Tetralin-glycerol as Solvent in Direct Liquefaction of Mukah Balingian Coal

Coal liquefaction is a process of converting solid coal into liquid form at high temperature and pressure with the role of solvent as hydrogen donor. Tetralin is the common solvent used in this process; however its high cost made it less favourable to be utilised in industrial field. Moreover, mainly high aromatic compounds were observed in the oil produced. Therefore, introducing a less expensive solvent for coal liquefaction process is very encouraging in order to reduce the operational cost involves. The aim of this work is to investigate the potential use of mixed tetralin-glycerol as solvent on liquefaction of Mukah Balingian (MB) coal in a batchwise reactor system. Solvent ratio of tetralin-glycerol, liquefaction temperature and reaction time were varied to evaluate their effect on percent of coal conversion and oil yield. Apparently, the results obtained showed that the maximum coal conversion was obtained at 70:30 tetralin-glycerol mixed ratio regardless of reaction time with the value over 70%, whereas the highest percent of oil yield at ca. 50% was produced with 80:20 tetralin-glycerol mixed. Interestingly, GC-MS analysis of oil produced with mixed solvent showed mainly the presence of alkanes and alcohols which was not obtainable by using tetralin or glycerol alone as solvent.