Oxidation Of Sulfur-containing Compounds Research Articles

The effect of the nature of metal-containing anions on the catalytic properties of imidazolium derivatives immobilized on silochrom in oxidative desulfurization

Two types of catalysts – Fenton catalysts based on Cu(I) and Fe(III), and polyoxometalates Mo(VI) and W(VI) – were compared in the oxidation of sulfur-containing compounds by hydrogen peroxide and desulfurization of oil stock. Heterogeneous samples were represented by imidazolium salts chemically anchored on the silochrom surface and containing chloride complexes of iron and copper or anions of phosphomolybdic and tungstophosphoric acids. Thiophene (T), dibenzothiophene (DBT) and methyl phenyl sulfide (MPS) as well as the diesel fraction with the initial sulfur content of 1080 ppm were used as the model substrates. The reactivity of thiophene substrates was found to depend on the nature of metal-containing anions: on Cu and Fe catalysts, thiophene > DBT, while on polyoxometalate catalysts, DBT > thiophene. This effect was interpreted using literature data. The catalyst based on tungstophosphoric acid provided desulfurization of the diesel fraction of oil to the sulfur content < 10 ppm, which corresponds to modern environmental standards.

Oxidative desulfurization of the straight-run gasoline fraction from the gas condensate of the Karachaganak field

An annual increase in the consumption of the automobile fuels makes us look for new ways of their obtaining. It is also important that the environmental and operational requirements for the quality of the motor fuels, obtained during oil production (associated petroleum gas, gas condensate) are systematically made more rigorous. One of the ways to solve the problems described above is to use the process of oxidative desulfurization to improve the quality of the petroleum products. In this case, oxidative desulfurization of the straight-run gasoline fraction, obtained from the gas condensate of the Karachaganak field, has been carried out. The oxidation process has been carried out with hydrogen peroxide in the presence of salts of the transition metals, molybdenum and vanadium. The optimal technological parameters (Patm, T=600C, 2 h, H2O2:S=4:1 (mol), Me:S=1:100 (mol)) of the oxidation process for the straight-run gasoline fractions have been selected. Under the optimal conditions of the oxidation process, the total sulfur content has been reduced by 89.9%. It has been shown that the molybdenum compounds exhibit greater activity in the oxidation of sulfur-containing compounds at a temperature of 600C, as compared to the vanadium compounds. A schematic diagram of the purification of the gasoline fractions from the sulfur-containing compounds by oxidative desulfurization, followed by its extraction desulfurization with the most effective N,N-dimethylformamide has been presented.

Immobilized Acid Catalysts in the Oxidation of Sulfur-Containing Compounds with Hydrogen Peroxide

Immobilized Acid Catalysts in the Oxidation of Sulfur-Containing Compounds with Hydrogen Peroxide

Oxidation of Condensed Thiophene Derivatives with Brønsted Acidic Ionic Liquid

Abstract—A catalyst based on ionic liquid consisting of a pyridinium cation having Bronsted acidity and a molybdenum anion (1-butyl-3-carboxypyridinium molybdate) is obtained. Its catalytic activity in the oxidation of sulfur-containing compounds is studied. The influence of the oxidation’s duration, temperature, and the quantity of the oxidation agent and catalyst on the conversion of dibenzothiophene (DBT) is also considered. The conversion of DBT is 100% in the presence of the catalyst under the following conditions: molar ratio H2O2 : S = 10 : 1, catalyst mass 0.02 g, reaction temperature 50°C, and duration 120 min.

Electron-hole interactions in choline-phosphotungstic acid boosting molecular oxygen activation for fuel desulfurization

Many studies have been conducted regarding the separation behavior of carriers (electrons and holes) because of involving the generation of superoxide radicals (O2−), hydroxyl radicals (HO), and hydrogen peroxide (H2O2) in the photocatalytic process of heteropolyacids. Instead, relatively little attention has been focused on the potential Coulomb interactions between photogenerated electrons (e−) and holes (h+). Herein, choline-phosphotungstic acid (Ch3-HPW) was synthesized via one-step acid-base neutralization reaction method, and characterized. The electronic excited state analysis of Ch3-HPW showed that the formation of singlet oxygen (1O2) was related to the electron-hole interactions in the photocatalytic process of ground state molecular oxygen (3O2) activation. Subsequently, a facile fuel photocatalytic oxidative desulfurization and extraction system was established on the basis of Ch3-HPW, air, and acetonitrile (MeCN), to better understand the 3O2 activation in specific applications. The main photocatalytic reaction conditions affecting the desulfurization process, including the amount of Ch3-HPW, the volume ratio of MeCN to model oil, the initial S-concentration, air/N2 bubbling, sulfur compounds, and fuel composition, were systematically investigated under UV radiation. The sulfur removal for model oil and straight-run gasoline in the system were 99.6% and 89.9%, respectively. The results of radical scavenger experiments, electron spin-resonance (ESR) spectroscopy, and density functional theory (DFT) calculations further demonstrated that 1O2, H2O2, and h+ played important roles in the oxidation of sulfur-containing compounds. A new method was developed for the desulfurization of liquid fuels using green and inexpensive O2 in this work to promote the development of photocatalytic process of exciton-involved HPA-based photocatalysts.

Catalyst for the oxidation of sulfur-containing compounds based on a polyamide membrane modified with cobalt phthalocyanine

The catalytic activity of phthalocyanine metal complex immobilized on the surface of a porous polyamide membrane is studied in the oxidation reaction of n-propyl mercaptan. Since noncatalytic oxidation is possible in the presence of oxygen, the kinetics of n-propyl mercaptan oxidation is analyzed as its aqueous alkaline solution passes through unmodified membranes. Characteristics of the catalyst’s performance are selected to evaluate the efficiency of the catalytic process. It is shown that the modified membranes with pore diameters of 1 and 2 μm are the most effective catalysts.

