Effects of addition of the catalyst (pyrrhotite) and sulfur on hydrogen transfer in liquefaction of Taiheiyo coal were investigated using tritium and ³⁵S. The coal liquefaction was performed at the initial pressure of 5.9 MPa and at 400°C for 30 min with tetralin solvent and tritium-labelled hydrogen, with or without the synthesized pyrrhotite catalyst and sulfur (or ³⁵S-labelled sulfur). The specific activities of tritium and ³⁵S in the reaction products were measured with a liquid scintillation counter. Amounts of exchanged and transferred hydrogens between the gas phase and coal/solvent, were calculated from the distributions of tritium and changes in the composition of products.
In the reaction with tritiated hydrogen and solvent, the dehydrogenation of tetralin to produce naphthalene and the hydrogen exchange reaction between gas phase and solvent were promoted by added catalyst and sulfur. Added sulfur produced hydrogen sulfide mainly with hydrogen of solvent. A part of added sulfur participated in the sulfur exchange reaction with the pyrrhotite catalyst. In the reaction with tritiated hydrogen, solvent and coal, the hvdrogen addition and exchange to coal and liquefaction products increased with the addition of catalyst and sulfur. It was suggested the sulfur promoted the formation of tetralyl radical in the hydrogen transfer from solvent to coal.

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Single ion chromatograms obtained by GC/MS were used for the evaluation of qualities of recycle solvents obtained from a lton/day coal liquefaction plant.
The compositional changes of n-paraffins, major aromatic compounds and C₀-C₄-phenanthrenes during the 50 days' operation were clarified. The content of n-paraffins (C₁₄-C₃₀) in a recycle solvent increased gradually from 6.6% to 15.9%. The aromatic compounds which increased relatively after 50 days were two and three cyclic compounds such as naphthalenes and acenaphthenes, and compounds containing five-menbered and dihydrophenalene-type naphthenic rings and pyrene ring. Phenan-threne and methylphenanthrenes decreased significantly, but the contents of C₂-C₄-phenanthrenes had minor changes.
C₂-C₄-Naphthalenes, phenanthrene and their hydrogenated homologues could be determined easily by using GC/MS chromatograms for the recycle solvents, and both the ratios of tetralins/ (naphthalenes+tetralins decalins) and (2H+4H+8H) / (0H+2H+4H+811+14H)-phenanthrenes were shown to be a good parameter for hydrogen donor ability of a liquefaction recycle solvent when the composition of the recycle solvent did not change remarkablly.

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Coal liquefaction solvents before and after hydrotreatment were analyzed by a capillary GC/MS, and the conversions of some polar compounds were determined by comparing the corresponding single ion chromatograms. The conversion of the polar fraction was estimated by the conversion of the individual polar compound obtained above. The separation of the polar fraction followed by GC/MS-chromatograms analyses enabled the determination of the conversions of many polar components during the hydrotreatment of the coal liquefaction solvent.

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