Post-combustion flue gas purification using ionic liquids

• Autor(a) principal: Sousa, Marco André Costa
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/29415
• topic: Absorption; Amino acid; CO2; Ionic liquids; CCS; Membrane contactor

Due to the emissions of greenhouse gases to the atmosphere the phenomenon known as global warming has risen awareness and real concern. The knowledge of the problem has driven many researchers to pursuit work on the development of new methodologies and processes able to mitigate the greenhouse gas effect by the capture and sequestration of greenhouse gases. Among the solvents proposed as innovative and feasible for the gas capture, namely CO2, the ionic liquids have stand out as those with the highest potential due to their exceptional properties. However, being possible to synthesize over one million different ionic liquids, their full characterization stands unrealistic. Aiming at identifying the families of ionic liquids with the highest potential, computational predictive tools, like COSMO-RS, and/or models and correlations have hampered the selection of the best solvents. In this thesis, ionic liquids based on amino-acids are evaluated as solvents with chemisorption for the capture of CO2 at low pressures and moderate partial pressures of the gas. For the characterization of the pVT phase diagram of the selected solvents a constant volume setup, isochoric cell, was design, developed and validated allowing to further evaluate the studied ionic liquids at temperature and pressure ranges of 30 to 80 ºC and up to 5 bar, respectively. Although, ionic liquids stand out as solvents with high potential their application on traditional separation units have been shown unfeasible. Nonetheless, other mechanisms and separation units, like the ionic liquid immobilization in silica or carbon particles or their use in gas-liquid membrane contactors, have been proposed as alternatives. Having as ultimately goal the selection of a solvent or mixture of solvents with high potential for the intended separation and their implementation on a continuous gas-liquid membrane contactor separation unit, the studied solvents were further evaluated for the diffusivity when supported in commercial membranes using the “time-lag” method.