Alternative alkali resistant deNOx catalysts

Alternative alkali resistant deNO_x catalysts were prepared using three different supports ZrO₂, TiO₂ and Mordenite zeolite. The majority of the catalysts were prepared by incipient wetness impregnation of a commercial support, with vanadium, copper or iron precursor, one catalyst was prepared by onepot sol–gel method. All catalysts were characterized by BET, XRPD and NH₃-TPD. Initial SCR activities of 8 out of 9 catalysts showed higher NO conversion at least at one temperature in the temperature range 300–500 ◦C compared to the conventional V₂O₅-WO₃/TiO₂ catalyst. After potassium poisoning (100–130 µmol of K/g of catalyst) the relative drop in SCR activity and acidity was lower for all the alternative catalysts compared to the industrial V₂O₅-WO₃/TiO₂ catalyst. Furthermore, Cu/MOR and Nano-V₂O₅/Sul-TiO₂ catalysts showed 8–16 times higher SCR activities than the conventional even after high potassium doping (250 and 280 µmol of K/g, respectively). The increased poisoning resistance was due to high substrate acidity (sulphated, heteropoly acid promoted and zeolite supports), substituting the active species of the catalyst (other than vanadium species, i.e. Cu, Fe) and new catalyst synthesis methods (Nano-V₂O₅/Sul-TiO₂ catalyst prepared by sol–gel method).