Mechanistic Study on the Plastic Phenomena of Coal

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• 作者：Masakatsu Nomura ; Koh Kidena ; Masataka Hiro ; and Satoru Murata
• 刊名：Energy & Fuels
• 出版年：2000
• 出版时间：July 2000
• 年：2000
• 卷：14
• 期：4
• 页码：904 - 909
• 全文大小：113K
• 年卷期：v.14,no.4(July 2000)
• ISSN：1520-5029

文摘

Highly coking coal, Goonyella coal, and slightly coking coal, Witbank coal, were submitted toruthenium ion catalyzed oxidation (RICO) reaction to clarify the structural features of the twocoals. Expected structural differences between the two coking coals were meager but interesting: Witbank coal has a little bit larger amount of longer methylene bridges (C15-C25) andlonger alkyl chains (C15-C30) than Goonyella coal. Combined use of ¹³C NMR and ¹H NMRspectra gave valuable information of the average aromatic ring size: Goonyella coal has largeraromatic rings than Witbank coal on average. To obtain the information about the evolution ofvolatile materials during heating which are supposed to be significant for the appearance of coalplasticity, two steps of heat treatment of the coals were performed: the first step is heating tothe softening temperature, and the second step is heating the resulting sample to resolidificationtemperature. Witbank coal gave a relatively larger amount of tar in the first step of the heatingthan in the case of Goonyella coal, while Goonyella coal gave a larger amount of tar in the secondstep of the heating compared with the corresponding fraction of Witbank coal. These stronglysuggest that a larger amount of metaplast, which is indispensable for the appearance of fluidity,could be produced during the plastic range (the temperature range from the softening temperatureto the resolidification temperature) in the case of Goonyella coal, this leading to its higher Gieselermaximum fluidity. We previously reported that these two coking coals have almost the sameamount of transferable hydrogen. Therefore, Witbank coal is supposed to consume relatively largeamounts of transferable hydrogen for the formation of tar during the heating to softeningtemperature, probably via oxygen functional group related reactions and carbon-carbon bondbreaking reactions. Due to a lower amount of transferable hydrogen in the char, subsequentbond cleavage reactions at the plastic range lead to recombination to show a very low value of itsGieseler maximum fluidity, although the three-dimensional structure framework of Witbank coalcollapses to a small extent.