Compared with the decomposition of pure pyrite in nitrogen, the initial decomposition temperature of the coal-derived pyrite is nearly lower by 100 ◦C [7,44,45]. It suggests that the indigenous hydrocarbon with hydrogen donor ability in coal can promote the
reduction of pyrite, though the overall deficit of hydrogen makes the thermal decomposition reaction of pyrite to prevail in pyrolysis [2]. Therefore, the thermal decomposition of the coal-derived pyrite is a complex process due to involving several steps of heat and mass transfer.