Effect of Calcination Temperature on the Activation Performance and Reaction Mechanism of Ce–Mn–Ru/TiO2 Catalysts for Selective Catalytic Reduction of NO with NH3

• Published in: ACS omega 2020-12, Vol.5 (51), p.33357-33371
• Main Authors: Ren, Zhixiang, Zhang, Hongliang, Wang, Guangying, Pan, Youchun, Yu, Zhengwei, Long, Hongming
• Format: Article
• Language: English
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.0c05194

In this study, anatase TiO2-supported cerium, manganese, and ruthenium mixed oxides (CeO x –MnO x –RuO x /TiO2; CMRT catalysts) were synthesized at different calcination temperatures via conventional impregnation methods and used for selective catalytic reduction (SCR) of NO x with NH3. The effect of calcination temperature on the structure, redox properties, activation performance, surface-acidity properties, and catalytic properties of the CMRT catalysts was investigated. The results show that the CMRT catalyst calcined at 350 °C exhibits the most efficient low-temperature (200 °C, which leads to a decrease in the N2 selectivity of the CMRT catalysts and further results in an increase in the production of NO and N2O byproducts. X-ray photoelectron spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy show that the CMRT catalyst calcined at 350 °C contains more Ce4+, Mn4+, Ru4+, and lattice oxygen, which greatly improve the catalyst’s ability to activate NO that promotes the NH3-SCR reaction. The Ru n+ sites of the CMRT catalyst calcined at 250 °C are the competitive adsorption sites of NO and NH3 molecules, while those of the CMRT catalyst calcined at 350 and 450 °C are active sites. Both the Langmuir–Hinshelwood (L–H) mechanism and the Eley–Rideal (E–R) mechanism occur on the surface of the CMRT catalyst at the low reaction temperature (100 °C).