CO 2 capture by Li 2 CaSiO 4 and enhancement with alkali carbonates

• Published in: Physical chemistry chemical physics : PCCP 2023-08, Vol.25 (33), p.21944-21956
• Main Authors: Wang, Zhen, Sun, Chenteng, Xu, Qian, Zou, Xingli, Cheng, Hongwei, Lu, Xionggang
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d3cp02338a

Alkali and alkali earth oxides show good CO capture performance for carbonation, while their regeneration occurs at high temperatures, leading to a high energy penalty. When alkali oxides and alkali earth oxides combine with SiO to form oxysalts, the regeneration temperatures can be reduced, and the CO adsorption capacity is maintained. In this study, the reaction between CO and Li CaSiO , composed of stoichiometric CaO, Li O, and SiO , was evaluated thermodynamically by DFT. The synthesized Li CaSiO with and without alkali carbonates was used as CO sorbents, and their CO adsorption performances were examined using thermal analyses. The phase and morphology of Li CaSiO before and after CO adsorption were characterized by XRD and SEM. According to the thermodynamic evaluation and the XRD results, Li CaSiO could adsorb CO and form CaCO and Li SiO . The thermal analyses showed that the regeneration of Li CaSiO started from 575 °C, at which it was difficult to realize the CO diffusion through the solid CaCO product layer. The mixed alkali carbonates can improve the kinetics and facilitate the CO adsorption of Li CaSiO . Alkali carbonates were effective in reducing the activation energy of the reaction and CO diffusion at low temperatures and improving the cyclic stability because of the dispersing carbonation products.