Removal of nitrogen oxides over catalyst by changing exhaust gases composition

The influence of addition of potassium or barium to Pd/Al2O3 catalyst on the catalytic performance of nitrogen oxides storage-reduction catalyst was studied. The catalysts: Pd-K-Al2O3, Pd-Ba-Al2O3and Pd-K/Ba-Al2O3 were prepared by impregnation method. Alumina spheres contained Pd=1 and 4 %, K=10%, and/or Ba=10%. The conversions of nitrogen oxides as function of fuel mixture composition were determined. Studies were carried at the temperature range 200-500oC. The influence of addition of potassium and barium to catalyst on its storage-reduction nitrogen oxide activity was considered. The highest conversion of NOx was obtained for Pd(4%)-K-Al2O3 catalyst. Results show that the highest conversion of NOx was obtained for Pd(4%)-K-Al2O3 catalyst it could be caused with different structure of catalyst surface. For all catalysts, during periodic changes of lean to rich mixture, NOx conversion is high during lean condition and is falling during rich condition and is later increasing repeatedly. catalysts composition influences the temperature range in which its activity is the highest. On the base of studied data conversion of NOx there was observde that catalysts composition influences the temperature range in which its activity is the highest. Although dispersion of palladium decreases when its concentration increases, a fall of nitrogen oxide conversion for catalysts containing higher concentration of palladium does not occur.