Deep Oxidative Desulfurization Research Articles

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

The development of simple and efficient desulfurization catalysts has garnered increasing attention in the field of desulfurization. In this study, comb-grafted polyethylene phosphomolybdenum-vanadium heteropoly acid catalysts (P-VPA-MomVn) were synthesized via the bulk polymerization method. The structure and morphology of the catalysts were investigated by FTIR, GPC, 1H NMR, XRD, XPS and SEM. By incorporating ionic liquid as an extractant, the P-VPA-Mo10V2 demonstrates high activity in oxidative desulfurization, removing all DBT from the model oil with a low O/S molar ratio under mild conditions. It is noteworthy that when the reaction temperature is 30 °C, the O/S molar ratio is 3, and the reaction time is 60 min, the catalyst exhibits excellent recycling lifetime of 10 cycles without a significant decline in activity. The incorporation of the ionic liquid further enhances its extraction efficiency, indicating that the catalyst not only possesses a stable structure but also holds strong prospects for industrial application.

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

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.

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.

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

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

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.

Synthesis and characterization of new nanocomposite PW11Mn@CuO@PAN as an efficient nanocatalyst for deep oxidative desulfurization of real/model fuels

To obtain clean fuel, a new nanocatalyst was synthesized utilizing K4PW11MnO39 (PW11Mn), copper oxide (CuO), and polyaniline (PAN) to applied as a uniform nanocatalyst for catalytic oxidation desulfurization (Cat-ODS) reactions. The as-prepared nanocomposite was formulated using various characterization techniques such as FT-IR, UV–vis, XRD, SEM, and EDX methods. Experiments pertaining of the elimination of sulfur-containing compounds present in real/model fuel were conducted through the implementation of Cat-ODS methodology. In contrast to the catalytic effectiveness displayed by the bulk substances, PW11Mn@CuO@PAN demonstrated a significantly enhanced performance in the Cat-ODS system. In accordance with the findings of the experiment, the inquiries conducted regarding the Cat-ODS of gasoline disclosed that the level of sulfur was diminished from 0.4997 to 0.0117 wt% with 98 % efficiency in 1 h contracting time at temperature of 35 °C. The PW11Mn@CuO@PAN can be repeatedly recycled for 5 times without experiencing a significant decrease in its activity.

Engineering surface framework TiO6 single sites for unprecedented deep oxidative desulfurization.

Catalytic oxidative desulfurization (ODS) using titanium silicate catalysts has emerged as an efficient technique for the complete removal of organosulfur compounds from automotive fuels. However, the precise control of highly accessible and stable-framework Ti active sites remains highly challenging. Here we reveal for the first time by using density functional theory calculations that framework hexa-coordinated Ti (TiO6) species of mesoporous titanium silicates are the most active sites for ODS and lead to a lower-energy pathway of ODS. A novel method to achieve highly accessible and homogeneously distributed framework TiO6 active single sites at the mesoporous surface has been developed. Such surface framework TiO6 species exhibit an exceptional ODS performance. A removal of 920ppm of benzothiophene is achieved at 60°C in 60min, which is 1.67 times that of the best catalyst reported so far. For bulky molecules such as 4,6-dimethyldibenzothiophene (DMDBT), it takes only 3min to remove 500ppm of DMDBT at 60°C with our catalyst, which is five times faster than that with the current best catalyst. Such a catalyst can be easily upscaled and could be used for concrete industrial application in the ODS of bulky organosulfur compounds with minimized energy consumption and high reaction efficiency.

