Diesel desulfurization using a UV-photocatalytic process

In this paper, the use of ultraviolet irradiation using TiO₂ as a photocatalyst for diesel desulfurization was studied in a batch reactor. The effects of operational parameters such as operation time, the presence of oxidant, oxidant type, and irradiation power on the performance of the desulfurization process were investigated. The results revealed that total sulfur and thiol group removals from diesel samples were about 61.91% and 58.64%, respectively, at the power of 18 W of UV irradiation and 2 wt% H₂O₂ as an oxidizing agent using 40 min of irradiation as an optimum time required. It was also found that hydrogen peroxide is the most promising oxidant for the desulfurization of diesel fuel. By increasing the power of ultraviolet irradiation from 18 W to 30 W, total sulfur removal and thiol group conversion were increased to 90% and 88%, respectively. However, total sulfur removal and thiol group conversion at 30 W ultraviolet irradiation with 2 wt% TiO₂ and without using any oxidants were about zero and 14%, respectively.     

Effect of various sono-oxidation parameters on the desulfurization of diesel oil

The influences of ultrasonic intensity, H₂O₂ concentration, ratio of H₂O₂ to oil and the addition of Fenton reagent on the oxidative desulfurization of diesel oil under ultrasonic irradiation were investigated. It was observed that the oxidative desulfurization of diesel oil fitted pseudo-first-order kinetics under our experimental conditions. Increasing the ultrasonic intensity increased the oxidative desulfurization efficiency of diesel oil. The addition of H₂O₂ enhanced the ultrasonic oxidative desulfurization efficiency of diesel oil. The sono-oxidation treatment in combination with Fenton reagent showed a synergistic effect for diesel oil desulfurization. The catalytic oxidative desulfurization process under ultrasonic irradiation process on diesel oils is an efficient and promising method.     

Oxidative Desulfurization of Fuel Oil: Modeling Based on Artificial Neural Network

Abstract

Oxidative desulfurization of fuel oil was investigated using a process consisting of oxidation and distillation steps. In the oxidation step, various organic carboxylic acid/H₂ O₂ systems, especially acetic acid/H₂ O₂, were used as oxidant. They oxidize both easy and refractory sulfur compounds and convert them into oxidized sulfur compounds. The oxidized sulfur compounds are finally removed from fuel oil by distillation in the presence of water. The sulfur content of fuel oil was decreased to levels as low as 20 ppm (up to 90%) in a short contact time, ambient temperature, and atmospheric pressure. The results showed that applying this process did not have any deleterious influence on the distillation characteristic, composition, and content of fuel oil that was examined. An artificial neural network, using back propagation (BP), was also utilized for modeling oxidative desulfuration process of fuel oil. The comparison between the output of ANN modeling and the experimental data showed satisfactory agreement.     

The Research of Ultra-deep Desulfurization in Diesel via Ultrasonic Irradiation Under the Catalytic System of H2O2-CH3COOH-FeSO4

Abstract

In recent years, many countries have drawn up strict laws regarding the sulfur-containing compounds of fossil fuels, especially the gasoline and diese. Ultra-deep desulfurization of fuel is a main component of fossil fuel development. The experiment imposes the photochemistry field on the catalytic oxidation system in order to broaden the newly desulfurization technology. The sulfur-containing compounds, such as dibenzothiophene (DBT) and its derivatives, in diesel fuel are oxidized to corresponding sulfones using H₂O₂-CH₃COOH-FeSO₄ oxidation systems via ultrasonic irradiation. Later, the oxidized sulfur compounds (sulfones) are extracted by a suitable polar solvent. The influences of the catalytic system, reaction time, and ultrasonic source (frequency, intensity) are tested on desulfurization efficiency. Experimental results show that the removal efficiency of the sulfur compound could amount to 97.5%, and the recovery of oil is above 92% under the catalytic system of H₂O₂-CH₃COOH-FeSO₄ by the assistance of ultrasound.     

A Novel Technology for Desulfurization of FCC Diesel Fuels: Combination of Hydrogenation and Oxidation-assisted Ultrasound

Abstract

This new route that integrates with hydrodesulfurization (HDS) and ultra-sound-assisted oxidation desulfurization (UAODS) technology can be studied to decrease the sulfur content of high sulfuric FCC diesel fuel. In the integrating technology, the conventional HDS unit continues to produce below 500 μg/g hydrotreated diesel fuels, with UAODS unit used to make sulfur content below 50 μg/g, or even below 10 μg/g of diesel fuels. Since it has been discovered that cavitation can be originated from ultrasonic irradiation in water, ultrasound is an increasingly used tool to enhance chemical process rate. The addition of Fenton's reagent can enhance the sono-oxidative desulfurization efficiency for diesel fuels. UAODS has more advantages in removing thiophene and alkyl-thiophenes that are less reactive than other organosulfur species present in these hydrocarbon streams (e.g., alkyl sulfides, mercaptans) using HDS technology. The key to success is that the oxidative desulfurization process must be cost-effective versus the HDS revamp alternative available to refiners.     

