The redox combustion of carbon monoxide for recovering pure carbon dioxide by using molten [formula omitted] mixtures

Abstract

Large-scale combustion systems, such as thermal power plants, emit large amounts of carbon dioxide, which can increase global warming. A molten salt redox combustion system was proposed to recover pure carbon dioxide exhausted from the combustion of fossil fuels. This system is composed of two successive processes by using reactions occurring in a molten salt. The molten salt is the mixture of the molten alkali metal sulfates and carbonates. The sulfate ions oxidize the fuels in first processes, being changed to reductive species such as sulfide ions. In this process, carbon dioxide and water are exclusively exhausted. The reductive species of sulfur compounds are oxidized to regenerate the sulfate ions by air in the second process. In this study, these above two processes were tried by using molten [ ( Na + ) 0.5 , ( K + ) 0.5 ] 2 [ ( CO 3 2 - ) 0.9 , ( SO 4 2 - ) 0.1 ] alternatively. The oxidation of carbon monoxide as fuel by sulfate ions and the regeneration of sulfate ions by air were investigated in the temperature range of 700–950 °C, respectively. These reactions were exothermic. The rate of the regeneration of the sulfate ions was extremely high. During the oxidation of carbon monoxide, the reaction was first order in carbon monoxide with an activation energy of 101 kJ mol −1. The optimum condition to recover pure carbon dioxide on practical operation was discussed.