Effects of active hydrogen and oxygen on organic sulfur transformation behavior during pyrolysis of high sulfur coal: A review

With consumption of high quality coal resources, clean and efficient conversion of high sulfur coal has attracted much attention, and especially the regulation of organic sulfur in high sulfur coking coal is very important. During pyrolysis transformation of organic sulfur in coal begins with cleavage of C-S bonds in the macromolecular structure of coal and stabilization of sulfur-containing free radicals, and active hydrogen/oxygen is an important factor affecting the transformation behavior of organic sulfur. It is found that, during coal pyrolysis under hydrogen-enriched or oxygen-enriched atmosphere or co-pyrolysis with biomass or oxygen-containing organic matter, the active hydrogen/oxygen in the system can weaken C−S bonds of organic sulfur, and promote their cleavage, timely combination with the generated sulfur-containing free radicals. This can promote sulfur in coal transform to the gas phase and reduce the secondary reaction of sulfur-containing free radicals with coal matrix. At the same time, during co-pyrolysis of high volatile and high sulfur coals, the relatively abundant active hydrogen/oxygen in volatile will also affect the organic sulfur transformation behavior in high sulfur coal, and reduce the sulfur content in coke, which provides a theoretical basis for directional regulation of sulfur in coal.