Catalytic efficiency of iron oxides in decomposition of H2O2 for simultaneous NOX and SO2 removal: Effect of calcination temperature

• The amorphous iron oxides to hematite mechanism with the calcination temperature rising was investigated.
• The effect of oxygen vacancy on the catalytic efficiency of H2O2 decomposition for NOX removal was studied.
• The promotional mechanism of the oxygen vacancy on the catalytic decomposition of H2O2 for NOX removal was proposed.

Iron oxide catalysts were used for the study of catalytic decomposition of H2O2 into OH radicals for simultaneous oxidation-removal of NOX and SO2. These catalysts were prepared by Fe(NO3)3·9H2O calcined at different temperatures. The objects were to determine the catalytic efficiency toward the oxidation-removal of SO2 and NOX in relation to the calcination temperature. 100% SO2 removal is achieved in all conditions, but NOX removal increases with the calcination temperature rising. SEM and TEM analyses indicated that the pellet-type particles containing hematite were firstly formed on the surface of large aggregates, and then peeled off from the surface layer by layer as the calciantion temperature increased from 100 to 300 °C. This separating process led to the increase of specific surface areas and the transformation from iron composition to hematite, thus benefiting the catalytic removal efficiency. At higher temperatures (>300 °C), the iron nitrate was gradually melted, dramatically reducing the specific surface areas. However, higher calcination temperature benefits the generation of oxygen vacancies, which had a more apparent promotional effect on the catalytic efficiency. And finally, the promotional mechanism of oxygen vacancies is deduced in this paper.

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