Oxygen transfer capacity of the copper component introduced into the defected-MgMnAlO4 spinel structure in CH4-CO2/air redox cycles

Oxygen carrier particles were fabricated by using defected-MgMnAlO 4 as a support particle with crystal defects, and by the Cu 2+ ions with a higher reduction potential substituted with Mg 2+ ions, in order to use methane-chemical looping combustion (CH 4 -CLC) reaction. The oxygen transfer capacities of the particles were compared when conducting redox reactions under H 2 /air or CH 4 -CO 2 /air systems. As a result, the oxygen transfer capacity increased as the amount of Cu ions added increased. In particular, in the CH 4 -CO 2 /air system, Cu 0.75 Mg 0.25 MnAlO 4 particle showed an excellent oxygen transfer capacity of 7.62%. The XPS result confirms that the Cu 2+ (also partially Mn 3+ ions) in the Cu 0.75 Mg 0.25 MnAlO 4 particle oxidize CH 4 , and then they are restored to their original state by receiving oxygen from the Al 3+ and Mg 2+ ions in the support. The oxygen vacancies in the lattice due to the Cu 2+ could easily induce oxygen delivery, and the reversible oxygen loss recovery by re-oxidation in the air reactor could be achieved. This is the most important factor in increasing oxygen transfer capacity. Ultimately, in this study, oxygen defects in the crystal lattices induced during the reaction seem to have a positive effect on the CH 4 combustion reaction.