An Integrated Carbon Dioxide Capture and Methanation Process
Xiaochen Zhang, Mengzhu Li, Xingwu Liu, Ang Li, Yuchen Deng, Peng Mi, Yu Zhang, Charlotte Vogt, Matteo Monai, Junxian Gao, Xuetao Qin, Xu Yao, Qiaolin Yu, Meng Wang, Guofu Wang, Zheng Jiang, Xiaodong Han, Casper Brady, Wei‐Xue Li, Zhou Wu, Jin‐Xun Liu, Bingjun Xu, Bert M. Weckhuysen, Ding Ma
Abstract
Reducing the ever-growing level of CO2 in the atmosphere is critical for the sustainable development of human society in the context of global warming. Integration of the capture and upgrading of CO2 is, therefore, highly desirable since each process step is costly, both energetically and economically. Here, we report a CO2 direct air capture (DAC) and fixation process that produces methane. Low concentrations of CO2 (∼400 ppm) in the air are captured by an aqueous solution of sodium hydroxide to form carbonate. The carbonate is subsequently hydrogenated to methane, which is easily separated from the reaction system, catalyzed by TiO2-supported Ru in the aqueous phase with a selectivity of 99.9% among gas-phase products. The concurrent regenerated hydroxide, in turn, increases the alkalinity of the aqueous solution for further CO2 capture, thereby enabling this one-of-its-kind continuous CO2 capture and methanation process. Engineering simulations demonstrate the energy feasibility of this CO2 DAC and methanation process, highlighting its promise for potential large-scale applications.