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首页> 外文期刊>Journal of Catalysis >Cobalt species in promoted cobalt alumina-supported Fischer-Tropsch catalysts
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Cobalt species in promoted cobalt alumina-supported Fischer-Tropsch catalysts

机译：促进型钴氧化铝负载的费-托催化剂中的钴种类

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The structure of cobalt species at different stages of the genesis of monometallic and Pt-promoted cobalt alumina-supported Fischer-Tropsch catalysts was studied using X-ray diffraction,UV-visible spectroscopy,in situ X-ray absorption,in situ magnetic method,X-ray photoelectron spectroscopy,and DSC-TGA thermal analysis.The catalysts were prepared by incipient wetness impregnation using solutions of cobalt nitrate and dihydrogen hexachloroplatinate.Both variation of catalyst calcination temperature between 473 and 773 K and promotion with 0.1 wt% of Pt had no significant affect on the size of supported C03O4 crystallites.The size of cobalt oxide particles in the calcined catalysts seems to be influenced primarily by the pore diameter of the support.Cobalt reducibility was relatively low in monometallic cobalt alumina-supported catalysts and decreased as a function of catalyst calcination temperature.The effect was probably due to the formation of mixed surface compounds between Co3O4 and Al2O3 at higher calcination temperatures,which hinder cobalt reduction.Promotion witfi platinum spectacularly increased the rate of cobalt reduction;the promotion seemed to reduce the activation energy of the formation of cobalt metallic phases.Analysis of the magnetization data suggests that the presence of Pt led to the reduction of smaller cobalt oxide particles,which could not be reduced at the same conditions in the cobalt monometallic catalysts.Promotion of cobalt alumina-supported catalysts with small amounts of Pt resulted in a significant increase in Fischer-Tropsch cobalt time yield.The efficient control of cobalt reducibility through catalyst calcination and promotion seems to be one of the key issues in the design of efficient cobalt alumina-supported Fischer-Tropsch catalysts.
机译：利用X射线衍射，紫外可见光谱，原位X射线吸收，原位磁性方法研究了单金属和Pt助催化的氧化铝负载的费托催化剂在不同成因阶段钴的结构。 X射线光电子能谱法和DSC-TGA热分析法。采用硝酸钴和六氢铂酸二氢盐溶液通过初湿浸渍法制备的催化剂。催化剂煅烧温度在473至773 K之间变化和0.1 wt％的Pt促进对负载的C03O4晶体的尺寸没有显着影响。煅烧催化剂中氧化钴颗粒的尺寸似乎主要受载体孔径的影响。单金属钴氧化铝负载的催化剂中钴的还原性相对较低，并且随着还原性的降低而降低。其作用可能是由于Co3O4和Co3O4之间形成了混合表面化合物d。Al2O3在较高的煅烧温度下，阻碍了钴的还原。促进机能铂显着提高了钴的还原速率;该促进作用似乎降低了钴金属相形成的活化能。磁化数据的分析表明，Pt的存在导致了较小的氧化钴颗粒的减少，而单金属钴催化剂在相同条件下无法还原。少量Pt的钴氧化铝负载催化剂的促进导致费托钴时间产率的显着增加。通过催化剂的煅烧和促进来有效控制钴的还原性似乎是设计高效钴铝负载的费托催化剂中的关键问题之一。

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