Dagang vacuum residue (VR) and its supercritical fluid extraction and fractionation (SFEF) tailing were separated into four group compositions (SARA) by chromatographyThe molecular structural features of the asphaltenes from VR and SFEF tailing were investigated with ruthenium ion catalyzed oxidation (RICO)By means of GCMS and GC analysis

the homologous series of n-alkanoic acids (C4—C33) and α

ω-di-n-alkanoic acids (C4—C24) were detected and measured quantitativelyThe distribution of these carboxylic acids obtained from the oxidation reaction was useful in determining the distribution of polymethylene bridge bonds and alkyl side chainsThe results indicated that the molar concentrations of n-alkyl side chains and polymethylene bridges decreased with the increase of chain length

and were characterized by eventoodd carbon number preferenceSFEF tailing asphaltene had less C25+ but more C17—C25 n-alkyl side chain than VR asphalteneFurthermore

the polymethylene bridge concentration of VR asphaltene was about 25 folds of SFEF tailing asphalteneThe above information demonstrated that cracking reaction might occur in the SFEF process.