Low-temperature deNO_x performance and mechanism: a novel FeVO₄/CeO₂ catalyst for iron ore sintering flue gas

Abstract

Developing deNO_x catalysts with lower activity temperatures range significantly reduces NH₃ selective catalytic reduction (SCR) operating costs for low-temperature industrial flue gases. Herein, a novel FeVO₄/CeO₂ catalyst with great low-temperature NH₃-SCR and nitrogen selectivity was synthesized using a dipping method. Characterization techniques such as X-ray diffraction, Raman spectroscopy, specific surface and porosity analysis, H₂ temperature-programmed reduction, NH₃ temperature-programmed desorption, X-ray photoelectron spectroscopy, and the in situ diffused reflectance infrared Fourier transform spectroscopy were used to investigate the catalytic mechanism. An appropriate addition for FeVO₄ in the catalyst was 5 wt.% from the results, and the active substance content reached the maximum dispersal capacity of the carrier. The NO_x conversion exceeded 90%, and the nitrogen selectivity was more than 98% over this catalyst at 200–350 °C. The activity was kept at 88% after 7.5 h of reaction at 200 °C for 7.5 h in 35 mg m⁻³ SO₂ gas. The remarkable deNO_x activity, nitrogen selectivity, and sulphur resistance performances are attributed to the low redox temperature, the abundance of medium-strong acid and strong acid sites, the sufficient adsorbed oxygen, and the superior Fe²⁺ content on the surface. The Langmuir–Hinshelwood mechanism was observed on the FeVO₄/CeO₂ catalyst in the NH₃ selective catalytic reduction of NO_x.