Alkaline Earth Metal-Induced Hydrogenation of the CaO-Captured CO<sub>2</sub> to Methane at Room Temperature
Guo‐Cui Mao, Xiao‐Tian Kan, Ming-Xiu Xiao, Wenlong Liu, Bao‐Xia Dong, Yun‐Lei Teng
Abstract
CaO is promising to be widely used to capture CO2. The produced CaCO3 can be considered as solid CO2, which is also a plentiful, convenient, and useful carbon resource. Here, for the first time, we report that an alkaline earth metal can selectively induce the hydrogenation of the CaO-captured CO2 (namely, the produced CaCO3) to CH4 under room-temperature ball-milling conditions. The effects of ball-milling conditions and different catalysts on the methanation performance were studied. The results show that the CH4 yield can reach 56.1%, and the CH4 selectivity is 100%. When adding metal Ni, the CH4 yield can be further increased. The experimental and density functional theory calculation results indicate that the in situ formed metal hydride plays a key role in the process of methanation. This work provides a novel and energy-saving method to convert the metal oxide-captured CO2/carbonate to CH4 at room temperature.