Highly efficient reduction of O₂-containing CO₂ via chemical looping based on perovskite nanocomposites

Purification/separation of CO₂ stream from carbon capture or other carbon source is highly energy consuming process. However, oxidative impurity of O₂ either deactivates catalysts in most carbon reduction systems, and thus reduces CO₂ conversion efficiency. Here we report an effective method for splitting O₂-containing CO₂ into CO, through a chemical looping scheme with Cu (5 at%) doped LaFeO₃ perovskites as efficient oxygen carriers. Up to 2.28 mol/kg CO yield was achieved with high stability in the presence of O₂, five times higher than that with the state-of-the-art oxygen carrier, while pristine LaFeO₃ perovskite only showed efficient capability of reducing pure CO₂. 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 CO₂ and O₂ in the re-oxidation step. We envision that the efficient CO₂ splitter with well-designed oxygen carriers have the potential to facilitate economical combination of impure carbon feedstock and carbon utilization system. © 2020