Catalytic performance of HZSM-5 modified by Mn/Fe-Mn in the NH3-SCR
Mn/Fe-Mn改性HZSM-5在NH3-SCR中的催化性能

A series of catalysts of manganese and iron-manganese supported on HZSM-5 seolites with different amounts of manganese and different molar ratios of iron/manganese were prepared hy ion-exchange. The activities of these catalysts for selective catalytic reduction ( SCR ) of NO by NH3 were tested, with a gas hourly space velocity (GHSV) of 12000 h~(-1). A combination of techniques such as SEM, BET sudace area and X-ray diffraction (XRD) were used to characterize the catalysts. The experimental results showed that the active components of the modified catalysts were highly scattered. The catalytic activities of these catalysts were better than that of HZSM-5, and the Fe-Mn/HZSM-5 catalyst showed the best catalytic activity. Furthermore, the addition of a certain amount Fe increased the catalytic activity and stability of the catalyst. The activity of (0.25) Fe-Mn/HZSM- 5( iron/manganeso molar ratio of 0.25 ) reached 98% at 300℃ , and remained above 90% when the temperature was 300-500℃. The effect of calcination temperature on the activity of (0.25) Fe-Mn/HZSM-5 in the SCR was also investigated. The activity of the catalyst was greatly influenced by calcination temperature and 550℃ was the best calcination temperature.