Fractionation of Coal for Obtaining Valuable ChemicalFeedstock by Solvent Extraction Using Non-polar Solventat Different Temperatures below 350°C

摘要

We have recently presented a new coal solvent extraction method that enhances the extraction yield dramatically.The method extracts coal using a flowing stream of a non-polar solvent such as tetralin under 10 Mpa at 350°C.The extract yield reached 65 to 80% for bituminous coals at 350°C,and the extract was separated into about 25 to 40% of soluble fraction at room temperature (soluble) and about 40% of solid fraction which precipitated from the extract at room temperature (deposit).It was found that the soluble and the deposit were almost free from inorganic materials.To utilize these clean carbonaceous materials for specific purposes,their fractionation and more detailed characterization are essential.Then the deposit obtained at 350°C from a subbituminous coal was further extracted by tetralin at different temperatures below 350°C.It was found that three extraction steps could fractionate the coal into 5 fractions.The fractions obtained were characterized by various analyses.Ultimate analysis and molecular weight measurement showed that the fraction obtained at lower temperature consisted of smaller molecular weight compounds having larger atomic H/C ratio in the parent coal.The melting and plastic behavior of a fraction was very close to that of a naphthalene-based pitch which was synthesized for producing high performance carbon materials.This result suggested a possibility of utilizing the fraction as a feedstock of high performance carbon materials.