CO2-to-CO conversion using a Ni-based oxygen carrier in a bubbling fluidized bed and its integration potential with chemical looping combustion

Abstract

The atmospheric concentration of carbon dioxide (CO2) continues to rise, contributing to the increase in the average global temperature. Technologies for capturing, storing, or converting CO2 into value-added compounds have been investigated as potential solutions to mitigate global warming. This study experimentally investigated the conversion of CO2 to carbon monoxide (CO) using Ni-based oxygen carriers in a bubbling fluidized bed, with the aim of evaluating their applicability to chemical looping combustion (CLC) systems. The performances of both fixed-bed and bubbling fluidized-bed reactors were compared, and the effects of reaction temperature (809-941 degrees C) and the oxygen carrier inventory on CO2 conversion were analyzed. Higher reaction temperatures enhanced CO2 conversion, yielding a maximum conversion of 82 % at 941 degrees C. Notably, a conversion of 78 % was achieved at 900 degrees C using only 0.03 kg of oxygen carriers in a bed height of 0.4 m. Under simulated CLCintegrated conditions, a solid circulation rate of 0.51 kg/h enabled the conversion of 63 % of the CO2 from the CLC fuel reactor into CO. Moreover, reducing the amount of CO2 supplied further enhanced the conversion efficiency. These findings demonstrate the feasibility of integrating CO2 splitting (CDS) into CLC.