Catalytic Oxidation and Desulfurization of Calcium-Hydroxide Gypsum Wet Flue Gas Using Modified MIL-53(Fe)

MIL-53(Fe) was prepared and modified with benzoic acid to prepare MIL-53(Fe)-BA additive, which was used to improve the catalytic oxidation rate of sulfite, prevent the scaling of the desulfurization tower, and improve the desulfurization efficiency during the wet flue gas desulfurization (WFGD) process of power plants. MIL-53(Fe)-BA exhibits abundant Lewis acid sites because of the appearance of coordination unsaturated Fe atoms. Due to the excellent sorption capacity, Ca(OH)2was used as the main SO2desulfurizer. The composite desulfurizers were prepared by mixing MIL-53(Fe)-based additives and Ca(OH)2, and were characterized by SEM, XRD, and FT-IR. A desulfurization unit was set up at laboratory scale to study the effect of catalytic oxidation additives on sulfite oxidation and desulfurization efficiency. The results showed that the addition of MIL-53(Fe)-BA can increase the oxidation capacity of sulfite by 159%, and greatly improve the desulfurization efficiency. These composite desulfurizers broaden the adaptability of the desulfurizing system to high-sulfur coals, and provide support for improving the desulfurizing efficiency of power plants.Keywords:catalytic oxidation;oxidative desulfurization;wet flue gas desulfurization;calcium hydroxide;MIL-53(Fe);Lewis acid sites