Ultrahigh-Resolution Magnetic Resonance Mass Spectrometry Characterization of Crude Oil Fractions Obtained Using n-Pentane

Abstract

In this work, crude oil fractions obtained using n-pentane were analyzed using atmospheric pressure photoionization coupled to ultrahigh-resolution magnetic resonance mass spectrometry. The crude oil was supported on Ottawa sand and transferred to a glass column. n-Pentane was added to the column, and the fractions drained at the bottom were collected. Results indicate that the fractions obtained are highly deficient in hydrogen and become more aromatic as the amount of n-pentane going through the column increases. The analysis of the fraction retained in the sand after the experiment indicates that this fraction is enriched in oxygen species and more aromatic than pentane-extracted asphaltenes from the same crude oil. It was also found that the material dissolved in n-pentane after the initial washing is more aromatic than the material remaining in the sand, suggesting that the sand plays a significant role in the strong adsorption of molecules containing more polar moieties but that are less aromatic. Also, molecules left in the sand are smaller (lower C carbons) than those eluted in the fractions; therefore, small molecules are retained preferentially. This study provides evidence that the presence of sand and likely of other inorganic substrates leads to asphaltenes that occupy a different compositional space from those obtained using standard procedures in the laboratory.

Ultrahigh-Resolution Magnetic Resonance Mass Spectrometry Characterization of Asphaltenes Obtained in the Presence of Minerals

“…More recently, ultrahigh-resolution magnetic resonance mass spectrometry (MRMS) showed that asphaltenes retained in the sand after fractionation using n -pentane lead to asphaltenes occupying a different compositional space from those obtained using standard precipitation procedures in the laboratory. This study also found that the species retained in the sand were enriched in oxygen species but less aromatic than those eluted with n -pentane . It can be expected that other inorganic substrates might also lead to asphaltenes that differ from those obtained in the absence of these minerals.…”

“…This study also found that the species retained in the sand were enriched in oxygen species but less aromatic than those eluted with n-pentane. 11 It can be expected that other inorganic substrates might also lead to asphaltenes that differ from those obtained in the absence of these minerals.…”

Molecular-Level Structural Analysis of Hydrotreated and Untreated Atmospheric Residue Oils via Atmospheric Pressure Photoionization Cyclic Ion Mobility Mass Spectrometry and Ultrahigh-Resolution Mass Spectrometry

“…Ultrahigh-resolution mass spectrometry (UHR-MS) based on Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) can be used to obtain the exact molecular weight of crude oil compounds within the mass error of the parts per billion (ppb) level , and clarify the chemical properties of the sample. As the magnetic field increases, a higher resolution and mass accuracy can be achieved, as demonstrated by a recent study on petroleum analyses based on 21 T FT-ICR MS. , …”

Virtual Special Issue of the 21st International Conference on Petroleum Phase Behavior and Fouling (PetroPhase2020)

“…The first paper 24 is on fractionation of asphaltenes with solid−liquid extraction and high-performance thin-layer chromatography and the characterization of petroporphyrins with matrix-assisted laser desorption/ionization (MALDI) FT-ICR MS. In the second paper, Bouyssiere, Marshall, and co-authors 25 report the aggregation tendencies in asphaltenes and the very first species to elute in the largest aggregates being more condensed polyaromatic compounds, via combining gel permeation chromatography (GPC) with online detection with FT-ICR MS. Rogel et al 26 use FT-ICR MS to characterize asphaltene fractions obtained from npentane and study the correlation of adsorption on sand with their compositions. Zhang, Yao, and co-authors 27 present the use of non-contact AFM for probing various adsorption conformations of archipelago structures, paving the road to image these nonplanar asphaltene molecules with this new technique.…”