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

Abstract

Changes in the structure of oil compounds subjected to hydrodesulfurization were investigated using ultrahigh-resolution mass spectrometry (UHR-MS) and cyclic ion mobility mass spectrometry (cIM–MS) techniques. The isolation of ions with a separation of less than 0.1 Da followed by collision-induced dissociation helped clarify the structure. The class and double bond equivalence (DBE) distributions of the HC class observed by UHR-MS indicated that sulfur-containing compounds were transformed to HC compounds, in accordance with the previously reported mechanisms. The transformation was further observed by examining the tandem mass spectra of HC class compounds with the DBE values. The fragility of the molecules to collision-induced dissociation increased after hydrodesulfurization as a result of the increased abundance of naphthenic rings in the processed oils. The structural change was influenced by the DBE, and the most significant structural changes corresponded to HC compounds with DBE of 7. It was considered that compounds with naphthalene in the core structure were dominant in the untreated oils; however, the number of compounds with multiple naphthenic rings increased after the treatment. Moreover, the abundance of HC compounds with short alkyl chains likely increased. The results indicate that UHR-MS and cIM–MS are effective tools to clarify molecular-level changes in processed oils.

Characterization of petroleum‐related natural organic matter by ultrahigh‐resolution mass spectrometry

“…148 Recently, Kim and co-workers successfully applied UHR-MS to analyze petroleum mixtures and processed oils by coupling it with cIM-MS having quadrupole isolation, where ion separation occurs within a window of approximately m/z 0.1. 149,150 In the latter study, 150 the transformation of the processed oils was further clarified using tandem MS. Most recently, Lu et al 151 conducted multidimensional molecular-level analysis on natural DOM in broader aquatic environments using an online combination of drift-time IM-MS, HPLC, and Q-TOF MS. Further, they compared the results with those of ESI FT-ICR MS to elucidate the isomeric information of natural DOM and its relationship with environmental degradation.…”

2021 Pioneers in Energy Research: Alan Marshall

“…Rogel and collaborators applied FT-ICR MS to study the compositional changes of asphaltenes precipitated in the presence of minerals, and they highlighted the high dependence of asphaltene composition on isolation conditions. Cho, Kim, Kim, and co-workers reported structural analysis of hydrotreating products to understand the structural transformation of the feed during hydrodesulfurization . These authors demonstrated the combination of ultrahigh-resolution FT-ICR and cyclic ion mobility mass spectrometry as an effective tool to overcome the limitation on structural determination of asphaltene molecules to shed important insights into hydrotreating mechanisms.…”

“…Cho, Kim, Kim, and co-workers reported structural analysis of hydrotreating products to understand the structural transformation of the feed during hydrodesulfurization. 50 These authors demonstrated the combination of ultrahigh-resolution FT-ICR and cyclic ion mobility mass spectrometry as an effective tool to overcome the limitation on structural determination of asphaltene molecules to shed important insights into hydrotreating mechanisms. The article of Medina, Corteś, Franco, and co-workers 51 conversion of asphaltenes using multiple complementary characterizations.…”

Molecular Structures of Refractory Sulfur Compounds in Heavy Oil Hydrodesulfurization Characterized by Collision-Induced Dissociation Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…Sulfur compounds were ionized directly by the APPI source, − while the derivatization with methyl iodide ,, or silver cation , was necessary for the ESI source. The transformations of sulfur compounds during hydroprocessings were studied for the coal tar, shale oils, VGO, , atmospheric residues, − and asphaltenes − by FT-ICR MS. Moreover, the combinations of gel permeation chromatography (GPC), high-performance liquid chromatography (HPLC), , thermogravimetry (TG), − and ion mobility (IM) − with high-resolution mass spectrometry were also applied to obtain more information about the structures of sulfur compounds in heavy oils.…”