Chromatographic liquid phase separation of n-alkane mixtures using zeolites

The separation of n-alkanes on zeolites in liquid phase was studied using pulse chromatography and by determining break-through profiles. Binary adsorption isotherms of alkane Mixtures were measured using a batch adsorption technique. Experiments were performed with zeolites ZSM-22, ZSM-5, Beta, Na-USY and MCM-41. Columns packed with zeolites allow an efficient separation, with selectivity strongly dependent on the zeolite pore size. Too small pores (ZSM-22) lead to diffusional limitations, while zeolites with large pores (Na-USY and MCM-41) have a low selectivity. Among all tested materials, ZSM-5 was the most selective adsorbent, giving large differences in adsorption selectivity between short and long alkanes.