Coal dehydrogenation using quinones or sulfur

Seven coals have been dehydrogenated with sulfur in refluxing o-dichlorobenzene with the rate of reaction being followed by analysis of the H2S swept from the reaction by an N-2 stream. Dehydrogenation using benzoquinone was not successful due to benzoquinone incorporation into the coal. The chief structure change on dehydrogenation with sulfur is loss of aliphatic hydrogen with a concomitant increase in coal aromaticity. Methyl hydrogen is lost. There is spectroscopic evidence for the formation of carboxyl which is contradicted by the fact that the equilibrium thermodynamics of their formation by the oxidizing agent sulfur is unfavorable. The rate of H2S formation drops sharply early in the reaction demonstrating that reactive hydrogen is selectively removed. Unfortunately, we could not determine whether the selectivity is due to high hydrogen chemical reactivity or easy hydrogen accessibility. Sulfur incorporation is low initially and increases as the reaction progresses. Dehydrogenation reduces the pyridine swelling of the coals.