(327b) Rapid Synthesis of Sn-BEA Zeolites with Tunable Si/Sn Ratio and Morphology

Authors: 
Chang, C. C., University of Massachusetts Amherst
Cho, H. J., University of Massachusetts
Fan, W., University of Massachusetts Amherst

Upgrading biomass to chemicals involves multiple catalytic steps that govern the market-viability of the final products, highlighting the importance of efficient catalysts. For example, in 2010, Moliner et al. reported Sn-BEA is highly active in glucose isomerization reaction, a crucial step for the conversion of biomass to valued chemicals.1 The inorganic catalyst resembles the selectivity and activity of enzymic catalysts and has advantages (easily regenerated and operated in wide reaction conditions) over biocatalysts. The discovery of Sn-BEA for glucose isomerization could potentially lower the cost in biomass refining process. In addition, the solid Lewis acid catalyst with the acidity originated from framework substituted Sn, has also shown superior catalytic properties in industry-relevant reactions such as Baeyer-Villiger oxidation, Meerwein-Ponndorf-Verley-Oppenauer redox reaction, and pentose/triose isomerization reactions.2

     However, long crystallization time (up to 40 day) for Sn-BEA might hinder further studies of the catalysts and potential applications in industrial practice. In this study, we demonstrate that, by using a seeding method, the crystallization time can be greatly reduced to 6 h. we systemically studied the synthesis parameters which affect the crystallization process, Sn incorporation and Si/Sn ratios., and demonstrated that the incorporation of Sn into zeolite BEA framework delays both nucleation and crystal growth rates. The use of Al-free zeolite BEA seeds can largely enhance the crystallization process by bypassing the need of nucleation. Si/Sn ratio in the synthesized samples can be controlled from 50 to 150 by tailoring crystallization temperature. The mesoporosity can also be introduced within the formed Sn-BEA by controlling the types of seeds used in the synthesis, which can benefit reactions involving bulky molecules. 

References:

(1)    Moliner, M.; Román-Leshkov, Y.; Davis, M. E., Proc. Nat. Acad. Sci. 2010, 107 (14), 6164-6168.

(2) (a)    Corma, A.; Nemeth, L. T.; Renz, M.; Valencia, S., Nature 2001, 412, 423-425; (b)    Corma, A.; Domine, M. E.; Valencia, S., J. Catal. 2003, 215 (2), 294-304; (c)    Choudhary, V.; Pinar, A. B.; Sandler, S. I.; Vlachos, D. G.; Lobo, R. F., ACS Catal. 2011, 1 (12), 1724-1728; (d)    Taarning, E.; Saravanamurugan, S.; Holm, M. S.; Xiong, J. M.; West, R. M.; Christensen, C. H., ChemSusChem 2009, 2 (7), 625-627.