Exploration on the removal mechanism of sulfur ether model compounds for coal by microwave irradiation with peroxyacetic acid

The removal mechanism of sulfoether in coal by microwave with peroxyacetic acid, was determined by evaluating changes in sulfur containing compounds after desulfurization by XANES and GC/MS. The highest occupied molecular orbital composition, the electrostatic potential distribution, and the sulfur containing bond dissociation energy (BDE) of model compounds molecules were also determined to support the experimental results. Results showed that sulfoether was easily oxidized to corresponding sulfoxide or sulfone in treated samples. Although benzyl sulfides were more readily oxidized than disulfides, the latter was easier to remove due to the higher breaking probability of the SS bond. The sulfur atoms within sulfur ether in coal are the active sites for electrophilic reaction. As sulfur atoms were oxidized, the sulfur containing BDEs decreased considerably and the dipole moments of sulfoether molecules increased. These findings suggest that the removal efficiency of sulfoether in coal may be improved by moderate and selective oxidation under microwave treatment.