Qingya Liu

Formation and reaction of ammonium sulfate salts on V2O5/AC catalyst during selective catalytic reduction of nitric oxide by ammonia at low temperatures

Abstract The formation rate and reaction rate of ammonium sulfate salts on V 2 O 5 /AC catalyst during selective catalytic reduction (SCR) of NO with NH 3 at low temperatures were studied using elemental analysis, transient response, and TPR methods. In the presence of SO 2 and H 2 O, ammonium sulfate salts deposit on the surface of the V 2 O 5 /AC catalyst, block the pores of the catalyst, and cause catalyst deactivation. Moreover, the deactivation rate increases with increasing H 2 O content in the flue gas. The deposition rate of the ammonium sulfate salts is governed by the rate difference between its formation and reaction with NO. In the presence of H 2 O, the formation rate of the ammonium sulfate salts is higher than that in the absence of H 2 O, and the reaction rate between the formed ammonium sulfate salts and NO is lower than that in the absence of H 2 O. SO 2 does not affect the reaction rate of the ammonium sulfate salts with NO. FT-IR and XRD analysis show that the ammonium sulfate salts formed in the presence of SO 2 and H 2 O on the catalyst surface at 250 °C is mainly (NH 4 ) 3 H(SO 4 ) 2 .