超声波作用下柴油深度氧化脱硫的研究

催化氧化脱硫是降低柴油硫含量的非加氢脱硫工艺，在催化氧化溶剂抽提的基础上，引入超声波为反应提供能量，考察了超声频率、声强等因素对脱硫效果的影响。结果表明。以H2O2-有机酸为氧化剂，在室温，剂油比为0．05，搅拌速率为300r／min，反应时间为15min，频率为28kHz，声强为0．408W／cm^2的条件下进行柴油催化氧化反应，将得到的产品与萃取剂（DMF）在室温下按照1：1混合，萃取两次后进行分离，其脱硫率为94．8％，而未加超声波的脱硫率仅为67．2％，说明超声氧化脱硫效果明显优于未加超声波的氧化脱硫反应。     

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

Abstract

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.     

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.     

Synthesis of amphiphilic peroxophosphomolybdates for oxidative desulfurization of fuels in ionic liquids

Three amphiphilic peroxophosphomolybdates [C₄mim]₃PMo₄O₂₄, [C₈mim]₃PMo₄O₂₄ and [C₁₆mim]₃PMo₄O₂₄ were synthesized and characterized. These catalysts were used for extraction and catalytic oxidative desulfurization of fuel with H₂O₂ as an oxidant and ionic liquid [C₄mim]BF₄ as an extractant. It was found that [C₁₆mim]₃PMo₄O₂₄ showed the highest catalytic activity and the sulfur content could decrease to 7.5 ppm. In contrast, the desulfurization system shows very low performance without H₂O₂ or ionic liquid. The detailed reaction conditions were optimized including reaction time, temperature, the dosage of H₂O₂ and catalyst, and different sulfur compounds. After the reaction, the catalysts and the ionic liquid can be cycled 8 times with a little decrease in desulfurization efficiency.     

超声波辐照浸渍法制备MnO2/γ-A12O3催化剂及其柴油催化氧化脱硫性能

 分别采用超声波辐照浸渍法和普通浸渍法制备了MnO₂/γ-Al₂O₃催化剂,运用电感耦合等离子体原子发射光谱（ICP-AES）和X射线衍射（XRD）对催化剂进行表征,在空气-异丁醛-MnO₂/γ-Al₂O₃体系中评价其对加氢柴油的氧化脱硫催化性能,并考察了反应温度、异丁醛用量、空气流量、溶剂类型和剂/油体积比对柴油氧化脱硫反应的影响。结果表明,超声波辐照浸渍法制备的MnO₂/γ-Al₂O₃催化剂对柴油氧化脱硫的催化性能明显优于普通浸渍法制备的催化剂。最适宜的催化柴油氧化脱硫反应的条件为：乙腈为溶剂、加氢柴油30 mL、温度35℃、异丁醛20 mmol、空气流量0.06 L/min、超声波辐照浸渍法制备的MnO₂/γ-Al₂O₃催化剂0.08 g、剂/油体积比1/6和催化氧化时间10 min。在此条件下可将柴油硫质量分数从542μg/g 降至31μg/g,柴油脱硫率和回收率分别为94.3%和93.3%。     

Application of Microwave Technology for Desulfurization of Diesel Fuel

The microwave technology was introduced for the desulfurization of diesel fuel. The atmospheric second side-cut diesel fraction, which was supplied by Liaohe Petrochemical Company, was desulfurized by an oxidation process under microwave irradiation. Hydrogen peroxide (H202), can oxidize the sulfur compounds in diesel fuel selectively and convert them into sulfones. Based on the rule of dissolution by similar substances,these sulfones are removed from diesel fuel because they could be dissolved in solvent phase. So the sulfur content of diesel fuel is decreased. The influence of the concentration of oxidizing reagent, solvent phase to oil phase volume ratio (S/O), irradiation pressure, irradiation time, and the irradiation power have been investigated.The optimum conditions for the refining process was determined. The sulfur removal rate was 59.7% under the optimum conditions of 8%H2O2, S/O=0.25, 0.05MPa, 6 min, and 375W, respectively. When no microwave irradiation was applied, the removal rate was 11.5% only.     

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.     

