資料載入中.....
|
請使用永久網址來引用或連結此文件:
http://ir.ncue.edu.tw/ir/handle/987654321/16853
|
題名: | Effects of Interfacial Charge and the Particle Size of Titanate Nanotube-Supported Pt Nanoparticles on the Hydrogenation of Cinnamaldehyde |
作者: | Chiu, Tsai-Chin;Lee, Hsin-Yi;Li, Pei-Hua;Chao, Jiunn-Hsing;Lin, Chiu-Hsun |
貢獻者: | 化學系 |
日期: | 2013-03
|
上傳時間: | 2013-06-05T09:36:44Z
|
出版者: | IOP Publishing Ltd. |
摘要: | The oxidation state and size of Pt nanoparticles attached to alkali metal titanate nanotubes (MTNTs=M2Ti3O7, M = Li +, Na+, K+, Cs+) via ion exchange (indicated by the added label '-IE') and wet impregnation (indicated by the added label '-IMP') methods varied systematically with the cation of the MTNTs. X-ray photoelectron spectroscopy revealed that the binding energy of Pt was reduced to a low value when the support was changed from LiTNTs to CsTNTs, yielding a Ptδ- oxidation state. Thus, a space charge layer (SCL) was constructed at the interface between the Pt particle and MTNT support; the former carried the negative charge, and the alkali cation and proton in the hydroxyl group of the latter carried the positive charge. Due to a higher M/Ti atomic ratio in MTNTs, a higher electron density accumulated on Pt particles in Pt/MTNTs-IMP than on those in Pt/MTNTs-IE. Sub-ambient temperature temperature-programmed reduction and transmission electron microscopy revealed that because of the difference in reducibility of PtOx/MTNTs, the mean Pt particle size followed the order Pt/CsTNTs > Pt/KTNTs > Pt/NaTNTs > Pt/LiTNTs and Pt/MTNTs-IMP > Pt/MTNTs-IE. DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) showed that owing to its interaction with SCL, cinnamaldehyde adsorbed on Pt mainly through the C=C bond at the Pt-MTNT interfaces, and the small Pt particles in Pt/LiTNTs adsorbed three times more cinnamaldehyde than those in Pt/CsTNTs. Due to the competition between the adsorption of cinnamaldehyde and C=C activation, Pt/KTNT-IMP is the most active Pt/MTNT catalysts, achieving a conversion of 100% in the hydrogenation of cinnamaldehyde at 2 atm and 313 K. The carbonyl stretching of adsorbed cinnamaldehyde was almost unperturbed by adsorption (at 1705 cm-1), suggesting that Ptδ- and the π electrons in the carbonyl group repel each other, so the CH=O group points upward and away from the Pt surface, preventing it from being hydrogenated and causing Pt/MTNTs to exhibit high 3-phenyl propionaldehyde selectivities of 75-80%. |
關聯: | Nanotechnology, 24(11): 115601 |
顯示於類別: | [化學系] 期刊論文
|
文件中的檔案:
檔案 |
大小 | 格式 | 瀏覽次數 |
index.html | 0Kb | HTML | 786 | 檢視/開啟 |
|
在NCUEIR中所有的資料項目都受到原著作權保護.
|