Comparison of the Chemistry of ClCH2CH(CH3)OH and ClCH2CH2CH2OH on Cu(100) and O/Cu(100)

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• 作者：Szu-Hui Li ; Zi-Xian Yang ; Shang-Wei Chen ; Szu-Han Lee ; Jong-Liang Lin
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 12, 2016
• 年：2016
• 卷：120
• 期：18
• 页码：9826-9835
• 全文大小：603K
• 年卷期：0
• ISSN：1932-7455

文摘

Thermal reactions of bifunctional 1-chloro-2-propanol and 3-chloro-1-propanol on Cu(100) and oxygen-precovered Cu(100) are presented in this article. X-ray photoelectron spectroscopy, reflection–absorption infrared spectroscopy and temperature-programmed reaction/desorption have been employed to investigate the decomposition process of 1-chloro-2-propanol on Cu(100). The competitive dissociation of the functional C–Cl and CO–H at 265 K results in the formation of ClCH₂CH(CH₃)O– and −CH₂CH(CH₃)O– surface intermediates at a 2:1 concentration ratio. This ratio decreases to ∼0.6:1 at 300 K. The −CH₂CH(CH₃)O– oxametallacycle is theoretically predicted to be bonded on the Cu(100) surface, with both the O and CH₂ at bridge sites. This surface intermediate decomposes mainly at 300 K producing CH₃C(O)CH₃ and CH₃CH═CH₂ in addition to H₂ and CO. Preadsorbed oxygen atoms can stabilize the oxametallacycle and increases its reaction temperature to ∼350 K. Moreover, propene formation is promoted relative to acetone. In the reaction of 3-chloro-1-propanol on Cu(100), a low-temperature (159 K) formation channel of ClCH₂CH═CH₂ is observed. Other products presumably from −CH₂CH₂CH₂O– reaction, including CH₂═CHCHO, CH₃CH₂CHO, C₂H₄, CO, and H₂, evolve at a temperature higher than ∼300 K. No propene from C–O dissociation is formed. Preadsorption of oxygen causes the evolution of these products to be shifted to ∼400 K, with additional CH₃CH₂CH₂OH and a small amount of CH₃CH═CH₂. The theoretical calculation indicates that −CH₂CH₂CH₂O– is bonded via the ³CH₂ and O at atop and bridge sites, respectively, and has an energy slightly higher than that of −CH₂CH(CH₃)O–, by 3.4 kcal·mol^–1.