Deep Desulfurization Research Articles

Facile Construction of Supported Polyoxometalate Ionic Liquids for Deep Oxidative Desulfurization of Fuel

Facile Construction of Supported Polyoxometalate Ionic Liquids for Deep Oxidative Desulfurization of Fuel

Uncovering structure-activity relationships in Brønsted acidic deep eutectic solvents for extractive and oxidative desulfurization

Modeling the structure-activity relationships (SARs) of deep eutectic solvents (DESs) is crucial for upgrading their catalytic performance in targeted reactions. Herein, a series of Brønsted acidic DESs are developed for the SARs research at molecular and atomic levels. Experimental and theoretical results suggest that the catalytic activity increases with the decreasing distances between O atom of active sites in DESs and S atom in sulfur compounds, and the R2 between EODS efficiency and the valid distances of O···S is above 0.9. Such geometric configuration can be optimized by altering the composition of DESs, which in turn substantially triggers the reaction acceleration between active intermediates and substrates. The resulting DES (TEAC/2BSA) achieved deep desulfurization for various sulfur compounds based on the optimal valid distances of O···S. This work contributes to a deep understanding of the reaction mechanism and enables the effective screening of task-specific DESs.

Comb-grafted poly(vinyl phosphate)-based molybdovanadate heteropoly acid for efficient deep oxidative desulfurization using ionic liquid extractants under mild conditions

Comb-grafted poly(vinyl phosphate)-based molybdovanadate heteropoly acid for efficient deep oxidative desulfurization using ionic liquid extractants under mild conditions

Achieving Ultra-Low-Sulfur Model Diesel Through Defective Keggin-Type Heteropolyoxometalate Catalysts

Various Keggin-type heteropolyoxometalate catalysts with structural defects and surface acidity were synthesized by immobilizing 12-phosphotungstic acid (HPW) on mesoporous SBA−15, to produce near-zero-sulfur diesel fuel. As the calcination temperature increased, the W=O and the corner-shared W–O–W bonds in the Keggin unit partially broke, creating oxygen defects, as evidenced by the Rietveld refinement and in situ FTIR characterization. All the catalysts contained Lewis (L) and Brønsted (B) acid sites, with L acidity predominant. The relative intensity of the IR band (I980) of W=O bond inversely correlated with the number of L acid sites as the calcination temperature varied, suggesting that oxygen defects contributed to the Lewis acid sites formation. In the oxidation of dibenzothiophene (DBT) in a model diesel within a biphasic system, DBT conversion exceeded 99% under the optimal reaction conditions (reaction temperature 70 °C, reaction time 60 min, H2O2/sulfur molar ratio 8, H2O2/formic acid molar ratio 1.5, catalyst concentration 2 mg/mL). The influence of fuel composition and addition of indole and 4,6-DMDBT on DBT oxidation were also evaluated. Indole and cyclohexene negatively impacted the DBT oxidative removal. Oxygen defects served as active centers for competitive adsorption of sulfur compound and oxidant. Both L and B acid sites were involved in transferring O atom from peroxophosphotungstate complex to sulfur in DBT, resulting in DBTO2 sulfone, which was immediately extracted by polar acetonitrile. This study confirms that structural defects and surface acidity are crucial in the deep oxidative desulfurization (ODS) reaction, and in enabling the simultaneous oxidation and separation of refractory organosulfur compounds in a highly efficient model diesel.

Mesoporous Silica Supported Hydrophilic Ionic Liquid Gel Microspheres for Solvent-Free Deep Oxidative Desulfurization.

