Highly efficient reduction of O_2-containing CO_2 via chemical looping based on perovskite nanocomposites

摘要

Purification/separation of CO_2 stream from carbon capture or other carbon source is highly energy consuming process.However,oxidative impurity of O_2 either deactivates catalysts in most carbon reduction systems,and thus reduces CO_2 conversion efficiency.Here we report an effective method for splitting O_2-containing CO_2 into CO,through a chemical looping scheme with Cu (5 at) doped LaFeO_3 perovskites as efficient oxygen carriers.Up to 2.28 mol/kg CO yield was achieved with high stability in the presence of O_2,five times higher than that with the state-of-the-art oxygen carrier,while pristine LaFeO_3 perovskite only showed efficient capability of reducing pure CO_2.Furthermore,the syngas productivity was doubled with Cu modification.Through experimental characterizations and ab initio calculations,we uncovered that the exsolution of metallic Cu on the surface of reduced perovskite was able to mitigate the competition between CO_2 and O_2 in the re-oxidation step.We envision that the efficient CO_2 splitter with well-designed oxygen carriers have the potential to facilitate economical combination of impure carbon feedstock and carbon utilization system.