Rare earth salt of 12-tungstophosphoric acid supported on iron oxide as a catalyst for selective catalytic reduction of NOx

Abstract

A series of rare earth Keggin-type tungstophosphorate doped iron oxide catalysts were prepared by physical mixing method. The effects of type and the content of rare earth element over NH3-SCR activity were investigated and the catalysts were characterized by FT-IR, XRD, SEM, EDS, XPS, BET, TGA, ICP-AES, H2-TPR and NH3-TPD. It is indicated that the addition of rare earth Keggin-type tungstophosphorate could increase the NH3-SCR activity of the iron oxide catalysts, while the effect of rare earth species on SCR activity over FeyOx is not obvious. Effects of O2 concentration, SO2 and SO2 + H2O on NH3-SCR activity over NdPW/FeyOx(25) and the control experiments were also investigated, the results of which illustrates that O2 exerts a significant promotion effect on the SCR reaction and the impact of SO2 (470 ppm) on catalytic activity is almost negligible. NdPW/FeyOx(25) presents appealing properties of hydrothermal stability and SO2-tolerance, and exhibits a great potential in practical applications.