(458d) Sn Containing Layered Zeolites Catalysts: Syntheses and Application in Biomass Conversion

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

E-mail: tsapa001@umn.edu

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 ^[4]. 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.

References

[1] A. Corma, V. Fornes, S. B. Pergher, Th. L. M. Maesen and J. G. Buglass, Nature, 1998, 396, 353-356.

[2] M. Tsapatsis, AIChE J., 2014, 2374-2381.

[3] 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.

[4] 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.

[5] D. Xu , G. R. Swindlehurst , H. Wu , D. H. Olson , X. Zhang and M. Tsapatsis, Adv. Funct. Mater., 2014, 24, 201–208.