Hydrogen peroxide oxidative desulfurization of model diesel fuel mixtures in the presence of crown ethers and transition metal peroxo complexes

The catalytic ability of crown ethers and their complexes with transition metal cations in the desulfurization reaction of mixtures that simulate diesel fuel has been investigated. It has been found that the use of monoaza-15-crown-5-ethers with an admixture of NbCl₅ resulted in a fourfold decrease of the total sulfur content, thereby indicating partial oxidation of benzothiophenes and dibenzothiophenes. The complexation of azacrown ethers with NbCl₅ has been studied by ¹H NMR spectroscopy. A moderate efficiency of adsorption purification procedure using silica and alumina for both initial and oxidized model mixtures has been revealed.     

Oxidative-extractive desulfurization of liquid fuel using stannous chloride-acetic acid mixture as catalyst

Present study reports catalytic oxidative-extractive desulfurization (COEDS) of model oil (dibenzothiophene (DBT) dissolved in iso-octane) using an acid mixture (composed of Lewis acid and organic acid (glacial acetic acid)) as catalyst and inorganic oxysalt, potassium dichromate, as oxidant. A series of acid mixtures were prepared by mixing different amount of Lewis acids (SnCl₂, CaCl₂ or CuCl₂) in specific amount of acetic acid and tested for the removal of sulfur from model oil. SnCl₂, which performed best as a Lewis acid, was used in further studies. Effect of Lewis acid to sulfur (molar) ratio was studied in the range of 1–5. Effects of other parameters i.e. oxidant to sulfur (O/S) molar ratio, temperature and time on desulfurization efficiency were also investigated. Fourier transform infrared (FTIR) spectroscopy of SnCl₂-CH₃COOH mixture, model oil (before COEDS), raffinate and extract layers was carried out to understand the removal mechanism. Apparent activation energy for COEDS process with SnCl₂-CH₃COOH system was calculated as 11.65 kJ/mol. At the optimized conditions of oxidant to sulfur molar ratio (O/S = 2:1) and Lewis acid to sulfur molar ratio (SnCl₂/S = 5:1), maximum 61.3% sulfur removal was observed from model oil containing 1000 ppm of sulfur at 308 K.     

水合物法天然气脱硫工艺研究

天然气中H2S的存在会给天然气的储存、输送、利用和环境都带来影响,必须对其进行脱硫净化。常规的天然气脱硫工艺有干法脱硫、膜分离、湿法脱硫和生物脱硫等。水合物法通过使H2S优先生成水合物并进入水合物相的工艺原理,实现天然气脱硫,与常规方法相比,具有工艺流程简单、能耗低、环保等独特优势,应用前景广泛。     

SVDS脱硫技术在硫磺回收装置的工业应用

为了满足GB 31570-2015《石油炼制工业污染物排放标准》的规定,提升区域环境质量,对广泛应用于催化烟气的脱硫技术进行了适应性改造,增加了气-气换热器和高效除雾器等设备,形成适合硫磺回收装置的文丘里脱硫技术(SVDS),并在独山子石化硫磺回收装置进行了工业应用。改造后,排放烟气中SO₂质量浓度从300 mg/m³降至30 mg/m³以下,满足GB 31570-2015中特别排放限值地区SO₂质量浓度的排放要求。在文丘里脱硫技术运行过程中,先后出现气-气换热器压降升高及碱液泵泵壳和叶轮腐蚀的问题,并制定了相应的解决措施,保证了碱洗设施的长周期运行。      

Optimization of Oxidative Desulfurization of Dibenzothiophene Using a Coordinated Ionic Liquid as Catalytic Solvent

Abstract

Oxidative desulfurization (ODS) of dibenzothiophene (DBT) in n-octane with hydrogen peroxide/acetic acid using a quaternary ammonium coordinated ionic liquid (IL) (C₄H₉)₄NBr · 2C₆H₁₁NO as catalytic solvent has been studied. The ODS mechanism by coordinated ionic liquid [(C₄H₉)₄NBr · 2C₆H₁₁NO] was also carried out. The sulfur-containing compounds in model oil were extracted into ionic liquid phase and oxidized to their corresponding sulfones by H₂O₂. The effect factors for desulfurization of model oil were investigated in detail by means of monofactorial and orthogonal experiments (L₁₆(4)⁴). The results showed that the desulfurization efficiency of model oil could reach 98.6% under the optimal conditions of oxidation time, oxidation temperature, molar ratio of H₂O₂/sulfur (O/S), and volume ratio of model oil to coordinated ionic liquid were 30 min, 50°C, 16, and 1, respectively. The influences to the desulfurization efficiency of DBT decreased in the following order: volume ratio of model oil to coordinated ionic liquid (C₄H₉)₄NBr · 2C₆H₁₁NO (V_{model oil}/V_IL) > molar ratio of O/S > oxidation temperature > oxidation time, according to extreme analysis of the orthogonal test. The coordinated ionic liquid (C₄H₉)₄NBr · 2C₆H₁₁NO can be recycled 5 times without a significant decrease in desulfurization.     

