van Steen Eric, Claeys Michael, Dry Mark E, van de Loosdrecht Jan, Viljoen Elvera L, Visagie Jacobus L
Catalysis Research Unit, Department of Chemical Engineering, University of Cape Town, Private Bag, Rondebosch 7701, South Africa.
J Phys Chem B. 2005 Mar 3;109(8):3575-7. doi: 10.1021/jp045136o.
The stability of nanosized materials differs significantly from the stability of bulk materials. In this study a thermodynamic analysis on the simultaneous oxidation and re-reduction of small metallic cobalt crystallites in the presence of water and hydrogen as a function of the crystallite diameter was performed as a model for catalyst deactivation in the Fischer-Tropsch synthesis. It is shown that spherical cobalt crystallites with a diameter less than 4.4 nm are likely to be oxidized under realistic Fischer-Tropsch synthesis conditions (p(H)(2)(O)/p(H)(2) < 1.5, T = 493 K).
纳米材料的稳定性与块状材料的稳定性有显著差异。在本研究中，作为费托合成中催化剂失活的模型，对在水和氢气存在下小尺寸金属钴微晶的同时氧化和再还原进行了热力学分析，该分析是作为微晶直径的函数进行的。结果表明，在实际的费托合成条件下（p(H₂O)/p(H₂) < 1.5，T = 493 K），直径小于4.4 nm的球形钴微晶可能会被氧化。