Solvent-free oxidative desulfurization can avoid environmental pollution caused by organic solvents as well as prevent loss of fuel during the oil-water separation process. In this work, first, hydrophilic ionic liquid gel microspheres with [BMIM]BF4 and PHEMA as the dispersion medium and gel network, respectively, were successfully prepared by using mesoporous silica microspheres as a supporting skeleton capable of stabilizing the gel through an anchoring effect, and then the catalyst [BMIM]PW and oxidant H2O2 were incorporated into the gel microspheres to construct a liquid compartment microreactor for deep desulfurization. The prepared microreactor (SiO2@[BMIM]PW/ILG-microspheres) has excellent extraction-catalytic capacity and exhibited ∼100% desulfurization ratio for a model oil of n-heptane with 500 ppm of DBT at 60 °C for 3 h without solvents. Additionally, the prepared microreactor can absorb hydrophilic desulfurization products after the reaction and has advantages of reusability and simple recovery without polluting the fuel oil, which is beneficial for potential petroleum industrial application.

Selective Separation of Thiophene Derivatives Using Metal-Organic Frameworks-Based Membranes.

The removal of sulfur compounds, particularly thiophene derivatives, from oil is crucial due to concerns about environmental issues. Therefore, the deep desulfurization of transportation fuels is currently an urgent problem, and numerous attempts have been made in this direction. Membrane-based desulfurization can be a good alternative to the traditional hydrodesulfurization method, which has several limitations. In this work, the use of membranes containing a metal-organic framework, MOF-5, doped with transition metals (Ag, Cu, Ni), in the adsorptive desulfurization process was studied. The efficiency of membranes was evaluated based on selective removal of thiophene and dibenzothiophene from model oil. Characterization techniques, including scanning electron microscopic (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), confirmed the successful synthesis and incorporation of metal-organic frameworks (MOFs) into mixed matrix membranes (MMMs). Desulfurization experiments showed that MOF-5/Ag exhibited the highest thiophene adsorption efficiency (86.8%), outperforming MOF-5/Cu and MOF-5/Ni. The enhanced performance is attributed to the strong interaction between silver and sulfur. These findings demonstrate the potential of MOF-based MMMs for efficient and selective desulfurization, offering a viable alternative to traditional hydrodesulfurization (HDS) methods.

Enhanced oxidative desulfurization of dibenzothiophene under visible light using carbon quantum dot-decorated novel Z-scheme BiVO4/MOF-808/CN photocatalyst: Mechanism, performance and stability

BackgroundPhotocatalytic oxidative desulfurization technology enabling the facile oxidation of these compounds to sulfones, deep desulfurization, operation at ambient temperature and pressure, and minimal energy consumption. MethodsThis study introduces a novel photocatalyst, BiVO4/MOF-808/CN integrated with carbon quantum dots (BMC-CQD), designed for the oxidative desulfurization of dibenzothiophene (DBT) under visible light irradiation. Significant findingsNovel approach was undertaken by integrating the photocatalyst BiVO4, g-C3N4 with MOF-808 and carbon quantum dots to enhance the interaction between semiconductors. This innovative photocatalyst addresses several limitations associated with MOF-808, including enhanced visible light absorption (2.21–2.60 eV), reduced electron-hole recombination, rapid charge transfer, high surface area (1370 m2/g), large pore volume (0.908 cm3/g). Under optimized conditions of a catalyst dosage of 1.5 g/L, a reaction temperature of 50 °C, an O/S molar ratio of 6, and an initial DBT concentration of 500 mg/L, the 10 %BMC-CQD photocatalyst achieved an impressive 99.5 % DBT removal efficiency in just 25 min. Incorporating CQD into the BMC framework significantly amplifies the removal rate of the DBT by 10.69, 2.13 and 8.7 times compared to the BiVO4, MOF-808 and CN, respectively. The radical trapping experiments have shown that the •OH and •O2− radicals play a key role in the DBT removal process.

