Effect Of Oxidation Reaction On The Structure Of Vacuum Residue And Desulfurization

With the emergence of the increasingly heavy,inferior,and high-sulfur crude oil,and the increasingly strict environmental protection regulations for sulfur mass fractions,further development of residue deep processing technology is required,and there is an urgent need for low-cost and desulfurization technology that can improve the quality of residue.Because the traditional hydrodesulfurization technology has the problems of large equipment investment,high operating cost and harsh operating conditions,and the oxidative removal of sulfide in the residual oil is simple to operate and the conditions are mild,which can reduce the hydrodesulfurization conditions due to steric hindrance.Condensed thiophene sulfides?such as DBT,4,6-DMDBT?that are difficult to remove are oxidized to sulfoxides and sulfone sulfides,and then combined with thermal decomposition process to remove sulfides.At present,the oxidative desulfurization technology of oil products is mainly aimed at light oils such as gasoline and diesel.However,there are few studies on the oxidation methods of heavy oils,especially vacuum residues.The composition of vacuum residues is very complicated,which leads to the desulfurization process.There are fewer studies on internal changes,Therefore,it is necessary to carry out research on the structural composition and sulfur distribution changes during residue oxidation.This thesis focuses on the change of the oxidation depth in the oxidation reaction on the subcomponents and sulfur distribution of vacuum residue,discusses the reaction mechanism,investigates the effect of oxidation on the structure of vacuum residue,and finally removes the decompression in combination with the thermal cracking process.Sulfide in residue oxidation oil.?1?First,study the properties of raw oil and the distribution of sulfides.Using CNOOC vacuum residue as raw material,tetrabutylammonium perchlorate?TBAP?and KIO₃as oxidant to selectively oxidize sulfide in vacuum residue.The results show that TBAP is used as the oxidant to determine the sulfur in the feed oil is about 20.47%is thioether sulfur,thiophene sulfur content is about 79.53%,thiophene sulfur is the main type of sulfur compounds in the feed oil.?2?Then study the change of oxidation depth on the distribution of subcomponents of vacuum residue and the distribution of sulfur in subcomponents.The CNOOC vacuum residue was oxidized with hydrogen peroxide.Fourier transform infrared spectroscopy?FTIR?and X-ray photoelectron spectroscopy?XPS?were used to analyze the changes of sulfide types.the influence of oxidation depth on the content of four subcomponents of saturated,aromatic,resin and asphaltene and sulfur distribution in vacuum residue was determined.The results show that sulfur compounds in vacuum residue are mainly sulfides and thiophenes,which were mainly converted into sulfoxide and sulfone after oxidation treatment;oxidation has little effect on the saturated content in the subcomponent of residue,but the sulfur content is significantly reduced;the aromatic and asphaltene content are reduced,and the sulfur content is also reduced;the asphaltene content is significantly increased,and the sulfur content is also increased.The research results are helpful to further improve the understanding of the sulfide oxidation law in vacuum residues.?3?Using nuclear magnetic resonance hydrogen spectroscopy?¹H-NMR?and modified B-L method,the average molecular structure parameters of residual oil were calculated,and the overall structure of the residue before and after oxidation was analyzed.The results show that the residue after oxidation has a high degree of aromatization,and the condensation is the main one.?4?Finally,using thermal cracking method to remove sulfide in vacuum residue oxidized oil,and combined with FTIR and XPS for characterization analysis.The results show that after thermal decomposition reaction,the S element content in thermal cracking residue decreased from 4.53%to 3.42%,the desulfurization rate reached 24.50%.