Ranking the Bronsted Acid Strength of Protonic Zeolites with VTIR Spectroscopy --- An Overview of Current Research

Many industrial applications of protonic zeolites as solid-acid heterogeneous catalysts rely on the strength or their Br nsted acidity, which (together with zeolite topology) affects both, catalytic activity and selectivity. Therefore, convenience to have an accurate (and simple) experimental technique for measuring acid strength. The enthalpy change, Delta H 0 , corresponding hydrogen bonding interaction a weak base (such CO dinitrogen) [Si(OH)Al] hydroxyl groups should directly correlate Nevertheless, because simplicity, bathochromic shift O-H stretching frequency, Deltaν (OH) is usually measured by IR spectroscopy at low temperature, correlated strength, ranking acidity. Herein use variable-temperature (VTIR) determine simultaneously demonstrated; followed abridged overview showing that direct correlation between Br.nsted can be misleading when Keywords: VTIR spectroscopy, br H-zeolites