Alkaline Earth Metal-Induced Hydrogenation of the CaO-Captured CO2 to Methane at Room Temperature

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 CaOcaptured CO2 (namely, the produced CaCO3) to CH4 under roomtemperature 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.

Automated summary

It has been discovered that alkaline earth metals can catalyze the hydrogenation of CO2 captured by CaO to produce CH4 under room temperature conditions. The addition of different catalysts can increase the yield of CH4, with metal hydrides playing a key role in the methanation process. This work provides a novel method to convert metal oxide-captured CO2 to CH4 at room temperature.