Mixed matrix membranes for gas separation : plasticization study on cellulose acetate and zeolite incorporated cellulose acetate MMMs

Abstract

One of the most attractive technologies for gas separation, such as CO2/Ch4 and C3H6/C3H8 separation is membrane separation, due to its low capital cost and low energy consumption. However, a significant limitation of this technology, involving CO2 separation, is plasticization. Plasticization in a glassy polymer membrane can occur by CO2 acting as a plasticizer. The polymer matrix swells upon sorption of CO2, accelerating the permeation of all gases. As a result, the polymer membrane loses its selectivity. The objectives of this work were to study the performance of mixed matrix membranes (MMMs) for Co2/CH4 and C3H6/C3H8 separation and to investigate the plasticization on the membrane resulting from CO2 sortion. MMMs were fabricated by the solution-casting method. NaA, CaA, NaX, Nay and silicalite individually used as a solid adsorbent were incorporated into celluloswe acetate (CA) MMMs. In addition, polyehylene glycol (PEG) used as a liquid adsorbent was incorporated into the solid adsorbent for enhancing the MMM performance. The results show that all types of the adsorbents studied had a positive effect on plasticizing suppression. The incorporation of CaA, Nay and silicalite can improve the C3H6/C3H8 selectivity. Furthermore, all types of MMMs studied, except for the silicalite-CA MMM, showed an enhancement of CO2/CH4 selectivity. The maximum C3H6/C3H8 and CO2/CH4 selectivity can increase to 2.9 and 3.6 times, respectively.