High-temperature 1H n.m.r. study of oxidized coal |
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Authors: | Tetsuro Yokono Kunio Miyazawa Yuzo Sanada Harry Marsh |
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Affiliation: | 2. Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, UK;1. Coal Research Institute, Faculty of Engineering, Hokkaido University, Sapporo 060, Japan |
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Abstract: | Two coking coals, a caking and a non-caking coal are examined in a Bruker pulsed 1H n.m.r. spectrometer in the temperature range 293–730 K. One coking and the caking coal are oxidized in air at 383 K for 13 days. Temperatures of signal appearance and loss are noted as well as the temperatures of minimum signal half-peak width (). There occurs no change in the above three temperatures with oxidation of the coals. The variation of () with temperature of the coal is also measured. Changes in () are more pronounced for the caking coal. The softening and solidification temperatures are below and above, respectively, those reported using the Gieseler method. Values of () increase beyond the minimum value as the fluidity continues to increase. This may be caused by an increase in average molecular weight of constituent molecules and/or an increasing concentration of free radicals in the fluid phase. This experimental approach may afford a new method to characterize coals which are to be used in liquefaction processes. |
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