Development of biocatalytic membranes containing ionic liquids for CO2 capture

Human activities have a direct impact on climate change. The concentration of CO2 in the atmosphere has constantly increased since the beginning of the industrial periods, resulting in a stronger greenhouse effect and an increased average temper- ature. In order to mitigate the impacts of global warming, CO2 emissions have to be reduced. One strategy under development is carbon capture and storage of CO2 emissions. The most widely used process is chemical absorption using amine-based solvents such as monoethanolamine (MEA). This technique is not without draw- backs such as its environmental impact, the high energy required to regenerate the solvent and the toxicity of the solvent. The subject of this thesis is the study of an alternative process for post-combustion capture, using a gas-liquid membrane contactor with carbonate solvents and composite bio-catalytic membrane. The carbonate solution absorption is improved by using enzymes enhanced membranes. The present work focuses on analysis and optimization of the absorption perfor- mance of a composite membrane with a PolyVinyliDene Fluoride base, modified by a thin poly(ionic liquid)s (PILs) film on which carbonic anhydrase enzymes are immobilized. The kinetics of a poly([VEIm][Br])-PVDF-PDA-CA composite mem- brane is determined experimentally. Three other PILs membranes are analyzed and compared to the Bromide composite-membrane : poly([VEIm][BF4])-PVDF-PDA- CA, poly([VEIm][NTf2])-PVDF-PDA-CA, poly([VEIm][Acetate])-PVDF-PDA-CA. The performance of the different membranes is analyzed and their absorption performance is improved thanks to a process modification, leading to a superior mass transfer coefficient compared to the previously better Br-based composite membrane. Their thermal stability at 40°C is also studied showing that the tetrafluoroborate-based composite membrane has better activity at higher temper- ature. This master’s thesis has thus showed that different promising biocatalyzed composite membranes form credible options for carbon capture under different circumstances.