Study on the desulfurization effect of coal by microwave-Fenton system

BACKGROUND Microwave-assisted and Fenton reagents were combined to enhance the removal effect of sulfur from coal. The coal samples before and after desulfurization were characterized by various testing methods such as X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. RESULTS The microwave-Fenton system showed the best desulfurization effect with a desulfurization rate of 77.52% at a microwave power of 800 W and irradiation time of 5 min, which was 82.96% higher than the maximum desulfurization rate of Fenton reagents alone. The desulfurization rates of pyrite sulfur, organic sulfur and sulfate sulfur can reach 88.76%, 58.77% and 59.33%, respectively. CONCLUSION The minerals in the treated coal samples were significantly reduced. The microwave-Fenton system can generate a large number of hydroxyl radicals to break the C-S bond, while exposing more sulfur-containing groups to the reagents, resulting in more oxidation of low-valent sulfur and sulfoxide to high-valent sulfone and sulfate sulfur. The model compound removal effect was measured, dibenzyl sulfide > diphenyl sulfoxide > diphenyl sulfoxide > dibenzothiophene, while the microwave-Fenton system could significantly enhance the desulfurization effect of the above four model compounds. It was found that with the increase in applied electric field, the reaction energy barrier decreased and the C-S bond was more easily broken, which was favorable to the reaction. (c) 2022 Society of Chemical Industry (SCI).