Coal-derived Products Research Articles

Reduction of viscosity of coal-derived products using CO2☆

Reduction of viscosity of coal-derived products using CO2☆

Selective heavy-atom perturbation for analysis of complex mixtures by room-temperature phosphorimetry

The technique of selective external heavy-atom pertubation (SEHAP) is applied to improve room temperature phosphorescence (RTP) analysis of complex samples. It is demonstrated that heavy atoms can selectively increase the phosphorescence emission of specific components in mixtures. The usefulness of many heavy-atom perturbers has been investigated for a wide variety of polynuclear aromatic compounds of environmental interest in coal-derived products. The SEHAP technique extends the analytical possibilities of RTP analysis since targeted components in complex samples can be selectively monitored. 9 figures, 4 tables.

Solvent extraction of coal-derived products

Procedure described should provide an analytical separation of three or four major solvent-defined solubility fractions from the multicomponent coal-derived oil. Separation is carried out below room temperature with solvents of increasing orientation solubility (polarity) parameter. One liter of solvent per fraction per 3g of starting material appears to be sufficient to define the separation. A pretreatment step has also been introduced by freezing the oil in liquid nitrogen, the resulting solid can be ground into a fine powder of great surface area, which contributes to the efficient extraction of the pentane soluble material at the onset of the procedure. Subsequent extractions include the use of benzene which dissolves asphaltenes; tetrahydrofuran or methylene chloride-methanol, which removes the preasphaltenes. The final residue is removed, washed and dried. The term preasphaltenes is used to reflect a class of solvent defined substances. The procedure has been described as having been effective in research efforts to provide reliable results of solvent separated fractions from coal-derived oils in less than 6.5 h on 3-4 g of material. One table shows weight percents of a number of coal liquefaction products ranging in viscosities from 100 to greater than 300 centistokes (70/sup 0/C). Samples of this kind aremore » also known to age under certain conditions of temperature and excess oxygen, causing changes in relative amounts. This summary has been designed as a guide for future development of a common method of separation and characterization of coal liquids. 2 tables, 1 figure.« less