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

The thermal behaviors of pure pyrite are studied under nitrogen and hydrogen atmospheres in a pressurized thermal balance. The transfer of pyrite in coal during pyrolysis and hydropyrolysis is investigated in a fixed-bed reactor. The results suggest that the indigenous hydrocarbon with hydrogen donor ability in coal can promote the reduction of pyrite in pyrolysis. At low temperatures, organic sulfur removals are almost the same in pyrolysis and hydropyrolysis of two coals. It is likely that indigenous hydrogen in coal is the dominant factor in organic sulfur elimination in the low-temperature stage. An increase 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. Oxygen affects the conversion of pyrite into organic sulfur through the competitive consumption of hydrogen. (C) 2000 Elsevier Science Ltd. All rights reserved.