NO oxidation performance and kinetics analysis of BaMO₃ (M=Mn, Co) perovskite catalysts

Perovskite is an efficient and emerging catalyst for NO oxidation. In this study, BaMnO₃ and BaCoO₃ perovskite catalysts were synthesized by the sol-gel method, and their catalytic oxidation performances of NO were studied. The catalytic performances indicated that BaMnO₃ and BaCoO₃ perovskites had the highest NO oxidation activities with the NO conversions of 78.2% at 350 °C and 84.3% at 310 °C, respectively. The high activities of BaMnO₃ and BaCoO₃ perovskite catalysts were related to the abundant surface adsorption oxygen (O_A = 76.21% and 78.57%, respectively) and the high concentration of Mn⁴⁺ (Mn⁴⁺/Mn = 66.95%) and Co³⁺ (Co³⁺/Co = 63.8%). Moreover, the results of FT-IR and kinetics revealed that NO and O₂ adsorbed on the surface of samples and combined with the B-O band to form bidentate nitrate and bridging nitrate, which eventually was converted into NO₂. The kinetics analysis revealed that the NO oxidation reaction followed the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. In addition, the activation energies were 36.453 kJ/mol for BaMnO₃ and 30.081 kJ/mol for BaCoO₃, implying that BaMnO₃ and BaCoO₃ provide low-cost and efficient catalysts, which can be comparable to Pt noble metal catalysts.