Improved chlorobenzene oxidation over Fe-Mn oxide by Ni doping: The effect of oxidative ability and surface acidity

Abstract

FMO was doped with nickel (NFMO) and lanthanum (LFMO) and compared for catalytic oxidation of chlorobenzene (CB), with NFMO showing superior activity (T90 = 192 ℃, 600 ppm CB/dry air, GHSV=20,000 h−1), CO2 selectivity and durability. And great water-resistance with T90 = 195 °C in humid air (H2O = 1.6 wt%), which is critical for real-world applications. The strong interaction between Ni and FMO enhances the contents of both reactive oxygen species (ROS) and surface Mn4+ species, which elevate the low temperature reactivity of NFMO. Both total acid content and Lewis/Brønsted acid ratio were enhanced during the nickel doping process. The stronger and more Lewis acid sites facilitated the dechlorination reaction and C-C band cleavage, further improving the catalytic performance at lower temperature. Oppositely, the addition of lanthanum reduced the total acid content and Lewis/Brønsted acid ratio, resulting in the Cl species accumulation at La-Fe or La-Mn interfaces and deactivation of LFMO.