1H and 13C NMR study of the adsorption of alcohols on charcoals with various pore structures

A 1H NMR study of methyl, ethyl, n‐propyl, isopropyl and allyl alcohols adsorbed on charcoals with various pore structures showed that the adsorption mechanism is by capillary condensation in pores with radii smaller than 30 Å, and by mono‐/multi‐layer adsorption on the solid surface of pores with larger radii. This mechanism is identical with that of adsorbed hydrocarbons. The 13C NMR parameters suggest that the adsorbed alcohols are preferentially oriented in the monolayer, with the methyl groups bonded to the solid surface. Longer chain alcohols are bent in capillaries with radii smaller than 10 Å. The broadening of the 13C resonances was partly eliminated in magic angle spinning experiments by using a spinning rate of 1.5–1.8 kHz.