Preparation of Iron Catalysts for NOx Removal from the Tail Gas of HNO3 Plants

In this paper new promoted Fe-NaY catalysts were prepared for ammonia selective catalytic reduction of NO. The prepared catalysts were characterized using X-ray diffraction (XRD), N2 adsorption-desorption, Furrier transform infrared (FTIR) and UV–Vis diffuse reflectance spectra (UV–Vis DRS) techniques. The catalytic results revealed that among the investigated promoters (Li, Na, K, Cs, Mg, Ca, Sr, Ba, Sm, La and Ce), the K, Ba and Ca promoted Fe/NaY catalyst showed higher activity. The apparent activation energies for these catalysts are close together and change in a limited range (14.3 kJ/mol for Mg/Fe/NaY to 38 kJ/mol for Ca/Fe/NaY) because main metal ion (Fe) is fixed in all of these catalysts. The results revealed that decreasing in band gap energy in absorption edge and increasing in total acidity in the Ca/Fe/NaY, Ba/Fe/NaY and K/Fe/NaY improve the catalyst performance. In presence cerium and samarium metal ions band gap energy increased. The NO conversion on the Na/Fe/NaY, Ca/Fe/NaY and K/Fe/NaY catalysts is more than 80%.