Effect of the Water-Vapor Content on the Oxidative Desulfurization of Sulfur-Rich Coal

Ukrainian sulfur-rich coal containing about 3.6 mass % of sulfur was studied. The desulfurization process was performed in the fluidized-bed reactor in dry (4 vol % of H 2 O vapor) and wet (30−70 vol % of H 2 O vapor) atmospheres in the temperature range of 350−450 °C. A significant influence of the water-vapor content in the reaction mixture on the sulfur removal during the oxidative desulfurization of the coal was observed especially at low temperatures. The extent of FeS 2 oxidation, the main sulfur-containing compound, was studied by Mössbauer spectroscopy. The Mössbauer data revealed different iron-containing products (FeSO 4 · n H 2 O, Fe 2 O 3, Fe 3 O 4, and Fe 1 - x S) formed in the course of the process carried out in dry and wet atmospheres. The promoting effect of water vapor on the pyrite transformation was observed especially at low temperatures. The mechanism of this promotion on the molecular scale was proposed.