Devolatilization and kinetics of maceral concentrates of bituminous coals

The potential of achieving effective utilization for a given coal using maceral separation is dependent on the differences in thermal characteristics of its maceral concentrates. In this paper, vitrinite-rich and inertinite-rich concentrates were obtained from five bituminous coals with R_random ranging from 0.64% to 1.73% using a float-sink procedure. The devolatilization characteristics and kinetics of maceral concentrates were investigated using thermogravimetric analysis at the heating rate of 8 °C/min^{− 1} from 50 °C to 1200 °C. The devolatilization is comprised of three regions characterized by different weight loss rates. During principal devolatilization, inertinite-rich concentrates are characterized by similar initial temperature, slight greater temperature of maximum rate of weight loss, and greater terminal temperature. The maximum rate of weight loss and the index of volatile matter released decrease with an increase in rank; the lower the rank, the greater the differences between vitrinite-rich and inertinite-rich concentrates. The principal devolatilization displays the greatest apparent activation energy, followed by post-principal devolatilization, and the least for initial devolatilization. During principal devolatilization, the apparent activation energy difference of vitrinite-rich and inertinite-rich concentrates is higher in lower-rank coal and becomes almost zero at the R_random of 1.73%. The minimum activation energy and apparent activation energy were in detail discussed.