چكيده به لاتين
Abstract:
Duo to pollution from sulfur and sulfur compounds, strict regulation have been imposed in sulfur content of transport fuels. The development of an effective method for desulfurization of transport fuels to produce ultr low sulfur fuel is very important issue for the petroleum refining industry. Hydrodesulfurization (HDS) is conventional desulfurization process in which operation at high temperature and pressure is required. High cost of hydrogen and high operating conditions of temperature and pressure and Safety issues, Makes the process is costly and difficult. To meet new standards, several alternative desulfurization have been proposed, including adsorptive desulfurization, biological desulfurization and oxidative desulfurization and so on. Oxidative desulfurization is a promising alternative in which sulfur containing compounds are oxidized by oxidizing compounds at first and separated by conventional separation process such as adsorption and extraction. One the best oxidation system is hydrogen peroxide and formic acid. Mild operation condition, inexpensive oxidant and catalyst the advantage of oxidative desulfurization process. The ultrasound irradiation incease the efficiency of oxidative desulfurization process. The shock wave generated by ultrasound waves, causing turbulency and increase surface area and mass transfer between two phases. In the present study, oxidative desulfurization of model fuel under ultrasound was studied. Benzothiophene was dissolved in toluene as model fuel and oxidation system containing hydrogen peroxide and formic acid was used. The optimum condition of three parameters including reaction temperature (40-70 ˚C), oxidant to sulfur molar ratio (10-50) and acid to sulfur molar ratio (150-400) using the response surface methodology was examined. Analysis of BT concentration was carried out using gas chromatography. Experiments were carried in Frequency of 20 kHz, sonication time of 20 min and power of 250 W. In optimum condition, temperature of 52 ˚C, oxidant to sulfur molar ratio of 10.82 and acid to sulfur molar ratio of 379.75, oxidation of benzothiophene was 95.13%. In the obtained optimum condition, effect of power of sound and sonication time were examined in range of 70-350 W and of 1-20 min respectively, and in power of 70 W and time of 15 min, percent of removal was 98.063%. First-order kinetics of oxidation was observed and the apparent reaction rate constant for benzothiophene at temperature of 52 ˚C and acid to sulfur molar ratio of 379.75 was showed to be 0.2438 min-1.
Keywords: hydrogenation desulfurization, Oxidation desulfurization, ultrasound waves, Benzothiophene, Gas chromatography, First-order kinetic
