Cerium Tungsten Oxide Composite Catalyst

Nitrogen oxides (NOx) are important atmospheric pollutants that can cause environmental problems such as acid rain and photochemical smog, as well as direct damage to the human respiratory system. In addition, it also has an important contribution to the increasingly serious ash pollution in our country. Therefore, effective control of NOx emissions is a major strategic need in China.

NH3 selective catalytic reduction is currently the most widely used NOx control technology, and has been successfully applied to catalytic elimination of fixed source NOx such as coal-fired power plants and NOx catalytic purification of mobile vehicles such as diesel exhaust. The NH3-SCR catalyst for industrial application is mainly V2O5-WO3-TiO2 catalyst prepared by using TiO2 as a carrier, V2O5 as an active component and WO3 as a catalytic aid. Because the catalyst contains vanadium, which is a toxic substance, and has problems of poor thermal stability, high N2O production at high temperature, and easy oxidation of SO2 to SO3, although China currently allows the production and use of vanadium-based catalysts, with the improvement of environmental protection requirements and advances in technology and the complete elimination of vanadium-based catalysts are only a matter of time.

Some scholars have proposed a preparation method of cerium-tungsten composite oxide catalyst, which adopts mixed precipitation method, and its main contents are as follows:

(1) Preparing a mixed solution of cerium source and tungstate, uniformly stirring under normal temperature conditions; (2) separating and washing the precipitate in the solution; (3) drying and roasting the obtained solid matter to obtain cerium tungsten composite oxide catalyst.

The specific content includes:

Dissolving ammonium tungstate in oxalic acid solution, adding cerium nitrate according to the molar ratio of cerium and tungsten to 1.0, stirring for 4 hours, carrying out the reaction, then filtering and washing the precipitate, and putting the obtained solid in an oven at 100~ It is dried at 110 ° C for 12 h, and finally calcined in a muffle furnace at 500 ° C for 5 h to obtain a powdery cerium-tungsten composite oxide catalyst.

The preparation method of the cerium-tungsten composite oxide catalyst does not require the use of a precipitating agent, and is extremely simple; the operating temperature window is wide, and is particularly suitable for an application environment in which the temperature of the exhaust gas of the motor vehicle is large, and can still exhibit excellent catalysis in a high space velocity environment. Performance is a very efficient SCR catalyst.

• < Prev
• Next >