化学学报 ›› 2009, Vol. 67 ›› Issue (15): 1759-1764. 上一篇    下一篇

研究论文

超临界条件下正庚烷的裂解与结焦

谢文杰 方文军* 李 丹 邢 燕 郭永胜 林瑞森

  

  1. (浙江大学化学系 杭州 310027)

  • 收稿日期:2008-09-29 修回日期:2008-12-10 出版日期:2009-08-14 发布日期:2009-08-14
  • 通讯作者: 方文军

Pyrolysis and Coking of n-Heptane under Supercritical Conditions

Xie, Wenjie Fang, Wenjun* Li, Dan Xing, Yan Guo, Yongsheng Lin, Ruisen   

  1. (Department of Chemistry, Zhejiang University, Hangzhou 310027)
  • Received:2008-09-29 Revised:2008-12-10 Online:2009-08-14 Published:2009-08-14
  • Contact: Fang, Wenjun

以正庚烷为碳氢燃料模型化合物, 考察其在超临界条件下的裂解和结焦情况, 着重探讨了裂解温度和雷诺数(Re)对裂解反应的影响. 在4.0 MPa和500~650 ℃范围内, 随着反应温度升高, 正庚烷的裂解转化率大幅度提高, 裂解反应及其产物的二次反应使结焦前驱物增加, 最终导致结焦严重; 在超临界条件下, 提高流体的湍动程度, 有利于抑制结焦. 采用扫描电镜(SEM)、透射电镜(TEM)、差示扫描量热(DSC)和X射线衍射(XRD)等技术分析固体焦的形貌特性, 结果表明正庚烷裂解结焦主要以金属催化作用产生的丝状焦为主, 丝状焦的生长是不锈钢发生渗碳现象的重要原因.

关键词: 碳氢燃料, 超临界, 裂解, 结焦, 渗碳

The pyrolysis and coking of n-heptane, as a model compound of hydrocarbon fuels, were investigated under supercritical conditions. The influences of temperature and Reynolds number (Re) on the cracking reactions were discussed. The conversion of n-heptane under 4.0 MPa increased evidently with temperature rising from 500 to 650 ℃. The thermal cracking and the secondary reactions of cracking products led to the increase of the precursors of coking, and finally resulted in coking seriously. Increasing the turbulence of the effluent flow could effectively inhibit coke formation. The coke samples have been characterized by the techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The analysis results showed that the filamentous coke formed during the pyrolysis of n-heptane resulted from metal catalysis and the formation of the filamentous coke might be the major factor of the carburization of the stainless steel.

Key words: hydrocarbon fuel, supercritical condition, pyrolysis, coking, carburization

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