Characterization of tars from Estonian Kukersite oil shale based on their volatility

Evaporation of primary tar during fossil fuel pyrolysis is one of the processes that can influence yield and composition of pyrolysis products. The objective of this paper was to illustrate the volatility of oil shale primary pyrolysis tars. The focus was on the less volatile heavy end of the tar. The primary tar for study was produced from pyrolysis of Estonian Kukersite oil shale. A portion of the tar was fractionated into six fractions according to their volatility via vacuum sublimation at 10−5 torr. Several different experimental methods were employed to study tar vaporization and the relationships between tar volatility and tar characteristics such as molecular weight distribution and molecular heterogeneity. Elemental and infrared analysis, TG/MS and field ionization mass spectrometry (FIMS) were used for tar characterization in this investigation.