Effect of Coal Liquefaction Conditions on the Composition of the Product Oil

Two methods, catalyst physically mixing method (method I) and catalyst impregnation method (method II) were employed for Beypazarı and Tunçbilek lignites liquefaction. Fe₂O₃ and Mo(CO)₆ were used as the catalysts. Oils obtained at the end of the catalytic coal liquefaction were qualitatively analyzed by gas chromatography (GC). With solvent/coal ratio increase, compounds with straight chain and high molecular weight were formed. Likewise, as the reaction time and catalyst concentration were increased, the number and the intensity of the compounds in the oils increased partially. Due to the increase in the reaction time, temperature and catalyst concentration, the oils were enriched in straight chain alkanes and aromatic polycyclic compounds. However, alkanes with straight chain were reduced by the effect of pyrolysis at temperatures over 400°C. Retention times of the compounds obtained by method II were higher than those of the compounds obtained by method I. Respectively, the compounds in the oils obtained by method II were found to have been composed by high quantities of high molecular straight chain alkanes and aromatic polycyclic compounds. Our data gave us ground to presume that the oils from both lignites were composed by straight chain alkanes and aromatic polycyclic compounds (tetralin, naphthalene and their derivatives, phenols, xylenols, biphenyl, naphthols, etc.). The oil compositions were strongly influenced by the liquefaction conditions.

Keywords:

• lignite
• catalyst impregnation
• direct liquefaction
• oils
• gas chromatography
• characterization

Acknowledgments

It is a pleasure to acknowledge the support of this work (Project No: İ.Ü.B.A.P.B. 2002/08) by the Scientific Research Projects Unit of Inönü University.

Notes

*: Standard compounds available