Study of mechanism, kinetics, and product characterization of thermal and catalytic liquefaction of Northeastern Indian coals using supercritical toluene

Abstract

The present research aimed at the direct coal liquefaction (DCL) of three Indian coals with toluene and Fe₂O₃ catalyst within a temperature range of 400 ℃- 450 °C. The maximum overall conversion of 41.87 wt% and oil yield of 16.25 wt% was observed for lignite coal, at 60 min residence time and 450 ℃ for catalytic, with an increase of 6 % and 4.72 %, respectively, compared to that of thermal liquefaction. The activation energies were in the 40 kJ/mol to 370 kJ/mol range. The CO₂ levels peaked at 15.45 vol% for catalytic and 11.18 vol% for thermal DCL in the case of lignite coal. The hydrogen sulfide and carbonyl sulfide gases with maximum concentrations of 563 ppm and 230 ppm, respectively, were also detected. The oil possesses carbon chains ranging from C₈ to C₂₅, whereas both asphaltene and preasphaltene fractions extend to a broader range of C₈-C₃₀.