Saib A M, Borgna A, van de Loosdrecht J, van Berge P J, Niemantsverdriet J W
Schuit Institut of Catalysis, Eindhoven University of Technology, P. O. Box 513, Eindhoven 5600 MB, The Netherlands.
J Phys Chem B. 2006 May 4;110(17):8657-64. doi: 10.1021/jp0573700.
The oxidation of nanosized metallic cobalt to cobalt oxide during Fischer-Tropsch synthesis (FTS) has long been postulated as a major deactivation mechanism. In this study a planar Co/SiO(2)/Si(100) model catalyst with well-defined cobalt crystallites, close to the threshold value reported for oxidation in the literature (4-10 nm), was prepared by the spin coating method. The planar Co/SiO(2)/Si(100) model catalyst was characterized with atomic force microscopy, X-ray photoelectron spectroscopy, and Rutherford backscattering. The surface oxidation behavior of the nanosized metallic cobalt crystallites of 4-5 nm was studied using in situ near-edge X-ray absorption fine structure under model FTS conditions, i.e., H(2)/H(2)O = 1, P(Total) = 0.4 mbar, and 150-450 degrees C. No surface oxidation of metallic cobalt was observed under these model FTS conditions over a wide temperature range, i.e., 150-400 degrees C.
在费托合成（FTS）过程中，纳米级金属钴氧化为氧化钴长期以来一直被假定为主要的失活机制。在本研究中，通过旋涂法制备了具有明确钴微晶的平面Co/SiO₂/Si(100)模型催化剂，其钴微晶尺寸接近文献报道的氧化阈值（4 - 10 nm）。采用原子力显微镜、X射线光电子能谱和卢瑟福背散射对平面Co/SiO₂/Si(100)模型催化剂进行了表征。在模拟费托合成条件下，即H₂/H₂O = 1、总压P(Total) = 0.4 mbar以及温度为150 - 450℃时，利用原位近边X射线吸收精细结构研究了4 - 5 nm纳米级金属钴微晶的表面氧化行为。在150 - 400℃的宽温度范围内，在这些模拟费托合成条件下未观察到金属钴的表面氧化现象。
