Coal liquefaction using semi-continuous solvent flow two-stage reactor system: Optimizing using response surface methodology (RSM)

Response surface methodology (RSM) was applied to optimize the condition for liquefaction process of Mukah Balingian (MB) low-rank Malaysian coal by using semi-continuous solvent flow two-stage reactor system. The reaction was performed by using tetralin as the solvent. A central composite rotatable design (CCRD) was employed to optimize the effect of three important reaction variables, i.e. flow-rate (ml/min), reaction time (min) and Ni loading (wt.%). A total of 20 experiments were conducted. It was concluded that the liquefaction should be carried out under solvent flow-rate of 1.12 ml/min, reaction time of 60 min and 5 wt.% of NiSiO₂ loading. Under the optimum conditions, the corresponding response value for oil+gas yield was 71.25 %.