Sulfur behavior in rapid pyrolysis of coals with chemical pretreatments

Lignite, subbituminous, and bituminous coals were pyrolyzed rapidly in a free-fall reactor under a nitrogen stream at 1253 K in order to clarify pyrolysis desulfurization behavior. Chemical pretreatments were carried out to search the efficient desulfurization. X-ray absorption near edge structure (XANES) was applied to the direct determination of the sulfur forms. XANES analysis indicated that lignite contained disulfide, which could contribute to the high extent of organic sulfur removal. Sulfone and sulfoxide formed by the pretreatments might also contribute to efficient desulfurization.