Flash Joule‐heating synthesis of MoO2 nanocatalysts in graphene aerogel for deep catalytic oxidative desulfurization

AbstractUltra‐high‐temperature flash Joule‐heating of organometallic precursor‐embedded reduced graphene oxide (rGO) aerogel represents a highly efficient approach for the ultrafast production of nanocatalysts, while such a methodology has been scarcely applied to 3D nanocarbon‐based aerogel monoliths. Herein, we demonstrate the rapid synthesis of MoO2 nanoparticles within the aerogel matrix via a 1‐s high‐temperature flash Joule‐heating process (~1700°C), resulting in the formation of the hybrid MoO2@rGO aerogel with uniformly distributed nanoparticles. Nitrogen adsorption/desorption analysis indicates discernible internal microstructural disparities attributed to the additional 1‐s flash‐heating and the substantial generation of MoO2 nanoparticles. This aerogel exhibits exceptional catalytic functionality, achieving up to 99.8% efficiency in converting dibenzothiophene to dibenzothiophene sulfone. Density functional theory calculations provide insights into the catalytic mechanism, revealing that the Mo center shows accumulated electron density contributed from the electron‐rich graphene substrate. This electron density enhancement significantly enhances the catalytic activity, enabling deep desulfurization. The proposed flash nanocatalyst synthesis approach presented here can be extended to fabricate multimetallic nanocatalysts and high‐entropy alloys within the cylindrical aerogel entity, exhibiting great potential for applications in industry‐relevant flow chemistry, electrochemistry, industrial catalysis, and beyond.

Deep oxidative desulfurization of real fuels by a new nanocomposite based on mono Cd(II)‐substituted Keggin‐type silicotungstate, cobalt ferrite and polyaniline as an efficient nanocatalyst

AbstractTo obtain clean fuel, synthesis and characterization of a novel nanocomposite based on mono CdII‐substituted silicotungstate (K3SiW11CdO39), cobalt ferrite (CoFe2O4), and polyaniline (PAN) was presented for the first time. K3SiW11CdO39@CoFe2O4@PAN was identified by FT‐IR, XRD, SEM, and EDX techniques. The outcomes of the characterizations have shown that K3SiW11CdO39 and CoFe2O4 are uniformly dispersed on the PAN surface. The K3SiW11CdO39@CoFe2O4@PAN was employed as a heterogeneous catalyst in the extractive coupled oxidative desulfurization (ECOD) of both real gasoline and dibenzothiophene (DBT) as a thiophenic model fuel. Under relatively mild reaction conditions, the catalytic performance of the as‐prepared nanocatalyst in the ECOD procedure was studied by incorporating acetic acid/hydrogen proxied as an oxidant system at a volume ratio of 1:2. Based on the results, the K3SiW11CdO39@CoFe2O4@PAN nanocatalyst demonstrated effectiveness of up to 95% with 0.1 g at 35°C under optimal operating conditions in the ECOD process. Additionally, the synthesized nanocatalyst exhibited the ability to undergo five consecutive runs in the ECOD process without any discernible reduction in its activity.

Efficient room-temperature oxidation of dibenzothiophene over mesoporous WO3@ZrO2-TiO2 composites derived from polymer-oriented self-assembly strategy

Deep removal of thiophenic sulfur compounds in fuel oil remains an enormous challenge to achieve ultra-clean diesel production. Herein, a polyoxometalate-based inorganic-organic hybrid derived mesoporous WO3@ZrO2-TiO2 composites has been prepared by a simple polymer-oriented self-assembly strategy using polyethyleneimine (PEI) as the structure-directing agent. It exhibits that the existence of mesoporous pore channels, Zr doped TiO2 matrix, and highly dispersed WO3 active sites on the ZrO2-TiO2 framework can facilitate the adsorption-oxidation process of thiophene-type sulfide and provide more accessible active sites. The as-prepared mesoporous WO3@ZrO2-TiO2 composite shows good catalytic activity for dibenzothiophene (DBT) at room temperature, removing 500 ppm of DBT from simulated oil within 80 min, making it a suitable alternative catalyst for deep oxidative desulfurization.

