Evolution behavior and active oxygen quantification of reaction mechanism on cube Cu2O for CO self-sustained catalytic combustion and chemical-looping combustion.

Catalytic combustion (CC) and chemical looping combustion (CLC) are promising technologies for energy saving and emission reduction of CO 2 in treatment of steelmaking off-gas. This work firstly reports and compares the evolution behavior and quantitative reaction mechanisms of cube Cu 2 O model catalyst for CC and CLC reactions. The Cu 2 O-CC exhibited the higher activity and stability than Cu 2 O-CLC. The typical characterization results suggested that the only surface unstable Cu 2 O was oxidized to CuO, and the excellent synergistic effect of metal-oxide interface (100) between Cu+/Cu2+ and active lattice oxygen species for Cu 2 O-CC reaction. But, for CLC reaction, Cu 2 O structure was collapsed, which caused the agglomeration of CuO x species and gradual decrease of reaction stability. Three different active oxygen species (surface cycle lattice oxygen, bulk lattice oxygen, and adsorbed oxygen) and the detailed reaction pathways were proposed by the in situ IR spectroscopy, isotopic (18O 2) transient exchange experiments and DFT simulation. The intrinsic activity of surface cycle lattice oxygen was higher in terms of TOF (13.5 × 10−3 s−1) and facile formation of C16O18O on the cubic interface of Cu 2 O-CC through adsorbed CO during CC process. The contribution degrees of Mars-van-Krevelen (M-K) and Langmuir–Hinshelwood (L-H) mechanisms for CC and CLC reactions were 76.6% and 23.4% for CC, and 89.7% and 10.3% for CLC on Cu 2 O catalyst, respectively. [Display omitted] • The cube Cu 2 O model catalyst was well prepared by liquid-phase reduction method. • The detailed evolution behavior and structure-activity relationship of cube Cu 2 O was carried out for CC and CLC reactions. • The roles of three different active oxygen species in CC and CLC reactions were clearly distinguished. • The contribution degrees of Mars-van-Krevelen and Langmuir–Hinshelwood mechanisms for CC and CLC reaction were proposed. [ABSTRACT FROM AUTHOR]