Monolayer Iron Carbide Films on Au(111) as a Fischer鈥揟ropsch Model Catalyst

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• 作者：Gilb猫re J. A. Mannie ; Lutz Lammich ; Yong-Wang Li ; J. W. (Hans) Niemantsverdriet ; Jeppe V. Lauritsen
• 刊名：ACS Catalysis
• 出版年：2014
• 出版时间：September 5, 2014
• 年：2014
• 卷：4
• 期：9
• 页码：3255-3260
• 全文大小：481K
• ISSN：2155-5435

文摘

Using scanning tunneling microscopy (STM), we characterize the atomic-scale details of ultrathin films of iron carbide (Fe_xC_y) on Au(111) synthesized as a potential model system for the active iron carbide phase in iron Fischer鈥揟ropsch synthesis (FTS) catalysts. The experiments show that room-temperature exposure of Fe islands gas to C₂H₄ deposited on the clean Au(111) surface results in partly converted Fe/Fe_xC_y islands. Multistep flash-heating treatment of the partly converted Fe/Fe_xC_y islands at 523 and 773 K results in pure highly crystalline Fe_xC_y islands with in-plane nearest-neighbor distances of 0.315 卤 0.005 nm. On the basis of the atom-resolved STM data, we propose that C₂H₄ dissociates at Fe island edges, after which the carbon diffuses inward into the interstitial region between the Fe and the Au substrate to form an Fe_xC_y surface that may be a good starting point for the investigation of iron carbide surfaces present under FTS conditions.

Keywords:

scanning tunneling microscopy; iron carbide; Fischer鈭扵ropsch synthesis; model catalyst; thin films