| Because of the world is reducing vehicle fuel emissions of sulphur,so all environmental regulations are constantly strengthened and improved,the low sulfur vehicle fuel even the free sulfur vehicle fuel will be required in the market.At present,the sulfur content in gasoline and diesel oil also has more stringent requirements in China and In January 2017 the vehicle fuel has been fully implemented in the V standard around the nation,which asks the sulfur content of gasoline and diesel were not higher than 10?g/g.Therefore,it is of great significance to research and develop a deep desulfurization technology to get more efficient,clean and economical vehicle fuel.The non emulsifying electrochemical oxidation-extraction desulfurization experiment and emulsion electrochemical oxidation-extraction desulfurization experiment were applied to straight-run diesel desulfurization,and results showed that the electrochemical oxidation coupled with organic solvent extraction desulfurization method can effectively reduce the sulfur content in diesel oil.In the electrochemical oxidation process the sulfur compounds in strong oxidizing environment could be transformed into sulfoxide and sulfone compounds with high boiling point and strong polarity,then using organic solvent to extract polar sulfide out completely.With the operation conditions of mass fraction of 20%NaCI as the supporting electrolyte,a constant DC current of 500mA,the reaction temperature 55? the reaction time 105min,V(electrolyte):V(crude oil)ratio of 3,speed 700r/min,NMP extraction to desulfurization to raw diesel materials,can make the sulfiur content straight run diesel reduce from 624.4?g/g to 96.7?g/g,and the desulfurization rate reached 84.51%.In this system,adding some surfactant into the electrolytic system so that water and oil can be emulsified formation,the electrochemical process oxidative desulfurization could be enhanced,so as to enhance the effect of desulfurization of diesel.The experimental results showed that the addition of surfactant can significantly improve the electrochemical oxidation desulfurization rate,when the addition of KHD303 surface active agent reached 5000?g/g can make the sulfur content of straight run diesel decreased to 8.1?g/g in emulsion system,and the desulfurization rate of up to 98.70%,which can meet the national standard V.Achieving deep desulfurization of straight run diesel oil in emulsion electrochemical oxidation-extraction process.The analysis also found that the effect of non emulsion extraction desulfurization process of electrochemical oxidation between emulsion extraction desulfurization process of electrochemical oxidation has great difference in the same operating conditions,and the order,reaction rate and activation energy of the two kinds of oxidation desulfurization reaction were studied.The results showed that the oxidative desulfurization reaction is the first the reaction.When the temperature reached 45 C,the oxidation rate constant of emulsion/non emulsion system was 0.0199 min-1,0.0179 min-1,respectively.When the temperature reached 55?,the oxidation rate constant of emulsion/non emulsion system was 0.0375 min-1,0.0346 min-1,respectively.According to Arrhenius's law,the apparent activation energy of sulfur compounds in the raw oil is obtained that Ea(emulsion),=6.9783(kJ/mol)and Ea(non emulsion)=9.1826(kJ/mol).Finally,carried on the preliminary exploration for the reaction mechanism of emulsifying electrochemical oxidation to straight run diesel with the model compounds containing in diesel oil.The experimental results showed that the model of sulfide was oxidized to strong polar and high boiling point sulfone compounds in the electrochemical oxidation process. |
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