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.