The Deep Oxidative Desulfurization of Fuels Using Na2WO4.2H2O in Acidic Ionic Liquids

The catalytic oxidation desulfurization system is composed of Na₂WO₄.2H₂O, H₂O₂, acidic ionic liquid, and phase transfer catalyst has been found suitable for deep removal of organic sulfur in fuels. Under the optimal conditions, the desulfurization efficiency is virtually 100%. Moreover, this acidic ionic liquid can be recycled five times without obviously decrease in activity. Meanwhile, the mechanism of oxidation desulfurization was also elaborated.     

Deep desulfurization of kerosene by electrochemical oxidation and extraction in Mn2+/Mn3+ electrolyte

In this paper, choosing the mixed solution of MnSO₄ solution and H₂SO₄ as electrolyte, with the progressing of electrolysis reaction, Mn³⁺ was generated as intermediate product, combining with water to produce the oxidation agent MnOOH, which was easy to oxidize the sulfur compounds to generate sulfoxide or sulfone. At the optimal electrochemical oxidation desulfurization conditions, the sulfur content of kerosene decreased from 180 µg/g to 8.87 µg/g and the desulfurization efficiency reached to 95.07%. And the cycle of electrolyte and mechanism of electrochemical oxidation desulfurization has been discussed.     

超重力场下络合铁法脱硫过程传质模型研究

H_2S是一种有毒有害气体,故天然气在使用之前必须进行脱硫处理。而超重力旋转填料床因其在巨大的剪切力作用下强化了传质,大大增加了设备的生产能力,且装置尺寸远远小于传统塔设备。超重力技术与氧化还原法结合在天然气脱硫领域具有较好的应用价值。因此,建立一个实用可靠的传质系数模型,对超重力技术脱硫的研究具有重要意义。用CH_4和H_2S的混合气模拟含硫天然气,并在某中试装置上用络合铁氧化还原法进行脱硫。根据所得的数据及旋转填料床中气液接触的特性,包括气体流量、液体流量、转子转速对体积传质系数的影响,采用Matlab进行相关数据拟合分析,得到传质系数经验模型。对经验模型进行分析对比,根据超重力装置气液传质的特性对经验模型进行了改进,得到最终的传质系数经验模型。最后,将建立的传质系数经验模型与实验得到的数据进行对比验证。经分析对比,模型与实验数据吻合程度较高,平均偏差仅为0.12%,且该模型可以外推到其他体积与该超重力装置近似的装置,但气体流量应为1~10 m~3/h,液体流量为0.1~1 m~3/h,转速为100~1 500r/min。     

Desulfurization by Oxidation/Adsorption Scheme over Ti3(PW12O40)4 Catalyst

Abstract

Due to the future specifications for sulfur content in gasoline, a lot of research work has been done to develop alternative methods for desulfurization. This work presents the results for the desulfurization by oxidation/adsorption scheme over Ti₃(PW₁₂ O₄₀)₄ catalyst. The desulfurization experiment was performed with hydrogen peroxide (H₂ O₂) as the oxidant in the presence of Ti₃(PW₁₂ O₄₀)₄/SiO₂-Al₂ O₃ catalyst and adsorbent prepared by the sol-gel method, by using dibenzothiphene (DBT) in petroleum ether as the model compound. The efficiency of Ti₃(PW₁₂ O₄₀)₄/SiO₂-Al₂ O₃ catalyst and adsorbent prepared by the sol-gel method towards DBT adsorption from model compound was studied. The effects of titanium content of the adsorbent and the reaction conditions, such as the reaction temperature, the amounts of adsorbent and hydrogen peroxide (H₂ O₂), and the reaction time, etc., on the desulfurization efficiency and regeneration performance of the catalyst were investigated. It was found that the Ti₃(PW₁₂ O₄₀)₄/SiO₂?Al₂ O₃ catalyst presented higher maximum desulfurization conversion than SiO₂-Al₂ O₃ solids. In addition, it showed higher desulfurization conversion after regeneration with N,N-dimethylamide. Optimal reaction conditions were determined as: a reaction temperature of 70°C, a Ti (titanium)/H(hydrogen) molar ratio of 3, an adsorbent amount of 5 wt%, a H₂ O₂/S molar ratio of 3, and a reaction time of 2 hr. As a result, the total sulfur content in the petroleum ether solution of DBT could be decreased after oxidation/adsorption scheme from an initial value of 200 μg/g to a value of 2 μg/g, and the desulfurization conversion reached 99%, which is a remarkable result. Further, the said adsorbent also had quite good regenerability.     

