Decomposition of pyrite and the interaction of pyrite with coal organic matrix in pyrolysis and hydropyrolysis

The thermal decomposition and reduction behaviors of pure pyrite crystals are studied under nitrogen and hydrogen atmosphere in a pressurized thermalbalance. The formation of nonstoichiometric sulfide, pyrrhotite, is influenced by nitrogen pressure. The indigenous hydrocarbon with hydrogen donor ability in coal can promote the reduction of pyrite. An increasing of organic sulfur in pyrolysis of Hongmiao coal indicates that the lack of the indigenous hydrogen may be the key factor determining the transformation of pyritic sulfur into organic sulfur. At low temperature, organic sulfur removals are almost the same in pyrolysis and hydropyrolysis. It is likely that indigenous hydrogen in coal is the dominant factor in organic sulfur elimination in this stage. Effects of external hydrogen gas are observed only at high temperature stage.