Dynamic oxygen migration and reaction over ceria-supported nickel oxides in chemical looping partial oxidation of methane

Abstract

The oxygen species over oxygen carriers determine the reaction performance in chemical looping partial oxidation of methane (CLPOM). This paper describes the dynamic migration and reaction of oxygen species over ceria-supported NiO oxygen carrier for CLPOM. At initial reaction stage, Ni-O species could be consumed rapidly and cause the full oxidation of methane to CO2. Afterwards, the active Ni-O-Ce species dominates the methane partial oxidation to promote the syngas yield. It is found that CO formation rate is linearly related with the content of oxygen species over Ni-O-Ce. Furthermore, the lattice oxygen from CeO2 would migrate through the bulk to complement the consumed Ni-O-Ce oxygen species. Eventually, 5NiO/(40CeO2-Al2O3) exhibit nearly three times as high as methane reaction rate of CeO2/Al2O3 and two times as high as CO formation rate of 5NiO/Al2O3. This work provides the comprehensive understanding of transport and reaction mechanism of oxygen species for chemical looping processes.