Highly Selective Room‐Temperature Catalyst‐Free Reduction of Alkaline Carbonates to Methane by Metal Hydrides

Abstract

The realization of effective CO2 conversion into valuable hydrocarbons is a promising way of addressing the current environmental and energy issues. A convenient, highly selective, and efficient method of CO2 methanation and the synthesis of COx‐free hydrogen/methane fuel mixtures by ball milling‐induced reactions of alkaline carbonates with metal hydrides (MHs) is reported. The natural resources of MgCO3/CaCO3 and MgH2/CaH2 are used as carbon and hydrogen sources, respectively. Mechanochemical investigations of the room‐temperature reactions indicate that some alkaline carbonates can be reduced by MHs under catalyst‐free conditions to selectively afford CH4 as the sole hydrocarbon product in yields of up to 73%. Moreover, the contents of methane in the gaseous products and its yield are shown, which mainly depend on the nature of metal carbonates/hydrides, rate and duration of ball milling, and reaction mixture composition. Thus, this study opens new ways to achieve the CO2 utilization and synthesize of COx‐free hydrogen and methane fuel mixtures.