Experimental and modeling study of the effects of multicomponent gas additives on selective non-catalytic reduction process

The influence of multicomponent additives on NO reduction by selective non-catalytic reduction process has been investigated experimentally in an electricity-heated tube reactor. The multicomponent additives are composed of two species of CO, CH4 and H2, and the molar ratio of their two components varies from 1/3 to 3/1. The results show that all the investigated additives could decrease the optimal temperature for NO reduction effectively, but the contributions of their components are different. The performance of multicomponent additive composed of CO and CH4 depends mainly on CH4 component. The function of CO component is shifting the temperature window for NO reduction to lower temperature slightly and narrowing the temperature window a little. The temperature window with multicomponent additive composed of H2 and CH4 is distinct from that with its each component, so both H2 and CH4 component make important contributions. While the fraction of CO is no more than that of H2 in multicomponent additives composed of them, the performance of multicomponent additives is dominated by H2 component; while the fraction of CO becomes larger, the influence of CO component becomes notable. Qualitatively the modeling results using a detailed chemical kinetic mechanism exhibit the same characteristics of the temperature window shift as observed experimentally. By reaction mechanism analysis, the distinct influences of CO, CH4 or H2 component on the property of multicomponent additive are mainly caused by the different production rates of OH radical in their own oxidation process.