Title: Dissolution Reaction of Coal by Hydrogen-donating Aromatic Solvents
Abstract: In order to clarify the mechanism of hydrogen-donor solvent extraction of coal, the reaction of Oyubari coal with various aromatic solvents under hydrogen pressure was investigated.The solvents generally fulfilled the main role of hydrogen donation to the coal, while at the low concentrations of hydrogen donating solvent the molecular hydrogen could participate in the extraction reaction. Therefore, hydroaromatic compounds such as tetralin having highly hydrogen donating character have shown a good effect on the liquefaction of coal. The dissolution of coal required only the minimum amount of hydrogen donating solvent, about 1.0g of tetralin per 1g of dissolved Oyubari coal, which could supply sufficient hydrogen to the thermally decomposed fraction of coal.Although high temperature was favorable for the extraction reaction, the optimum temperature was determined to be 420-450°C because of the coking and gasification of coal and loss of solvents. Since the extraction was very fast in the early stage, most of reaction completed within 30 minuted.The gaseous products were mainly composed of hydrogen from the dehydrogenation of tetralin and methane from the thermal cracking of coal.Coal extracts were ashless and low sulfur solid materials.