Studies of DeNOx catalytic activity over some transition metal oxide catalysts

NOx pollution due to increased motor vehicle use in urban cities of India is today’s major environmental concern. Catalytic converters with noble metal catalyst are common for petrol driven vehicles for reducing CO, HC and NOx; but for Diesel driven vehicles and especially for NOx removal, catalytic converters are not common. There are several techniques to control NOx emissions from diesel exhaust, but After Treatment Technique has better advantages and more convenient. To study the SCR (Selective Catalytic Reduction ) of NO (Nitric Oxide) by transition metal catalysts; a series of catalyst of 2%, 5% and 8% wt% loading of Silver, Iron, Chromium and Vanadium over γ-alumina support have been prepared, characterized and tested in a stream of synthetic diesel exhaust gas which contains propane as reducing agent. The catalysts have been characterized by BET surface area, pore volume and XRD techniques. The catalytic activity has been tested between 1000-500oC reaction temperatures and GHSV 6,000 h-1 to 18,000 h-1. It was found that 5% Silver catalyst has given maximum 43% and 5% Iron catalyst has given maximum 39% NO conversion between 2000-4000C reaction temp- eratures. The study suggests that low cost silver and iron based transition metal oxide catalysts can be used for removal of NOx pollution from diesel exhaust gas