Sorption phenomena of methanol on Taiheiyo coal heat treated to 125℃ were investigated by repeated uptake and desorption experiments. From the isotherm changes, it is concluded that larger amount of methanol was sorbed in the 1st run for the sample re-heated at 70℃ compared to the case of both the 1st and the 2nd run for the sample re-heated at 125℃. Heat of sorption and the rate of vapor pressure change during sorption process are almost the same in the 1st and the 2nd run for the sample re-heated at 70℃. It is indicated that a small amount of methanol, which is detached from the sample after re-heated at 70℃, did not interact with the sample so strong. However, some amount of methanol, which might desorb after re-heated at 125℃, still remained in the sample interacting strongly at 70℃. Change in the rate of methanol sorption occured only with the existance of methanol which has strong interaction with a certain site in the coal sample.
