Solid Waste of Fly Ash toward Energy-Efficient CO<sub>2</sub> Capture
Linlin Chen, Shijian Lu, Lei Zhang, Chunjin Zhang, Ling Liu, Guo‐Jun Kang, Hua Tang, Siming Chen
Abstract
Catalytic CO 2 absorption–desorption has attracted broad interest due to its potential for improving CO 2 absorption efficiency and reducing energy consumption in CO 2 separation. However, most utilized catalysts are synthetic and pure, with the development of a natural and hybrid catalyst with acid–base bifunctional catalytic characteristics remaining a significant challenge. In this work, three fly ashes (1-FA, 2-FA, and 3-FA) with different compositions were used as catalysts, and the provided synergistic benefits in the overall MEA-CO 2 absorption–desorption processes were evaluated. The results showed that Brønsted acid sites, Lewis acid sites, and Lewis base sites were available on the fly ash surface, which provided proton and electron donation capability. 1-FA exhibited the best catalytic performance by enhancing the CO 2 cyclic absorption capacity by 6.7–26.1%, improving the CO 2 desorption rate with the highest value of 96.0%, and decreasing the sensible heat by 24–28% compared to MEA as a blank run. Furthermore, 1-FA exhibited comparable catalytic performance to typical HZSM-5. The results of this study demonstrated that fly ash with zero cost and high availability could serve as a good hybrid catalyst candidate for CO 2 absorption and desorption.