The Preparation and Catalytic Activity in NH3+NO Reaction of Ag/gamma-A12O3 Catalyst

Ag/γ-Al₂O₃ catalyst was prepared by wet impregnation method with different Ag loadings and calcination temperature, which were characterized by Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), scanning electron microscope-energy dispersive X-ray (SEM-EDX) and their catalytic activity in NH₃+NO reaction were investigated on in a quartz tubular fixed-bed microreactor to compare preparation methods on the catalytic activity of De-NO_x. 1.2wt. % catalyst calcined at 550°C shows higher de-NO_x activity at broader temperature window. The highest NO conversion rate of about 75% over a wide range of temperature was obtained at 350°C. As the temperature increases, both the temperature range for NO reduction and the light-off temperature of NH₃ shiftes to lower temperature region. Over 650°C, NO_x conversion efficiency declines. Below 2%, highly dispersed Ag⁺ ions are predominant Ag species, and they are responsible for the selective reduction of NO to N₂. With higher Ag loading, Agn clusters are predominant.