Separation and Characterization of Reactive and Non-Reactive Sulfur in Petroleum and Its Fractions

Abstract

We present an efficient, easy-to-use chromatographic method to separate reactive and nonreactive sulfur compounds in crude oil for subsequent quantitative analysis and molecular characterization. Sulfur compounds in petroleum samples are separated by ligand exchange chromatography (LEC) on a silver-modified strong-cation exchange (SCX) solid-phase extraction (SPE) cartridge. LEC separation takes advantage of the bonding affinity of different sulfur types with silver-cations. The elution of a particular sulfur type (reactive or nonreactive) depends on the "strength" of the solvent used. One solvent mixture elutes nonreactive sulfur compounds (thiophenics and diaryl sulfides) into the first fraction. A second solvent mixture elutes reactive S-compounds (sulfides and disulfides) into the second fraction. A third reactive sulfur class (thiols) irreversibly reacts with the impregnated silver-ion to form silver thiolates that are insoluble in the solvent mixtures employed. The distribution of reactive and nonreactive sulfur in a sample can be determined by measurement of sulfur content in separated fractions. The isolated fractions are also well-suited for molecular characterization by a variety of techniques including gaschromatography-based methods (e.g., GC or GC × GC-SCD, GC-MS) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), both of which are demonstrated herein.

Investigation of Island/Single-Core- and Archipelago/Multicore-Enriched Asphaltenes and Their Solubility Fractions by Thermal Analysis Coupled with High-Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…The Tol/THF/MeOH-fraction, however, is enriched in low-DBE S1-class species with DBE 2 as most prominent. In the literature, low-DBE sulfur compounds have been attributed to sulfides, thiolanes and thianes [88,89]. Similar was observed for the Petrophase-2017 asphaltene, where the THF fraction exhibited higher alkylated compounds with low DBEs as well [48].…”

Hydrogen/deuterium exchange in mass spectrometry

“…Recently, APPI‐HDX was used for identification of S‐compounds in thiol‐enriched oil sample . Here sulfur‐containing species were separated into thiophenes, sulphides, and thiol fractions by the ligand exchange chromatography method and then analyzed by (+) APPI HDX MS. The abundant HDX product ions observed in the thiophene and sulphide fractions was M +.…”

Exploring Complex Mixtures by Cyclic Ion Mobility High-Resolution Mass Spectrometry: Application Toward Petroleum

“…Due to the extensive research in the last decades, light petroleum fractions can be analyzed in-depth by various chromatographic, spectroscopic, and mass spectrometric techniques . In this respect, gas chromatography coupled to mass spectrometry (GC × GC-MS) , has proven to be a powerful approach. Nonetheless, heavy petroleum fractions remain problematic and thus serve as ideal sample materials for the evaluation of novel instrumental developments. − …”