Catalytic CO<sub>2</sub> Capture via Ultrasonically Activating Dually Functionalized Carbon Nanotubes
Yangyan Gao, Xin He, Keke Mao, Christopher K. Russell, Sam Toan, Aron Wang, TeYu Chien, Fangqin Cheng, Armistead G. Russell, Xiao Cheng Zeng, Maohong Fan
Abstract
High energy consumption and high cost have been the obstacles for large-scale deployment of all state-of-the-art CO 2 capture technologies. Finding a transformational way to improve mass transfer and reaction kinetics of the CO 2 capture process is timely for reducing carbon footprints. In this work, commercial single-walled carbon nanotubes (CNTs) were activated with nitric acid and urea under ultrasonication and hydrothermal methods, respectively, to prepare N-doped CNTs with the functional group of −COOH, which possesses both basic and acid functionalities. The chemically modified CNTs with a concentration of 300 ppm universally catalyze both CO 2 sorption and desorption of the CO 2 capture process. The increases in the desorption rate achieved with the chemically modified CNTs can reach as high as 503% compared to that of the sorbent without the catalyst. A chemical mechanism underlying the catalytic CO 2 capture is proposed based on the experimental results and further confirmed by density functional theory computations.