Reexamining the Molecular/Macromolecular Model of Coal from Comparative in Situ Variable-Temperature 1H NMR Studies of Argonne Premium Coal 601 and Its Pyridine Extraction Residue

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• 作者：Jincheng Xiong and Gary E. Maciel
• 刊名：Energy & Fuels
• 出版年：2002
• 出版时间：May 2002
• 年：2002
• 卷：16
• 期：3
• 页码：791 - 801
• 全文大小：114K
• 年卷期：v.16,no.3(May 2002)
• ISSN：1520-5029

文摘

We have carried out the first systematic in situ variable-temperature ¹H NMR study, usingthe CRAMPS (combined rotation and multiple pulse spectroscopy) technique, of the residue frompyridine extraction of Argonne premium coal 601. The change of molecular mobility in the residueunder various thermal treatments and pyridine swelling conditions were monitored quantitativelythrough a proton dipolar-dephasing experiment based on CRAMPS detection. Correlations amongmolecular structure, molecular mobility and solvent-extraction components were establishedthrough comparative variable-temperature ¹H CRAMPS studies on the C₅D₅N-saturated originalcoal and its extraction residue. A critical review of the molecular/macromolecular (M/M) structuralmodel of coal has been made on the basis of the new results, showing that the relationshipsbetween the M/M model and molecular dynamics is much more complicated than previouslythought. Both the molecular phase and the macromolecular phase can show molecular dynamicsbehavior ranging from a lack of substantial motion to extremely mobile behavior with correlationtimes as short as 30 ns. Without systematic variable temperature studies, correlation betweenmolecular mobility and the M/M model cannot be established correctly by NMR.