Oxidation Extraction Desulfurization Of Visbreaking Diesel Fuel

There are many kinds of products in the refining of petroleum,but mostly used for fuel,like gas fuel,liquefied gas fuel,distillate fuel（gasoline,diesel and kerosene）and residual fuel.Diesel plays an important part in distillate fuel.In recent years the environment became more and more worse all over the world,therefore many countries have strictly required to impose restrictions on the sulfur content of fuel.Traditional hydrodesulfurization requires higher pressure,higher temperature and higher activity catalysts to make the requirements of low sulfur diesel production.But oxidized desulfurization can deeply desulfurize fuel at normal temperature and ordinary pressure,so oxidized desulfurization is considered one of the most promising desulphurization methods.Firstly,the sulfur composition of visbreaking cracked diesel oil was analyzed by GC-SCD,most sulfur compounds is thiophene（Th）benz othiophene（BT）and dibenzothiophene（DBT）derivatives in visbreaking diesel fuel.And the most abundant of sulfur content in diesel fuel is BT derivatives,the content of them reached above 90%.In the experiment,The oxidative property of ozone was analyzed by ozone oxidative simulating oil,BT was dissolved with octane as solvent in the preparation of simulated oil.The effects of oxidation temperature,the concentration of BT and ozone on the desulfurization rate of simulating oil.The results show that the reaction temperature of 40℃when O₃ oxidation effect best,high ozone concentration is beneficial to the oxidation of BT,high initial concentration of BT need longer time to reach high desulfurization rate.In this paper,Oxidation-Extraction process was used to desulfurize of visbreaking diesel oil,O₃ was used as oxidant,formic acid was used as catalyst,DMF was used as extraction agent and polar oxides such as sulfoxide and sulfone were extracted and separated from diesel oil by polar organic solvent.The effects of oxidation time,oxidation temperature,ratio of extractant to oil and amount of formic acid on the desulfurization rate of diesel oil in the reaction system were investigated,and the optimum reaction conditions were determined.The results showed that oxidation temperature was 50℃,oxidation time was 6h,formic acid and diesel quality ratio was 15%,the extraction temperature was 30℃,extraction time was 10min,the rest time was 15min,extraction series at one.In this case the sulfur content of visbreaking diesel oil decreased from 4980μg/g to 490 ug/g and the desulfurization rate was 90%.Finally,the desulfurization process of visbreaking cracked diesel oil was studied by one-step oxidation-extraction method.A reaction system consisting of O₃ as oxidant,acetone oxide and visbreaking diesel oil.The effects of oxidation time,oxidation temperature and amount of acetone on the desulfurization rate of diesel oil.The results showed that oxidation temperature was 25℃,oxidation time was 2.5 h and acetone and diesel quality ratio was 2:1.In this case the sulfur content of visbreaking diesel oil was drastically reduced,and the desulfurization rate was 91%,The activation energy of oxidation reaction was calculated to be 35.58kJ/mol.In the article,the basic properties of visbreaking cracked diesel oil before and after oxidation were investigated.Contrast analyze ofvisbreaking,the density of oxidized low sulfur diesel decreased slightly,the distillation range of diesel oil is basically unchanged,the cetane number is slightly higher,the kinematic viscosity decreased,the acidity and color have been greatly improved.The diesel oil before and after oxidation was compared and analyzed by infrared spectrum and GC-SCD chromatography.The aromatics in oxidized low sulfur diesel were removed,and the content of BT decreased significantly,Th and DBT has been basically removed,the sulfur content of diesel oil decreased from4980μg/g to 448 ug/g.