Influence of ionic liquid pretreatment on coal desulfurization

Combining ionic liquid pretreatment with H2O2 oxidation desulfurization to remove sulfur from coal is a very valuable subject. In this work, three different types of ionic liquid were used to pretreat coal samples, and then the pretreated coal was treated by 30% H2O2 with the assistance of ultrasound, which is compared with the desulfurization effect of raw coal with the same method. The swelling characteristics and contact angle changes of coal samples before and after pretreatment were measured, and the samples before and after pretreatment were characterized by BET, SEM, TG. And the form sulfur changes of coal samples before and after being treated were determined by chemical methods, FT-IR and XPS were used to determine the sulfur-containing functional groups and the sulfur morphological change of coal samples before and after treatment, and different types of ionic liquid recovery experiments were also carried out. The results show that the ionic liquid pretreatment had a swelling effect on the coal samples and improved the wettability of the coal samples. The ionic liquid pretreatment increased the specific surface area and average pore size of the coal sample, as well as the coal particle gap increases, cracks developed on the coal surface. The characterization of the desulfurized samples find that the desulfurization rate of the ionic liquid pretreated coal treated by H2O2 with the assistance of ultrasound was significantly increased compared to the raw coal under the same conditions. Ionic liquid pretreatment promoted coal desulfurization, and more sulfur in coal was removed. The ionic liquid recovery experiments reveal that ionic liquid could be stably recovered, the FT-IR characterization experiment of ionic liquids indicate that the recovered ionic liquid had no obvious change of structural properties compared to the fresh ionic liquid.