Abstract
Contents and rates of the sulfur sorption on the reduced iron from hematite and limonite were measured in the atmosphere of H2-H2S mixture of sulfur activity less than unity by combining the thermogravimetric method with the reaction interruption method. The sulfur content by the former was a half the content by the latter presumably owing to the sorbed sulfur exchanged with sorbed oxygen. In this study, the saturated content of sulfur, which is attained after enough long time, was estimated by the latter and the sorption rate was measured by the former. The equilibrium content was properly expressed by the Langmuir's isotherm. The simulation of the sorption rate by the parallel model, in which the diffusion of gas molecules in the pore and the diffusion of adsorbed species on the wall of the pore were taken into account, was tried. It was successful with the sulfur sorption of the reduced iron from limonite and the diffusion was mainly surface diffusion at 873 K, but it gradually shifted to the diffusion in pore with increasing temperature. But any trial was unsuccessful with that from the hematite. The reason may be attributed to, in the reduced iron from the hematite, the contribution of sulfur segregated on the grain boundary of reduced iron is significant relative to the total sorption content to the content of sulfur adsorbed on the surface pore.
