Abstract

The influence of sulfate on the selective catalytic reduction of NO_x on the Ag/Al_2O_3 catalyst was studied when CH_4 was used as a reducing agent. Various preparation methods influenced differently on the deNO_x activity. Among the methods, cogelation precipitation gave best activity. When sulfates were formed on the surfaces of samples prepared by impregnated and deposition precipitation, deNO_x activity was enhanced as long as suitable forming condition is satisfied. The major sulfate formed in Ag/Al_2O_3 catalyst was the aluminum sulfate and it seems that this sulfate acted as a promoter. When Mg was added to the Ag/Al_2O_3 catalyst it promoted deNO_x activity at high temperature. Intentionally added sulfate also enhanced deNO_x activity, when their amount was confined less than 3 wt%.

• Keywords: Ag/Al_2O_3;Sulfur poisoning;DeNOx;Selective catalytic reduction;Mg sulfate;