Extraction of Oxidized Sulfur-containing Compounds from Gas Oil using Dimethylformamide and Dimethyl Sulfoxide: a Comparative Study

The combination of extraction methods and oxidative desulfurization due to high efficiency and good operating conditions can be considered as a viable alternative for conventional desulfurization methods. In this study, the oxidation/extraction desulfurization method was investigated to remove sulfur-containing compounds from gasoil fuel. Gasoil with a total sulfur content of 1550 ppm was selected as feed. Hydrogen peroxide-formic acid system was used as the oxidation system. The gasoil desulfurization and recovery after oxidation were 96.38% and 20.64%, respectively. Three polar solvents (i.e., acetonitrile, dimethylsulfoxide and dimethylformamide) were considered as potential candidates for the extraction of oxidized sulfur-containing compounds from gas oil. Acetonitrile solvent was rejected due to its low density close to gasoil density. Thus, the effect of solvent to fuel ratio (0.5-2) and number of extraction stages (1-3) were investigated for dimethylsulfoxide and dimethylformamide. It was found that the achieved desulfurization for dimethylformamide was higher than that of dimethylsulfoxide. But, the gasoil recovery after the extraction was higher for dimethylsulfoxide in comparison with dimethylformamide. The highest gasoil desulfurization and recovery were obtained 97% and 96%, respectively.