Marzieh Hamidzadeh - Chemistry and Chemical Engineering Research Center of Iran, Tehran, Iran Catalyst Research Group, Petrochemical Research and Technology Company, National Petrochemical Company, P.O. Box ۱۴۳۵۸–۸۴۷۱۱, Tehran, Iran,
Mitra Ghassemzadeh - Chemistry and Chemical Engineering Research Center of Iran, Tehran, Iran
Aliakbar Tarlani - Chemistry and Chemical Engineering Research Center of Iran, Tehran, Iran

Nitrogen oxides (NOx) are a very arousing and great significance family of air polluting chemical compounds. This paper explains how nitrogen oxides are formed and whycontrol emission of them is important. This paper also introduces the available NOx removal technologies and effect of the catalysts in these methods and suggests somecatalysts for decreasing NOx emission from mobile and stationary sources. Automobiles and other mobile sources produce 50 percent of the NOx that is emitted. Electric power plants contribute about 20% of the total NOx emissions and the portion of the otherindustries is about 30 percent. Therefore, control of NOx emission from mobile source is very important challenge in the world but NOx removal in stationary source with catalytically methods is easier in our plants in Iran. Catalysts are the best solution to decrease the amount of exhaust gas pollutants and this article focus on the selective catalytic reduction technology by different reducing agents, the reaction mechanism and catalyst developments

NOx removal, technologies, catalysts, air pollutions