm)[2] can allow only CO2 (0.33 nm) to pass through the pore channels, while excluding the transport of larger N2 (0.364 nm).[3] However, conventionally synthesized near cubic Si-CHA particles have a wide size distribution (~1-20 μm).[4-6] The wide size distribution prevents forming a close-packed layer, though the layer is critical in manufacturing zeolite films as desired in the secondary growth methodology.[7,8]

 In an attempt to overcome this, anisotropic plate-like Si-CHA particles, discovered as the minor product along with the dominant near cubic Si-CHA particles, were adopted to make a uniform Si-CHA layer. Selected area electron diffraction and X-ray diffraction characterizations verified the CHA phase of the plate-like particles. The plate-like CHA particles could be selectively deposited on a porous the α-Al2O3 disc despite their lower abundance in a mixture. The uniform CHA layer was formed with a high surface coverage and the uniformity of the plate-like CHA deposits allowed a preferred out-of-plane orientation. The subsequent secondary growth of the seed layer allowed for the continuous CHA membranes. The corresponding CO2/N2 separation performance will be discussed in detail.

References

 [1] Camblor, M. A.; Corma, A.; Diaz-Cabanas, M. J.; Baerlocher, C. Journal of Physical Chemistry B 1998, 102, 44.

 [2] Hedin, N.; DeMartin, G. J.; Roth, W. J.; Strohmaier, K. G.; Reyes, S. C. Micropor. Mesopor. Mater. 2008, 109, 327.

 [3] Breck, D. W. Zeolite molecular sieves: strcucture, chemistry, and use; John Wiley & Sons, Inc., 1974.

 [4] Eilertsen, E. A.; Arstad, B.; Svelle, S.; Lillerud, K. P. Micropor. Mesopor. Mater. 2012, 153, 94.

 [5] Olson, D. H.; Camblor, M. A.; Villaescusa, L. A.; Kuehl, G. H. Microporous Mesoporous Mater. 2004, 67, 27.

 [6] Trzpit, M.; Rigolet, S.; Paillaud, J. L.; Marichal, C.; Soulard, M.; Patarin, J. Journal of Physical Chemistry B 2008, 112, 7257.

 [7] Jiang, H. Y.; Zhang, B. Q.; Lin, Y. S.; Li, Y. D. Chinese Science Bulletin 2004, 49, 2547.

 [8] Snyder, M. A.; Tsapatsis, M. Angew. Chem., Int. Ed. 2007, 46, 7560.


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