Effect of heating rate and temperature on pyrolysis desulfurization of a bituminous coal

Non-caking bituminous Ermelo coal was pyrolyzed using a fixed bed with thermogravimetric analyzer in a nitrogen stream at atmospheric pressure up to 1173 K with heating rate of 20–100 K/min. The desulfurization was assessed for final temperatures of 773–973 K. The sulfur content in residual char depended on the heating rate as well as the terminal temperature. Sulfur form analysis clarified that the change in total sulfur, which showed a minimum, was due to the change in organic sulfur during the course of pyrolysis. Sequential changes of sulfur forms at different heating rates were successfully simulated kinetically based on a proposed volume reaction model and desulfurization scheme which considers competing phenomena between the uptake reaction of hydrogen sulfide by the organic matrix and dispersion of hydrogen sulfide within a coal particle. Rapid pyrolysis using a free fall pyrolyzer confirmed that the high heating rate was favorable for sulfur removal from the solid phase.