Publicação
Development of new materials for CO2 capture: Evaluation of material's morphology
| Resumo: | Carbon dioxide (CO2) is known as one of the major greenhouse gases responsible for the ongoing global warming, causing extreme weather patterns and natural calamities that affect today's society. During the last century, the concentration of CO2 in the atmosphere has increased drastically, due to the growing fossil fuel utilization and industrial activities. There-fore, mitigating CO2 emissions and the implications they bring to the ecosystems has become an emergency. Over the last few years, carbon capture and utilization (CCU) technologies have been the focus of attention, as they represent a potential solution not just to reduce the CO2 emis-sions by capturing it directly from the industrial facilities, but also to convert the captured CO2 into other value-added products and useful substances (such as cyclic carbonates) to face the ever-growing energy supply-demand. In the field of CCU, ionic liquids (ILs), materials that present unique properties that can be adjusted by changing the combination of cation/anion pairs, have been reported to exhibit promising results. Furthermore, the development of IL-derived materials through the intro-duction of functional groups (such as amines) or the integration with solid sorbents (like pol-ymers) can address some drawbacks inherent to ILs, namely their limited CO2 uptake capacity and production costs, resulting in materials with novel properties and optimized performance for carbon capture and conversion. Based on this, the main goal of this work was to develop chitosan@IL-derived compo-sites to use in CCU applications, as chitosan is an abundant natural polymer, with ease of processability and CO2-philic groups in its structure. Hence, with the assistance of polyelec-trolyte complexation and freeze-drying methodologies, porous cryogel beads based on chi-tosan@IL-derived composites have been produced. Several experimental parameters have been modified to assess their effect on the beads' morphology, which were characterized by techniques such as BET, FTIR, NMR, and SEM. Furthermore, the CO2 sorption capacity of the beads, as well their catalytic activity in the cycloaddition reaction of CO2 to styrene oxide to produce styrene carbonate were evaluated through FTIR and 1H NMR, respectively. The re-sults show that the chitosan@IL-derivatives are promising materials for CO2 capture under environmental conditions (1 bar, 20ºC). Additionally, when used as a catalyst, it was possible to achieve a conversion of 72% and a selectivity >99% for the styrene carbonate in just 4h at a CO2 pressure of 5 bar, temperature of 80ºC, and in the presence of TBA.Br as co-catalyst. |
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| Autores principais: | Santos, Duarte Nuno Botelho dos |
| Assunto: | Ionic Liquids IL-derivatives Chitosan CO2 Capture Catalysis |
| Ano: | 2021 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | Carbon dioxide (CO2) is known as one of the major greenhouse gases responsible for the ongoing global warming, causing extreme weather patterns and natural calamities that affect today's society. During the last century, the concentration of CO2 in the atmosphere has increased drastically, due to the growing fossil fuel utilization and industrial activities. There-fore, mitigating CO2 emissions and the implications they bring to the ecosystems has become an emergency. Over the last few years, carbon capture and utilization (CCU) technologies have been the focus of attention, as they represent a potential solution not just to reduce the CO2 emis-sions by capturing it directly from the industrial facilities, but also to convert the captured CO2 into other value-added products and useful substances (such as cyclic carbonates) to face the ever-growing energy supply-demand. In the field of CCU, ionic liquids (ILs), materials that present unique properties that can be adjusted by changing the combination of cation/anion pairs, have been reported to exhibit promising results. Furthermore, the development of IL-derived materials through the intro-duction of functional groups (such as amines) or the integration with solid sorbents (like pol-ymers) can address some drawbacks inherent to ILs, namely their limited CO2 uptake capacity and production costs, resulting in materials with novel properties and optimized performance for carbon capture and conversion. Based on this, the main goal of this work was to develop chitosan@IL-derived compo-sites to use in CCU applications, as chitosan is an abundant natural polymer, with ease of processability and CO2-philic groups in its structure. Hence, with the assistance of polyelec-trolyte complexation and freeze-drying methodologies, porous cryogel beads based on chi-tosan@IL-derived composites have been produced. Several experimental parameters have been modified to assess their effect on the beads' morphology, which were characterized by techniques such as BET, FTIR, NMR, and SEM. Furthermore, the CO2 sorption capacity of the beads, as well their catalytic activity in the cycloaddition reaction of CO2 to styrene oxide to produce styrene carbonate were evaluated through FTIR and 1H NMR, respectively. The re-sults show that the chitosan@IL-derivatives are promising materials for CO2 capture under environmental conditions (1 bar, 20ºC). Additionally, when used as a catalyst, it was possible to achieve a conversion of 72% and a selectivity >99% for the styrene carbonate in just 4h at a CO2 pressure of 5 bar, temperature of 80ºC, and in the presence of TBA.Br as co-catalyst. |
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