Hybrid Solvent ([emim][Ac]+water) To Improve the CO2 Capture Efficiency in a PVDF Hollow Fiber Contactor

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• 作者：Lucía Gómez-Coma ; Aurora Garea ; Ángel Irabien
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2017
• 出版时间：January 3, 2017
• 年：2017
• 卷：5
• 期：1
• 页码：734-743
• 全文大小：562K
• ISSN：2168-0485

文摘

Postcombustion processes based on membrane contactors and ionic liquids have emerged in recent years as an alternative to traditional systems used to capture CO₂. In this work, nondispersive absorption in a polyvinylidene fluoride (PVDF) hollow fiber membrane contactor was used as a CO₂ capture system. The ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([emim][Ac]) was chosen for the study due to its chemical reaction with CO₂. Different amounts of distilled water were added to [emim][Ac] to address the issues associated with the viscosity of the ionic liquid. The presence of water may also facilitate the binding of CO₂. The purpose of this combined sorbent containing water and an ionic liquid comprising a carboxylate moiety such as acetate, which provides reversible chemical interaction with CO₂, was to achieve competitive efficiencies with traditional processes based on power stations and alkanolamines. The best combination of water–IL was found to be, 70% [emim][Ac]–30 vol % water. This mixture achieved a K_overall coefficient 5 times higher than that obtained with only the IL. By using 30 vol % water, a CO₂ capture efficiency of 72.5% and an overall mass transfer coefficient (K_overall) of 9.34 × 10^–5 m s^–1 were accomplished. The values of K_overall achieved in the present work lead to the conclusion that the hybrid solvent is clearly competitive with traditional alkanolamine solvents. The simulation results of sensitivity analysis showed that only two hollow fiber membrane contactors (total length 0.6 m) or a K_overall of 1.70 × 10^–4 m s^–1 were required to reach an efficiency of 90%. The addition of water to the ionic liquid allows the hybrid solvent to be used in an intensified process.