COMPARISON BETWEEN THE PERFORMANCE OF CONVENTIONAL AND HIGH-METAL Co-Mo AND Ni-Mo CATALYSTS IN DEEP DESULFURIZATION OF KUWAIT ATMOSPHERIC GAS OIL

ABSTRACT

Due to environmental constraints, sulfur content of diesel fuel has been restricted to very low levels (500 ppm maximum) in many countries. As a result, a greater emphasis has been placed in recent years on the development of catalysts and processes for deep desulfurization of diesel blending streams to produce low sulfur diesel fuel. In the present work we have compared the performance of a conventional Co-Mo catalyst with that of high metal loading Co-Mo and Ni-Mo catalysts in deep desulfurization of Kuwait atmospheric gas oil. The tests were carried out in a fixed bed reactor unit using 75 ml of catalyst under the conditions: P=32 bar; LHSV = 4h^?1; H₂/oil ratio = 100 ml/ml; temperature range = 330 ? 390°C. HDS activity of the high molybdenum Co-Mo catalyst was superior to that of the conventional Co-Mo hydrotreating catalyst. High metal loading Co-Mo/Al₂O₃ catalyst also showed a substantially higher HDS activity than the Ni-Mo/Al₂O₃ catalyst containing a similar high metal loading. The unreacted sulfur compounds remaining in the product after high severity hydrotreating were identified as dibenzothiophenes with alkyl substituents next to the sulfur atom. The desulfiirization of such low reactive alkyl dibenzothiophenes was found to occur at a substantially lower temperature over the high metal loading Co-Mo catalyst compared with the conventional Co-Mo catalyst. The results have been explained on the basis of the stacking and dispersion of MoS₂ slabs as well as in terms of the nature of the sulfur vacancies in the MoS₂ layers in these catalyst systems.     

Oxidative Desulfurization of Diesel Fuel Using Ultrasound

Abstract

Catalytic oxizdation is a non-HDS technology to remove sulfur compounds from diesel fuel, and ultrasound irradiation was introduced to provide energy for this reaction. The effects of reaction temperature, time, and the ratio of oxidant and oil were investigated. The results show that under certain conditions, the optimal conditions were as follows: volume ratio of oxidant to oil was 1:10, reaction temperature was 50°C, and oxidation time was 10 min.     

外加磁场对催化裂化柴油氧化脱硫作用的研究

以石油醚为溶剂,二苯并噻吩为模型硫化物,配制成模拟油,在螺线管磁场中对油品进行氧化脱硫实验。结果表明,在外加磁场作用下,以30%过氧化氢为氧化剂,当电流强度为11 A、剂油比3.0、反应温度0 ℃、反应时间60 min时,模拟油中的硫含量可以从1 000μg/g降至118 μg/g。对于硫含量为5 647μg/g的催化裂化柴油（25 mL）,在氧化剂过氧化氢（30%）用量5 mL、反应时间60 min、反应温度0 ℃、螺线管电流强度为11 A的条件下,催化裂化柴油的平均脱硫率为70.3%;而无磁场时催化裂化柴油的平均脱硫率为67.2%。     

Oxidation Desulfurization of Thiophene Using Phase Transfer Catalyst/H2O2 Systems

Abstract

In our study, an effective phosphomolybdic acid/hexadecyltrimethyl-ammonium bromide catalyst for oxidative desulfurization of thiophene in a model compound was formed. The oxidation activities of thiophene for a series of heteropoly acids were estimated. The results show that the oxidation activity of thiophene increased with increasing oxidation time, oxidation temperature, and the volume of 30% H₂ O₂ oxidant. The optimal values are 150 min, 40°C, and 3 mL, and sulfur removal attained 96.3% when phosphotungstic acid/hexadecyltrimethylammonium bromide was used as a catalyst.     

Oxidative Desulfurization of Fuel Oil: Modeling Based on Artificial Neural Network

Oxidative desulfurization of fuel oil was investigated using a process consisting of oxidation and distillation steps. In the oxidation step, various organic carboxylic acid/H₂ O₂ systems, especially acetic acid/H₂ O₂, were used as oxidant. They oxidize both easy and refractory sulfur compounds and convert them into oxidized sulfur compounds. The oxidized sulfur compounds are finally removed from fuel oil by distillation in the presence of water. The sulfur content of fuel oil was decreased to levels as low as 20 ppm (up to 90%) in a short contact time, ambient temperature, and atmospheric pressure. The results showed that applying this process did not have any deleterious influence on the distillation characteristic, composition, and content of fuel oil that was examined. An artificial neural network, using back propagation (BP), was also utilized for modeling oxidative desulfuration process of fuel oil. The comparison between the output of ANN modeling and the experimental data showed satisfactory agreement.     

Kinetics of Oxidative Desulfurization of Sulfur Compounds in Diesel Fuel

Abstract

The oxidation of diesel fuel sample was carried out using tertiary butyl hydroperoxide oxidant in the presence of two commercially available Ni-Mo catalysts. The studies were carried out by changing reaction conditions such as treat ratios (oxidant/sulfur molar ratio), WHSV, temperature, etc., to achieve product diesel with sulfur content of <20 ppm. The results of the study on diesel were compared by carrying out similar experiments on model compound, namely, dibenzothiophene dissolved in sulfur-free liquid paraffin oil. GC-PFPD instrument was used to identify and group different sulfur compounds present in diesel and the kinetics of desulfurization was studied.     

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.     

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%.