Aqueous polyalkylated imidazoles have gained interest as potential CO₂ capture solvents due to their high oxidative stability and low vapor pressures compared to traditional amines. In this work, 21 aqueous solutions of polyalkylatedimidazoles were screened as absorbents for CO₂ capture and four solvent candidates were further characterized by measuring the vapor-liquid equilibria and the heat of absorption of CO₂. The pK_a values of the imidazoles were measured and a positive correlation between the absorption capacity and pK_a of polyalkylated imidazoles was found. Increasing the pK_a of imidazoles to 9 by alkylation improved the CO₂ absorption capacity significantly. Based on the equilibrium experiments, the cyclic capacities of the selected solvents varied from 0.8 to 2 mol CO₂/kg solvent. Furthermore, the heat of absorption of CO₂ of the studied imidazoles was lower compared to primary amines. In general, the tested polyalkylated imidazoles are more feasible for processes with partial pressures of CO₂ above 50 kPa. Trimethylimidazole that forms bicarbonate precipitate might be applicable for post combustion CO₂ capture as a high cyclic capacity is obtained even at CO₂ partial pressures around 10 kPa. The present study gives new important knowledge of the absorption properties of polyalkylated imidazoles.

与传统胺相比，聚烷基化咪唑水溶液由于具有较高的氧化稳定性和较低的蒸气压而成为潜在的CO ₂捕集溶剂，因此引起了人们的关注。在这项工作中，筛选了21种聚烷基化咪唑水溶液作为捕获CO _2的吸收剂，并通过测量气液平衡和吸收CO ₂的热量进一步表征了四种候选溶剂。测量咪唑的p K _a值，发现聚烷基化的咪唑的吸收能力与p K _a正相关。通过烷基化将咪唑的p K _a增加至9可改善CO₂吸收能力明显。根据平衡实验，所选溶剂的循环容量在0.8至2 mol CO ₂ / kg溶剂之间变化。此外，与伯胺相比，所研究的咪唑的CO ₂吸收热更低。通常，对于CO ₂分压高于50 kPa的过程，所测试的聚烷基化咪唑更可行。形成碳酸氢盐沉淀的三甲基咪唑可能适用于燃烧后的CO ₂捕集，因为即使在10 kPa左右的CO ₂分压下也可以获得高循环容量。本研究为聚烷基化的咪唑的吸收性能提供了新的重要知识。