Sn containing layered zeolites catalysts: syntheses and application in biomass conversion
Limin Ren, Qiang Guo, Michael Tsapatsis
Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE, Minneapolis, MN, 55455, USA
Among microporous zeolitic materials, there is a set whose structures are made up of ordered lamellar sheets. These layered zeolites could be manipulated by pillaring or exfoliation (delamination) [1-3] to form zeolites with high external surface area and hierarchical meso-microporous structures. Moreover, direct synthesis of inter-grown single unit cell lamellae is also a possible . Here, we will report on two types of hierarchical Sn containing layered zeolites (layer expanded Sn-MWW and Sn-SPP) synthesis and their application for catalysis.
We have designed two routes for preparing hierarchical Sn-MWW zeolite catalysts. For the first route, a solid state exchange (SSE) method was applied for introducing Sn into the pillared MWW framework. A pillared MWW zeolite was first prepared, and then an acid leaching procedure was performed for creating vacancies for incorporating Sn. For the second route, pillared Sn-MWW zeolite was directly prepared by pillaring the Sn-MWW precursor. Pillared Sn-MWW materials prepared through both routes have shown ordered mesoporosity, preserved intra-layer crystallinity, higher external surface area and pore volume.
The Sn-SPP zeolite was prepared via one-step hydrothermal synthesis using commercially available tetrabutylphosphonium hydroxide (TBPOH) as SDA through a repetitive branching during crystal growth [4,5]. The house-of-cards arrangement of the nanosheets creates a permanent network of 2- to 7-nanometer mesopores along with high external surface area and reduced micropore diffusion length. Only tetrahedrally coordinated framework Sn sites were observed in the Sn-SPP zeolite which exhibited Lewis acidity.
The catalytic performance of these materials on biomass conversion reactions will be presented and discussed.
 A. Corma, V. Fornes, S. B. Pergher, Th. L. M. Maesen and J. G. Buglass, Nature, 1998, 396, 353-356.
 M. Tsapatsis, AIChE J., 2014, 2374-2381.
 S. Maheshwari, E. Jordan, S. Kumar, F. S. Bates, R. L. Penn, D. F. Shantz and M. Tsapatsis, J. Am. Chem. Soc., 2008, 130, 1507-1516.
 X. Zhang, D. Liu, D. Xu, S. Asahina, K. A. Cychosz, K. V. Agrawal, Y. Al Wahedi, A. Bhan, S. Al Hashimi, O. Terasaki, M. Thommes and M. Tsapatsis, Science, 2012, 336, 1684-1687.
 D. Xu , G. R. Swindlehurst , H. Wu , D. H. Olson , X. Zhang and M. Tsapatsis, Adv. Funct. Mater., 2014, 24, 201–208.
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