Glass transition temperature of Illinois No.6 coal was determined by differential scanning calorimetry to be 589K. In order to enhance the mobility of protons, the coal was heated to 623K beyond the glass transition at a rate of 5K/min. The coal was then directly transferred to a Curie-point pyrolyzer without exposure to air and was pyrolyzed at 1037K. The char yield was decreased to 59kg per 100kg of original coal, 3kg smaller than that of the original coal. This reduction was ascribed to the effective donation of hydrogen radicals to coal fragments, caused by the increase in proton mobility.
