Separation of CO2/CH4 Using Polymeric Gas Separation Membrane

Gas separation membranes used for CO₂/CH₄ separation applied in the industrial sector are membrane modules in either a flat sheet or hollow fiber form made of mainly polymeric materials such as polyimide, polysulfone and cellulose acetate. L.M. Robeson (2008) described CO₂/CH₄ permselectivity as upper bound in 2008 based on the data gathered from previous research findings. In this study, the membrane performance of different polymeric materials was examined by comparing the data on CO₂/CH₄ permselectivity obtained through a literature review and the upper bound proposed by Robeson. The results showed that polyimide had CO₂ permeability of 0.096­–4,211.12 and CO₂/CH₄ permselectivity of 10.8–87, which exceeded the upper bound, while polysulfone had CO₂ permeability of 1.4–72 and CO₂/CH₄ permselectivity of 16–44, which did not exceed but were near the upper bound. Other separation membrane materials such as cellulose acetate and polycarbonate were shown to have CO₂ permeability and CO₂/CH₄ permselectivity values that were not yet near the upper bound described by Robeson. On the other hand, the thermally rearranged materials, which are currently under active research, had CO₂ permeability of 5–5,903 and CO₂/CH₄ permselectivity of 3.8–124, which exceeded the upper bound.