Thermochemical Reduction of Carbon Dioxide with Alkali Metal Hydrides, Producing Methane and Hydrogen Fuels at Moderate Temperatures

Abstract

The use of CO2 for the production of fuels has attracted much attention because CO2 can be considered a cheap, nontoxic, and abundant C1 feedstock. In this study, we demonstrated for the first time that CO2 can be effectively reduced by alkali metal hydrides (LiH or NaH) to produce CH4 and H2 fuels concurrently by virtue of heat treatment at moderate temperatures. The yield and mole percent of methane in the gas products for both reaction systems depended upon the reaction temperature and time, and optimal performance was obtained at approximately 450 °C within 48 h. The analysis of the mechanism indicated that amorphous carbon, as an intermediate, plays an important role in the process of CO2-to-CH4 conversion. Alkali metal hydride–CO2 systems are promising reaction systems for the storage and in situ preparation of H2–CH4 mixture fuels.