New insights on the effects of SO2 on NO oxidation from flue gas with H2O2 vapor over Fe2O3/SiO2

The positive effects of SO2 on NO oxidation with H2O2 vapor over a Fe2O3/SiO2 catalyst were investigated. In well-designed experiments, the pretreatment of S-contained gaseous species and NO oxidation were carried out. The results indicated that the sulfate species from the oxidation of SO2 could significantly promote NO oxidation. In the radical scavenger and ESR tests, the H2O2 decomposition over SO2-pretreated Fe2O3/SiO2 produced center dot OH and center dot SO4- . The center dot OH was dominant for NO oxidation. The XPS tests verified the Fe(III) reduction and the surface SO42- species formation on Fe2O3/SiO2. According to the kinetic studies, the NO adsorbed Eley-Rideal model gave the best fit, indicating that the adsorbed NO over SO2-pretreated Fe2O3/SiO2 was oxidized by H2O2. The systematic research revealed that the generation of center dot OH from H2O2 decomposition over adsorbed H2SO4 was faster than that over Fe2O3/SiO2.