Investigation of Cu–Fe and Mn–Ni oxides as oxygen carriers for chemical-looping combustion

• Cu–Fe and Mn–Ni oxygen carriers have been examined for chemical-looping combustion.
• Investigations on reactivity were performed in a batch fluidized-bed reactor.
• Conversion of methane and syngas (CO2 in H2) has been experimentally assessed.
• Mechanical and chemical properties of the oxygen carriers are presented.
• Several materials showed high reactivity and sufficiently high mechanical strength.

Combined Cu–Fe and Mn–Ni oxygen carriers were investigated as bed materials for chemical-looping combustion. The aim was to identify material combinations which yield oxygen carriers with a high reactivity towards gaseous fuels, such as CO, H2 and CH4, as well as sufficient mechanical durability. For this purpose, 18 different oxygen carriers were spray-dried and calcined at defined temperatures.Gas conversion as well as release of gaseous oxygen was investigated in a batch fluidized bed reactor setup at temperatures between 850 and 1050 °C. For testing the mechanical durability, a jet-cup attrition rig was used. Moreover, properties like specific surface area, oxygen transfer capacity and crystalline phase composition were examined to physically and chemically characterize the oxygen carrier particles.For both the Cu–Fe and Mn–Ni-based materials, oxygen carriers could be produced which showed a high reactivity with gaseous fuels like CO or CH4 while having a sufficiently high mechanical strength. These properties make them interesting candidates for application in chemical-looping combustion.