COLD SELECTIVE CATALYTIC REDUCTION OF NITRIC-OXIDE FOR FLUE-GAS APPLICATIONS

Commercial selective catalytic reduction (SCR) processes for the reduction of NO to N2by NH3require temperatures above 300 °C. Significant SCR activities have been measured for transition metal sulfates as the catalysts, at temperatures as low as 30 °C. Under commercial SCR throughput and gas composition conditions, a 10% NiSO4/Al2O3catalyst exhibited NOxconversion of over 50% in the temperature range 50-120 °C and another activity peak at 200-250 °C with nearly 80% NOxconversion. The low-temperature SCR activity was attributed to the Brønsted acidity of the surface. The Brønsted acidity, and hence the SCR activity, decreased upon the adsorption of water and increased with the presence of SO2in the gas phase. © 1990, American Chemical Society. All rights reserved.