LIQUEFACTION OF COAL AND MACERAL CONCENTRATES IN A STIRRED MICRO-AUTOCLAVE AND A FLOWING-SOLVENT REACTOR

Compositions of lighter liquefaction product fractions from a stirred micro-autoclave and a flowing-solvent reactor were compared by gas chromatography-mass spectrometry (g.c.-m.s.). Tetralin was used as vehicle for liquefaction of a set of coals and maceral concentrates; high-pressure hydrogen and a mixture of finely powdered Fe2O3 catalyst precursor and elemental sulfur were used in the micro-autoclave. Similar conversions (sample weight loss) were observed in the two reactors when relatively long hold times (400 s) were used in the flowing-solvent reactor. Compared with products prepared in the micro-autoclave, only a negligible proportion of material released from the coal in the flowing-solvent reactor could be detected within the molecular mass interval between tetralin itself and the upper detection limit of the chromatographic column: most aromatic constituents observed by g.c.-m.s. in products from the flowing-solvent reactor were identified as resulting from the thermal reactions of tetralin. This result suggests that nearly all components identified in products from the stirred micro-autoclave were formed from larger and/or more polar species released from the coal during secondary reactions of primary coal solubilization products. The concentrations of a limited number of alkylaromatic homologous series identified in the oil fraction of the stirred autoclave products were quantitatively determined by g.c.-m.s.. Analysis of successive product fractions from the flowing-solvent reactor, collected during time-temperature-resolved experiments, indicated that the greater part of the C20-C36 Straight-chain aliphatic hydrocarbons identified in the product mixture was released from the coal between 340 and 390-degrees-C.