Abstract: Coke-forming is a serious problem in vacuum residue processing, and affected by its compound classes distribution. Deepening its understanding at the molecular level is important in guiding vacuum residue processing. The detailed carbon numbers and double bond equivalent (DBE) distributions of various compounds in vacuum residues were obtained by Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS) and were grouped into 10 categories according to the carbon number distribution of the aromatic hydrocarbons, S1 compounds (single S atom in molecule), S2 compounds (two S atoms in molecule), and N1 compounds (single N atom in molecule), respectively. The cluster analysis was applied for 71 kind of vacuum residues based on above molecular group compositions. Results showed that 71 vacuum residues were divided into type I, type II, and type III according to their molecular composition characteristics. To verify the accuracy of cluster analysis, carbon residue value of the vacuum residue was acted as the basis of rational judgment of the cluster analysis. The type I vacuum residues have the lowest carbon residue values, and is classified as less coking residue. The carbon residue value of type III vacuum residues is the highest, belonging to coking residue. The type II vaccum residue is in the middle. This work used cluster analysis to classify vacuum residue samples based on their molecular composition, the effective management of FT-ICR MS data could be realized, and the molecular composition of vacuum residue is closely linked to its processing performance is proved.

Key words: coking, vacuum residue, FT-ICR MS, cluster analysis, carbon residue