Abstract
Global warming has been progressing in recent years due to an increase in the concentration of carbon dioxide in the atmosphere. As a solution to this problem, the generation of methane from carbon dioxide by the Sabatier reaction is being considered. Since methane is the main component of city gas, existing infrastructure can be used with simple repairs. In our previous study, it was found that methane can be generated without any external heating upon ball-milling with LaNi5 alloy powder. However, the ball-milling induced phase separation into La-compounds and metallic Ni, suggesting that the LaNi5 actedioned as a catalyst precursor. It was also suggested that the release of atomic hydrogen affected methanation. Herein, we investigated the influence of atomic hydrogen on the mechanochemical methanation using Mg2Ni hydrogen storage alloy in a vibratory ball-milling apparatus. Mg2NiHx and Mg2NiDy were used as starting materials, and the gas atmosphere in the vial was controlled by H2 + CO2 or D2 + CO2 to investigate possible kinetic isotope effect (KIE). The result indicated that the KIE was not observed, suggesting that the hydrogen supply is not the rate determining step in the mechanochemical methanation process.
