Adsorption separation of liquid-phase C5-C6 alkynes and olefins using FAU zeolite adsorbents

Abstract

Isoprene is of great importance as a valuable monomer for most chemical industries owing to the increasing demand for synthetic rubber. To obtain polymer-grade olefins, the removal of alkyne compounds from isoprene is mandatory and challenging. Adsorption separation using zeolites is one of the most promising alternatives for alkyne/olefin separation. Herein, a combination of batch, fixed bed column experiments and configurational-bias grand canonical Monte Carlo (CB-GCMC) simulations was applied to study alkyne’s selective adsorption from binary liquid-phase isoprene/1-pentyne mixtures in faujasite (FAU) zeolites. The adsorption separation performance, including the adsorption capacity and selectivity, was obtained based on the liquid-phase measurement method developed in this study. FAU zeolites exhibited 218 mg/g alkyne adsorption capacity and relatively high adsorption selectivity at low alkyne concentrations. Liquid adsorption separation of linear alkyne/olefin mixtures, covering 1-pentyne/1-pentene (C5) and 1-hexyne/1-hexene (C6), in FAU zeolites, was performed further to investigate the separation performance for alkynes and olefins. The binary isotherms for the 1-pentyne/isoprene system and extended studied olefin/alkyne systems were reproduced well by CB-GCMC simulations. The visualized average occupation profiles of adsorbate molecules in FAU zeolites showed that alkyne and olefin molecules were mainly distributed near the 4-rings and 6-rings. The concentrated areas were arranged perpendicular to each other.