Performance Analysis of Blended Membranes of Cellulose Acetate with Variable Degree of Acetylation for CO ₂/CH ₄ Separation

Abstract

The separation and capture of CO ₂ have become an urgent and important agenda because of the CO ₂-induced global warming and the requirement of industrial products. Membrane-based technologies have proven to be a promising alternative for CO ₂ separations. To make the gas-separation membrane process more competitive, productive membrane with high gas permeability and high selectivity is crucial. Herein, we developed new cellulose triacetate (CTA) and cellulose diacetate (CDA) blended membranes for CO ₂ separations. The CTA and CDA blends were chosen because they have similar chemical structures, good separation performance, and its economical and green nature. The best position in Robeson’s upper bound curve at 5 bar was obtained with the membrane containing 80 wt.% CTA and 20 wt.% CDA, which shows the CO ₂ permeability of 17.32 barrer and CO ₂/CH ₄ selectivity of 18.55. The membrane exhibits 98% enhancement in CO ₂/CH ₄ selectivity compared to neat membrane with only a slight reduction in CO ₂ permeability. The optimal membrane displays a plasticization pressure of 10.48 bar. The newly developed blended membranes show great potential for CO ₂ separations in the natural gas industry.