Sustainable Intensification Strategies for the Production of Cyclic Carbonates from CO2

• Autor(a) principal: Paninho, Ana Inês Brandão
• Data de Publicação: 2018
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/43093
• topic: Carbon Dioxide; Carbonates; Green Chemistry; Epoxides; Supercritical; Ionic Liquids; Bio-based epoxides; Catalyst; Aerogel; Continuous Flow; Dióxido de Carbono; Carbonatos; Química Verde; Epóxidos; Supercrítico; Líquidos Iónicos; Epóxidos bio-renováveis; Catalisador; Aerogel; Processo Continuo; Domínio/Área Científica::Engenharia e Tecnologia

[ENG] Global warming, caused mostly by the increasing of greenhouse gas concentrations in the atmosphere, has became one of the most serious environmental concerns. Between the major greenhouse gases, carbon dioxide had the most significant increase. Its high availability, non-flammability, low toxicity and independency from the food supply chain, makes CO2 utilization as a carbon feedstock an important topic from both industrial and academic perspectives. The aim of this work was to develop process intensification strategies for cyclic carbonate production from CO2 and epoxides. Cyclic carbonates are versatile molecules which may become a future platform to introduce CO2 as a renewable carbon feedstock into the chemical sector. Indeed, cyclic carbonates find use in a wide range of applications as electrolytes for lithium batteries, polar aprotic solvents, pharmaceutical intermediates and also as monomers in polymer production. For the first time, zinc (II) complexes of arylhydrazones of β-diketones (AHBD) combined with ionic liquids were used as catalysts for the production of cyclic carbonates. Different cation and anion families were explored in order to understand the effect of specific functional groups on the final reaction yield and selectivity. Results confirmed the importance of the nucleophilicity of the anion, with halogens presenting the better results. Regarding the cation structure, it was possible to conclude that the bulkiness of the structure was the more important factor to have in consideration. Also the effects of pressure, temperature, type of solvent and catalyst concentration were studied and a high-pressure extraction process for an efficient product separation and recycling of the catalytic system was proposed. Finally, in the context of developing a green continuous flow process for CO2 conversion into cyclic carbonates, two different engineering approaches were investigated. On one hand a supported ionic liquid onto an alginate aerogel matrix was prepared, characterized and applied as catalytic system. On the other hand, a continuous flow process using a bulk ionic liquid phase as catalyst was carried out. Both processes allowed for cyclic carbonate production from a bio-based epoxide (limonene oxide) in the production of limonene carbonate, a 100% renewable cyclic carbonate. This thesis provides new opportunities for cyclic carbonate production from CO2 and epoxides in the context of sustainable processing.