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The hydrogen transfer behavior of five different ranks of coals on their reaction with the tritium-labeled toluene or tetralin in the temperature range from 200 to 400 °C for 5−360 min has been investigated. The behavior of hydrogen in functional groups was also traced. The extensive hydrogen transfer to coal occurred with tetralin even at 300 °C, while only a small amount of hydrogen was transferred from toluene. The hydrogen exchange of functional groups occurred with tetralin, although it was difficult for hydrogen exchange to take place with toluene. The transfer of hydrogen/tritium from the tritiated tetralin to the coals occurred not only by the conversion of tetralin into naphthalene but also by hydrogen exchange. This showed that although tetralin can readily be dehydrogenated to the aromatic, the tetralyl radicals formed by the reaction with coal radicals are also reactive as hydrogen acceptors. On the other hand, some structural elements existing in the coals should be good hydrogen donors, which transfer hydrogen to the tetralyl radicals. The enhancement of hydrogen transfer reactions occurred with the lower rank Illinois No. 6, Wandoan, and Beulah-Zap coals, compared to the higher rank Upper Freeport and Pocahontas No. 3 coals because of the existence of a relatively large amount of thermally labile or sensitive oxygen functional groups in these coals.

The hydrogen exchange of an Argonne Pocahontas #3 (POC) coal with tritiated gaseous hydrogen in the presence of a Pt/Al 2 O 3 catalyst was carried out using a fixed-bed reactor at a temperature range of 200-250 °C. Then, the tritiated coal sample was re-exchanged with hydrogen in a gaseous hydrogen atmosphere at different raising temperature rates. The changes in radioactivity of tritium releasing from the tritium-labeled coal sample in the temperature-programmed elimination (TPE) of tritium was monitored by a radioanalyzer in situ. The release profile of tritium was fit using three Gaussian distribution functions in TPE. On the basis of the waveform analysis, the amounts and activation energies of the hydrogen exchange for every type of exchangeable hydrogen were estimated. The values of exchange activation energies are 8.8 ( 0.5, 10.7 ( 0.5, and 16.3 ( 0.5 kcal/ mol for three types of exchangeable hydrogen, respectively. The amount of type-I hydrogen was independent of the exchange reaction temperature. In contrast to this, the amount of types II and III of exchangeable hydrogen increased with an increasing exchange temperature, suggesting that the amount of types II and III of hydrogen in the coal is dependent upon the exchange temperature.