Water-lean solvents are solvents for CO₂ capture which contain at least one amine and one organic diluent. Carbamate-forming amines in nonaqueous water-lean solvents typically absorb CO₂ through the formation of carbamate species. Conversely, tertiary amines in nonaqueous amino-organic mixtures cannot form carbamate nor undergo bicarbonate formation. However, protic organic diluents might take part in an alkylcarbonate formation pathway: in this route, the diluent is deprotonated by the amine, and its conjugate base is then able to react directly with CO₂ to form an alkylcarbonate. This is an interesting reaction mechanism, as it offers a possibility for formulating solvents that deviate from the two most common reaction pathways for CO₂ absorption (i.e., carbamate and bicarbonate formation). The present study introduces a simple way for evaluating alkylcarbonate-forming water-lean solvents based on the properties of its single constituents, namely the basicity of the amine and the autoprotolysis constant of the organic diluent. Our theoretical framework shows that higher CO₂ absorption capacities can be obtained for solvents containing amines with high pKa and diluents with low pKs. We assess both the challenges and possibilities for alkylcarbonate-forming solvents and propose a framework for their development and utilization in the industry.

贫水溶剂是用于CO ₂捕获的溶剂，其包含至少一种胺和一种有机稀释剂。在非水贫水溶剂中形成氨基甲酸酯的胺通常通过形成氨基甲酸酯物质吸收CO ₂。相反，非水氨基-有机混合物中的叔胺不能形成氨基甲酸酯，也不能形成碳酸氢盐。然而，质子有机稀释剂可能参与烷基碳酸酯的形成途径：在该途径中，稀释剂被胺去质子化，然后其共轭碱能够直接与 CO ₂反应形成烷基碳酸酯。这是一个有趣的反应机制，因为它为配制偏离 CO ₂的两种最常见反应途径的溶剂提供了可能性吸收（即氨基甲酸盐和碳酸氢盐的形成）。本研究介绍了一种简单的方法来评估形成烷基碳酸酯的贫水溶剂，该方法基于其单一成分的性质，即胺的碱性和有机稀释剂的自质子分解常数。我们的理论框架表明，对于含有高 pKa 胺和低 pK 稀释剂的溶剂，可以获得更高的 CO ₂吸收能力。我们评估了形成烷基碳酸酯的溶剂的挑战和可能性，并为其在行业中的开发和利用提出了一个框架。