Gasification of Graphite and Coke in Carbon鈥揅arbon Dioxide鈥揝odium or Potassium Carbonate Systems

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• 作者：Kejiang Li ; Jianliang Zhang ; Zhengjian Liu ; Xiaojun Ning ; Tianqiu Wang
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2014
• 出版时间：April 9, 2014
• 年：2014
• 卷：53
• 期：14
• 页码：5737-5748
• 全文大小：683K
• 年卷期：v.53,no.14(April 9, 2014)
• ISSN：1520-5045

文摘

The thermodynamics of possible reactions, including gasification and reduction reactions, in carbon鈥揷arbon dioxide鈥搒odium or potassium carbonate systems was analyzed first. And then, the gasification reactions of graphite and coke with CO₂ in this system were studied kinetically by temperature programmed thermogravimetry. The results showed that the carbon conversion curve shifted to a lower temperature zone after Na₂CO₃ or K₂CO₃ was added, and graphite was more susceptible than coke to be catalyzed by Na₂CO₃ or K₂CO₃. Ten kinetic equations were adopted to simulate the reaction process using the method of Coats鈥揜edfern. The Avrami鈥揈rofeev equation was found to be the most probable kinetic equation, with which the values of activation energy and frequency factor were calculated. The kinetic simulation indicated that the activation energy of coke carbon had been activated to the lowest level by its inner factors, thus it was difficult to be reduced by adding Na₂CO₃ or K₂CO₃. The kinetic compensation effect was confirmed to exist in both graphite gasification and coke gasification. X-ray diffraction and Raman spectra were used to characterize the inner difference between graphite and coke, which showed that coke carbon structure was greatly different from graphite structure because of its highly disordered and heterogeneous carbon structure.