| dc.description.abstract |
Two Turkish lignites were extracted with tetralin in a batch autoclave under nitrogen or hydrogen atmosphere. The isothermal extraction temperatures ranged from 325 to 425 °C at 25 °C intervals and the isothermal extraction periods were 0, 30, 60 and 120 min. After removal of char and solvent, the remaining products, which were completely soluble in tetrahydrofuran, were separated into three fractions: preasphaltenes (benzene insolubles), asphaltenes (benzene soluble, n-pentane insolubles) and oils (n-pentane solubles) by successive extractions with benzene and n-pentane. The variations in coal conversion and soluble product composition were investigated with respect to the extraction conditions. The conversion was low below 350 °C but high above 375 °C. As the conversion of the lignites increases, transformation of tetralin to naphthalene also increases. An increase in extraction period affects the product composition but not the percentage conversion, at temperatures of 400 °C and above. In general, the effect of type of gaseous atmosphere on the total conversion was minor. Depending on the extraction conditions, however, the gaseous atmosphere affected the soluble product composition. © 1992. |
|