Transformation and regulation of sulfur during pyrolysis of coal blend with high organic-sulfur fat coal

Sulfur transformation and distribution during pyrolysis of an industrial coking coal blend with a high organic-sulfur fat coal was studied in a fixed-bed reactor. Sulfur K-edge X-ray absorption spectroscopy was used to study the sulfur speciation in cokes. Two coals with high volatiles were selected to regulate the sulfur transformation behavior during pyrolysis and the interactions between volatile matters and nascent cokes were investigated. The addition of high organic-sulfur fat coal to coal blend resulted in the increase of sulfur content in coke, but the desulfurization rate also increased during coal blend pyrolysis. Higher amount of sulfur-containing radicals in volatile matters from high organic-sulfur fat coal promoted the interactions with nascent coke and resulted in the higher sulfur retention on the coke surface. Adding high volatile coal into coal blend affected the interactions between different coals and the sulfur transformation. The interactions between sulfur-containing radicals and nascent coke could be inhibited by volatile matters from high volatile coals. Further characterizations confirmed that the volatile matters from high volatile coal, which had a more overlapping temperature range to sulfur release in coal blend, leading to the lower sulfur content in coke, higher desulfurization and weaker S K-edge spectral intensity. The interactions between external volatile matters and nascent coke primarily occurred on the coke outer surface.