Bituminous coal phenanthrene extraction

Chemical interactions take place between the solvent and bituminous coal during phenanthrene extraction. The net effect of the interaction is hydrogen excnange between phenanthrene and the coal. The formation of chemical bonds between phenanthrene and coal also occurs to a small extent, as a side reaction. 

In the higher-rank bituminous coals, a- and fS-naphthol are both effective solvents, but for subbituminous coal, (S-naphthol may produce even less extract than phenanthrene, but a-naphthol may extract as much is 83% w/w of the coal. Ring compounds, such as phenanthrene, appear to be superior for extracting bituminous coals of medium rank. 

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