Core structure analysis of heavy oil components with Fourier transform ion cyclotron resonance mass spectrometry

A core structure estimation method for molecules in heavy petroleum fractions was developed based on FT-ICR MS. The mass analysis of molecules in Middle Eastern vacuum residue was conducted by a combination of FT-ICR MS with a fractionation technique. To obtain mass information about the core structures, collision induced dissociation Fourier transform ion cyclotron resonance mass spectrometry (CID FT-ICR MS) was performed for the three or more-ring aromatic fraction (3A+) and asphaltene (As) fractions. The differences in the double bond equivalent (DBE) distribution before and after CID indicated that the dissociation of the internal linkages of the parent ions had occurred, suggesting that archipelago-type molecules were contained in the 3A+ and As fractions. The proposed method enabled us to assign a core structure to each detected fragment ion successfully. The estimated core structures of the As fraction are similar to the core structures proposed in previous studies. Thus, the proposed method provides reasonable core structures for heavy petroleum fractions.