Research On Molecular Composition And Distribution Of Vacuum Residue

The detailed research on the molecular composition of petroleum is of great significance for understanding and guiding the processing of vacuum residue.Fourier transform ion cyclotron resonance mass spectrometry?FT-ICR MS?has ultrahigh mass accuracy and mass resolution,and can obtain abundant information on the molecular composition of vacuum residue.However,at present,there is still a lack of comprehensive and systematic understanding of the relationship between microscopic molecular composition information and macroscopic physicochemical properties and processing performance of vacuum residue.In this study,the molecular composition of 83 vacuum residues was characterized by the combination of atmospheric pressure photoionization source?APPI?and FT-ICR MS,and the molecular composition database of vacuum residues was established.The density?20°C?,elemental content,four-component?SARA?content,and metal content of the selected samples basically cover the current common residue types.In order to guarantee the quality of the database,the repeatability and consistency of the method were examined in detail,and a set of data quality control program with practical value was proposed,which can effectively guarantee the data quality of the molecular composition database.Based on the detailed molecular composition data of the vacuum residues database,the similarity of the vacuum residue samples was calculated.Similar processing performance vacuum residue samples could be selected by combining the similarity of the vacuum residue samples and the content of metal,resins,and asphaltenes which the former is dominant.The results show that when the similarity of vacuum residue with Daqing,Shengli,and Tahe vacuum residue beyond 0.860,0.840,and 0.870,respectively,the molecular composition and macroscopic properties are similar to Daqing,Shengli,and Tahe vacuum residue.This method realizes the molecular level management and application of the vacuum residue database.Since the distribution of compounds types and DBE has a significant effect on the coking of vacuum residue,based on the carbon number and DBE data of the five compounds of HC,S₁,S₂,N₁ and N₁S₁,vacuum residue samples of the database could be divided into three types of vacuum residues by using cluster analysis.The three types of vacuum residues include type I vacuum residues,which is represented by Daqing vacuum residue,and are difficult to forming coke,type II vacuum residues represented by Shengli vacuum residue and their coke-forming tendency are middle,Tahe vacuum residue is representative of type III vacuum residues that are easy to form coke.The classification results of the molecular composition agree well with the actual processing performance of the residues.This classification achieves the management of the coking performance of the vacuum residue database samples.It is possible to predict macroscopic physicochemical properties of the samples from their molecular composition,and to provide more information for vacuum residue processing possible ways.