Experimental study on desulfurization by ionic liquids/H₂O₂ system

Four different kinds of ionic liquids(ILs), namely, 1-butyl-3-methylimidazolium bromide(BmimBr), 1-butyl-3-methylimidazolium tetrafluoroborate(BmimBF₄), 1-butyl-3-methylimidazolium hydro-sulfate(BmimHSO₄), and 1-butyl-3-methylimidazolium dihydrophosphate(BmimH₂PO₄) were selected to add to the H₂O₂ solution (30%), respectively, to obtain four mixed solutions. Then, two kinds of deashed high-sulfur coal (LS, QX) desulfurization experiments were tested with above mixed solutions under mild conditions, respectively. The contents of different sulfur forms in coal samples before and after desulfurization were determined by wet chemical method, and the coal samples before and after desulfurization were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and thermogravimetric (TG). The results show that the addition of ionic liquids can make the H₂O₂ oxidation desulfurization ability enhance, and pyrite sulfur and organic sulfide sulfur in coal are obviously removed. After treated by the ILs/H₂O₂ system, the small size particle decreases, the space among the particles increases, and the pits on the coal surface become obvious. Moreover, the thermogravimetric test results show that the total weight loss of the coal sample treated by the ILs/H₂O₂ system increases and the peak temperature of some volatile substances lowers.