Compatible Membrane Materials for 3rd Generation Solvent Membrane Contactors

One of the main limitations of post combustion CO2 capture technology is represented by its energy demand, which decreases the power plant efficiency. Currently, absorption using the state-of-the-art amine-based solvents is the leading technology. An option to reduce the penalty for CO2 capture is to use membrane contactors with third generation solvents, which promise a significant reduction of the energy and installation costs, smaller solvent hold and increases the industrial scalability of the process. Although porous materials are frequently employed for membrane contactors, the use of composite membranes (dense layer coated on a porous support) can help in preventing typical issues, such as wetting and bubbling, optimizing the operative performance of the system. High compatibility between the solvent and the membrane material must be ensured in order to achieve durable CO2 capture performance over time. In the present work, a screening of several materials for the dense layer is carried out in order to identify the membrane/solvent system with the highest compatibility. Fluorine-based polymers exhibit the best balance between gas permeation and durability towards organic solvent, since the presence of the strong carbon-fluorine bonds make them chemically stable in presence of a wide variety of solvents. In addition, acceptable CO2 permeability of this group of materials has been reported. Hence, the properties of different fluoropolymers have been investigated in terms of gas permeation, solvent absorption and induced structural modification (e.g., swelling, chain degradation and contact angle measurement) in the presence of the absorbent. Also the influence of the solvent presence on the gas transport coefficient in porous support has been taken into account.