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High performance liquid chromatography (HPLC) is a well established analytical technique in the study of crude oil, and it has recently become more integrated within the field of petroleomics as a ...

High-resolution mass spectrometry enables molecular characterization of heavy petroleum fractions for petroleomics research. However, results from mass spectrometry are usually not quantitative. Th...

Asphaltene structure is one of the most controversial topics in petroleum chemistry. The controversy is centered on the organization of aromatic cores within asphaltene molecules (single aromatic core, island and multiple aromatic core, archipelago) and specifically the inconsistency between the island model and the composition of the products derived from asphaltene pyrolysis/thermal cracking. Such products are consistent with the coexistence of island and archipelago asphaltene structural motifs. However, the archipelago model continues to lack the widespread acceptance of the petroleum community, in part due to mass spectrometry results in support of the island model. In the first and second part of this series, we demonstrated that the disproportionally high atmospheric pressure photoionization (APPI) ionization efficiency (monomer ion yield) of island species is due to weak nanoaggregation of large aromatic cores which do not extensively aggregate in toluene, whereas more archipelago-dominant fractio...

Advances in high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) enable molecular-level characterization of ultracomplex asphaltene samples. Such analyses most often reveal compounds that are highly aromatic but alkyl-deficient in nature and, thus, support the classical “island” model of asphaltene architecture. However, recent works that combine chromatographic separations with mass spectrometry for the analysis of crude oils have shown that differences in ionization may greatly affect the analysis of complex mixtures (known as the matrix effect). Simply, compounds that ionize with greater efficiency are preferentially observed and mask the detection of poorly ionized compounds. Asphaltenes are not immune to this phenomenon. In the first of this series (10.1021/acs.energyfuels.7b02873), it was demonstrated that asphaltenes generated by different precipitants showed greatly varied monomer ion yields (ionization efficiencies). This work focuses on the development of an ex...

For decades, discussion of asphaltene structure focused primarily on molecular weight. Now that it is widely accepted that asphaltene monomers are between ∼250 and 1200 g/mol, disagreement has turned to asphaltene architecture. The classic island model depicts asphaltenes as single core aromatic molecules with peripheral alkyl side chains, whereas the less widely accepted archipelago model, includes multiple aromatic cores that are alkyl-bridged with multiple polar functionalities. Here, we analyze asphaltene samples by positive-ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry and perform infrared multiphoton dissociation to identify their aromatic core structures to shed light on the abundance of island and archipelago structural motifs. Our results indicate that island and archipelago motifs coexist in petroleum asphaltenes, and unlike readily accessible island motifs, asphaltene purification is required to detect and characterize archipelago species b...

With adoption of the petroleomics concept, significant effort has been made to create extensive databases of molecular structures and chemical and physical properties of complex petroleum mixtures. By collation of the available information provided by petroleomics, this study develops a new structure-based lumping kinetic model for hydrodesulfurization (HDS) of light gas oil. An advanced experimentation system, analytical technique, and computer software tool are employed to generate the necessary data. The model contains 16 structure-based lumps, each of which includes species having a similar structure and reactivity. The model allows for the tracking of changes in molecular structure type of the input and output mixtures during HDS. Its prediction capability is validated over a wide range of HDS operation temperatures (200–375 °C).

The complex geochemical characteristics of crude oils can provide important information on oil generation, such as the input of organic matter and their depositional environments, also supporting exploration, extraction, and production. This work reports the first organic geochemical evaluation of oils from the first commercial Brazilian onshore field (Carmopolis, Sergipe, Brazil) via both classical biomarkers and petroleomics data collected via ultrahigh-resolution and accuracy Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Gas chromatography/mass spectrometry (GC/MS) was used to characterize the oil composition in terms of n-alkane, isoprenoid, terpane, and sterane biomarkers, whereas either positive or negative electrospray ionization (ESI) and FT-ICR were used to profile the polar constituents of the oils. GC/MS revealed geochemical characteristics that classify the oil at different levels of thermal evolution and biodegradation. FT-ICR MS attributed molecular formulas to mor...

In this study, maltenes of atmospheric pressure residue oils were fractionated into five fractions and the fractions were examined by elemental analysis, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and 1H nuclear magnetic resonance (NMR) spectroscopy. The obtained data were compared to examine the correlations among the data. The correlation coefficients (R2) were 0.88 and 0.89 respectively between the N and S contents determined by elemental analysis and summed relative abundances of N and S containing compounds observed by FT-ICR MS. Especially, correlation between S content and summed relative abundances of S containing compounds was observed. Further, correlation between %1Hnon-aro determined from NMR data and %Cnon-aro obtained from FT-ICR MS data was observed. %1Hnon-aro was calculated from the relative summed area of peaks in the non-aromatic region (0.5–4.5 ppm) of the NMR spectra. %Cnon-aro values were calculated from double bond equivalence values by assuming linear ...

