The separation and removal of from its mixtures with is gaining increasing interest due to the novel processes in which these two gases are mixed, such as the non-thermal plasma activated reaction of splitting, a promising utilisation route that could be performed using renewable energy. The aim of this review is to propose a novel database suitable for membrane scientists to evaluate the feasibility of membrane-based separation processes involving such gas mixture, not included in the original Robeson’s works on the upper bound, nor in later developments. For this reason, we reviewed the data on the permeation, diffusion and sorption of these two gases in different classes of polymers, from polyolefins to polyimides and green polymers, spanning over a wide range of permeability values. Furthermore, we propose an upper bound for this separation, and provide a theoretical explanation for it. The separation mechanism is solubility-driven, and all polymeric membranes inspected in the literature show a -selective behaviour, despite a very limited, or unfavourable, diffusion selectivity for , which is consistent with empirical correlations. Consequently, the observed selectivity values are determined by the solubility-selectivity and are comprised mainly in the range 7–20, in agreement with known empirical correlations between the solubility and the critical temperature of the penetrants. Temperature has a detrimental effect on selectivity, as the activation energy for permeation of is always lower than that of . In general, while the permeability can vary over several orders of magnitude depending on the polymer nature, selectivity mostly ranges between 7 and 20, which makes the trade-off mechanism between permeability and selectivity rather weak in the case of this mixture. Such an effect provides a wider variety of design choices, and makes this separation attractive for polymeric membranes, if carried out at low temperatures and with CO-philic materials. A preliminary calculation of the separation obtainable with single-stage membrane unit for a binary mixture is carried out for some representative polymers.

中文翻译：

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探索用于 CO2 捕获和利用过程的 CO2/CO 混合物的膜分离：挑战和机遇

由于将这两种气体混合的新颖工艺，例如非热等离子体激活的分裂反应，从其混合物中分离和去除越来越受到关注，这是一种可以使用可再生能源进行的有前途的利用途径。本次综述的目的是提出一个适合膜科学家的新型数据库，以评估涉及此类气体混合物的基于膜的分离过程的可行性，该数据库未包含在原始 Robeson 的上限工作中，也不包含在后来的开发中。因此，我们回顾了这两种气体在不同类别聚合物（从聚烯烃到聚酰亚胺和绿色聚合物）中的渗透、扩散和吸附数据，涵盖了广泛的渗透率值。此外，我们提出了这种分离的上限，并为其提供了理论解释。分离机制是溶解度驱动的，并且文献中检查的所有聚合物膜都显示出选择性行为，尽管扩散选择性非常有限或不利，这与经验相关性一致。因此，观察到的选择性值由溶解度选择性决定，主要在 7-20 范围内，与渗透剂溶解度和临界温度之间已知的经验相关性一致。温度对选择性有不利影响，因为渗透的活化能始终低于 的渗透活化能。一般来说，虽然渗透率可以根据聚合物性质变化几个数量级，但选择性大多在 7 到 20 之间，这使得在这种混合物的情况下渗透率和选择性之间的权衡机制相当弱。这种效应提供了更广泛的设计选择，并且如果在低温下且使用亲CO材料进行的话，则使得这种分离对于聚合物膜具有吸引力。对于一些代表性聚合物，对二元混合物的单级膜单元可获得的分离进行了初步计算。