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Restructuring and redispersion of silver on SiO2 under oxidizing/reducing atmospheres and its activity toward CO oxidation
Qu, ZP; Huang, WX; Cheng, MJ; Bao, XH; Bao XH(包信和); Bao XH(包信和)
刊名JOURNAL OF PHYSICAL CHEMISTRY B
2005-08-25
DOI10.1021/jp050152m
109期:33页:15842-15848
收录类别SCI
文章类型Article
部门归属5
项目归属502
产权排名1;1
WOS标题词Science & Technology ; Physical Sciences
类目[WOS]Chemistry, Physical
研究领域[WOS]Chemistry
关键词[WOS]CARBON-MONOXIDE OXIDATION ; SELECTIVE OXIDATION ; PT/ALUMINA CATALYSTS ; OXYGEN ; SURFACE ; GAS ; TEMPERATURE ; ADSORPTION ; REDUCTION ; ALUMINA
英文摘要The effects of oxygen-hydrogen pretreatments of nanosilver catalysts in cycle mode on the structure and particle size of silver particles, and subsequently the activity of the catalyst toward CO oxidation (or CO selective oxidation in the presence of H-2) are reported in this paper. Ag/SiO2 catalyst with silver particle sizes of ca. 6 similar to 8 nm shows relatively high activity in the present reaction system. The adopting of a cycle of oxidation/reduction pretreatment has a marked influence on the activity of the catalyst. Oxygen pretreatment at 500 degrees C results in the formation of subsurface oxygen and activates the catalyst. As evidenced by in-situ XRD and TEM, the following H-2 treatment at low temperatures (100 similar to 300 degrees C) causes surface faceting and redispersing of the silver particles without destroying the subsurface oxygen species. The subsequent in-situ FTIR and catalytic reaction results show that CO oxidation occurs at -75 degrees C and complete CO conversion can be obtained at 40 degrees C over such a nanosilver catalyst pretreated with oxygen at 500 degrees C followed by H-2 at 100 degrees C. However, prolonged hydrogen treatment at high temperatures (> 300 degrees C) after oxygen pretreatment at 500 degrees C induces the aggregation of silver particles and also depletes so much subsurface oxygen species that the pathway of CO oxidation by the subsurface oxygen species is inhibited. Meanwhile, the ability of the catalyst to adsorb reactants is greatly depressed, resulting in a 20 similar to 30% decrease in the activity toward CO oxidation. However, the activity of the catalyst pretreated with oxygen at 500 degrees C followed by hydrogen treatment at high temperatures (> 300 degrees C) is still higher than that directly pretreated with H,. This kind of catalytic behavior of silver catalyst is associated with physical changes in the silver crystallites because of surface restructuring and crystallite redispersion during the course of oxygen-hydrogen pretreatment steps.
语种英语
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WOS记录号WOS:000231426000029
引用统计
被引频次:80[WOS]   [WOS记录]     [WOS相关记录]
文献类型期刊论文
条目标识符http://cas-ir.dicp.ac.cn/handle/321008/93093
专题中国科学院大连化学物理研究所
通讯作者Bao XH(包信和); Bao XH(包信和)
作者单位Chinese Acad Sci, Dalian Inst Chem Phys, State Key Catatlysis, Dalian 116023, Peoples R China
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GB/T 7714
Qu, ZP,Huang, WX,Cheng, MJ,et al. Restructuring and redispersion of silver on SiO2 under oxidizing/reducing atmospheres and its activity toward CO oxidation[J]. JOURNAL OF PHYSICAL CHEMISTRY B,2005,109(33):15842-15848.
APA Qu, ZP,Huang, WX,Cheng, MJ,Bao, XH,包信和,&包信和.(2005).Restructuring and redispersion of silver on SiO2 under oxidizing/reducing atmospheres and its activity toward CO oxidation.JOURNAL OF PHYSICAL CHEMISTRY B,109(33),15842-15848.
MLA Qu, ZP,et al."Restructuring and redispersion of silver on SiO2 under oxidizing/reducing atmospheres and its activity toward CO oxidation".JOURNAL OF PHYSICAL CHEMISTRY B 109.33(2005):15842-15848.
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