Of the estimated 5 million barrels of crude oil released into the Gulf of Mexico from the Deepwater Horizon oil spill, a fraction washed ashore onto sandy beaches from Louisiana to the Florida panhandle. Here, we compare the detailed molecular analysis of hydrocarbons in oiled sands from Pensacola Beach to the Macondo wellhead oil (MWO) by electrospray (ESI) and atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to identify major environmental transformation products of polar, high molecular weight (C>25) “heavy ends” (high-boiling species) inaccessible by gas chromatography. The petrogenic material isolated from the Pensacola Beach sand displays greater than 2-fold higher molecular complexity than the MWO constituents, most notably in oxygenated species absent in the parent MWO. Surprisingly, the diverse oxygenated hydrocarbons in the Pensacola Beach sediment extracts were dominant in all ionization modes investigated, (±) ESI and (±) APPI....

The technique of choice for petroleomics has been ultra-high-resolution and high-accuracy Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), but other techniques such as ion mobility have been shown to provide additional or alternative information about crude oil composition. Using the traveling wave ion mobility (TWIM) cell of a hybrid Q-TWIM-TOF first-generation Synapt instrument and electrospray ionization in both the positive and negative ion modes, different crude oil samples with different polar compound profiles and petro fuels (diesel and gasoline) with or without additives were analyzed using either CO2 or N2 as the drift gas. Parameters such as gas pressure, velocity, and wave height were optimized for each type of crude oil or fuel sample. The ability of TWIM–MS to separate crude oil components according to their classes was verified by comparison with FT-ICR data. Results showed separation of several classes of polar compounds (NO, O2, and N), and their separation was imp...

Crude oil samples are uniquely complex because of the number of compounds present that can only be resolved using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The FT-ICR MS technique has been redefined for examining the composition of crude oil and its products, which has led to a new field called “petroleomics”. The chemical composition ultimately determines the chemical and physical properties and the behavior of petroleum and its products. “Petroleomics” predicts the properties and behavior of petroleum using its composition to solve production and processing problems. This paper correlates the chemical composition of crude oil with the total acid number (TAN), which enables the development of prediction models using partial least squares (PLS) and support vector machines (SVMs) as alternative multivariate calibration methods that allow for the application of FT-ICR MS analysis in direct measurements. The prediction models using PLS and SVM demonstrated low prediction errors...

The determination of the nitrogen content of petroleum products is important because nitrogen compounds decrease product quality and can be difficult to remove through processes such as hydrotreating. In recent years, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been used to study the nitrogen species present in petroleum samples (petroleomics), with the goal of identifying hydrotreatment resistant species. While open column separations of petroleum samples are common, there has been little work done that employs a high-performance liquid chromatography (HPLC) separation prior to FT-ICR MS analysis. In this work, distillate cut and treated gas oils are separated on a commercially available dinitrophenyl “DNAP” column and the fractions are collected offline and analyzed by FT-ICR MS. HPLC separations on the “DNAP” column are shown, along with separations on a custom synthesized HPLC column (HC-Tol). Four peak regions are identified on the “DNAP” chromatograms, and the nitroge...

The ability of time-of-flight (TOF) mass spectrometry using an ultrahigh resolving power (Rp of 100 000 at m/z 400)analyzer (HRT) to provide a proper platform for comprehensive petroleomic studies has been evaluated. The innovative HRT design for ultrahigh resolution using a “zig-zag” multi-reflecting analyzer with a folded flight path, efficient ion refocusing, and no substantial loss of ion transmission was tested. For comparison, samples were also analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) using variable Rp (from 100 000 at m/z 400 to 400 000 at m/z 400). Both HRT and FT-ICR MS data were processed and compared using software specifically designed to process either TOF or FT-ICR data for petroleomic studies. Owing to the increase in Rp with m/z, the 100 000 at m/z 400 Rp of the HRT is found to be, overall, comparable to that of a 200 000 at m/z 400 FT-ICR. This Rp is sufficient to allow for proper resolution, correctly resolve most isobaric interferences, and acc...

A Liaohe crude oil was separated as saturates, aromatics, resins, and asphaltenes (SARA) and neutral nitrogen fractions. The crude oil and its subfractions were analyzed by negative-ion electrospra...

