Nonpolar Compositional Analysis of Vacuum Gas Oil Distillation Fractions by Electron Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Abstract

We analyzed three vacuum gas oil distillation fractions, 295−319 °C, 319−456 °C, and 456−543 °C, with a home-built external electron ionization (EI) 7 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. EI at 10 eV allows soft ionization of aromatic compounds in the vacuum gas oil range. Unambiguous elemental composition assignment provides insight into compositional variations at the molecular level; for example, ultrahigh resolving power (m/Δm 50% ≈ 300 000 at m/z 300) and mass accuracy (<0.4 ppm) readily resolve C3/SH4 doublets (3.4 mDa mass difference) across the full m/z range of interest. To our knowledge, this is the first time that hydrocarbons and sulfur-containing hydrocarbons have been completely mass-resolved across the full VGO range. Aromatic hydrocarbons are the major detected components in all three samples. In addition, many sulfur-, nitrogen-, and oxygen-containing compounds were directly observed. The concentrations of the heteroatomic species increase with boiling point. Detailed data analysis revealed compound types (rings plus double bonds) and their carbon number distributions for hydrocarbon and heteroatomic compounds in the distillation fractions and increasing average molecular weight (or carbon number distribution) and aromaticity with increasing boiling temperature of the petroleum fractions. The present analysis requires only micrograms of sample, is fast (single time-domain data set acquired in a few seconds), and highly reproducible.

Fourier transform ion cyclotron resonance mass spectrometry in the speciation of high molecular weight sulfur heterocycles in vacuum gas oils of different boiling ranges

“…The number of assigned S 1 compounds (compounds containing one sulfur atom) from Pd-1 was 11, 94, and 106 in the three boiling ranges in increasing order of distillation temperature, and the number of S 1 compounds in Pd-2 was 188, 225, and 281, respectively. This corroborates the trend of an increasing number of S 1 members with increasing boiling temperature as was observed by low-voltage electron ionization FT-ICR MS [15]. Information on the molecular weight distribution pattern is given by the number-average molecular weight, M n , and the weight-average molecular weight, M w. These numbers were calculated for S 1 compounds in Pd-2 of all three VGOs [22].…”

“…This procedure allows the use of ESI for the analysis of PASHs. Recently, continuous-flow field desorption [14] and lowvoltage electron ionization [15] coupled with FT-ICR MS were reported for the study of VGOs of different origin and of different boiling ranges, respectively. Other reports [16] compared the use of the derivatization method using ESI detection with atmospheric pressure photoionization (APPI) and indicated that the range in the first case mentioned was limited to double bond equivalent (DBE) values below 15 and therefore the APPI approach was favored.…”

Characterization of Heavy Oil by FT-ICR MS Coupled with Various Ionization Techniques

“…The resolution of FT-ICR MS was improved by increasing the magnetic field to 5.6 T SCM in the compositional analysis of raw diesel fuel 13) . Different boiling cuts of VGO were characterized by 7 T SCM with low voltage EI to sup press fragmentation and demonstrated an increase in the observed mass range up to m/z 500 depending on the boiling temperature of the VGO cut 14) . Heavy distillate is believed to contain much higher molecular weight species than m/z 500 4) .…”

Application of Clustering Methods for Interpretation of Petroleum Spectra from Negative-Mode ESI FT-ICR MS

“…1 FT-ICR MS was shown to be effective for identifying the molecular composition of crude oils. [2][3][4][5][6][7][8][9][10][11][12] One of the most important goals of petroleomics is to predict the reactivities and properties of crude oils based on molecular information, which is obtained using high-resolution mass spectroscopy. Interpretation of high-resolution mass spectra can cause difficulties because of the large amounts of information contained in each spectrum.…”