Desulfurization reaction model and experimental analysis of high sulfur coal under hydrogen atmosphere

The reaction between hydrogen and high-sulfur coal at high temperature was investigated. Crashed and sieved high-sulfur coal sample was placed in a 23 mm I.D. differential reactor. The release of hydrogen sulfide at run temperature and under different hydrogen atmospheres was recorded by a hydrogen sulfide detector. Desulfurization yield was obtained through the elemental analysis of residual char. The grain reaction and random pore models were modified to facilitate the description of reaction kinetics characteristics. Hydrogen was observed to promote the desulfurization rate considerably; i.e., more than 65% of sulfur in coal could be removed. The releasing curves of H2S in the hydropyrolysis process exhibited two peaks. The desulfurization process in the hydropyrolysis of high-sulfur coal could be regarded as two stages based on the evolution profiles of H2S. The first peak at 250–450 °C was derived from the desulfurization of aliphatic sulfide. The second peak at 450–650 °C was produced from the sulfur in pyrite and aromatic thiophenic structure. The desulfurization of high sulfur could be described more effectively with the grain reaction model than with the random pore model. The random pore model was only adopted in the initial stage of sulfur removal of high-sulfur coal under hydrogen atmosphere. The grain reaction model was adequate for the entire stage.