Zeolite and Metal-Organic-Framework Nanosheet Crystallization for Membrane Separations and Catalysis

The ability to control crystal size and morphology is essential for enabling optimal use of micro- and meso-porous materials in separation and catalysis applications. In the last 15 years, our group is developing methods to synthesize zeolite and, more recently, metal-organic-framework nanosheets. They hold promise for ultra-selective highly-permeable gas separation membranes because their molecularly-sized pores can ensure the desirable separation selectivity and increased permeance along their thin dimension. Moreover, pillared or self-pillared (intergrown) nanosheets provide reduced diffusion lengths that are desirable in certain adsorption and catalysis applications. I will describe a crystal growth methodology based on controlling the frequency of rotational intergrowths (twining) that enabled direct-crystal growth of the zeolite framework MFI as self-pillared [1] and free-standing nanosheets [2]. I will also describe recent results on direct synthesis of metal-organic-framework nanosheets and their use in thin film formation.

Zhang, X.; Liu, D.; Xu, D.; Asahina, S.; Cychosz, K.; Varoon, K.; Al Wahedi, Y.; Bhan, A.; Al Hashimi, S.; Terasaki, O.; Thommes, M.; Tsapatsis M., Direct Synthesis of Self-Pillared Zeolite Nanosheets by Repetitive Branching. Science, 336, 1684-1687, 2012.

Jeon, M.Y.; Kim, D., Kumar; P., Lee, P.S.; Rangnekar, N.; Bai, P.; Shete, M.; Elyassi, B.; Lee, H.S.; Narashimharao, K.; Basahel, S.N.; Al-Thabaiti, S.; Xu, W.Q.; Cho, H.J.; Fetisov, E.O.; Thyagarajan, R.; DeJaco, R.F.; Fan, W.; Mkhoyan, K.A.; Siepmann, J.I.; Tsapatsis, M., Ultra-Selective High-Flux Membranes from Directly Synthesized Zeolite Nanosheets, Nature, 543(7647), 690-694, 2017.