Comparative IR and 1H-MAS NMR study of adsorption of CD3 CN on zeolite H-Beta: evidence of the presence of two families of bridged Bronsted sites

The IR and H-1-MAS NMR spectroscopy of zeolite H-beta in interaction with CD3CN is described, Two families of strong Si(OH)AI Bronsted sites have been clearly distinguished: a first family, characterized by an NMR signal at 4.4 ppm and an IR peak at 3614 cm(-1) (isolated bridged hydroxys) and a second family, characterized by a broad band in the 3-7 ppm NMR range and in the 3600-3200 cm(-1) IR range, due to bridged hydroxys which are perturbed by H-bond interactions with the zeolitic framework. This last family of hydroxys form weaker adducts with acetonitrile.