Asphaltenes, the most aromatic of the heaviest components of crude oil, are critical to all aspects of petroleum use, including production, transportation, refining, upgrading, and heavy-end use in paving and coating materials. As such, efficiency in these diverse disciplines mandates proper chemical accounting of structure−function relations of crude oils and asphaltenes, the vision of petroleomics (Asphaltenes, Heavy Oils and Petroleomics; Mullins, O. C., Sheu, E. Y., Hammami, A., Marshall, A. G., Eds.; Springer: New York, 2007). Indeed, the molecular characterization of asphaltenes is required as well as the detailed understanding of the hierarchical colloidal structures of asphaltenes and petroleum. With great prescience, Professor Teh Fu Yen and co-workers proposed a hierarchical model of asphaltenes to account for many of their characteristics known at that time (Dickie, J. P.; Yen, T. F. Macrostrucutres of asphaltic fractions by various instrumental methods. Anal. Chem. 1967, 39, 1847−1852). This m...

The compositional analysis (speciation) of heavy oil products is a key step to improve our understanding of hydrotreatment processes and reaction mechanisms. Thus, detailed characterization of polar fractions, such as asphaltenes, should be considered. Here, we employ atmospheric pressure photoionization Fourier transform ion cyclotron mass spectrometry to monitor the evolution of the asphaltene hydrocarbon and sulfur families in deep hydrotreatment processes (fixed and ebullated beds). The results suggest that the complexity of the asphaltenic fractions (in terms of chemical polydispersity) is drastically lowered with increased process severity. In either fixed or ebullated beds, the evolution of the sulfur species is quite similar in class composition, aromaticity (DBE/carbon number ratio), and polycondensation (DBE). The compositional changes are marked by a drastic increase in aromaticity to highly polycondensed dealkylated aromatic structures. Asphaltene disaggregation followed by a dealkylation of t...

Molecular characterization of sulfur-containing species in petroleum is important because sulfur-containing compounds are detrimental to the environment and the refining processes. In a recent report, the sulfur-containing compounds in a vacuum bottom residue (VBR) were methylated to enhance their detectability by electrospray ionization (ESI) mass analysis. The most abundant sulfur compounds exhibited relatively low double bond equivalents (4 < DBE < 12). Alternatively, atmospheric pressure photoionization (APPI) mass analysis can provide molecular characterization without chemical derivatization. Here, we compare the sulfur speciation of a petroleum vacuum bottom residue by ESI and APPI with a 9.4 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Even after methylation, ions produced by APPI extend to much higher DBE than by ESI. Moreover, analysis of the saturates and aromatics fractions of underivatized VBR by APPI shows comparable ionization efficiency across a broad DBE range. ...

Although crude acids are minor constituents in petroleum, they have significant implications for crude oil geochemistry, corrosion, and commerce. We have previously demonstrated that a single positive-ion electrospray ionization (ESI) high-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) experiment can resolve and identify 3000 chemically different elemental compositions of bases (basic nitrogen compounds) in a crude oil. Here, we show that negative-ion ESI high-field FT-ICR MS can selectively ionize and identify naphthenic acids without interference from the hydrocarbon background. When combined with prechromatographic separation, ESI FT-ICR MS reveals an even more detailed acid composition. An average mass resolving power, m/Δm50% ≥ 80 000 (Δm50% is mass spectral peak full width at half-maximum peak height) across a wide mass range (200 < m/z < 1000), distinguishes as many as 15 distinct chemical formulas within a 0.26 Da mass window. Collectively, more than 3000 chemically ...

Extra heavy petroleum crude oil (50% of the mixture boils at >566 °C) has been analyzed directly, without prior fractionation, by a high-field (9.4 T) Fourier transform ion cyclotron resonance mass spectrometer coupled to an external micro-electrospray ion source. At an average mass resolving power, (m/Δm50% ≈ 50 000), a single wideband (250−1250 Da) mass spectrum exhibited ∼5000 resolved peaks with an average mass of 617 Da (e.g., up to 7−10 resolved peaks at each nominal mass). Their elemental compositions were positively identified by accurate mass measurement with an average deviation of less than 1 mDa from each assigned elemental composition. The number of elemental compositions at each nominal mass, the number of sulfur/oxygen atoms in a molecule, and aromaticity each increase with increasing mass. On the basis of elemental composition alone, we resolve more than 3000 distinct chemical formulas (excluding 13C isotopic species). Of the 3000 unique elemental compositions, we identify 12 major heteroa...