Synthesis of La_1-xSr_xCoO_3-δ and its catalytic oxidation of NO and its reaction path

The oxidation rate of NO to NO₂ is a critical parameter in the removal of NO_x within selective catalytic reduction (SCR) systems. LaCoO_3-δ is a kind of potential catalyst to enhance the oxidation of NO to NO₂, it may offers an economic and stable alternative to noble metal catalysts, particularly at elevated temperatures. This study aimed to enhance the catalytic efficiency of LaCoO_3-δ through strontium (Sr) doping. La_1-xSr_xCoO_3-δ (with varying x values of 0.1, 0.2, 0.3, 0.4) was synthesized using a sol-gel method. La_1-xSr_xCoO_3-δ exhibited superior NO oxidation catalytic activity compared to LaCoO_3-δ, with the most notable enhancement observed at x = 0.3 (84 % conversion). This improvement can be attributed to the substitution of La³⁺ with Sr²⁺, which induces lattice distortion and charge imbalance, thereby creating more oxygen vacancies that enhance the catalytic oxidation capability of La_1-xSr_xCoO_3-δ. However, it's important to note that an excessive amount of Sr can result in the formation of SrCO₃ deposits on the surface of La_1-xSr_xCoO_3-δ, thereby diminishing its catalytic oxidation performance. The catalytic oxidation reaction behavior adhered most closely to the O₂-adsorbed E-R model, the surface defects in La_1-xSr_xCoO_3-δ playing a pivotal role in the catalytic reaction.