Reasons of deactivation of |SCR denitrification catalyst for low nitrogen modification


Release time:

2024-04-25

SCR catalysts may lose their activity, a phenomenon known as catalyst deactivation. However, there are many reasons for catalyst deactivation, mainly divided into physical reasons and chemical reasons.

At present, selective catalytic reduction (SCR) technology is widely used in coal power plants and other industrial processes to reduce nitrogen oxide emissions. Catalysts are the core of SCR systems, and we most often use cellular catalysts, which can efficiently convert nitrogen oxides (NOx) into nitrogen (N₂) and water (H₂O) at a certain temperature and catalysis. Over time, SCR catalysts may lose their activity, a phenomenon known as catalyst deactivation. However, there are many reasons for catalyst deactivation, mainly divided into physical reasons and chemical reasons.

1. Chemical inactivation
Chemical inactivation often involves the change of the surface chemical properties of the catalyst, heavy metals, alkali metals and other harmful substances in the flue gas, as well as other corrosive gases, will cause the activity of the catalyst to react chemically, resulting in the active point of the catalyst being covered or changing its chemical properties, such as: After the alkali metal potassium and sodium are deposited on the surface of the catalyst, they react with the active ingredients in the catalyst to form compounds that are difficult to remove, thereby hindering the normal reaction of NOx and NH3 on the surface of the catalyst, resulting in the deactivation of the catalyst.

2. Physical inactivation
Physical inactivation is often related to the change of the physical structure of the catalyst. In SCR systems, the catalyst is exposed to high temperature or flue gas containing dust for a long time, which will affect the physical change of the catalyst. For example, dust in the flue gas will block the pores of the catalyst, reducing the surface area of the gas through the catalyst, thus reducing the denitrification efficiency. In the high temperature environment, it will also lead to the sintering of catalyst materials, which will lead to changes in the microstructure of the catalyst and affect the activity of the catalyst.

In addition to physical and chemical reasons, improper operation may also lead to catalyst deactivation, and improper temperature control of the SCR system may cause the catalyst to be exposed to excessive temperatures, accelerating the sintering and deactivation of the catalyst.

In order to effectively extend the service life of the catalyst and maintain the efficient operation of the SCR denitration system, it is necessary to carry out regular detection and maintenance of the catalyst. Once the activity of the catalyst is found to decline, regeneration measures should be taken in time to remove the blockage or sediment on the surface of the catalyst through physical or chemical methods. Optimizing the operating conditions to ensure that the SCR denitration system is carried out at a predetermined temperature and the amount of ammonia injected is also an important measure to prevent catalyst deactivation. Effectively slow down the speed of the catalyst, reduce operating costs, and effectively reduce environmental pollution.