Wei Chu

Publications (5)53.65 Total impact

• Article: Glow-discharge plasma-assisted design of cobalt catalysts for Fischer-Tropsch synthesis.

  Wei Chu, Li-Nan Wang, Petr A Chernavskii, Andrei Y Khodakov
  Angewandte Chemie International Edition 02/2008; 47(27):5052-5. · 13.45 Impact Factor
• Article: Advances in the development of novel cobalt Fischer-Tropsch catalysts for synthesis of long-chain hydrocarbons and clean fuels.

  Andrei Y Khodakov, Wei Chu, Pascal Fongarland
  Chemical Reviews 06/2007; 107(5):1692-744. · 40.20 Impact Factor
• Article: Effects of zirconia promotion on the structure and performance of smaller and larger pore silica-supported cobalt catalysts for Fischer–Tropsch synthesis

  Jingping Hong, Wei Chu, Petr A. Chernavskii, Andrei Y. Khodakov
  Applied Catalysis A: General. 382(1):28-35.
• Article: Effect of promotion with ruthenium on the structure and catalytic performance of mesoporous silica (smaller and larger pore) supported cobalt Fischer–Tropsch catalysts

  Jingping Hong, Petr A. Chernavskii, Andrei Y. Khodakov, Wei Chu
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  ABSTRACT: The effects of promotion with ruthenium on the structure of cobalt catalysts and their performance in Fischer–Tropsch synthesis were studied using MCM-41 and SBA-15 as catalytic supports. The catalysts were characterized by N2 physisorption, H2-temperature programmed reduction, in situ magnetic measurements, X-ray diffraction and X-ray photoelectron spectroscopy. It was found that monometallic cobalt catalysts supported by smaller pore mesoporous silicas (dp = 3–4 nm) had much lower activity in Fischer–Tropsch synthesis than their larger pore counterparts (dp = 5–6 nm). Promotion with ruthenium of smaller pore cobalt catalysts led to a considerable increase in Fischer–Tropsch reaction rate, while the effect of the promotion with ruthenium was less significant with the catalysts supported by larger pore silicas.Characterizations of smaller pore cobalt catalysts revealed strong impact of ruthenium promotion on the repartition of cobalt between reducible Co3O4 phase and barely reducible amorphous cobalt silicate in the calcined catalyst precursors. Smaller pore monometallic cobalt catalysts showed high fraction of barely reducible cobalt silicate. Promotion with ruthenium led to a significant increase in the fraction of reducible Co3O4 and in decrease in the amount of cobalt silicate. In both calcined monometallic and Ru-promoted cobalt catalysts supported by larger pore silicas, easy reducible Co3O4 was the dominant phase. Promotion with ruthenium of larger pore catalysts had smaller influence on cobalt dispersion, fraction of reducible cobalt phases and thus on catalytic performance.
  Catalysis Today.
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  Article: Cobalt species in promoted cobalt alumina-supported Fischer–Tropsch catalysts

  Wei Chu, Petr A. Chernavskii, Léon Gengembre, Galina A. Pankina, Pascal Fongarland, Andrei Y. Khodakov
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  ABSTRACT: 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 Co3O4 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 with 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.
  Journal of Catalysis.