چكيده به لاتين
Due to the requirement of the stringent rules for ultra-low sulfur content of hydrocarbon fuels in the world and Iran, it is necessary to develop alternative methods for desulfurization of fossil fuel. The ultrasound-assisted oxidative desulfurization (UAOD) process has great potential as an unconventional method for this target. The main concern to develop the oxidation desulfurization systems is their long reaction time. In this research, among different oxidation schemes hydrogen peroxide-formic acid has been selected. Response Surface Methodology has been applied to find the optimum conditions of UAOD process and also to study the influences of the operating parameters like oxidant to sulfur molar ratio (no/ns), acid to sulfur molar ratio (nacid/ns), power per fuel oil volume, temperature and reaction time. An experimental investigation was conducted on the ultrasound-assisted oxidative desulfurization (UAOD) of a sulfur containing compound (i.e., dibenzothiophene 500 ppmw) in toluene as a model light fuel oil. More than 97% sulfur conversion was achieved under the optimum conditions (i.e., oxidant to sulfur molar ratio of 26.7, acid to sulfur molar ratio of 74.6, ultrasound power per fuel oil volume of 7 W/mL, and temperature of 50 °C). One of the novel achievements through the current work results was 95% sulfur conversion, which has been achieved in only 80 seconds sonication under the optimum reaction conditions. Consequently, based on these results and using RSM, an experimental investigation was conducted on the ultrasound assisted oxidative desulfurization (UAOD) of non-hydrotreated kerosene with total sulfur content of 2490 ppmw. The influences of various operating parameters have been investigated. 95.46% sulfur removal of kerosene has been achieved in the sonication time of 10.5 min under the optimum oxidation conditions (i.e., no/nS =15.02, nacid/ns= 107.8, and the ultrasound power per fuel oil volume of 7.6 W/mL) followed by a liquid-liquid extraction stage. The effect of number of extraction stages and temperature on the desulfurization has also been investigated. Meanwhile, a new method for reduction of hydrocarbon loss through kerosene recovery stage has been proposed. Afterward, in a novel study, the effects of static pressure in the direct probe UAOD system was investigated for the kerosene, which shows a slight improvement in oxidative desulfurization. 96% sulfur removal of kerosene has been achieved in the optimum conditions (i.e., pressure of 0.03 barg, ultrasound power of 390 W, and sonication time of 22 min).
