Detailed Characterization of Petroleum Sulfonates by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Abstract

Petroleum sulfonates obtained from heavy vacuum gas oil (HVGO) were characterized by negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry [(−) ESI FT-ICR MS] to better understand the chemical nature of their surface-active components. Electrospray ionization (ESI) analysis showed that sulfonates contain mainly O3S, O3S2, O4S, and NO3S classes, which means that the sulfonation reaction does not occur selectively for aromatic hydrocarbon (HC) class compounds because it also reacts with N, S, and O heteroatom classes. Because sulfonates were separated by solubility into lipophilic and hydrophilic categories, it was confirmed that the same classes compose hydrophilic and lipophilic sulfonates. Moreover, this procedure revealed that lipophilic sulfonate extracts contain organic acids (O2 class) that are related to the total acid number of the starting HVGO. However, selective isolation of the surface-active species using the “wet-silica” procedure allowed for detection t...