Development of a magnetic Cu-based oxygen carrier for the chemical looping with oxygen uncoupling (CLOU) process

Chemical looping with oxygen uncoupling (CLOU) is an efficient process for solid fuel combustion with CO2 capture. This process requires a material that is capable of releasing gaseous O2 within a high temperature window. Screening was performed of reactive CuO-based oxygen carriers prepared for the CLOU process with magnetic properties for easy separation from solid fuel ashes. The effects of the CuO fraction, method of preparation (with prior preparation of the magnetic Fe-Mn support or by direct mixing of Cu, Fe and Mn oxides) and calcination conditions on oxygen carrier performance were studied. Three oxygen carriers were chosen owing to their good Cu activity, reactivity and magnetism, and were prepared by fluidized-bed granulation for evaluation in a batch fluidized bed reactor. Two of these, both with a 30% CuO content, showed similar performance throughout the process. One was prepared by physically mixing components with a Mn/Fe ratio of 1:1, and the other was prepared using a previously calcined Fe-Mn support, mixed with CuO. Both oxygen carriers showed high reactivity for gaseous oxygen release, sustained reactivity and magnetism with redox cycles, in addition to low attrition rates and no agglomeration problems.