The CO_2 gasification of Taiheiyo coal char with different formation processes was conducted at 1073K in a fixed bed to investigate the dependence of gasification reactivity on the formation history of char, such as, the cooling and exposure of char to air before gasification. The reactivity degradation of the char undergoing cooling and exposure to air was observed, and could be attributed to the decrease in reactive site of the char by temperature-programmed desorption spectra of CO_2 and CO.