One Pot Synthesis of Phosphomolybdenate Based Hybrids for Efficient Oxidative Desulfurization

With increasing stringent standard of sulfur content in fuels, there is a growing need for high-efficiency deep desulfurization to meet ecological and environmental demands. Herein, a series of heteropolyacid catalysts with phosphomolybdic acid base melamine (MHPMo-n) were synthesized by one-pot method and applied to oxidative desulfurization. Further, the optimum conditions for desulfurizations could be explored, which the desulfurization rate of the catalyst could reach 100% within 60 min under the conditions of m(catalyst)= 0.01 g, T = 40 °C, O/S = 3. Furthermore, the catalyst demonstrated excellent catalytic efficiency during the five cycles. One-pot method of phosphomolybdic acid base melamine provides a new idea for the synthesis of catalysts with outstanding catalytic properties for oxidative desulfurization (ODS).

Deep eutectic solvents as sustainable and extraordinary all-in-one systems for oxidative desulfurization

Deep oxidative desulfurization (ODS) using deep eutectic solvents (DESs) was a promising and environmentally friendly technique. Herein, we report an innovative and straightforward approach for achieving efficient oxidative desulfurization using DESs. These DESs serve as all-in-one systems, encompassing catalysts, oxidants, and solvents. The results demonstrate the excellent desulfurization performance of a DES derived from meta-chloroperoxybenzoic acid (mCPBA) and dimethylethanolamine (DMAE) for the removal of dibenzothiophene (DBT) from model oil. The use of multi-component DES systems enhances efficiency and reduces toxicity compared to individual solvent components, resulting in deep desulfurization levels. The influence of crucial extraction parameters, such as extraction time, temperature, and amount of DES, was investigated. The results demonstrated that the mCPBA/DMAE-based DES exhibited the highest desulfurization efficiency, reaching up to 99 % under optimal conditions (60 °C, 90 min, and 1 mL of DES). Moreover, the exceptional stability and reusability of DESs were confirmed, as they maintained sustained desulfurization efficiency even after six cycles of reuse.

Synthesis of amorphous titanium isophthalic acid catalyst with hierarchical porosity for efficient oxidative desulfurization of model feed with minimum oxidant

Deep desulfurization is an indispensable technique for obtaining clean fuel and the preparation of novel materials for upgrading desulfurization efficiency is highly pursued. Herein, we develop a novel amorphous titanium isophthalic acid (Ti-IPA) catalyst with hierarchical porosity and highly dispersion of Ti-OH defect sites via solvothermal method. Ti-IPA is suitable for a variety of oxidant desulfurization (ODS) reaction systems due to its amphiphilic nature. The optimal Ti-IPA reveal extraordinary ODS performance for oxidizing 1000 ppm sulfur of dibenzothiophene-to-dibenzothiophene sulfone in model feed within 12 min at 40 ℃ with minimum oxidant/sulfur molar ratio of 2 (the sulfur oxidation efficiency reached 99.5 %), and the reaction time can be altered to 5 min at 50 ℃. The activity per unit mass of Ti-IPA reaches 52.2 mmol h−1g−1 at 50 ℃, outperforming all the reported Ti-based organic materials. Quenching and EPR tests indicate that Ti-IPA adopts non-free-radical ODS mechanism. Experimental and characterization results verify that the terminal OH capped on the Ti defect sites can easily react with oxidant to form peroxo-titanium intermediates, which manipulate the sulfur oxidation efficiency.

Highly efficient C16-PW9/SiO2 designed based on trivacant tungstophosphate ([A-PW9O34]9−) for rapid oxidative desulfurization under mild conditions

In order to achieve ultra-low sulfur fuel production, it is essential to design highly efficient catalysts for deep desulfurization. In this work, trivacant Keggin-type tungstophosphate PW9 (Na9[A-PW9O34]•7H2O) was innovatively utilized to synthesize polyoxometalate-based supported silica C16-PW9/SiO2. The intact presence of polyoxometalates (POMs) was evidenced by several techniques of describing the structure and composition of the obtained hybrid samples. Compared with the saturated tungstophosphate ([PW12O40]3−), the [A-PW9O34]9− showed better coordination, which can coordinate with five ILs (C16MIM). More ILs make it easier for the catalyst to attract DBT to the vicinity of PW9, and the abundance of metal oxide W = O on PW9 endows the catalyst’s excellent catalytic activity. Specifically, C16-PW9/SiO2 exhibited excellent oxidative desulfurization performance, achieving 100 % dibenzothiophene (DBT) conversion efficiency at 50 °C for 10 min, and the turnover frequency (TOF) number reached 723.4 h−1, which is higher than the catalysts of the POMs type that have been published. The strategy of combining lacunary polyoxometalates with ionic liquids offers a fresh viewpoint on the creation of POM-based catalysts.

