Oxidative-extractive desulfurization of liquid fuel using stannous chloride-acetic acid mixture as catalyst

摘要

Present study reports catalytic oxidative-extractive desulfurization (COEDS) of model oil (dibenzothiophene (DBT) dissolved in iso-octane) using an acid mixture (composed of Lewis acid and organic acid (glacial acetic acid)) as catalyst and inorganic oxysalt, potassium dichromate, as oxidant. A series of acid mixtures were prepared by mixing different amount of Lewis acids (SnCl2, CaCl2 or CuCl2) in specific amount of acetic acid and tested for the removal of sulfur from model oil. SnCl2, which performed best as a Lewis acid, was used in further studies. Effect of Lewis acid to sulfur (molar) ratio was studied in the range of 1-5. Effects of other parameters i.e. oxidant to sulfur (O/S) molar ratio, temperature and time on desulfurization efficiency were also investigated. Fourier transform infrared (FTIR) spectroscopy of SnCl2-CH3COOH mixture, model oil (before COEDS), raffinate and extract layers was carried out to understand the removal mechanism. Apparent activation energy for COEDS process with SnCl2-CH3COOH system was calculated as 11.65kJ/mol. At the optimized conditions of oxidant to sulfur molar ratio (O/S = 2:1) and Lewis acid to sulfur molar ratio (SnCl2/S = 5:1), maximum 61.3% sulfur removal was observed from model oil containing 1000ppm of sulfur at 308K.