Hydrogen bonding boosted oxidative desulfurization by ZnCl2/boric acid/polyethylene glycol-based ternary deep eutectic solvents

Deep eutectic solvents, as the novel and green solvents, are widely applied in various fields because of its unique and excellent quality, such as simple synthesis, non-toxic, biodegradable, wide range of liquids and strong solvation ability. In this work, a series of ternary deep eutectic solvents were synthesized using ZnCl2, boric acid (BA) and polyethylene glycol (PEG) with appropriate molar ratios by hydrogen bonds. Compared with binary DESs, ZnCl2/2BA/2PEG showed a better desulfurization performance, and 98.7 % sulfur removal was achieved. The hydrogen bonding interaction is considered as the key factor to the formation of DES and to promote the desulfurization reaction. In addition, BA and ZnCl2 play a synergistic and positive role in the desulfurization system. The DES was immiscible with fuel and could be reused for six cycles without a significant reduction in activity. The possible mechanism of the positive effect of hydrogen bonding interaction and O2•− free radicals was proposed. This work offers more possibility for designing new types of DESs for deep desulfurization of fuel oils and other applications in relation to extraction or catalysis.