[Ten years of major development in chemical science and technology] 041-2023 USTC develops a new method for capturing carbon dioxide at normal temperature and pressure through supramolecular structure transformation

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This post was last edited by Fish in the Desert on 2023-5-14 11:01 On May 4, news came from the University of Science and Technology of China that a research team composed of Professor Liu Bo from the University, Professor Xu Qiang from the Southern University of Science and Technology, and Professor Cafer T. Yavuz from the King Abdullah University of Science and Technology developed a new method for capturing and storing carbon dioxide, which can achieve reversible capture and release of carbon dioxide at normal temperatures and pressures. 　　The research team proposed a new carbon dioxide capture technology based on supramolecular structure transformation, using cheap guanidine sulfate to co-crystallize with carbon dioxide to form a stable crystalline carbon dioxide clathrate (hereinafter referred to as the clathrate). Compared with existing technology, this technology has the characteristics of high selectivity, low energy consumption, stable adsorbent, and non-corrosiveness. It is suitable for storage and transportation. The guanidine sulfate aqueous solution after releasing pure carbon dioxide can also be directly used for a new round of capture. 　　Carbon capture is an important part of Carbon Capture Utilization and Storage Technology (CCUS). * * “The "double carbon" goal is of great significance and is also an important source of "green carbon" in the future. At present, carbon dioxide capture is mainly accomplished through physical or chemical adsorption processes based on pressure and temperature swings. Although physical adsorbents have the advantages of low adsorption heat and easy regeneration, water vapor and carbon dioxide in the flue gas and environment compete for adsorption, which reduces the selectivity, capacity and cycle performance of the adsorbent. Although chemical adsorbents such as ethanolamine and organic guanidine have high selectivity, the regeneration process of the adsorbent requires huge energy consumption. 　　How to reduce energy consumption when capturing and releasing carbon dioxide is of great significance. Based on previous research results, the research team further applied dynamic hydrogen bonding framework structure transformation to carbon dioxide capture. Under normal temperature and pressure conditions, they successfully simulated the dynamic behavior of carbon dioxide hydrate and developed a new method of capturing and storing carbon dioxide. They used carbon dioxide and guanidine sulfate to co-crystallize to form an inclusion complex to achieve a single selective capture of carbon dioxide, and released high-purity carbon dioxide with low energy consumption through the collapse of the inclusion complex structure. The obtained guanidine sulfate can be directly used in the next cycle to achieve a low-energy carbon capture cycle. 　　From a scientific sense, the problems faced by physical adsorption and chemical adsorption to capture carbon dioxide all originate from the strength of its adsorption. Therefore, regulating the interaction between carbon dioxide and adsorption materials is the key to innovating carbon dioxide capture. The researchers found that inclusion complexes can be obtained from guanidine sulfate aqueous solutions at temperatures near room temperature and carbon dioxide pressures of tens of kilopascals. Further structural analysis revealed that the carbon dioxide is enclosed in a framework built through hydrogen bonding and electrostatic interactions between guanidine cations and sulfate groups. The researchers also found that carbon dioxide only has electrostatic interactions with the guanidine ions in the framework, which is also the driving force for the crystallization of inclusion complexes. Moderately strong interactions enable the capture and release of carbon dioxide under mild conditions. 　　In addition, the volume density and mass fraction of carbon dioxide in the clathrate are 0.252 g/cm3 and 17% respectively; a unit volume of the clathrate contains 60 times the volume of carbon dioxide gas under the same temperature and pressure conditions, and the pressure of carbon dioxide reaches 6 MPa under the same temperature and volume, revealing its huge potential in carbon capture, storage and transportation. In the next step, the research team will actively promote the assessment of carbon capture energy consumption and cost at small and medium-scale pilot scale, with a view to realizing the superiority of carbon capture in both energy consumption and economics. (Zhongke)