Ag-loaded CeO2 catalysts for soot and C3H6 oxidation: Effect of Ag/Ce3+ on oxygen vacancies. (1st February 2023)

• Record Type: Journal Article
• Authors: Dou, Chenglong; Lei, Lili; Li, Zonglin; Meng, Zhongwei; Wang, Pan
• Is Part Of: Thermal science and engineering progress. Volume 38(2023)
• Publication Date: 2023-02-01
• Subjects: Ag-CeO2 -- Soot oxidation -- Oxygen vacancies -- Ag/Ce3+ -- C3H6 oxidation; Heat engineering -- Periodicals; Heat engineering; Thermodynamics; Periodicals; 621.402
• DOI: 10.1016/j.tsep.2023.101673
• Languages: English
• ISSNs: 2451-9049

Abstract

Highlights: The impregnation of Ag made CeO2 exhibit the excellent activity of soot oxidation and the activation energy of soot is significantly reduced, which Ag(8.5)-CeO2 having the best soot oxidation activity. The Ag-CeO2 reduced the ignition temperature of C3 H6 by more than 50 °C and increased the conversion by 36.1 %. The concentration changes of NO and NO2 were primarily concentrated in the temperature range of 250 °C ∼ 345 °C under the C3 H6 oxidation. The high Ag/Ce 3+ ratio may be facilitated the production of oxygen vacancies on the Ag-CeO2 surface. Abstract: A series of Ag-loaded Ag-CeO2 catalysts (4.5, 6.5, 8.5 wt%) were prepared by incipient wetness impregnation method for soot and C3 H6 oxidation based on the thermogravimetric analyzer and fixed-bed tubular reactor. Meanwhile, the structural properties and electronic states of the catalysts have been studied by nitrogen adsorption and desorption, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Compared with pure soot combustion, the Ag loading of 8.5 wt% reduced the temperature at which the soot reached the maximum weight loss rate from 630 °C to 278 °C and effectively reduced the activation energy of soot from 171.44 KJ/mol to 26.33 KJ/mol. The study indicates that Ag-CeO2 has better catalytic activity at Ag loading of about 8.5 wt%. The result of C3 H6 oxidation showed that the participation of Ag-CeO2 reduced the ignition temperature of C3 H6 by more than 50 °C and increased the conversion by 36.1 %. The temperature range of NO/NO2 change during the oxidation of C3 H6 was concentrated between 250 °C and 345 °C. In addition, the characterization of the catalysts showed that Ag(8.5)-CeO2 had the highest Ag/Ce 3+ ratio of 0.43 and the highest number of oxygen vacancies, indicating that the high Ag/Ce 3+ atomic ratio may enhance the generation of oxygen vacancies on the Ag-CeO2 surface. This work helps demonstrate the oxidation performance of Ag-CeO2 on soot and C3 H6 as well as to prepare highly active Ag-CeO2 .