Mixed matrix membranes for gas separation: effects of various glycol incorporated into activated carbon and ultem

Abstract

Solid-liquid mixed matrix membranes (MMMs) composed of molecular sieves and liquid addi-tives in a polymer matrix have the potential to provide economical as well as high-performance gas separation. MMMs are conceptually designed based on the advantages of three materials; the processability of polymers, the superior gas transport properties of molecular sieves, and the higher gas solubility in liquid additives. MMMs have been successfully fabricated in this study by individually incorporating polyethylene glycol (PEG) and butanediol isomers (1,2-, 1,3-, 1,4-, and 2,3-butanediols) into pores of activated carbon and Ultem polymers, followed by the solution-casting. N₂, H₂, C0₂, and CH₄ permeances were determined using single gas measurements. The selectivitiy for C0₂/CH₄ for MMMs incorporated with only activated car-bon (AC), and activated carbon with liquid additives (PEGAC; 1,2AC; 1,3AC; 1,4AC; and 2,3AC) was enhanced. The enhancement of C0₂/CH₄ selectivity was attributed to an increase to C0₂ solubility into liquid additives or glycol isomers. The results from 1,2AC and 2,3AC MMMs demonstrate that the position of hydroxyl groups attached to carbon atoms on the car-bon backbones plays an important role in the permeance of and selectivity to the polar gas mo-lecule (C0₂).