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.     

Influence of resins and asphaltenes on the structural and rheological properties of petroleum disperse systems

The structural and rheological properties of resin-free model petroleum mixtures (MPM) with an asphaltene content of 0 to 6 wt % and the same mixtures with added 3.85 wt % petroleum resins have been investigated. The composition of the mixtures simulates the amount of the main hydrocarbon-group components and distillate fractions in light paraffin-base oils (ρ₄ ²⁰ = 747.7–789.1 kg/m³). Temperature–dynamic viscosity relationships for cooling the MPM have been obtained, most of which displayed abnormalities in the temperature range of ~40–60°C. Calculations of the viscous-flow activation energy (E _μ) have shown that there are abrupt changes in E _μ in this abnormality region, which are an indication of structuring processes. By means of Fourier-transform laser diffractomery of MPM solutions in kerosene, it has been found that the particle size of the petroleum mixtures is qualitatively related to the revealed abrupt changes in E _μ. It has been shown that these abnormalities correspond to the formation of paraffin–asphaltene associates and their existence is determined by the critical concentration of resins and asphaltenes in the mixtures.     

The Deep Oxidative Desulfurization of Fuels Catalyzed by Surfactant-type Octamolybdate in Acidic Ionic Liquids

Four surfactant-type octamolybdates were synthesized, characterized, and then used as effective catalysts associated with H₂O₂ as oxidant in the acidic ionic liquid, which has been found suitable for deep removal of organic sulfur in fuels. Under the favorable conditions, the sulfur removal could reach almost 100%, which was much better than desulfurization performance by the simple extraction with acidic ionic liquid. Moreover, this acidic ionic liquid can be recycled six times by distillation without obviously decrease in activity. Meanwhile, the mechanism of oxidation desulfurization was also elaborated.     

Hydrogen sulfide removal from hydrocarbon gas mixtures by diethanolamine (computer simulation)

The quantum-chemical simulation of the interactions underlying the absorption extraction process of hydrogen sulfide from gas streams with diethanolamine (DEA) has been performed. It has been shown that molecular complexes are formed without any barrier in the gas phase, whereas both molecular and ionic complexes are formed in the aqueous phase. It has been found that the use of the IPCM continuum solvation model fails to adequately reproduce the value of the heat of the reaction. A promising method for describing the absorption process of hydrogen sulfide extraction with alkanolamines using the supramolecular approach based on a discrete solvation model has been proposed. The approach takes account of intermolecular interactions in the DEA–H₂S–H₂O system and makes it possible to determine structural and energy parameters of the resulting associates and the mechanism of the process.     

Deep Desulfurization of Light Oil Using the Imitating Silver Salt ILs Method

Abstract

Sulfides in oils are harmful in many ways, in particular, deterioration of the environment resulting from sulfur dioxide. A novel desulfurization process for light oil has been investigated. A mixture consisting of benzothiophene (BT), dibenzothiophene (DBT), and oil fractions (235°C–270°C) refined by acid–alkali treatment was employed for alkylation desulfurization tests in a nitrogen atmosphere. The results showed that at a reaction temperature of 30°C, ratio of bromoethane (CH₃CH₂Br) to sulfur of 30:1 (mol/mol), ratio of silver tetrafluoroborate (AgBF₄) to sulfur of 6:1 (mol/mol), and reaction time of 16 hr, the desulfurization yield could reach 76.3%.     

The Removal of Thiophene from n-Heptane/Thiophene Mixtures by Polyethylene Glycol-Block-Polyacrylonitrile Membranes

Abstract

Polyethylene glycol-block-polyacrylonitrile (PEG-b-PAN) copolymers were synthesized and membranes were prepared for sulfur removal from thiophene/heptane mixtures by pervaporation. The desulfurization performance of n-heptane/thiophene mixtures with 1,000 μg·g^?1 sulfur content was considerably influenced by the PEG molecular weight (M _PEG ) and weight content (W _PEG ) in the block copolymer. The maximum separation factor and moderate permeate flux displayed for the block copolymer membrane with M _PEG = 20,000 and W _PEG = 26 wt%. The effect of feed temperature on pervaporation was also analyzed. It was found that the total flux increased with temperature, the sulfur enrichment factor increased before 352 K and decreased then. The pervaporation performance was mainly in terms of PEG microphase separation behavior in the PEG-b-PAN block copolymer and PEG solubility properties in n-heptane/thiophene mixtures with temperature.     

