Partial Oxidation of n-Tetradecane over 1 wt % Pt/γ-Al2O3 and Co0.4Mo0.6Cx Carbide Catalysts: A Comparative Study

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• 作者：Daniel J. Haynes ; David A. Berry ; Dushyant Shekhawat ; Tian-Cun Xiao ; Malcolm L. H. Green ; James J. Spivey
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2008
• 出版时间：October 15, 2008
• 年：2008
• 卷：47
• 期：20
• 页码：7663-7671
• 全文大小：404K
• 年卷期：v.47,no.20(October 15, 2008)
• ISSN：1520-5045

文摘

Catalytic partial oxidation (CPOX) of liquid fuels is being widely studied as an option for producing a hydrogen-rich gas stream for fuel cells. However, deactivation of catalysts by carbon deposition and sulfur poisoning in this process is a key technical challenge. Here, the deactivation of Co_0.4Mo_0.6C_x has been compared to that of 1 wt % Pt/γ-Al₂O₃ in a fixed-bed catalytic reactor, using mixtures of n-tetradecane and either 1-methylnaphthalene (1-MN) or dibenzothiophene (DBT) to simulate diesel fuel. The results show that Co_0.4Mo_0.6C_x is stable and active for the CPOX of n-tetradecane at 850 °C, 50000 scc/(g_cat h), and an O/C ratio of 1.2. This catalyst produces slightly lower H₂ and CO yields than Pt/γ-Al₂O₃, but still close to equilibrium values for 5 h. A low concentration of sulfur (50 ppmw as DBT) has little effect on either activity or selectivity for the carbide or Pt/γ-Al₂O₃ catalyst. However, the presence of 1-MN or a high sulfur concentration (1000 ppmw as DBT) deactivates both catalysts, resulting in reaction products that are typical of gas-phase reactions in a blank reactor. The addition of 1-MN or 1000 ppmw DBT to n-tetradecane produces qualitatively similar results on both catalysts: H₂ production decreases continuously in the presence of either 1-MN or DBT, and CO drops to a stationary level. This drop in synthesis gas yields corresponds to an increase in steam, CO₂, and olefin yields, suggesting that the contaminants deactivate sites that are active for steam and dry reforming reactions downstream of the reactor inlet, where rapid oxidation takes place. Once the contaminants are removed, initial activity returns more quickly for the carbide than for Pt/γ-Al₂O₃.