Desulfurization of Saudi Arabian crudes by oxidation–extraction method

Abstract

The oxidation–extraction desulfurization of Saudi Arabian crudes was conducted with hydrogen peroxide–acetic acid oxidation system. The selection of extractant, the optimization of oxidation–extraction conditions, and the exploration of desulfurization mechanism were studied. As DMF was used as the extractant, the optimal desulfurization rate of 35.11 % and oil recovery of 95 % were obtained at 70 °C with the molar ratio of peracetic acid to sulfur of 8:1, the molar ratio of acetic acid to hydrogen peroxide of 2:1 and the volume ratio of extractant to oil of 1:1. The desulfurization effect of different fractions in the treated Saudi Arabian crudes was found to obey the following order: gasoline–diesel fraction >VGO fraction >VR fraction, due to different types and structures of sulfur compounds. The oil quality was less affected and most sulfides were mainly extracted via DMF.

Oxidative Desulfurization of Heavy Oils with High Sulfur Content: A Review

“…From Ox/S = 5 to Ox/S = 10, sulfur content reached 1.43 wt.%S instead of 2.15 wt.%S. Without further study of optimal Ox/S ratio, Ox/S ratio higher than the stoichiometry are sometimes preferred, as reported by Otaibi et al (2015) [34] using a ratio of 8 when performing an ODS reaction of a crude oil fraction containing 2.5 wt.%S. This high ratio could be explained, not only by the initial sulfur content, but also by the heavy nature of the petroleum fraction used requiring high oxidant amount due to side reactions that can proceed, such as oxidation of aromatic hydrocarbons.…”

“…Similarly, in 2016 Mokhtar et al [18] chose DMF for extraction of oxidized crude diesel. DMF was also reported as more adapted for extraction from more complex mixtures like crude oil [34]; however the DMF is classified as a substance of very high concern by the European Chemicals Agency (ECHA) since 2012. Unexpectedly, a nonpolar solvent, n-heptane, was proposed by Mohammed et al [31] for the extraction of oxidized crude oil.…”

“…Some articles compared the efficacies of formic acid and acetic acid. In 2015, Farshi & Shiralizadeh [26] and Otaibi et al [34] concluded that better ODS results were obtained using acetic acid. Farshi et al [24] found that the use of formic acid for oxidizing heavy fuel oil led to formation of byproducts such as sticky polymer materials.…”

“…Captivating work was realized by Otaibi et al (2015) [34] and by Abu Bakar et al (2016) [32]. The authors compared oxidative desulfurization rates for various petroleum fractions from the same crude oil, initially containing 1.12 wt.%S for Abu Bakar et al and 2.5 wt.%S for Otaibi et al Oxidation was carried out using hydrogen peroxide and acetic acid followed by extraction with DMF.…”

“…Shiraishi and Hirai (2004) [24] used decane as solvent to increase the fluidity of vacuum gas oil. Other studies proposed to substitute the magnetic stirrer applied to lighter feeds with electrical stirring for perfect mixing conditions in the case of ODS of viscous crude oil [34] and heavy fuel oil [26]. In this latter work, Farshi & Shiralizadeh (2015) [26] reported oxidative desulfurization of heavy fuel oil using hydrogen peroxide and acetic acid.…”