Mechanism investigation of three-dimensional porous A-site substituted La1-xCoxFeO3 catalysts for simultaneous oxidation of NO and toluene with H2O

To provide insight into optimizing flue gas treatment, the reaction mechanism for simultaneous oxidation of NO and toluene with H2O using a A-site substituted La1-xCoxFeO3 (x = 0-0.4) catalysts with three-dimensional porous structure was investigated. The results demonstrated that the partial substitution of La in porous LaFeO3 by Co can induce the structural distortion, promote the specific surface area, enhance more active site exposure and produce abundant reactive oxygen species, including lattice oxygen with higher mobility, more surface adsorbed oxygen as well as oxygen vacancies, which improved the catalytic activities remarkably. Besides, NO and toluene have mutual promoted effects in the reaction system. The inhibition effect of H2O on simultaneous oxidation of NO and toluene was confirmed in that H2O consumes the chemisorbed active oxygen atoms. Without H2O, absorbed NO reacts with chemisorbed oxygen to form NO2, and absorbed toluene is oxidized by lattice oxygen to generate intermediate species which finally completely oxidized into CO2 and H2O. With H2O, H2O react with chemisorbed oxygen to produce -OH species that occupied active sites for toluene adsorption. NO interacts with -OH species to form stable nitrate species, which offsets the inhibitive effect of H2O on NO oxidation due to the consumption of chemisorbed oxygen.

Automated summary

The study demonstrated that partial substitution of La with Co in LaFeO3 can induce structural distortion, promote specific surface area, enhance active site exposure, and produce more reactive oxygen species, leading to significantly improved catalytic activities. Additionally, NO and toluene have mutual promotion effects in the reaction system, while the presence of H2O inhibits the oxidation of NO and toluene by consuming active oxygen atoms.