Calorimetric study on the state of C1–C4 alcohols sorbed on silicalite

Abstract

Differential molar heats of sorption have been determined calorimetrically for methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol and 2-methylpropan-1-ol on silicalite as a function of pore filling . The results suggest that the first alcohol molecules sorbed interact wtih lattice defects; as the number of alcohol molecules rises, they are sorbed on the regular silicalite framework. A comparison of the heat of sorption curves of methanol, propan-1-ol and propan-2-ol at low pore fillings with that of triethylamine on silicalite supports the view that most of the defects in the silicalite lattice consist of internal silanol groups which predominantly occur as vicinal pairs. From a comparison of the heat of sorption curves of the alcohols studied with those of alkanes and diethyl ether, it is concluded that a substantial contribution to the heat of sorption of the alcohols on the regular silicalite framework stems from hydrogen-bonding interactions of the alcohol molecules with framework oxygen atoms and/or with each other.