Selective methanation of carbonate@carbon composite formed by the reaction of carbon dioxide with alkali metals

Summary We systematically studied the thermochemical behaviors of alkali metals under the carbon dioxide (CO 2 ) atmosphere and first investigated the hydromethanation performance of the alkali metal carbonate@carbon product formed in the reaction of CO 2 with alkali metals. The on‐set reaction temperature of alkali metals with CO 2 is at about 466, 584, and 595°C, respectively, following Li < Na < K. The experimental results indicate that CO x ‐free methane can be selectively and efficiently generated by hydrogenation of these carbonate@carbon composites at 450°C without a catalyst. Among these carbonate@carbon composites, the Li 2 CO 3 @carbon composite shows superior methanation performance. The selectivity of methanation is near 100%. The yield and content of methane are able to reach 30.3% and 26.6 mol%, respectively. This work provides an alternative method to produce methane, utilizing CO 2 resources.