Heavy metals impregnated TiO2 catalysts for the multi-pollution reduction of coal-fired flue gas

Abstract

Abstract The synergistic conversion of VOCs and NO in SCR region of power plants is still a challenge and its catalytic redox mechanism needs to be further understood. Heavy metal oxide loading can effectively expand the low-temperature VOCs and NO potency of catalysts. Here, a series of single heavy metal oxide (CeOX, CrOX, and MnOX) modified TiO2 catalysts were prepared to study their performance of removing VOCs (benzene and toluene) and NO between 260\xa0°C and 420\xa0°C. The catalytic potency was thoroughly investigated, and their physicochemical properties were assessed by a variety of instruments. Performance evaluation of catalysts found that CrOX/TiO2 achieved over 99% VOCs removal and 78.20% denitration efficiency at 340\xa0°C, which was hopeful to be applied to industrial SCR areas. The excellent performance of CrOX/TiO2 should be attributed to the strong redox capacity and abundant surface active oxygen. Also, the in-situ DRIFTS results verified that the NH3-SCR reaction of CrOX/TiO2 catalyst at 340\xa0°C was governed by the combination of the Eley–Rideal mechanism and the Langmuir–Hinshelwood mechanism. More importantly, it confirmed that alkoxides, benzoates, and anhydrides are the main intermediates, indicating that the reaction pathway may be as follows: benzene → benzoquinone → … → CO2 and H2O, and toluene → benzyl alcohol → benzaldehyde → benzoic acid →…→ CO2 and H2O.