Effect of Pd–Ru alloy membrane thickness on H<Subscript>2</Subscript> flux from steam reforming products

The influence of the thickness of a Pd–Ru alloy membrane on the H₂ flux from binary mixtures containing about 5 and 20% CO, CO₂, CH₄, and steam has been studied. It has been shown that with a decrease in the membrane thickness from 30 to 10 μm, the negative influence of these impurities on the H₂ flux increases. In experiments with pure H₂, it has been established that a decrease in the membrane thickness does not affect the nature of the rate-limiting step in the H₂ flow mechanism. The values for the effective activation energy of the H₂ permeability of the 30- and 10-μm membranes are 13.6 and 23.4 kJ/mol, respectively. A mathematical model describing the flow of hydrogen from binary mixtures through membranes of various thicknesses with varying temperature and pressure is proposed.     

Zinc-Substituted Polyoxometalate for Oxidative Desulfurization of Dibenzothiophene

Abstract

An oxidative desulfurization process for model compound has been studied using Na₁₂[WZn₃(H₂O)₂(ZnW₉O₃₄)₂] · 46H₂O as catalyst and 30 wt% aqueous hydrogen peroxide as the oxidizing agent. The effects of the reaction time, the reaction temperature, the amount of the oxidizing agent and the catalyst on the removal of dibenzothiophene (DBT) were investigated. The oxidated resultant was removed by extraction with polar solvent to reduce the sulfur level in the model compound. The maximum removal of DBT was up to 70%.     

VISCOSITY BEHAVIOR: CORRELATION OF WATER-IN-OIL EMULSIONS IN PRESENCE OF SOLIDS

This is a study of viscosity behavior of oil–water emulsions-solid mixtures. It uses three oils in the presence of different volume fractions (0.005 – 0.02) of fine solids that have different affinities for water. It has been revealed that suspensions and emulsion-solid mixtures of each oil have identical viscosity at the same shear rate. This is an indication that emulsions behave as continuous phase, whilst solids behave as dispersed phase. Consequently, it is possible to correlate the relative viscosity (η_r) data with formulas available in literature for predicting the viscosity of suspensions and emulsions. Relative viscosity is defined as the emulsion-solid mixture viscosity over the pure emulsion viscosity. It has also been found out that Richardson equation [η_r = exp(a ?_s)] with values of 80 and 87 for the parameter a, fits the relative viscosity data of the two light oils used and the heavy one, respectively. The emulsion-solid mixtures prepared in the presence of both hydrophobic and hydrophilic solids were correlated by the same model. Furthermore, The viscosity of pure emulsions of two of the oils studied was found to fit both Krieger's hard sphere model and Roscoe's model but the third oil was found to fit Eilers' model.     

A novel method for synthesis of benzyl alkyl ethers using vanadium-based metal complex catalysts

A novel method has been developed for the synthesis of benzyl alkyl ethers in 25?C85% yields via the reaction of toluene with alcohols in a CCl₄ medium catalyzed by Et₃N-activated VO(acac)₂.     

Desulfurization using an oxidation/catalysis/adsorption scheme over H3PW12O40/SiO2−Al2O3 1

A desulfurization experiment was performed with tert-butyl hydroperoxide (t-BuOOH) as the oxidant in the presence of H₃PW₁₂O₄₀/SiO₂₋Al₂O₃ as the catalyst prepared by the sol-gel method, by using dibenzothiphene (DBT) in petroleum ether as the model compound. This work presents the results for the desulfurization by an oxidation/catalysis/adsorption scheme. The effects of catalyst amounts, t-BuOOH amounts, reaction temperature, and reaction time on the desulfurization efficiency and regeneration performance of the catalyst were studied. It was found that the H₃PW₁₂O₄₀/SiO₂-Al₂O₃ catalyst presented a higher maximum desulfurization conversion than SiO₂-Al₂O₃ solids also prepared by the sol-gel method. In addition, the H₃PW₁₂O₄₀/SiO₂-Al₂O₃ catalyst showed a higher desulfurization conversion after regeneration with N,N-dimethylamide. It was also found that the oxidation agent t-BuOOH resulted in a higher desulfurization conversion than hydrogen peroxide (H₂O₂). The text was submitted by the authors in English.