In Situ Synthesis of Hierarchical POM@HUSY with Tunable Lewis and Bro̷nsted Acid Sites for Deep Oxidative Desulfurization of Dibenzothiophene

In Situ Synthesis of Hierarchical POM@HUSY with Tunable Lewis and Bro̷nsted Acid Sites for Deep Oxidative Desulfurization of Dibenzothiophene

Enhanced photocatalytic aerobic oxidative desulfurization of diesel over FeMo6Ox nanoclusters decorated on CuS nanosheets

Photocatalytic aerobic oxidative desulfurization (PAODS) presents a promising and carbon-neutral avenue for desulfurizing petroleum products. However, existing photocatalysts encounter limitations in activating oxygen and show sluggish kinetics in sulfide-to-sulfone conversion, hampering widespread implementation. Herein, we present a FeMo6Ox nanocluster-modified CuS photocatalyst for PAODS reaction using air as an oxygen source. Through experimental characterization and density functional theory (DFT) calculations, we elucidate that the incorporation of FeMo6Ox nanoclusters can modulate the CuS electron density, which results in the generation of electron trap states and facilitates the separation of electron-hole pairs. We show that the variation of water content in air alters the generation efficiency of different reactive oxygen species (ROS), highlighting the potential to optimize moisture levels for achieving the highest catalytic efficiency. The optimized catalytic system exhibits a record specific activity of 10.42 mmol g−1 h−1, and more importantly, achieves deep desulfurization of authentic diesel, showcasing its appealing application prospects.

Deep Desulfurization of High-Sulfur Petroleum Coke via Alkali Catalytic Roasting Combined with Ultrasonic Oxidation.

The sulfur in petroleum coke is harmful to carbon products, underscoring the importance of desulfurization for high-sulfur petroleum coke. This paper proposes a method combining alkaline catalytic roasting with ultrasonic oxidation for the deep desulfurization of high-sulfur petroleum coke. The results show that the desulfurization rate reaches 88.99% and the sulfur content is reduced to 0.83 wt.% under a coke particle size of 96-75 μm, sodium-hydroxide-to-petroleum-coke ratio of 50%, roasting temperature of 700 °C, and holding time of 2 h. The alkali-calcined petroleum coke is ultrasonically oxidized and desulfurized in peracetic acid. The results show that, under a hydrogen peroxide content of 10%, hydrogen-peroxide-(liquid)-to-petroleum-coke (solid) ratio of 20 mL/g, acetic acid content of 5 mL, ultrasonic power of 300 W, reaction temperature of 60 °C, and reaction duration of 4 h, the sulfur content is reduced to 0.15 wt.% and the total desulfurization reaches 98.01%. Through a series of characterizations, the proposed desulfurization mechanism is verified. Alkali roasting effectively removes a significant portion of sulfur in petroleum coke. However, the elimination of certain sulfur compounds, such as the more complex thiophene, presents challenges. The thiophene content is subsequently removed via ultrasonic oxidation.

