Hydrogen bonding to oxygen in siloxane bonds drives liquid phase adsorption of primary alcohols in high-silica zeolites

Upon liquid phase adsorption of C-1-C-5 primary alcohols on high silica MFI zeolites (Si/Al = 11.5-140), the concentration of adsorbed molecules largely exceeds the concentration of traditional adsorption sites: Bronsted acid and defect sites. Combining quantitative in situ(1)H MAS NMR, qualitative multinuclear NMR and IR spectroscopy, hydrogen bonding of the alcohol function to oxygen atoms of the zeolite siloxane bridges (Si-O-Si) was shown to drive the additional adsorption. This mechanism co-exists with chemi- and physi-sorption on Bronsted acid and defect sites and does not exclude cooperative effects from dispersive interactions.

Automated summary

During the liquid phase adsorption of C-1-C-5 primary alcohols on high silica MFI zeolites, the concentration of adsorbed molecules exceeds the traditional adsorption sites. This additional adsorption is driven by hydrogen bonding between the alcohol function and the zeolite siloxane bridges, while chemi- and physi-sorption on traditional sites also occur simultaneously.