Isolation and characterization of sulfur compounds in high-boiling petroleum fractions

Abstract

The purpose of this study was to develop methods for the isolation and characterization of sulfur compounds i n vacuum gas oils. Two separation schemes were devised. One method involved oxidation of the sulfur compounds to sulfones using an excess of hydrogen peroxide followed by separation from the hydrocarbons using liquid-solid chromatography. Characterization was achieved by mass spectrometric analysis of the sample before and after removal of the thermally unstable sulfones and by direct examination of the isolated sulfones using ultraviolet and infrared spectrophotometry and nuclear magnetic resonance spectrometry. The second and more desirable technique involved stepwise oxidation of the sulfur compounds to sulfoxides using a limited amount of hydrogen peroxide followed by separation of the polar sulfoxides f r o m the hydrocarbons by liquid-solid chromatography. The sulfoxides were reduced back t o the parent sulfur compounds and isolated in relatively pure state by liquid-solid chromatography. These sulfur compound concentrates, being free of hydrocarbon contamination, were then analyzed by mass spectrometry, thin layer chromatography, ultraviolet spectrophotometry, and nuclear magnetic resonance spectrometry. For comparison, a third method was used which was based upon dealkylation over alumina at 500° C followed by gas chromatography using a microcoulometric sulfur detector for separation and measurement by compound classes. The results of the isolation and characterization work confirmed the reliability of the dealkylation method for the rapid routine analysis of high-boiling petroleum fractions for sulfur compound types. These methods were useful in studying the kinetics and mechanisms of hydrodesulfurization during process development.O'DONNELL ( I ) isolated sulfur compounds from a California coastal asphalt by oxidation of the sulfur compounds to sulfones, then separated them from the hydrocarbons by liquidsolid chromatography. The sulfones, being much more polar than the aromatic hydrocarbons, were easily isolated without contamination from the hydrocarbons and vice versa. However, O'Donnell did not fully characterize the isolated materials by instrumental techniques. Drushel and Miller (2) converted sulfur compounds in petroleum fractions to sulfones, rendering them amenable to polarographic reduction. In their studies it was not necessary to isolate the sulfones. The oxidized sample yielded polarographic reduction waves corresponding to benzo-and dibenzothiophene dioxides (listed as thiophenes and diary1 sulfides). Good recovery for a wide range of samples from kerosine to molecular still cuts (mol wt 200 to 1000) indicated essentially quantitative conversion of the sulfur compounds to sulfones by oxidation with hydrogen peroxide.A number of workers have successfully isolated sulfur compounds from petroleum by controlled oxidation of the sulfur compounds to sulfoxides with hydrogen peroxide. (1) G. O'Donnell, ANAL. CHEM., 23, 894 (1951). (2) H. V. Drushel and J. F. Miller, Ibid., 30, 1271 (1958...

Determination of polycyclic aromatic sulfur heterocycles (PASH) in diesel fuel by high performance liquid chromatography and photodiode‐array detection

“…Owing to their greater polarity, the sulfones are eluted from the reversed phase column before the corresponding thiophenes In contrast, the elution behavior of the sulfoxides was somewhat surprising. Whereas the sulfoxides of the benzo[b]naphthothiophenes were retarded and eluted, a s would be expected from their polarity, between the sulfones and the thiophenes, the sulfoxides of the benzo-and dibenzothiophenes eluted before the corresponding sulfones [ 191 The oxidation products could, by means of their UV-spectra, be clearly differentiated using the photodiode-array detector Table 3 shows the elution sequence and the wavelengths of the absorption maxima for the benzothiophenes and sulfones studied. Application of this oxidation method to the polyaromatic fraction of a diesel fuel showed the procedure to be applicable to real samples.…”

Mass Spectrometry in Organic Geochemistry

“…44.) DRUSHEL and SOMMERS [79] have described the analysis of aromatic sulfur compound concentrates from high boiling petroleum fractions. BAKER et ai.…”

“…Application of mass spectrometry to other studies of sulfur compounds can be found in the papers of NAGY and GAGNON [135], BIRCH et al [250], JEWELL and HARTUNG [206], AMBERG [251], and DRUSHEL and SOMMERS [79]. DINNEEN et al made a detailed mass spectrometric investigation of the sulfur compounds of shale oil [155].…”

Application of solid‐phase microextraction to the determination of polycyclic aromatic sulfur heterocycles in Bohai Sea crude oils

“…Several methods for separating and characterizing PASHs in crude oil have been reported. Drushel and Sommers have studied an oxidation–reduction procedure that was effective for isolating PASHs fractions. However, it was found that the recoveries of selected PASHs are not stable, varying from 0 to 70%, depending on their structures.…”