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

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 NH 3 -SCR activity were investigated and the catalysts were characterized by FT-IR, XRD, SEM, EDS, XPS, BET, TGA, ICP-AES, H 2 -TPR and NH 3 -TPD. It is indicated that the addition of rare earth Keggin-type tungstophosphorate could increase the NH 3 -SCR activity of the iron oxide catalysts, while the effect of rare earth species on SCR activity over Fe y O x is not obvious. Effects of O 2 concentration, SO 2 and SO 2  + H 2 O on NH 3 -SCR activity over NdPW/Fe y O x(25) and the control experiments were also investigated, the results of which illustrates that O 2 exerts a significant promotion effect on the SCR reaction and the impact of SO 2 (470 ppm) on catalytic activity is almost negligible. NdPW/Fe y O x(25) presents appealing properties of hydrothermal stability and SO 2 -tolerance, and exhibits a great potential in practical applications. [ABSTRACT FROM AUTHOR]