Zeolites are a class of crystalline aluminosilicates with many properties, such as high surface area, strong acidity, and high thermal stability, that result in excellent performance in catalytic applications.  Typically, the pore sizes of conventional zeolites are &lt; 1 nm, significantly restricting the size of molecules with access to active sites within the zeolite micropores.  To address this limitation, several strategies have been developed to introduce additional porosity to zeolite materials with larger pore diameters, usually in the mesopore range (2 – 50 nm).   One method with significant success in generating mesoporous zeolites is soft-templating, where small organic molecules are added to the seed crystallization solution and are incorporated into the growing zeolite crystals.  After crystallization is complete, these soft templates are then removed by calcination and leave behind larger diameter mesopores.<br/>A critical aspect to ultimately controlling the surface area, pore volume, and other material properties of mesoporous zeolites synthesized with the soft-template approach is the ability to characterize the incorporation of the soft template molecules into the zeolite structure.  Typically, characterization has focused on the properties of the zeolite itself and not on the soft template and its incorporation.   Here, we will present results from combining characterization techniques such as ATR-FTIR, thermogravimetric analysis (TGA), and gas physisorption experiments to provide insights into the extent of template incorporation and the effects of synthesis parameters such as template loading on the physical properties of the final zeolite material.<br/>ATR-FTIR and TGA both provide measurements of the extent of template incorporation along with complementary information on the structure (IR band frequencies) and nature of incorporation (physisorbed or covalently bonded to zeolite surface).  By combining these results with data on the surface area and pore size distributions of the calcined zeolite product, we gain insights into the mechanism of the soft-templating approach.

Characterization of soft-templated mesoporous zeolites: Techniques and insights

253rd National Meeting (2017)

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