Improved SCR for marine applications

Magazine article, 2013

The effect of sulfur, water, and varying NO/NO 2 concentrations on the NO x reduction over a commercial urea-SCR catalyst for marine applications was studied. A system approach where reaction temperature, gas flow, and gas feed composition was considered. In the presence of both SO 2 and water, the activity for NO x reduction decreased, in particular at high concentrations of SO 2 , low temperatures and high space velocities. This might be explained by the formation of ammonium sulfate salts at low temperatures. These problems could be avoided by keeping the temperature high enough, i.e., > 300°C, and the space velocity and the SO 2 concentration at < 12,200/hr and 500 ppm, respectively. The highest NO x reduction was achieved an equimolar ratio (50:50) of No/NO 2 and was significantly increased at all temperatures (250°-350°C) and might prove future opportunities for improved SCR systems for marine applications.