Deep Oxidative Desulfurization of Planar Compounds Over Functionalized Metal–Organic Framework UiO-66(Zr): An Optimization Study

Deep Oxidative Desulfurization of Planar Compounds Over Functionalized Metal–Organic Framework UiO-66(Zr): An Optimization Study

Development of an electrochemical reactor with rotating anode for fast and ultra-deep catalytic desulfurization of diesel: experimental and modeling

A novel electrochemical reactor with a rotating anode attached to its end with four baskets as catalysts holders is proposed for deep desulfurization of diesel fuel. In this reactor two experimentally prepared catalysts of (5% manganese oxide (MnO2)/modified activated carbon (MAC) and 5% iron oxide (Fe2O3)/MAC) were used for an efficient desulfurization process. This design is characterized by conducting two functions at the same time, which are to agitate the reaction mixture and to move the catalyst over all areas of the reaction vessel. Several experiments were conducted at different operating conditions such as voltage, reaction time, and agitating speed. Results showed that the proposed basket reactor is excellent and highly effective in removing dibenzothiophene (DBT) in diesel. The removal efficiency of sulfur compounds is significantly improved by enhancing reaction times, stirring speed, and cell voltage up to 3 volts and drops at higher than 3 volts. At all operating conditions, the 5% Fe2O3/MAC catalyst showed higher performance than the 5% MnO2/MAC catalyst. This result can be attributed to the high reactivity of Fe2O3/MAC toward DBT removal and its magnetic activity which could enhance the oxidation reaction. Under the best operating conditions, the removal efficiencies reached 98.8%, and 93.1% for 5% Fe2O3/MAC and 5% MnO2/MAC, respectively. A model for the proposed reactor was also developed using an artificial neural network (ANN) software. The modeling data displayed an excellent agreement between the experimental and predicted data. This interactive model produced an accurately strong basis for the behavior of the new electrochemical desulfurization (ECDS) process.

Deep Oxidative Desulfurization Utilizing Hybrid Keggin Catalyst with 1-methyl-3-octyl imidazolium hexafluorophosphate

تعتبر إزالة الكبريت بالأكسدة العميقة موضوعًا مهمًا لأبحاث التحفيز البيئي لإنتاج الديزل منخفض الكبريت.أحد العوامل المساعدة التي تم استخدامها مؤخرًا لإزالة مركبات الكبريت المقاوم من نموذج الديزل بالاكسدة هو بولي أوكسوميتالات من نوع كيجن. في هذا العمل, تم اختبار العامل المساعد من نوع كيجن TBAPW11O39 , نموذج الديزل, بيروكسيد الهيدروجين(H2O2) وسائل ايوني من نوع OMIM(PF6)) تحت ظروف تفاعل مختلفة. تم التقاط مركب الكبريت ثنائي بنزوثيوفين (DBT) من نموذج الديزل في السائل الايوني (IL) ثم يتأكسد الى سلفون مع بيروكسيد الهيدروجين كمؤكسد باستخدام TBAPW11O39 في مفاعل نوع (batch) . تم دراسة تأثيرزمن(30-180 دقيقة) و درجة حرارة (T) التفاعل(343,3232,303 كلفن) و وزن العامل المساعد(0.5-6) غم / لتر و النسبة المولية O/S) H2O2/ DBT) من 1:1الى 1:5(مول/مول) والنسبة الحجمية IL/diesel (1/10 – 5/10) (مل/مل).أظهر العامل المساعدد فعالية عالية لإزالة DBT باستخدام بيروكسيد الهيدروجين ، وبلغت اعلى إزالة للكبريت بنسبة 96٪ في الظروف المثلى (10 مل من نموذج الديزل ، T = 343 K ، وزن العامل المساعد=3 غم / لتر، النسبة المولية المؤكسد/مركب الكبريتH2O2/DBT))=1:5 والنسبة الحجمية السائل الايوني/الديزل= 2/10 لمدة 120 دقيقة). تشير هذه النتائج إلى أن ازالة الكبريت بالأكسدة التحفيزية مع الاستخلاص باستخدام العامل المساعد كيجن الهجينة لنموذج وقود الديزل هي طريقة فعالة وتوفر وعدًا لتحقيق إزالة الكبريت بعمق كبير.

