Spectroscopic characterization of solvent soluble fractions of petroleum vacuum residues

NMR and FTIR spectroscopic techniques were used to investigate the effect o f different solvent extraction schemes on the composition and chemical natu re of species of vacuum residues of two Indian crude oils (namely Jodhpur a nd Heera) extractable into polar (ethyl acetate) and non-polar (n-pentane a nd n-heptane) solvents. The obtained soluble fractions were found to consis t of mainly simple aliphatic and naphthenic ring structures, while insolubl e fractions consisted primarily aromatic compounds. The results were used t o draw inferences on the relative utility of different extraction schemes t o upgrade vacuum residues as feedstocks for secondary conversion processes in petroleum industry.