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
Bibliographical noteThis work was supported by the National Natural Science Foundation of China (Nos. 51774159 and 21706108), the Yunnan applied basic research projects (No. 2018FD032), and the Qinglan Project of Kunming University of Science and Technology. The work of X.B.L. and X.C. was supported by the Center for Advanced Materials for Energy and Environment. X.B.L. acknowledges support from the China Scholarship Council (CSC) graduate scholarship.
- Chemical looping
- CO2 reduction
- Oxygen impurity
- Perovskite nanocomposites