Bifunctional pyridinium-based Brønsted acidic porous ionic liquid for deep oxidative desulfurization

Porous ionic liquids have been highlighted with special interest for their desirable catalytic activity and extraction properties. Herein, bifunctional porous ionic liquids (denoted UiO-66-BAPILs) were synthesized by dispersing UiO-66 into a pyridinium-based Brønsted acidic ionic liquid ([BSPy][CF3SO3]) for oxidative desulfurization. The permanent cavity of UiO-66 moiety in UiO-66-BAPILs was validated as well-preserved by the SO2 uptake experiments and molecular size simulations. Under the optimum reaction conditions, the sulfur removal could reach up to 99.5% with hydrogen peroxide as the oxidant. Additionally, bifunctional UiO-66-BAPILs were deemed as both extractants and catalysts during the reaction. A possible mechanism has been proposed that UiO-66-BAPILs extract the aromatic sulfur compounds via π···π interactions and C-H···π interactions and meanwhile oxidize them with peroxysulfonic acids and •OH radicals. These findings will open up new avenues to facilitate the catalytic oxidation performance by constructing bifunctional Brønsted acidic porous ionic liquids.

Preparation of the MoO3- Fe3O4 nanocomposites for deep oxidative desulfurization of model fuel: Optimization and experimental design

In the present study, the catalytic activity of the MoO3-Fe3O4 of molybdenum oxides prepared by the impregnation method was investigated in the extractive oxidative desulfurization (EODS) process. Structural characterization of the nanocomposite catalysts was studied by XRD, N2 adsorption–desorption isotherm, FT-IR, and VSM analyses. The EODS technology was applied to remove sulfur from a model fuel (dibenzothiophene in n-octane, DBT) using H2O2 as the oxidant, acetonitrile as the extracting solvent, and MoO3-Fe3O4 as the catalysts. Among the catalysts with various loadings of MoO3 on Fe3O4 nanoparticles (3, 6, 9, 12, and 15 wt%), the catalyst with 9 wt% MoO3 demonstrated the highest performance. Subsequently, the optimal design of the experiments using response surface methodology (RSM) based on Box-Behnken design (BBD) was applied to study the effects of the independent parameters such as O/S molar ratio, reaction temperature, and catalyst dosage on sulfur removal efficiency. Optimization studies were performed, and maximum sulfur removal efficiency of 98 % was achieved under the optimal conditions of 58 °C, O/S molar ratio: 5.9, and 0.116 g of 9 wt% MoO3-Fe3O4 as catalysts. The activity of the catalyst remained unchanged after six times recycling in the EODS process. Additionally, a catalytic reaction mechanism was proposed.

Onboard Miniature Jet Fuel Desulfurizer for Mobile Fuel Cell Power Systems

Owing to its high energy density and wide availability, jet fuel is a promising fuel for solid oxide fuel cell (SOFC) power systems. However, fuel‐reforming catalysts and SOFC anodes are easily poisoned by sulfur compounds present in the jet fuel. Therefore, effective removal of sulfur from the jet fuel is essential before its feeding to the SOFC system. Herein, a novel adsorptive desulfurization reactor for onboard desulfurization of jet fuel in mobile SOFC systems is developed. A laser‐based 3D printing method is used to fabricate the one‐piece stainless steel reactor that significantly simplifies the assembly and reduces the overall weight. The desulfurization performance of the reactor is evaluated using a regenerable nickel‐based sorbent under varying operating conditions. A strong influence of temperature and fuel flow rate on the desulfurization performance is observed. The results confirm that the developed desulfurization system is capable of reducing the sulfur content in jet fuel to a few ppm to sub‐ppm level. The proposed desulfurization system offers unique advantages in terms of geometric design flexibility, space optimization, scalability, and modularity for any onboard and/or on‐demand deep desulfurization needs in addition to fuel cell power systems for transport and portable applications.