Isolation of Sulfides from Petroleum for Molecular Characterization by Alumina and Silica Gel Adsorption

Abstract

Sulfide (sulfur ether or thioether) is a kind of chemically active compound in petroleum, which has special significance in both geochemistry and oil processing. However, the molecular characterization of sulfides is a challenge because the composition of sulfides is very complex and each individual sulfide generally has a very low concentration. Separation is necessary for an in-depth characterization of these compounds, but it is not easy to achieve thus far. Here, we developed a method for the isolation of sulfides from petroleum fractions. Sulfides have different adsorption behaviors from the petroleum matrix on the aluminum oxide and silica gel. The petroleum fraction was first separated by an alumina column to obtain the mixture of sulfides and nonpolar hydrocarbons, and then the mixture was transferred into the second column, which was packed with silica gel. Hydrocarbons were removed by a nonpolar solvent, and sulfides were eluted from the column with a polar solvent. Isolated fractions were characterized by high-resolution mass spectrometry and gas chromatography (GC). Results show that the method is simple and practical. The purity of the sulfide fraction is acceptable for composition analysis by GC-relevant techniques. The method could be used for routine analysis of sulfides in crude oil and its products.

Review on Sulfur Compounds in Petroleum and Its Products: State-of-the-Art and Perspectives

“…Wu et al 34 found that sulfides have different adsorption selectivities on silica gel and alumina and developed a simple method for the separation of sulfides in petroleum using two-step column chromatography. The purity of the thioether component obtained by this method is not as high as that obtained by the methylation−demethylation method, but the process is very easy to implement.…”

“…Wu et al 34 investigated the retention behavior of sulfide compounds on the adsorption columns of alumina and silica gel and determined that the distribution of sulfides in SARA was dependent on the adsorbent used. Silica gel was found to have a stronger adsorption than alumina for sulfides and the authors proposed a separation method for sulfide separation.…”

Carbon dots: An innovative luminescent nanomaterial

“…First, the arrangement of benzene rings in the carbon core leads to the formation of specific edge structures, such as zig-zag and armchair. [64,89] It has been proved that the CDs localization at the zig-zag edge reduces the bandgap by lowering the conduction band, while that of the armchair edge effectively widens the bandgap, causing a blueshift of emission wavelength. In addition, by synthesizing aromatic macromolecules with specific edge structures, Müllen et al found that specific edge arrangements would lead to a significant change in the molecular vibration signals and polarity, resulting in unique magnetism, catalysis, electron transfer, and optical waveguide properties.…”

Molecular Characterization of Heavy Petroleum by Mass Spectrometry and Related Techniques

“…Extensive research has been done by multiple laboratories on selective isolations of various sulfur types including reactive and nonreactive sulfur compounds, such as sulfides, thiophenes, and mercaptans. − Isolation of metalloporphyrins is another active area of research. A cyclograph separation scheme was developed to selectively isolate nickel porphyrins from C7 asphaltenes to enable identification without mass overlap interference .…”