Effect of Manganese Oxide over Cu–Mn-Based Oxygen Carriers for Chemical Looping Combustion

Abstract

This study examined the effects of Mn on Cu-Mn-based mixed metal oxides used as oxygen transfer particles in the chemical looping combustion process. Chemical looping combustion of fuel is induced by the oxygen contained in the metal oxide. The oxidation reaction of the metal oxide particles reduced in the fuel reactor occurs in the air reactor. The metal oxide, which allows oxygen transfer, circulates between the fuel reactor to air reactor and supplies oxygen in the fuel reactor. Both reactors are operated at high temperatures (>850 °C) and the heat of reaction is recovered to produce electricity and heat. Oxygen carriers must have high thermal stability, high oxygen capacity, and rapid transfer rate, and should have a high attrition resistance because they are used in a circulating fluidized bed reactor. Cu exhibits high oxygen transfer rates, but it cannot be used for chemical looping combustion under high temperature conditions because of its low thermal stability. In this study, Mn was mixed to improve the thermal stability of the Cu component and the effect of these was investigated. This study examined copper metal oxide and the stability of Cu according to the temperature that the spinel structure had been synthesized. As a result, the spinel structure was well maintained in the oxidation-reduction cyclic-repeated tests and the migration of Cu was not severe. The spinel structure had high durability. Overall, Mn inhibits the migration of Cu because it forms a spinel structure with Cu.