Polymer Materials for Membrane Separation of Gas Mixtures Containing CO2

In recent decades, the need to capture carbon dioxide from industrial gas streams, its storage, and utilization has been justified as a rule by environmental problems. However, the capture of CO₂ from industrial gas mixtures is an independent important issue of chemical technology. The review addresses consideration and analysis of polymer materials for the membrane separation of CO₂-containing mixtures which are of interest for purification of natural gas, biogas, and flue gases and separation of hydrogen from methane and water gas conversion products. Therefore, gas pairs CO₂/CH₄, CO₂/N₂, and CO₂/H₂ are relevant for membrane separation. Promising polymer materials should possess the beneficial combination of CO₂ permeability and selectivity for the gas pair of interest, that is, should be located near the upper bound of the Robeson diagram or be above it. For separation of the first two gas pairs good gas-separation parameters are exhibited by rigid-chain highly permeable glassy polymers of various classes (polymers of intrinsic microporosity, polyimides, polynorbornenes, polybenzoxazoles). For separation of the gas pair CO₂/N₂ the most advantageous properties are shown by polymers bearing functional groups capable of specific interactions with carbon dioxide (aliphatic polyethers and polyimides with their oligomer moieties, polynorbornenes carrying Si‒O–C and Si–O–Si groups, polymers with ionogenic groups). Thermally stable barrier polymers based on polybenzoxazoles show promise for purification of hydrogen from carbon dioxide at high temperatures.