O2–CO2 Mixed Gas Production Using a Zr-Doped Cu-Based Oxygen Carrier

Oxyfuel combustion using O 2 –CO 2 mixed gas as the oxidant is a promising technology for effectively capturing high concentration CO 2 . Chemical looping air separation (CLAS) is a novel approach with a low energy footprint for O 2 –CO 2 mixed gas production. In this work, a series of Zr-doped Cu-based oxygen carriers were prepared by the sol–gel combustion method and used to produce the O 2 –CO 2 gas mixture. The effects of doping Zr on phase structure, surface topography, O 2 absorption/desorption, and cyclic reaction of Cu-based oxygen carriers were studied by experiments. The influencing mechanism of Zr doping on O 2 release of Cu-based oxygen carrier was investigated using density functional theory (DFT) calculations. The results indicate that the addition of Zr enlarges the specific surface area and refines the grains. The Zr-doped Cu-based oxygen carriers have high desorption reaction rates. The oxygen release capacity increases with the increasing Zr doping amount. The cyclic operation indicates that the Zr-doped Cu-based oxygen carriers have high cyclic stability. The DFT calculation results show that, compared with the pure CuO, the Zr-doped CuO has lower oxygen vacancy formation energy, lower energy barriers for oxygen desorption and O anion diffusion, and narrower band gap, which indicates that the Zr-doped CuO releases oxygen more easily than the pure CuO and has a lower energy barrier of electron transfer, thus leading to a higher reactivity.