It has been reported that the prethermal treatment with hydrogen-donor solvent and/or catalyst could be effective to increase oil yield on brown coal liquefaction. In this paper, prethermal treatment conditions in the initial stage of liquefaction were investigated by using the process solvent and iron-based catalyst in relation to the hydrogen transfer from solvent or catalyst to coal. In the initial stage of liquefaction, highly yield of HS (n-hexane soluble) fraction was obtained by using hydrogen-donor solvent. High H/C value of THFI (THF insoluble) was obtained by adding γ-FeOOH as catalyst, resulted in higher HS yield. It was considered that the combination of hydrogen-donor solvent and highly active catalyst such as γ-FeOOH in the prethermal treatment stage is quite effective to increase oil yield.
