Catalyst is the core technology of SCR system, which directly affects the denitration efficiency.  The catalyst activity will exhibit different properties under different conditions, we display the various factors which affect tungsten trioxide SCR flue gas denitration catalyst, including: tungsten trioxide content, airspeed, oxygen concentration and so on.

1. Content of tungsten trioxide

Experimental results show that the increasing of tungsten trioxide brings the catalyst window broaden, and the catalyst has best activity at the content of 8%, the denitration rate reaches to 95% or more at the temperature range of 250~400° C; when further increasing the content of tungsten oxide, the catalyst activity tends to decline.

2.Airspeed

Experimental results show that with the airspeed increasing, NOx removal rates decreased at different temperature, that is to say increasing the airspeed will reduce the denitration activity.

3. Oxygen concentration

With the increasing content of oxygen, the denitration rate soared, and when it reaches to 3% (the extreme value), the denitration rate turns to balance as the oxygen content continues to increase. This suggests that control the oxygen content in flue gas at 3%, the denitration can get the best results.

4.NOx initial volume fraction

With the increasing of the NOx volume fraction, the reaction rate rises easing, even reaches to saturation. This is because the reaction concentration gradient increases when the gas flowing through the catalyst surface, thus to increase the reaction rate and improve the denitration efficiency.

5.Ratio of ammonia and nitrogen 

The ratio of ammonia and nitrogen refers to ammonia/NOx, it is an important factor in SCR reaction which directly determines the denitration activity. The reducing agent is insufficient when the ratio is too low and causing denitration efficiency decreased; however when it comes too high, it will bring bad influences like ammonia escape, air pollution, catalyst poisoned and equipment corroded by the time denitration efficiency increased.