Promotion of SO2 resistance of Ce–La/TiO2 denitrification catalysts by V doping

Abstract

Conventional cerium-based denitrification catalysts show good catalytic activity at moderate and high temperatures, but their denitrification performance may be decreased due to poisoning by SO₂ in the flue gas. In this paper, V was introduced into Ce–La/TiO₂ catalysts by a ball-milling method, and the effects of the V content on catalyst denitrification performance and SO₂ resistance were investigated. Fourier-transform diffuse reflectance in situ infrared spectroscopy was used to examine the denitrification mechanism and evaluate the catalysts for surface acidity, redox characteristics, and SO₂ adsorption. After introducing V, Brønsted acids played the dominant role in the catalytic reaction by increasing the number of acidic sites on the catalyst surface, adsorbing NH₃ to participate in the reaction, and improving the sulfur resistance by inhibiting SO₂ poisoning. The Ce³⁺ and O ratio on the catalyst surface were also enhanced by V doping, which reduced interactions between SO₂ and the primary metal oxide active ingredients. The modified catalyst inhibited the formation of sulfate species on the catalyst surface and prevented the generation of additional nitrate species on the surface, which protected the main active sites. After V doping, the NH₃-SCR reaction on the catalyst surface followed the Langmuir–Hinshelwood mechanism.