Improvement of oil yield and its distribution from coal extraction using sulfide catalysts

Extraction of Mae Moh lignite using toluene–tetralin mixture was performed in a batch reactor at a temperature range from 370 to 490 °C and under initial hydrogen pressure up to 12 MPa. Experiments were carried out to investigate the effects of temperature and initial hydrogen pressure on coal conversion, liquid yield and liquid composition. The effect of catalysts Fe2S3, Fe/Ni and Ni/Mo impregnated into activated carbon was also studied. In the absence of a catalyst, the oil yield decreased with temperature above 410 °C and the content of naphtha and kerosene increased while light gas oil and gas oil decreased with increasing temperature. The presence of catalyst would benefit the formation of lighter components, kerosene and light gas oil. Extraction in the presence of Ni/Mo catalyst, the liquid yield reached 64.6 wt% (daf) which included naphtha 2%, kerosene 72.8%, light gas oil 14.9%, gas oil 2.4% and long residue 7.9%. For GC–MS analysis, the fraction of kerosene was composed of tetralin, naphthalene, dodecamethyl-cycloheptasiloxane, methyl dodecanoate, tetradecamethyl-cycloheptasiloxane, ethyl dodecanoate, methyl tetradecanoate and dibutyl phthalate.