Reversible CO2 capture and release under ambient conditions is crucial for energy-efficient carbon capture and storage. Here, we report the pressure swing crystallization of CO2 in a single-crystalline guanidinium sulfate-based clathrate salt under practical conditions of 52 kPa and 298 K, with a high CO2 density (0.252 g cm−3) and capacity (17 wt %). The captured CO2 is released as a pure stream through moderate means of pressure or temperature stimulation, all while the desorbed Gua2SO4 is ready for another cycle. The clathrate is selective exclusively to CO2 even in the presence of common flue gas components, such as water vapor and N2, owing to the specific electrostatic interaction between the CO2 and guanidinium cations. The mechanism unraveled through single-crystal studies is distinctively different from physisorption or chemisorption, opening up a promising venue for future carbon capture and storage technologies through rapid CO2 solidification using an abundant salt.
Bibliographical noteKAUST Repository Item: Exported on 2023-05-03
Acknowledgements: We acknowledge support from the Chinese Academy of Sciences, the National Key Research and Development Program of China (2021YFA1500402), the National Natural Science Foundation of China (NSFC; 21571167, 51502282, and 22075266), and the Fundamental Research Funds for the Central Universities (WK2060190053 and WK2060190100).