Abstract Due to the costs involved, the capture of CO2 in post-combustion is not currently seen as economically viable. Aiming at changing the perception of post-combustion CO2 from a costly and non-profitable process to a valuable commodity and fostering the development of the next-generation of technologies, novel solvents and their mixtures have been investigated. In this work, mixtures of non-volatile ionic liquids were screened by COSMO-RS aiming to find mixtures with positive excess volumes that could present an increased CO2 capture by physical sorption. The most promising mixtures identified by COSMO-RS, [C4C1im][DMP] or [C4C1im][NTf2] + carboxylate-based protic ILs were characterized through the measurement of their thermophysical properties, namely density and viscosity. Both properties were measured for pure ILs and their binary mixtures at different temperatures and compositions. The temperature dependence of density of pure ILs was described using the Gardas and Coutinho model while viscosity was accurately described using the Vogel−Tammann−Fulcher equation. The Redlich-Kister equation was used to predict the excess molar volumes and the non-ideality of the mixtures’ viscosity was assessed using the Grunberg and Nissan mixing law. The excess molar volumes for mixtures containing [C4C1im][DMP] show large positive values all over the range of compositions and temperatures, making them good candidates for CO2 capture. To the best of our knowledge, the excess molar volumes obtained in this work were the highest reported so far. COSMO-RS was able to correctly predict the trend of the experimental excess molar volumes for these mixtures. Regarding viscosity, mixtures of [C4C1im][DMP] with the carboxylate-based protic ILs led to the desired viscosity decrease compared to the pure aprotic IL, and large deviations from ideality were observed. The mixing of ILs is thus an efficient way to fine-tune the properties, in this case decreasing the viscosity while increasing the sorption capacity.

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用于 CO2 捕获的非理想离子液体混合物的选择和表征

摘要 由于所涉及的成本，在燃烧后捕获 CO2 目前在经济上不可行。为了将燃烧后 CO2 的观念从昂贵且无利可图的过程转变为有价值的商品，并促进下一代技术的发展，对新型溶剂及其混合物进行了研究。在这项工作中，COSMO-RS 筛选了非挥发性离子液体的混合物，旨在找到具有正过量体积的混合物，这些混合物可以通过物理吸附增加 CO2 捕获。通过 COSMO-RS、[C4C1im][DMP] 或 [C4C1im][NTf2] + 羧酸盐质子离子液体鉴定的最有希望的混合物通过测量它们的热物理性质（即密度和粘度）来表征。在不同温度和组成下测量纯离子液体及其二元混合物的两种性质。使用 Gardas 和 Coutinho 模型描述纯 IL 密度的温度依赖性，而使用 Vogel-Tammann-Fulcher 方程准确描述粘度。Redlich-Kister 方程用于预测过量摩尔体积，并使用 Grunberg 和 Nissan 混合定律评估混合物粘度的非理想性。含有 [C4C1im][DMP] 的混合物的过量摩尔体积在整个组成和温度范围内显示出较大的正值，使其成为 CO2 捕获的良好候选者。据我们所知，在这项工作中获得的过量摩尔体积是迄今为止报道的最高的。COSMO-RS 能够正确预测这些混合物的实验过量摩尔体积的趋势。关于粘度，与纯非质子 IL 相比，[C4C1im][DMP] 与基于羧酸盐的质子 IL 的混合物导致所需的粘度降低，并且观察到与理想情况的较大偏差。因此，混合离子液体是微调性能的有效方法，在这种情况下，可以降低粘度，同时增加吸附能力。