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

Mengze Zhang; Xiao Zhu; Liqiang Zhang; Yang Li; Jun Li; Xiao Xia; Chunyuan Ma; Yong Dong

doi:10.1021/acsomega.1c01722

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

ACS Omega. 2021 May 12;6(20):13484-13495. doi: 10.1021/acsomega.1c01722. eCollection 2021 May 25.

Authors

Mengze Zhang¹, Xiao Zhu¹, Liqiang Zhang¹, Yang Li², Jun Li¹, Xiao Xia¹, Chunyuan Ma¹, Yong Dong¹

Affiliations

¹ National Engineering Laboratory for Reducing Emissions from Coal Combustion, Engineering Research Center of Environmental Thermal Technology of Ministry of Education, Shandong Key Laboratory of Energy Carbon Reduction and Resource Utilization, School of Energy and Power Engineering, Shandong University, Jinan, Shandong 250061, China.
² Xi'an Thermal Power Research Institute Co., Ltd, Xi'an 710054, China.

Abstract

Denitration (De-NO _x ) 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 _x conversion over ACs. Experimental studies on NO _x 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 _x removal over ACs, especially the NO₂ conversion. Under dry conditions, a disproportionation reaction of NO₂ over ACs dominated NO _x 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 _x conversion. Increasing the NO₂/NO ratio in the simulated flue gas enhanced the NO _x conversion rate over ACs. -C(ONO₂) deposition on ACs generated by the disproportionation route inhibited NO _x conversion with time. O₃ oxidation was found to be efficient in increasing the NO₂/NO ratio and intensifying the NO _x conversion compared with commercially direct NH₃-SCR over ACs. Increasing the temperature and decreasing the gas hourly space velocity can promote NO _x 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 _x from sintering flue gas.