SCR denitrification technology has the advantages of high denitrification efficiency, over 90%, good selectivity and reliable technology. Catalyst is the core of SCR denitrification technology. At present, the commonly used SCR denitrification catalyst is based on titanium dioxide as carrier, V₂O₅ as active component, WO₃ or MoO₃ as structural promoter. The activity of catalyst directly determines the efficiency of denitrification.

Tungsten oxide is a semiconductor photocatalyst with visible light response. Tungsten oxide particles can absorb most of the visible light occupying the room space. However, because the conduction band is located at the energy level of oxygen-specific oxidation-reduction, oxygen can not be reduced in the electrons stimulated by the conduction band, and the amount of reactive oxygen species is insufficient. Therefore, tungsten oxide can not show high photocatalytic activity in the environment of visible light irradiation but not ultraviolet light irradiation.

At present, the main methods for preparing Ti-W alloys are high temperature vacuum melting, powder metallurgy and mechanical alloying. However, these methods have some disadvantages, such as high production cost, complex process or low purity of products, which reduce the properties of Ti-W alloys and greatly limit their application.

With the rapid development of economy, the demand for tungsten and cobalt in machinery manufacturing, geology, mining, construction, electronics and chemical industries is increasing. As rare metal elements, tungsten and cobalt are also the main raw materials of cemented carbide. Therefore, it is very meaningful to recycle tungsten and cobalt from scrap cemented carbide.