Weijia Ren1,2, Qi Xin1,2, Zhesheng Hua1,2, Zhong Zheng1,2, Lifeng Xiao1,2, Shaojun Liu1,2, Chenghang Zheng This email address is being protected from spambots. You need JavaScript enabled to view it.1,2, Yang Yang This email address is being protected from spambots. You need JavaScript enabled to view it.1,2 1 State Key Lab of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
2 State Environmental Protection Center for Coal-Fired Air Pollution Control, Zhejiang University, Hangzhou 310027, China
Received:
February 20, 2023
Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.
Revised:
July 18, 2023
Accepted:
August 8, 2023
Download Citation:
||https://doi.org/10.4209/aaqr.230032
Ren, W., Xin, Q., Hua, Z., Zheng, Z., Xiao, L., Liu, S., Zheng, C., Yang, Y. (2023). Research on Performance and Mechanism of the NH3-SCR Reaction over Fly Ash-derived Mn-Ce/Zeolite X. Aerosol Air Qual. Res. 23, 230032. https://doi.org/10.4209/aaqr.230032
Cite this article:
Zeolite X was synthesized from fly ash under optimized conditions, which was supported with Mn, Ce, and Mn-Ce respectively. Fly ash-derived zeolite X catalysts exhibited similar catalytic performance as compared with the commercial zeolite X catalyst. XRD, N2 adsorption, SEM, XPS, and H2-TPR were used to investigate the relationship among the structure, physicochemical properties, and catalytic activities of the catalysts. Finally, the mechanism of NH3-SCR reaction on Mn-Ce/zeolite X was systematically performed by using diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The characterization results showed that the amorphous structure and good dispersion between Mn and Ce on the surface of the zeolite changed the electronic properties of the active components, improved its low-temperature catalytic activity, brought it characteristics of Mn and Ce at the same time, and broaden the reaction temperature range. The NO conversion rate of Mn-Ce-FX catalyst remained above 80% at 200°C–300°C. From DRIFTS we suggest that Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism are simultaneously carried out on the catalyst surface. According to the FTIR results, the Eley-Rideal mechanism has a great influence on the reaction below 250°C, and the Brønsted acid sites adsorb a large amount of NH3, resulting in an excellent low-temperature activity. When above 250°C, Langmuir-Hinshelwood mechanism plays a dominant role. The nitrates on the surface gradually convert to bidentate nitrates, impeding the SCR reaction, could be one of the reasons for reducing the high-temperature activity.HIGHLIGHTS
ABSTRACT
Keywords:
Fly ash, Catalyst, Emission controls