The Oxidation of Sulfur-Containing Compounds Using Heterogeneous Catalysts of Transition Metal Oxides Deposited on the Polymeric Matrix

We investigate the activity of heterogeneous catalysts of transition metal oxides deposited on the polymeric matrix in the oxidation of sulfur-containing compounds. It is shown that MnO2-10/CuO-10 has the highest catalytic activity. The physicomechanical properties of polymeric heterogeneous catalysts of transition-metal oxides, including the specific surface area, elongation at break and breaking strength, specific electrical resistance, and volume resistivity were studied by using an Inspekt mini 3 kN universal tensile machine in accordance with TCVN 4509:2006 at a temperature of 20 ± 2°C. Results show that heterogeneous polymeric catalysts were stable␣under severe reaction conditions. Scanning electron microscopy, and energy-dispersive analysis are used to study the surfaces of the catalysts. Microstructural characterization of the catalysts is performed by using x-ray computed tomography. We demonstrate the potential application of polymeric heterogeneous catalysts of transition-metal oxides in industrial wastewater treatment.

Polymeric Heterogeneous Catalysts of Transition‐Metal Oxides: Surface Characterization, Physicomechanical Properties, and Catalytic Activity

We investigate the physicomechanical properties of polymeric heterogeneous catalysts of transition-metal oxides, specifically, the specific surface area, elongation at break, breaking strength, specific electrical resistance, and volume resistivity. Digital microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive analysis are used to study the surfaces of the catalysts. The experimental results show that polymeric heterogeneous catalysts of transition-metal oxides exhibit high stability and can maintain their catalytic activity under extreme reaction conditions for long-term use. The oxidation mechanism of sulfur-containing compounds in the presence of polymeric heterogeneous catalysts of transition-metal oxides is confirmed. Microstructural characterization of the catalysts is performed by using X-ray computed tomography. The activity of various catalysts in the oxidation of sulfur-containing compounds is determined. We demonstrate the potential application of polymeric heterogeneous catalysts of transition-metal oxides in industrial wastewater treatment.

Oxidative Desulfurization of Fuel Catalyzed by Amphiphilic Peroxomolybdate

The oxidation of sulfur-containing compounds (benzothiophene [BT], dibenzothiophene [DBT], and 4,6-dimethyldibenzothiophene [4,6-DMDBT]) was studied in an emulsion system composed of model oil, hydrogen peroxide, and an amphiphilic catalyst [C7H7C12H25(CH3)2N]2Mo2O3(O2)4. The most suitable conditions were suggested: n (DBT): n (catalyst): n (H2O2) = 1:0.1:10, at 60°C for 2 hr. Under optimized experimental conditions, the removal of DBT, BT, and 4,6-DMDBT could reach 98.0, 94.0, and 62.7%, respectively. The oxidation product sulfones could be readily separated by extraction. The catalyst could be recycled five times without a significant decrease in catalytic activity.

Oxidative Desulfurization of Fuel Oil with Hydrogen Peroxide Catalyzed by Keggin-type Polyoxotungstate in a DC Magnetic Field

The oxidation of sulfur-containing compounds was conducted in a DC magnetic field-assisted system, composed of model compound or diesel, 30 wt% hydrogen peroxide, and an iron mono-substituted Keggin-type heteropolytungstate [(C4H9)4N]4 [PW11Fe(H2O)O39] catalyst. By combining oxidative desulfurization (ODS) in a magnetic field and acetonitrile extraction, when magnetic field intensity was at 17.3 mT, the removal efficiency of the model compound dibenzothiophene (DBT) in petroleum ether with 1,000 ppm S can reach 98% at 70°C within 30 min with O/S ratio = 3 and catalyst dosage 5%, with 2% increase over that without magnetic field assistance. Under the same reaction conditions, the sulfur level of diesel oil was reduced from 5,647 to 508 ppm. This shows that the DC magnetic field facilitates the oxidation of sulfur-bearing compounds, which allowed greater sulfur removal efficiency under milder reaction conditions.

Ultra-deep desulfurization of diesel by selective oxidation with [C 18H 37N(CH 3) 3] 4[H 2NaPW 10O 36] catalyst assembled in emulsion droplets

The oxidation of sulfur-containing compounds (benzothiophene, dibenzothiophene, and their derivatives) in diesel was conducted in emulsion oxidative system (water in oil [W/O]) composed of diesel, 30 wt% hydrogen peroxide, and an amphiphilic catalyst [C 18H 37N(CH 3) 3] 4[H 2NaPW 10O 36] under mild conditions. The amphiphilic catalyst in the W/O emulsion system exhibits very high catalytic activity such that all sulfur-containing compounds in either model or actual diesel can be selectively oxidized into their corresponding sulfones using hydrogen peroxide (O/S ⩽ 3) as an oxidant. The catalytic oxidation reactivity of sulfur-containing compounds was found to be in the following order: benzothiophene < 5-methylbenzothiophene < dibenzothiophene < 4,6-dimethyldibenzothiophene. Although benzothiophene is relatively difficult to oxidize, it can be efficiently oxidized in the emulsion system. The sulfones can be readily separated from diesel by an extractant. The sulfur level of a prehydrotreated diesel can be lowered from 500 to 0.1 ppm after oxidation and then extraction, whereas the sulfur level of a straight-run diesel can be decreased from 6000 to 30 ppm after oxidation and extraction.

Oxidation of Sulfur-Containing Compounds with HOF·CH3CN

The HOF·CH3CN complex, easily prepared by passing F2 through aqueous acetonitrile, is an exceptionally efficient oxygen transfer agent. All types of sulfides have been oxidized to sulfones in excel...