Crosslinked Polystyrene Beads Modified with Sulfonyl Groups and Their Application in Aromatic/Aliphatic Hydrocarbons Separation

The separation of aromatic hydrocarbons from aromatic/aliphatic mixtures was investigated with cross- linked polystyrene(CPS) beads modified with sulfonyl groups. Three sulfonating agents, i.e. benzenesulfonyl chloride(BsCl), 4-toluene sulfonyl chloride(TsCl) and methanesulfonyl chloride(MsCl) were used to prepare sulfonyl CPS beads by Friedel-Crafts reaction. The CPS beads modified with BsCl exhibited higher sulfonation rate than those modified with MsCl and TsCl and obtained optimum selectivity in the experiments of toluene/n-heptane separation. Further separation tests with various other aromatic/aliphatic mixtures were carried out at an initial aromatic concentration of 13%(mass fraction) with the results showing that the modified beads have preferential selectivity for aromatic hydrocarbons in all aromatic/aliphatic mixtures, and especially a separation factor of 8.21 and a swelling ratio of 30% for toluene/cyclohexane system. The thermal stability and regeneration test indicate that the used polystyrene beads can be recovered through heat-drying and reused effectively.