Distinct structure-activity relationship and reaction mechanism over BaCoO3/CeO2 catalysts for NO direct decomposition.

The dependency on morphology is crucial for achieving highly efficient direct decomposition of NO. Herein, a BaCoO 3 /CeO 2 catalyst is synthesized using CeO 2 small particles (p), spheres (s) and rods (r) as supports. The NO conversion to N 2 (NTN2) at 800 °C follows the order BaCoO 3 /CeO 2 -r (78.8 %) > BaCoO 3 /CeO 2 -s (75.9 %) > BaCoO 3 /CeO 2 -p (56.9 %) > BaCoO 3 (8.6 %) at a space velocity 1 g s/cm3. BaCoO 3 /CeO 2 -r exhibts high tolerance to O 2 and stability with conversion decreasing from 78.8 % to 74.6 %, 60.0 % and 50.0 % at 800 °C with 1, 5 and 10 vol% O 2 , respectively. The high redox activity, higher active oxygen mobility and NO adsorption capability ensures its superior performance, while the high surface area (31.29 m2/g) and uniform distribution of active sites on the surface further promote the activity. The mechanism of NO direct decomposition is elucidated by in situ Diffuse reflectance infrared Fourier transform spectroscopy, 18O 2 isotopic transient exchange experiments and density functional theory (DFT) calculation. [Display omitted] • CeO 2 of different microstructures were used as catalyst supports. • The structure-activity relationship was investigated. • The high NO to N 2 conversion reached at 78.8 % at 800 °C over BaCoO 3 /CeO 2 -r. • The intermediate and competitive adsorption of NO and O 2 were discussed. • The reaction pathways with/no O 2 in NO direct decomposition were elaborated. [ABSTRACT FROM AUTHOR]