Property of alumina to adsorb long chain normal-paraffin hydrocarbons

That alumina can strongly absorb long chain normal-paraffin hydrocarbon was found when alumina was used in the preparative group-type separation of heavy petroleum fractions. The reason for the above property of alumina may be that the normal-paraffin hydrocarbons can extend closely on the alumina surface.One molecule of long chain normal-paraffin hydrocarbon can be adsorbed by many active sites of alumina surface. The longer chain normal-paraffin hydrocarbon can be adsorbed by more active sites of alumina surface; this results in the longer chain normal-paraffin hydrocarbon has a stronger adsorption on alumina.