(765b) Hierarchically Organized, Honeycomb-Like MFI Zeolites By Sequential Intergrowth

Crystalline microporous zeolites are renowned as one of the most important adsorbents and heterogeneous catalysts and are widely used in the petroleum, petrochemical, and chemical industries.  However, the presence of pore apertures only at the micropore length scale (< 2 nm) sometimes limits their applications pertinent to diffusion of bulky molecules. The fabrication of hierarchically organized zeolites is among the most promising solutions to overcome such molecular transport problems as the hierarchical zeoliltes will provide multidimensional spatial networks on different length scales with improved characteristics relevant to diffusion of molecules and ions [1,2].

Here, we report the construction of hierarchically organized, honeycomb-like MFI zeolites by sequential intergrowth using a simple organic structure-directing agent (OSDA) without meso- or macroporogens. The selection of an appropriate OSDA and optimized synthesis conditions that can form plate-like zeolites with enhanced rotational intergrowths seems to be a key to achieving a hierarchical structure with three classes of porosity in one structure: the intrinsic microporosity of the zeolite framework together with mesoporosity existing within the zeolite plates and macroporosity stemming from the complex intergrown structure [3]. This concept would be applicable to other zeolite frameworks and related porous crystalline materials that can form such rotational intergrowths.

[1] X. Zhang, D. Liu, D. Xu, S. Asahina, K. A. Cychosz, K. V. Agrawal, Y. A.Wahedi, A. Bhan, S. A. Hashimi, O. Terasaki, M. Thommes, M. Tsapatsis, Science 2012, 336, 1684 – 1687.

[2] W. Fan, M. A. Snyder, S. Kumar, P.-S. Lee, W. C. Yoo, A. V. McCormick, R. L. Penn, A. Stein, M. Tsapatsis, Nat. Mater. 2008, 7, 984 – 991.

[3] W. Chaikittisilp, Y. Suzuki, R. R. Mukti, T. Suzuki, K. Sugita, K. Itabashi, A. Shimojima, T. Okubo, Angew. Chem. Int. Ed. 2013, 52, 3355 –3359.