The reporter recently learned from the University of Science and Technology of China that Professor Liu Bo of the school and Professor Xu Qiang of the Southern University of Science and Technology cooperated with an international research team to use carbon dioxide as a guest molecule to simulate the structure of carbon dioxide hydrate for the first time, using cheap guanidine sulfate and carbon dioxide co-crystallization to form The stable clathrate realizes the reversible capture and release of carbon dioxide under ambient temperature and pressure conditions. This is expected to be a promising carbon capture and storage method, and the relevant research results were recently published in Cell Reports Matter Science.
Carbon capture is an important part of carbon capture utilization and storage technology, which is of great significance to the realization of the national "double carbon" goal. At present, carbon dioxide capture is mainly accomplished by physical or chemical adsorption processes based on pressure and temperature swings. The physical adsorbent uses a porous material with a high specific surface area, and carbon dioxide molecules enter the pores of the adsorbent through weak interactions. Although it has the advantages of low heat of adsorption and easy regeneration, the water vapor in the flue gas and the environment competes with carbon dioxide molecules for adsorption, which greatly reduces the selectivity, capacity and cycle performance of the adsorbent. Although chemical adsorbents such as ethanolamine and organic guanidine have high selectivity, their regeneration process requires huge energy consumption. How to reduce the energy consumption of carbon dioxide capture and release is of great significance.
Based on the previous work, the researchers further applied the transformation of the dynamic hydrogen bond framework structure to carbon dioxide capture. The researchers found that crystalline carbon dioxide clathrates can be obtained from an aqueous solution of guanidine sulfate at around room temperature. Further structural analysis revealed that carbon dioxide was encapsulated in a framework built between guanidine cations and sulfate radicals via hydrogen bonding and electrostatic interactions. Surprisingly, there is only an electrostatic interaction between carbon dioxide and guanidine ions in the framework, which is also the driving force for the co-crystallization of carbon dioxide and guanidine sulfate to form clathrate crystalline precipitates. Moderately strong and weak interactions enable both carbon capture and release to proceed under mild conditions. In addition, the clathrate formed by the co-crystallization of carbon dioxide and guanidine sulfate per unit volume contains 60 times the volume of carbon dioxide gas at the same temperature and pressure, and the pressure of carbon dioxide at the same temperature and volume reaches 6 MPa, revealing its role in carbon capture. Great potential for storage and transport. (Reporter Wu Changfeng)
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