Intensification of NO Conversion over Activated Coke by Ozone Oxidation for Sintering Flue Gas at Low Temperatures

Denitration (De-NO ) over activated cokes (ACs) for sintering flue gas needs intensification. Gaseous reactions in a gas mixture containing NO, NO₂, and NH₃, with the effect of O₂ concentration and moisture, were taken into consideration in the study of NO conversion over ACs. Experimental studies on NO conversion with and without NH₃ over ACs were conducted using a fixed-bed reactor at 100 °C. The results demonstrated that moisture significantly affected NO removal over ACs, especially the NO₂ conversion. Under dry conditions, a disproportionation reaction of NO₂ over ACs dominated NO conversion with no NH₃, whereas apparent fast selective catalytic reduction (SCR) over the ACs was observed in the presence of NH₃. Regardless of the presence of absence of NH₃ in wet mixtures, NO₂ adsorption on ACs via the disproportionation route dominated the NO conversion. Increasing the NO₂/NO ratio in the simulated flue gas enhanced the NO conversion rate over ACs. -C(ONO₂) deposition on ACs generated by the disproportionation route inhibited NO conversion with time. O₃ oxidation was found to be efficient in increasing the NO₂/NO ratio and intensifying the NO conversion compared with commercially direct NH₃-SCR over ACs. Increasing the temperature and decreasing the gas hourly space velocity can promote NO conversion over ACs after O₃ oxidation. NO oxidized with O₃ coupled with NH₃ spray and continuous regeneration of ACs is a potential method for removing NO from sintering flue gas.