Evaluation of Different Methodologies to Determine the Molecular Weight of Petroleum Fractions

Abstract

The correct characterization of petroleum fractions is crucial to correctly describe the processes in which they are involved. Most of the properties required to complete the characterization of these mixtures can be determined by well established methods. However, in the case of molecular weight, it is frequently determined by empirical correlations because of the scarcity of reliable methods. This work aims at evaluating the suitability of different techniques to calculate the molecular weight of petroleum mixtures. Cuts from three different crude oils within the whole range of boiling temperatures were analyzed by gel permeation chromatography (GPC) and high temperature gas chromatography (HT-GC). The former is a direct methodology to obtain the molecular weight. The latter, however, requires a process calculation as it yields the distillation curve, which must be converted into composition distribution. In this work, this calculation was performed by means of two continuous distribution models of different complexity. The molecular weight values obtained by GPC and HT-GC-based models were in good agreement, despite their different approach.

Past to Future: Application of Gel Permeation Chromatography from Petroleomics and Metallopetroleomics to New Energies Applications: A Minireview

“…40 In this work, GPC was used to obtain molecular weight information and the smaller molecular weight portion of the residues were compared to GC-MS analysis; results were similar. Espada et al 41 employed GPC using PLgel columns and a mobile phase of 1,2,4-trichlorobenzene at 145 °C to determine the molecular weight of fractions with boiling points ranging from 105 to 565 °C. Their results showed that molecular weight increased with boiling point and GPC yielded similar results to high-temperature (HT) GC while being a more straightforward technique.…”