Effects of O2/CO/CO2 on NH3 reducing NO at 1073–1773 K in different flow reactors-Part Ⅱ: The effects of CO, CO2 and the complex atmosphere

Following Part Ⅰ [1], this paper investigated the effects of CO, CO2 and the complex O2/CO/CO2 atmosphere on NO reduction by NH3. Different from the SNCR process, the absence of O2 was emphasized in most experiments and the temperature range is much wider in the present work. Two types of flow reactors and three detailed chemical kinetic models were used as well. Experimental results indicate that some complex reactions proceed at low temperatures in the presence of CO or CO2, leading to a little bit change of the outlet NO concentration. Within the temperature window, CO and CO2 can both affect the NH3/NO reaction, which is associated with the residence time, while the mechanisms are different. At high temperatures close to 1773 K, CO promotes NO reduction, but CO2 inhibits it. As for the complex atmosphere, the specific configuration of the flow reactor has a dramatic effect on the experimental results, which is consistent with experiments focusing on the separate effect of O2. With CO oxidation, obvious NO net formation and two temperature windows were respectively obtained in two distinct gas-preheated reactors. Besides, N2O forms in the presence of CO2 but disappears with excess CO. Moreover, there are obvious disagreements between modeling predictions and experimental results, especially in the absence of O2. However, some characteristics of the overall reaction can still be captured.