Silicotungstic acid modified Ce-Fe-O-x catalyst for selective catalytic reduction of NOx with NH3: Effect of the amount of HSiW

摘要

The HSiW(x)/Ce-Fe catalysts were used to research the effect of silicotungstic acid contents on the catalytic activity in the selective catalytic reduction of NOx with NH3. Doping different contents of silicotungstic acid affected surface species and redox property as well as the catalytic activity. With the increasing amount of HSiW (x = 5%, 10% and 20%), the redox reaction between Fe3+/Fe2+ and Ce4+/Ce3+ enhanced, which could improve the ratio of Ce3+ and Fe3+. And then, more Ce3+ increased the ratio of chemisorbed oxygen (O-alpha). Besides, the type and strength of acid sites over HSiW((x))/Ce-Fe was affected by the HSiW contents. These factors facilitated the catalytic performance. Thus, the NOx conversion of HSiW(x)/Ce-Fe(x = 20%) was higher than 90%, which maintained in a wide temperature range between 200 and 400 degrees C.