Phenylpropanoic acid-based DESs as efficient extractants and catalysts for the removal of sulfur compounds from oil

A series of Bronsted-Lewis acidic deep eutectic solvents (DESs) of C9H10O2 center dot XZnCl2 (X from 0.5 to 3) were synthesized by simple mixing. The DESs were characterized by infrared spectroscopy, electrospray ionization mass spectrometry, and thermogravimetric analysis. The desulfurization of a model oil was investigated using C9H10O2 center dot XZnCl2 as the extraction agent and catalyst, and H2O2 as the oxidant. The effects of the molar ratio of phenylpropanoic acid to zinc chloride, reaction temperature, oxygen to sulfur (O/S) molar ratio, and volume ratio of DESs to oil on the desulfurization rate were investigated. The optimal conditions for desulfurization were determined to be a phenylpropanoic acid to zinc chloride ratio of 2: 1, a reaction temperature of 50 degrees C, an O/S ratio of 6, a DESs to oil volume ratio of 0.25: 1, and a model oil dosage of 5 mL. Under the optimal conditions, a desulfurization rate of 99.23% in 80 min was achieved. The recyclability of the DESs was also investigated, and the results showed that the desulfurization rate decreased slightly after five runs. These results demonstrate that C9H10O2 center dot 0.5ZnCl(2) DESs exhibit high desulfurization activity and stability in extraction and oxidation desulfurization systems. (C) 2016 Elsevier Ltd. All rights reserved.