Hydrothermal aging mechanism of K/CeO2 catalyst in soot catalytic combustion based on the Ostwald ripening mechanism

被引：3

作者：

Li, Zonglin ^{[1
]}

Wang, Pan ^{[1
]}

Ao, Chengcheng ^{[1
]}

Meng, Zhongwei ^{[2
]}

Zhang, Lidong ^{[3
]}

机构：

[1] Jiangsu Univ, Sch Automot & Traff Engn, Zhenjiang 212013, Peoples R China

[2] Xihua Univ, Sch Energy & Power Engn, Key Lab Fluid & Power Machinery, Minist Educ, Chengdu 610039, Peoples R China

[3] Univ Sci & Technol China, Natl Synchrotron Radiat Lab, Hefei 230026, Peoples R China

来源：

THERMAL SCIENCE AND ENGINEERING PROGRESS | 2023年 / 37卷

基金：

中国国家自然科学基金;

关键词：

Soot catalytic combustion; K; CeO; 2; catalyst; Hydrothermal aging; DFT; OXIDATION; CERIA; CO; TEMPERATURE; STABILITY; SURFACES; IMPACT; OXYGEN; VAPOR;

D O I：

10.1016/j.tsep.2022.101593

中图分类号：

O414.1 [热力学];

学科分类号：

摘要：

The thermogravimetric analysis (TGA) experiment of CeO2 and K/CeO2 catalysts prepared with the incipient wetness impregnation method was carried out for the soot catalytic combustion at different K loadings before and after hydrothermal aging. The structure, morphology, and catalytic activity of CeO2 and K/CeO2 catalysts were thoroughly investigated with the means of N2 adsorption/desorption, XRD, XPS, and H2-TPR. The density functional theory (DFT) operation was applied to explain the mechanism of the decrease in catalytic activity of CeO2 and K/CeO2 catalysts after hydrothermal aging. TGA showed that the Tmax of the hydrothermal aging K/ CeO2 catalyst was 505 degrees C, which was higher than CeO2 at 473 degrees C. After hydrothermal aging, CeO2 catalysts were less agglomerated than K/CeO2, and the ratio of Ce3+/Ce4+ decreases, but the mobile oxygen OII/OI ratio in the lattice were increased compared to CeO2 catalysts. DFT calculations showed that K doping significantly increases the surface energy and decreases the oxygen vacancy formation energy of (111), (200), (220), and (311) crystal planes, leading to enhanced catalytic combustion performance of the K/CeO2 catalyst soot based on the Mars-Van Krevelen mechanism. Furthermore, K doping decreased the adsorption energy of H2O and the energy barrier of K atoms diffusing near the surface of K/CeO2 catalyst crystals from 5.92 eV to 2.46 eV, which resulted in the loss of the active center number because of migration and coalescence (sintering) caused by crystal plane instability based on the Ostwald ripening mechanism.

引用

页数：11