Research on deeply modified Fenton sludge for the selective catalytic reduction of NOx: Promotion mechanism of acidification reorganization

[Display omitted] •The active components of the catalysts were reconfigured to improve dispersion.•The 1.4RFS-10 catalyst showed NOx conversions above 90 % at 210–430 °C.•The low-temperature activity of the RFS catalysts has been significantly improved.•The optimum acidification dosage and alkali dosage were explored in detail.•High dispersed Fe2O3 promotes catalyst reducibility and NH3-SCR activity. Fenton sludge is a kind of hazardous industrial waste produced during the Fenton oxidation process, and it has extremely high application potential in the field of NOx control. However, the irregular distribution of active components limited its low-temperature activity. Herein, we proposed an efficient and high-value acidification recombination method for the preparation of iron-based denitrification catalysts using pretreated Fenton sludge. The active components in the Fenton sludge were reconfigured and evenly covered on the support material to improve the synergistic catalytic performance between the components. Well dispersed Fe2O3 is more favorable to accelerate charge transfer to form Fe3+. And the high proportion of Oβ can effectively compensate for the charge imbalance of the RFS catalysts, which is beneficial to enhance the reducibility and the formation of Lewis acid sites on the catalyst surface. The effects of acidification dosage and recombinant alkali dosage on the catalytic activity and physicochemical properties of the catalysts were investigated. When the acidification dosage is 1.4 time and the recombinant alkali dosage is 10 (pH = 10), the catalyst has the most excellent catalytic activity. It can achieve more than 90 % NOx conversion in the range of 205 − 461 °C, and the overall pattern shows that the catalytic activity further increases with increasing acidification dosage or recombinant alkali dosage. This study verified the stimulation effect of deep modification on the catalytic properties of Fenton sludge, revealed the promotion mechanism of acidification recombination process on denitrification performance, and improved its industrial applicability in the field of flue gas denitrification.