Study On Forms And Conversion Behavior Of Sulfur Structures Of MR-Residue Heavy Components By XANES

Heavy oils contain a lot of macromolecules,which also contain a lot of heteroatoms,such as sulfur,nitrogen,oxygen and various metal elements.So asphaltene and resin molecules have obvious polarity.Through quantitative analyzing sulfur structures of asphaltene and resin molecules of MR-residue,the conversion behavior of sulfur at different time,hydrogen-oil ratio,pressure and reactor outlet in hydrogenation thermal reaction is studied and the relationships among sulfur structures,polarity and association are analyzed.XANES spectra of sulfur functional groups of asphaltene and resin are acquired by synchrotron radiation.Through analyzing qualitatively by higher derivative spectra and quantifying by gauss curve fitting,the results showed that the forms of sulfur structures are similar in heavy different components,including mainly thiophene,sulfoxide,sulfone,and sulfate.With the prolongation of hrdrogenation reaction,the absolute content of thiophene,sulfoxide and sulfone of heavy components decreased gradually,while the absolute content of sulfate increased gradually.The results showed that the activity of reduced sulfur and intermediate sulfur was higher and they were removed easily.In contrast,the activity of oxidized sulfur was low,indicating that they were difficult to be removed.Through determining refractive index,dielectric constant and relative molecular weight in toluene solution,the average dipole moments of heavy components were calculated.The polarity of asphaltene and resin is characterized by the average dipole moment.The results showed that the polarity is related to sulfur absolute content of asphaltene in hydrogenation reaction.As sulfur content increased,the polarity of asphaltene increased.The change trend of the polarity is similar to the change trend of the reduced sulfur content in asphaltene.Through analyzing the data of ~1H-NMR of heavy components,the average structure parameters are calculated.The association of asphaltene and resin is characterized by the average structure parameters.The results showed that the association is related to sulfur absolute content of heavy components in hydrogenation reaction.As sulfur content decreased,the association of asphaltene and resin decreased.The change trend of the association is similar to the change trend of the reduced sulfur content in asphaltene.