Studies on CO2 absorption performance by imidazole-based ionic liquid mixtures

Conventional and functional imidazole-based ionic liquids (abbr. ILs) were mixed based on their advantage and disadvantage on CO2 reduction. Additionally, CO2 absorption effect and regeneration performance of imidazole-based IL mixtures were discussed. It was showed that imidazole-based IL mixtures had good fluidity and smooth of transferring CO2. It had better absorption capacity of CO2 for the mixtures of [bmim][BF4] (or [bmim][Tf2N]) and [NH2e-mim][BF4] than the single IL, and lower absorption capacity for the mixtures of [bmim][CH3CO2] and [NH2e-mim][BF4] than [bmim][CH3CO2]. While the cation of conventional imidazolium ILs became longer and the mixtures could absorb CO2 more obviously, more strong effect was shown on CO2 absorption with the anion [Tf2N] than the anion [BF4] for the conventional imidazolium IL. CO2 absorption capacity of the imidazole-based IL mixtures had maintained 75%–85% of the initial capacity during 10 times absorption/regeneration cycles, while the quality of the regeneration was unchanged.