Storage and in-situ preparation of H2-mixed CH4 fuel by thermochemical reduction of inorganic carbonates with activated metal hydrides

Abstract

Converting CO2 into methane is realistic and conducive to addressing environmental and energy issues. The mixture of hydrogen and methane shows superior combustion efficiency, while the investigation on the storage and in-situ preparation of hydrogen-mixed methane was neglected. In this work, thermochemical reduction of solid CO2 (inorganic carbonates) with solid hydrogen (activated metal hydrides) was first investigated, and we successfully prepared COx-free H2-mixed CH4 fuel with high yields and selectivity. As respects to the inorganic carbonate-metal hydride systems, the volume energy density can reach as high as 12055.4 kJ/mol, CH4 yield can reach 84.5% with approximate 100% selectivity, and the CH4 content ranging from 8.6% to 88.1% is able to be tuned. It was confirmed that the nature of inorganic carbonates/hydrides, heatingtime and temperature, and the composition of the reaction mixture has a significant influence on methane yield and content. These results demonstrate that heat treatment of nanosized inorganic carbonates and activated metal hydrides is a promising process for in-situ preparation of H2-mixed CH4 fuel and CO2 utilization.