A study of the gasification of carbon black with molten salt of Li2CO3 and K2CO3 for application in the external anode media of a direct carbon fuel cell

•The carbon–carbonate mixture is considered as external anode media of DCFCs.•A gasification reaction in carbon–carbonate mixture was investigated experimentally.•Based on the experiments, a simplified reaction model of was suggested.•The model covers thermal, carbonate-catalysed, metal-catalysed gasifications.

The characteristics of gasification reactions for carbon–carbonate mixtures were experimentally investigated at high temperatures up to 900 °C, considering the application of the mixtures to the external anode media of a direct carbon fuel cell. A thermo-gravimetric analysis (TGA) was conducted in either a nitrogen or carbon dioxide ambient environment for Li2CO3, K2CO3 and a mixture of these two substances with carbon black. Changes in the exit gas composition were also monitored during the heating process. It was shown that gasification in the mixture media occurs much more rapidly than carbonate decomposition at elevated temperatures, even for low concentrations of CO2. It was also shown that the loading of carbonates to carbon significantly affects the global gasification reaction; it increased the reaction rate by an order of magnitude and decreased its activation energy. Based on the experimental observations, a simplified reaction model of gasification was suggested for the anode media of a DCFC, regarding carbonate-catalysed and metal-catalysed pathways of Boudouard reactions.