REDUCTION OF CLC MATERIALS MN AND CU OXIDES FROM FIRST PRINCIPLES CALCULATIONS

摘要

Chemical looping combustion(CLC)is a promising novel method for carbon capture in power plants.CLC is based on the alternating oxidation and reduction reactions on the air and fuel reactors.Oxygen needed for combustion in a fuel reactor is transferred by an oxygen carrier from an air reactor.Carriers are typically made out of metal or metal oxide which are oxidized in air reactors and reduced in fuel reactors.The commercial use of CLC is hindered by many factors e.g.slow reaction kinetics,in particular slow reduction,of oxygen carriers is identified as one of the main obstacles.A possible solution to improve reaction kinetics is to use nanoscale oxygen carriers instead of conventional carriers that have larger particle size .CLC with oxygen uncoupling(CLOU)is a variant of CLC where gas-phase oxygen reacts with fuel.Cu-and Mn-based oxides have been identified as promising materials for CLOU .Cu oxides have also shown potential as nano carriers due to faster reduction and oxidation kinetics compared to the conventional carriers.It has been suggested that improved kinetics is due to easier diffusion in nanoscale owing to reduced bulk-to-surface ratio but the detailed atomic level understanding is missing.