NOX abatement catalyst with low SO2 oxidation activity

The commercially available catalytic processes for NOx abatement involve the use of transition metal ions such as V 4+/5+ , W 6+ , Cu 2+ etc. on a titania (anatase) or zeolite support. The metal ions catalyse the reaction between nitric oxide, ammonia and oxygen to give nitrogen and water. Using Indian ilmenite, high surface area titania (anatase) has been obtained which when doped with optimum amounts of transition metal ions, yields a catalyst capable of converting NOx with more than 90% efficiency within a temperature window of 250–450°C. Moreover this catalyst has minimal SO 2 oxidation activity even at high temperatures (450 °C). This catalyst therefore has the potential of commercial use in coal fired thermal power plants where the NOx has a high level of SO 2 impurity. Accelerated ageing tests have also been carried out on this catalyst and these studies indicate that the expected lifetime would be greater than or equal to five years. Spectroscopic and other physico-chemical data on the fresh and used catalysts are also presented.