A. V. Akopyan

Oxidative desulfurization of diesel fraction with hydrogen peroxide in the presence of catalysts based on transition metals

The oxidative desulfurization of a straight-run, nonhydrotreated diesel fraction (boiling range 178–342°C) containing benzothiophene, dibenzothiophene, their alkyl-substituted derivatives, and thioxanthene by the action of hydrogen peroxide in the presence of transition metal compounds (Na2MoO4, Na2WO4, NaVO3, WO3, tungstic acid, and heteropoly tungstate/molybdate H3PMo6W6O40) in a biphasic system followed by the extraction of the oxidation products with dimethylformamide has been studied. The oxidation of the hydrocarbon fraction in the presence of heteropoly tungstate/molybdate under biphasic conditions provides for the removal of up to 82% of total sulfur.

Oxidative desulfurization of hydrocarbon fuel with high olefin content

The influence of olefins on the oxidative desulfurization of model mixtures and catalytically cracked gasoline has been studied. It has been established using model mixtures and a wide-cut fraction of catalytically cracked gasoline that the presence of olefins in fuel suppresses the oxidative desulfurization process as a result of occurrence of side oxidation reactions of unsaturated compounds. It has been shown that under the given conditions, it is preferable to use neutral catalysts based on transition metal salts for the oxidative desulfurization, rather than catalysts of acidic nature.

Reduction of sulfur content in shale oil by oxidative desulfurization

The oxidative desulfurization of shale oil obtained by thermal extraction of organic matter from shale rock using an oxidative catalytic system composed of hydrogen peroxide, a molybdenum salt, and acids of different natures has been studied. It has been shown that the application of this method in combination with extraction of the oxidation products of organic sulfur compounds makes it possible to remove up to 94% of total sulfur from the synthetic oil.

Hydrogen peroxide oxidative desulfurization of model diesel mixtures using azacrown ethers

Hydrogen peroxide oxidative desulfurization of model diesel fuel mixtures in the presence of azacrown ethers and their complexes with niobium pentachloride at 40–80°C has been studied. It has been found that the use of complexes of azacrown ethers with NbCl5 leads to a decrease in the total sulfur content in the model mixtures to 13% of the initial amount. The structure of the azacrown ether used has little effect on the extent of desulfurization of the model mixture.

Peroxide oxidative desulfurization of a mixture of nonhydrotreated vacuum gas oil and diesel fraction

Oxidative desulfurization of a model mixture on the basis of vacuum gas oil and diesel fuel by hydrogen peroxide in the presence of formic acid has been studied. A technology of a two-phase system with a phase-transfer catalyst has been employed for the desulfurization. The optimum reaction time is 6 h and the hydrogen peroxide: sulfur molar ratio is 4: 1. As a result of successive triple oxidative desulfurization, 90% of total sulfur is removed from the model mixture.

Peroxide Oxidative Desulfurization of Crude Petroleum

The oxidative desulfurization of crude petroleum from the Maiorskoe field (Orenburg oblast, Russia) with hydrogen peroxide in the presence of organic and inorganic acids has been studied. A procedure for the recovery of oxidized sulfur-containing compounds from the petroleum by extracting the oxidation products with polar solvents (N,N-dimethylformamide, acetone, methyl ethyl ketone, or methanol) or thermal decomposition of oxidized sulfur compounds has been selected. As a result of the oxidative desulfurization, up to 80% total sulfur is recovered from the petroleum, with the change in the physicochemical characteristics of the petroleum being insignificant.

Immobilized ionic liquids based on molybdenum- and tungsten-containing heteropoly acids: Structure and catalytic properties in thiophene oxidation

Comparative analysis of heterogeneous catalysts for the peroxide oxidation of thiophene is conducted. The catalysts are imidazole ionic liquids (ILs) containing anions of phosphomolybdic and phosphotungstic acids immobilized on mineral supports. Immobilization is implemented by the covalent bonding of an IL fragment to a silica surface or by adsorption on alumina. The catalysts are active not only in the model oxidation of thiophene in isooctane, but also in the desulfurization of a straight-run diesel fraction and the “synthetic crude oil” derived from oil shale.

Ozone-assisted oxidative desulfurization of light oil fractions

A catalytic system for oxidative desulfurization has been created, which is a transition metal salt bearing an organic ligand and capable of forming an active oxidative complex in the interaction with ozone and further oxidizing sulfur compounds present in fuel followed by the adsorption of the oxidation products on silica gel. In this case, a direct contact of ozone with the fuel is avoided, making the process safer. The effect of the reaction and ozonation conditions on the desulfurization process has been studied. Total sulfur content was decreased to 180 ppm for the straight-run gasoline fraction and to 900 ppm for the diesel fraction.

Oxidative Desulfurization of Hydrocarbon Feedstock

Papers published in the past decade on oxidative desulfurization of hydrocarbon raw materials using hydrogen peroxide, oxygen, and ozone as oxidants, and also using ultrasonic treatment and adsorption and extraction methods for separating the oxidized sulfur-containing compounds are summarized and systematized.

Oxidative Desulfurization of Straight-Run Diesel Fraction

Oxidative desulfurization of straight-run nonhydrotreated diesel fraction with hydrogen peroxide in the presence of Na2MoO4 or Na2WO4, dibenzyl peroxide, and potassium permanganate; by air bubbling; and in the presence of ionic liquids has been studied. The oxidation products have been recovered from the oxidized diesel fraction using alumina, silica gel, or activated charcoal or via extraction with acetonitrile, N,N-dimethylformamide, or acetone. The best results of the diesel desulfurization have been achieved in the case of dibenzyl peroxide as an oxidizing agent in the presence of Na2MoO4.