Kinetics of selective reduction of nitrogen oxides on a cellular platinum catalys

Abstract

Kinetics of the selective reduction of nitrogen oxides by using ammonia on a supported cellular platinum catalyst is considered in the article. The calculations allowed determining the kinetic areas of these reactions on the catalysts concerned. The effects of temperature and volumetric flow rate on the efficiency of the purification process were investigated. The values of the rate constants for nitrogen oxides reduction and ammonia oxidation reactions were calculated on the basis of experimental studies with the use of mathematical modeling methods. The influence of monobasic organic acids, acetic and formic acids, on the activity of the catalysts of this type was determined. The samples of catalysts modified with formic acid showed the highest activity. This fact can be explained by a high rate of the main reactions of NOx reduction compared to the rate of ammonia oxidation side reactions. The causes of a decrease in the activity of catalysts with change in temperature were established. The surplus of temperature results in a decrease in the concentration of ammonia below stoichiometry, which leads to the reduction in effectiveness of the process.