Recently, the research team of  Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences (CAS) has made progress in the application of molten salt doped sodium orthosilicate (Na₄SiO₄) adsorption materials for high temperature carbon dioxide capture and thermochemical energy storage. The article entitled "Performance improvement of Na₄SiO₄ doped with Li₂CO₃-K₂CO₃ for high-temperature CO₂ capture and thermochemical energy storage" has been published in the journal of “Chemical Engineering Journal”. Associate Prof. Changjian Ling is the first author, and Prof. Zhongfeng Tang is the corresponding author.

Molten salt has the advantages of wide operating temperature range, low working pressure, strong heat transfer and storage and good chemical stability. As an ideal heat transfer and storage working medium, molten salt plays an important role in the fields of nuclear energy, energy storage, solar energy and high temperature catalysis. Under the background of "two-carbon strategy", the research on high temperature carbon dioxide capture and thermochemical heat storage by using the advantages of molten salt has become a hot spot. In this work, molten salt adsorption materials doped with Li₂CO₃-K₂CO₃ (LiKCO₃) eutectic salt were prepared by molten salt doping method, and the dynamic, isothermal, and cyclic CO₂ capture performances and the TCES performances of adsorption materials based on the CO₂/Na₄SiO₄ reaction system were systematically investigated. The results indicated that the maximum CO₂ sorption capacity of molten salt adsorption material reached 20.64 wt% at 725 °C, the maximum conversion efficiency and thermochemical energy storage density reached high levels of 95.7% and 788 kJ/kg, respectively, and the cyclic sorption capacity was about 50% higher than that of un-doped adsorption material. The CO₂ chemisorption mechanisms on the molten salt adsorption materials co-adsorption surfaces were studied via density functional theory (DFT) calculations. The results demonstrated that molten salt doping could enhance CO₂ adsorption energy and C–O_S covalent interaction on the sorbent surface and reduce the energy levels of the system. These changes were beneficial to CO₂ chemisorption and agreed well with the experimental values, which provided a new strategy for the design of high temperature CO₂ capture and thermochemical energy storage materials.

This study has received support from the National Natural Science Foundation of China and the Foundation from Qinghai Science and Technology Department.
Link: https://doi.org/10.1016/j.cej.2023.14692