Molecular Composition Of Ruthenium Ion Catalyzed Oxidation Products Of Petroleum Fractions: Characterized By Electrospray Ionization Fourier Transform Ion Cyclotron Resonane Mass Spectrometry And Gas Chromatography Mass Spectrometry

Molecular structure of heavy oil is a controversial issue in petrochemical field.Ruthenium ion catalyzed oxidation(RICO)is an avaiable approach to investigate heavy oil molecular structure.The information of aromatic-attached alkyl side chains and bridge chains between the aromatic nucleus can be obtained by analyzing the molecular compositions of the oxidation products of heavy oil.Traditional methods in the analysis of the oxidation products is by gas chromatography(GC),but the composition information reflected by GC is not complete.In this paper,we study molecular composition of RICO products combined with electrospray ionization(ESI)Fourier transform ion cyclotron resonance mass spectrometer(FT-ICR MS),and optimize the RICO experimental conditions based on the results.Then we used RICO reaction to study structure and composition of alkyl side chains and bridge chains of different heavy oil and different distillates.ESI FT-ICR MS analytical results revealed that the molecular composition of the RICO reaction products is very complex.There are a large number of components which haven't been detected by conventional gas chromatography,including hardly volatile macromolecular compounds and a number of heteroatomic compounds,which has an important meaning for interpretation of heavy oil molecules composition.We found that under classical RICO experimental conditions,obvious overoxidation phenomenon happened to the reactant.A 24-hour reaction time ensured adequate reaction of aromatics,but caused some reactants and products further oxidized to the multi-oxygen compounds.Through the study of reaction conditions,we find that the 1-hour reaction time can not only give a suitable reaction conversion rate,but also can greatly limit the side reactions.By RICO reaction,we studied composition of alkyl side chains of crude oil and its narrow cuts.We found that in conventional crude oil,alkyl-substituted on the aromatic core inclined to mono-substituted and n-alkyl side chains substituted.While in biodegradable crude oil,the alkyl side chains suffered serious degradation,so in its corresponding fractions,alkyl-substituted on the aromatic core inclined to multi-substituted and short side chains substituted.N-dicarboxylic acids does not exist in RICO products of distillates,neither in RICO products of most heavy oil,which indicate that bridge bonds structure are not common in heavy oil molecules.