2,6-Di-tert-butylpyridine Sorption Approach to Quantify the External Acidity in Hierarchical Zeolites

By K. Góra-Marek, K. Tarach, Minkee Choi. 2014

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This work was aimed to evidence that substituted pyridine, 2,6-di-tert-butylpyridine, is a suitable probe for the quantitative investigation of the external acidity in hierarchically structured zeolites. The 2,6-di-tert-butylpyridine was too large to enter the micropores, even in wide pore zeolites, and nearly no sites in nonmesoporous zeolites were available. Accessibility studies of acid sites in zeolites TNU-9 and BEA involving quantitative IR measurements with hindered 2,6-di-tert-butylpyridine as a probe were performed. The extinction coefficients of the 1615 cm–1 diagnostic bands of 2,6-di-tert-butylpyridine interacting with Bronsted acid sites were determined. Lewis acid sites were not detected with the probe. The accessibility factor (AF) for the 2,6-di-tert-butylpyridine probe molecule was defined as the number of sites detected by adsorption of the dTBPy (external sites) divided by the total amount of acid sites in the studied zeolites as quantified by pyridine sorption. Upon desilication result...

Subfields: Industrial and Manufacturing Engineering, Inorganic Chemistry, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/bca7795eba6ba4cfb413378ce951852eb17c1028