Molecular-Level Characterization of Refinery Streams by High-Resolution Mass Spectrometry

Abstract

Compositional changes of hydrocarbon fractions affect the physical properties and performance for a specific application. Various techniques, such as liquid chromatography and nuclear magnetic resonance spectroscopy, are normally used for determination of hydrocarbon analysis in petroleum fractions. These techniques provide limited information regarding the hydrocarbon classes. Mass spectrometry offers a unique advantage over these techniques by providing detailed information on hydrocarbon classes present in samples. Commonly used methods in mass spectrometry provide 19, 22, and 33 classes of hydrocarbons in petroleum fractions. These methods are useful in understanding relative changes in composition in the samples during further processing in refineries. The major problem with these methods is validation of results, which poses a challenge to researchers. In the present study, a high-resolution mass spectrometry (HR-MS) technique has been optimized to characterize the petroleum fractions in terms of 33 hydrocarbon classes (HC33), comprising 5 classes of saturates, 13 classes of aromatics, and 15 classes of sulfur aromatics, for detailed hydrocarbon-type analysis. About 40 samples covering a wide range of petroleum streams, such as light cycle oil (LCO), clarified light oil (CLO), and vacuum gas oil (VGO), in the boiling range of 170–650 °C have been analyzed for 33 classes of hydrocarbons. To validate the results, a correlation of sulfur compounds by HC33 with the total sulfur content as determined by wavelength-dispersive X-ray fluorescence (WDXRF) has been carried out. The saturate content was determined using saturates, aromatics, resins, and asphaltenes (SARA) by thin-layer chromatography–flame ionization detection (TLC–FID) and compared to that obtained by HC33 for the samples. Results obtained from HC22 and HC33 methods were also correlated through analysis of variance for saturate, aromatic, and sulfur aromatic classes. The observed F value for the groups is less than F critical, indicating there is no significant difference between the two methods. Further, on the basis of mass spectrometry analysis, a case study on the importance of detailed hydrocarbon-type analysis (33 classes) for problem solving in VGO hydroprocessing has been reported.

Detailed Characterization of Refractory Refinery Streams for Use as Feedstocks for Diesel Production in Low-Pressure Hydrotreating Units

“…43 Some chromatographic methods allow the characterization of different classes of hydrocarbons and the understanding of compositional changes during their further processing in refineries. 44 Additionally, these techniques can be used for both qualitative and quantitative identification of major components in the process streams. By analyzing the carbon species present in refinery streams, reaction kinetics in secondary processes can be monitored and HDT processes can be optimized to produce the desired feedstocks.…”

Hydrotreating of Light Cycle Oil over Supported on Porous Aromatic Framework Catalysts

“…The use of the catalytic system PAF-NiMeS/PAF-AlCl 3 could be most promising for hydrotreating LCO from the position of both hydrodearomatization, hydrocracking, hydroisomerization and hydrodesulphurization reactions. LCO contains a large number of aromatic compounds, mostly diaromatic (35-55 wt %) and monoaromatic (10-35 wt %) hydrocarbons, and to a lesser extent polyaromatic hydrocarbons (5-10 wt %) with three or more benzene rings in the structure [34]; the predominant diaromatic hydrocarbons are represented basically by different alkyl-substituted naphthalenes. The source of sulfur in LCO is various benzothiophenes and dibenzothiophenes, as well as disulfides in trace amounts.…”

Compositional Characterization of Pyrolysis Fuel Oil from Naphtha and Vacuum Gas Oil

“…On the other hand, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) showed that GC methods do not characterize all the heavy poly-aromatic compounds in coal tar 27 . Even though high resolution FT-ICR-MS enables accurate determination of the molecular mass and chemical nature of heavy compounds [28][29][30] , accurate quantification remains a challenge 31,32 . Complicated sample matrices can alternatively be analyzed via Nuclear Magnetic Resonance (NMR) spectroscopy, which provides information on the relative abundance of chemical families 33,34 .…”

“…On the other hand, Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) showed that GC methods do not characterize all the heavy poly aromatic compounds in coal tar . Even though high-resolution FT-ICR-MS enables accurate determination of the molecular mass and chemical nature of heavy compounds, − accurate quantification remains a challenge. , Complicated sample matrices can alternatively be analyzed via nuclear magnetic resonance (NMR) spectroscopy, which provides information on the relative abundance of chemical families. , Similarly, poly aromatic compounds can be separated using liquid chromatography; − nevertheless, the developed methods are time-consuming and still primarily qualitative. Due to the inherent limitations of each discussed analytical method only a combination of different analytical techniques can result in quantitative characterization of fractions such as PFO.…”