Aromatic-selective size exclusion chromatography: A new dimension in petroleum characterization

The shifting of focus of petroleum products from fuels to petrochemicals demands the comprehensive characterization of petroleum components, particularly of aromatic compounds. Reliable characterization will help in the conversion of low-value aromatics to high-value petrochemicals using different processing conditions. To that end, we have applied an aromatic-selective size exclusion chromatographic method for the characterization of aromatic compounds in high-boiling fractions (cuts), distilled from three crude oils differing in density (or API gravity). Crude oils were fractionated to predefined cut temperatures and the average compositional information (in terms of M-n and M-w) was obtained. It was found that the compositions of the distilled cuts displayed marked similarities, irrespective of the crude oil's origin. The compositional information was further supported by high performance liquid chromatography and comprehensive two-dimensional gas chromatography. The increase in average molar mass of the residue fraction was reflected in the increase in density of each crude oil studied. This method is simple to adapt, fast (< 30 min), and suitable for providing average compositional information. Moreover, the analysis time can further be reduced (< 10 min) using smaller particle size columns, as demonstrated in the case of polymer analysis. This new approach will provide a rapid alternative for average compositional information of aromatic compounds in complex petroleum samples to support high-throughput process experiments.

Automated summary

The characterization of aromatic compounds in petroleum samples is important for the conversion of low-value aromatics to high-value petrochemicals. In this study, a size exclusion chromatographic method was applied for the characterization of aromatic compounds in high-boiling fractions from different crude oils. The compositional information obtained showed similarities in the distilled cuts, regardless of the origin of the crude oil. The method is simple, fast, and suitable for providing average compositional information.