The initial catalysts were metal catalysts such as Pt-Rh and Pt, and monolithic ceramics such as alumina were used as carriers, which had the characteristics of high activity and low reaction temperature, but the high price limited its application in power plants.
Therefore, since the late 1960s, three Japanese companies, Hitachi, Mitsubishi and Takeda Chemical, have developed catalysts based on TiO2 through continuous research and development, and gradually replaced Pt-Rh and Pt series catalysts. The components of this kind of catalyst are mainly V2O5(WO3), Fe2O3, CuO, CrOx, MnOx, MgO, MoO3, NiO and other metal oxides or their mixtures. Usually, in the SCR system, TiO2 _ 2, Al _ 2O _ 3, ZrO2 _ 2, SiO2 _ 2 and activated carbon (AC) react with reducing agents such as liquid ammonia or urea, which has become the application of SCR denitrification engineering in power plants.