The hydrogen exchange reactions of Argonne Premium coals and Wandoan coal with tritiated gaseous hydrogen and tritiated water were carried out to investigate the effect of the particle size of coal on the hydrogen exchange reaction. Coals with several particle sizes (<100 mesh and <20 mesh for Argonne Premium coals, <250 mesh, 250-150 mesh, and 20-22 mesh for Wandoan coal) were used, and it was found that the particle size of coal only slightly affected the hydrogen exchange ratio of coal in both cases of tritiated gaseous hydrogen and water. These results suggest that most of hydrogen exchanged with gaseous hydrogen or water, e.g., hydrogen in functional groups, is located on not only the exterior surface but also interior surface of coal, where hydrogen atom generated in the presence of the catalyst or proton generated from water can easily approach, even in the case of larger particle size of coal.
Hydrogen exchange reactions of coal with tritiated water and gaseous hydrogen were investigated to estimate the mobility of hydrogen in coal using not only a batch type reactor but also a flow type reactor. Specifically, the reactivities of functional groups were traced in these reactions. In the reaction of coal with tritiated water at 100°C the hydrogen exchange of functional groups such as hydroxyl group in coals could be estimated. In the pressurized system using stainless batch type reactor aromatic hydrogen at ortho-and para-positions of a functional group could also be estimated by the hydrogen exchange reactions of coal and tritiated water at higher temperature. In hydrogen exchange reactions of coals with tritiated gaseous hydrogen using a flow reactor, reaction temperature was controlled exactly. The use of a Pt/Al 2 O 3 catalyst promoted the generation of hydrogen radicals which reacted with coal. This method enables us to estimate the reactivity of a functional group with a hydrogen radical. Further, it was found that the particle size of coal only slightly affected hydrogen exchange ratio of coal in both cases of tritiated gaseous hydrogen and tritiated water.
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