Effect of Copper Contents on Sulfur Poisoning of Copper Ion-Exchanged Mordenite for NO Reduction by NH3

Low temperature selective catalytic reduction of NO by NH3 over V2O5 supported on TiO2–SiO2–MoO3

“…Similar promoting effect of MoO 3 on the SO 2 oxidation activity has been observed for the V 2 O 5 /TiO 2 catalyst [8]. The improvement of SO 2 oxidation activity by the incorporation of MoO 3 to TS by the coprecipitation method seems be related to the formation of polymeric vanadate species which are responsible for the oxidation of SO 2 as well as for the oxidation of NH 3 [16].…”

“…It is well known [7,8] that the deactivation of SCR catalysts in the presence of SO 2 at low temperatures is primarily due to the blocking and filling of catalyst pores caused by the formation of ammonium sulfate compounds such as (NH 4 ) 2 SO 4 and NH 4 HSO 4 on the catalyst. Since these ammonium salts are formed by an equilibrium reaction among NH 3 , SO 3 and H 2 O, the higher concentrations of NH 3 and SO 3 and lower temperatures favor the formation of these ammonium salts.…”

“…Therefore, for commercial use, any catalysts employed for the low-temperature SCR process should be highly resistant to poisoning caused by SOx present in flue gases. It is well known [7,8] that SOx poisoning at low temperatures is due to deactivating agents, ammonium salts produced by the reaction of SO 3 generated from the oxidation of SO 2 with ammonia over the SCR catalyst. Therefore, the inhibition of the oxidation of SO 2 to SO 3 plays a critical role in the improvement of resistance to SOx poisoning at lower temperatures.…”

“…NiSO 4 /Al 2 O 3 [9], MnOx/A1 2 O 3 [10], MnOx-FeOx/TiO 2 [11], CuO-NiO/ TiO 2 [12], Cu-exchanged mordenite [13] and V 2 O 5 / activated carbon [14] have been studied for the lowtemperature SCR reaction. These catalysts exhibit comparatively high SCR activities at low temperatures below 200°C, but there are few studies on the lowtemperature SCR reaction in the presence of SOx, where the sulfur tolerance of the catalyst is a key point for industrial use.…”

Honeycomb Reactor Washcoated with Mordenite Type Zeolite Catalysts for the Reduction of NOx by NH3

“…In addition, the sulfur tolerance of the SCR catalyst is one of the most important features for its commercial application. Several researchers have already observed SO 2 deactivation behavior over a copper-containing mordenite-type zeolite catalyst in a packed-bed reactor (Nam et al, 1988;Ham et al, 1992Ham et al, , 1995. It was reported that the deactivation agents on the catalyst surface were ammonium salts, such as (NH 4 ) 2 SO 4 and/ or NH 4 HSO 4 , and the reaction temperature was an important parameter to manage the catalyst deactivation by SO 2 .…”