NMR Study of the Adsorption of Hydrocarbons on Several Typical Native Charcoals Ⅲ. ¹³C NMR Study of Adsorbed Benzene, Cyclohexane, n-Pentane and n-Hexane

The ¹³C NMR parameters of benzene, cyclohexane, n-pentane and n-hexane adsorbed in charcoals with various pore structures further show the existance of two states of the adsorbed molecules, i.e. molecules adsorbed on the solid surface and those condensed in the capillary. These two kinds of molecules are exchanging fast, In examining the adsorption of n-pentane and n-hexane chain molecules on the charcoals, the ¹³C resonance lines of the three carbon atoms in different chemical environments were well resolved, but were broadened due to the unaveraged chemical shift anisotropy of the molecules adsorbed on the surface. The similarty of the shift to high field broadening of the spectral lines and spin lattice relaxation times of the three different carbons suggests that the adsorbed chain molecules lie flat on the solid surface.