Core-shell Na2WO4/CuMn2O4 oxygen carrier with high oxygen capacity for chemical looping oxidative dehydrogenation of ethane

Abstract

Chemical looping oxidative dehydrogenation (CL-ODH) of ethane utilizes lattice oxygen of oxygen carrier, to substitute molecular oxygen, which makes high oxygen capacity as significant as ethane conversion and ethylene selectivity. Promoter were usually used to increased ethylene selectivity of bare oxygen carriers, but the overall oxygen capacity is limited to 3 wt%. In the current work, a core-shell oxygen carrier with Na2WO4 as the shell material and spinel-type CuMn2O4 as oxygen source was prepared. The core-shell structure were characterized by SEM, HTEM and XPS. Deep reduction with thirty consecutive ethane pulses was exhibited in a fixed bed. At 720 °C, up to 58.8% ethane conversion, 86.4% ethylene selectivity, and effective oxygen capacity up to 4.8 wt% were achieved with H2 conversion > 90%. Furthermore, in the light of effective oxygen capacity, the phase transformation from CuMn2O4 to Cu, MnO, Mn3O4 and CuMnO2 is determined as the desired phase change for this CL-ODH process. The connection between the dynamic phase change and the enlarged oxygen capacity will also shed light in future oxygen carrier design for chemical looping processes for chemical productions.