Deep oxidative desulfurization of gas oil by iron(III)-substituted polyoxometalate immobilized on nickel(II) oxide, ((n-C4H9)4N)4H[PW11FeO39]@NiO, as an efficient nanocatalyst

Sulfur compounds are among the most unfavorable constituents of petroleum derivatives, so stringent regulations have been established to curb their atmospheric emissions. In this regard, a new nanocomposite ((n-C4H9)4N)4H[PW11FeO39]@NiO) was synthesized composed of quaternary ammonium bromide salt of ironIII-substituted Keggin-type polyoxometalate immobilized on nickel(II) oxide nanoceramics via sol–gel method. The assembled (n-C4H9)4N)4H[PW11FeO39]@NiO nanocomposite was identified by FT-IR, UV–Vis, XRD, SEM, EDX, and TGA-DTG methods. The characterization results exhibited that ((n-C4H9)4N)4H[PW11FeO39] dispersed uniformly over the surface of the NiO nanoceramics. The ((n-C4H9)4N)4H[PW11FeO39]@NiO nanocomposite was employed as a heterogeneous nanocatalyst in the extractive coupled oxidation desulfurization (ECOD) of real gas oil and dibenzothiophene (DBT) as a model compound. Under relatively moderate conditions, the catalytic performance of the ((n-C4H9)4N)4H[PW11FeO39]@NiO in the ECOD procedure was studied by incorporating acetic acid/hydrogen peroxide as an oxidant system at a volume ratio of 1:2. According to the ECOD results, the ((n-C4H9)4N)4H[PW11FeO39]@NiO demonstrated the effectiveness of up to 95% with 0.1 g at 60 °C under optimal operating conditions. Moreover, the ((n-C4H9)4N)4H[PW11FeO39]@NiO nanocatalyst could be separated and reused for five runs without a noticeable decrease in the ECOD process. This study provides a promising way to meet the target of ultra-low sulfur as an essential process in oil refineries.

Synthesis of Flower-Like Cobalt–Molybdenum Mixed-Oxide Microspheres for Deep Aerobic Oxidative Desulfurization of Fuel

Flower-like cobalt–molybdenum mixed-oxide microspheres (CoMo-FMs) with hierarchical architecture were successfully synthesized via a hydrothermal process and subsequent calcination step. The characterization results show that CoMo-FMs were assembled from ultrathin mesoporous nanosheets with thicknesses of around 4.0 nm, providing the composite with a large pore volume and a massive surface area. The synthesized CoMo-FMs were employed as catalysts for the aerobic oxidative desulfurization (AODS) of fuel, and the reaction results show that the optimal catalyst (CoMo-FM-2) demonstrated an outstanding catalytic performance. Over CoMo-FM-2, various thiophenic sulfides could be effective removed at 80–110 °C under an atmospheric pressure, and a complete conversion of sulfides could be achieved in at least six consecutive cycles without a detectable change in chemical compositions. Further, the catalytic mechanism was explored by conducting systemic radical trapping and transformation experiments, and the excellent catalytic performance for CoMo-FMs should be mainly due to the synergistic effect of Mo and Co elements.

Deep oxidative desulfurization of simulated and real gas oils by NiFe2O4@SiO2-DETA@POM as a retrievable hybrid nanocatalyst

Magnetic nanoparticles surrounded with a silica shell are useful materials to immobilize active agents on their surface. Here, a heteropolyacid-functionalized hybrid nanomaterial (NiFe2O4@SiO2-DETA@POM) was prepared and characterized by X-ray powder diffraction patterns (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA/DTG), vibrating sample magnetometer (VSM), the field emission scanning electron microscopy (FE-SEM), and the electron-dispersive X-ray spectroscopy (EDS). The synthesized hybrid nanostructure was used as a solid nanocatalyst in oxidative desulfurization (ODS) of real fuel and simulated gasoline samples. The ODS process of benzothiophene (BT) and dibenzothiophene (DBT) as model compounds in the presence of NiFe2O4@SiO2-DETA@POM and by using urea-hydrogen peroxide/acetic acid as a safer oxidizing agent was investigated. A good result was obtained by removing 97% of benzothiophene and 98% of dibenzothiophene. Also, 96% of the sulfur compounds were eliminated when the ODS process was tested on a real crude oil sample (600ppm) under an optimized dosage of nanocatalyst, urea-hydrogen peroxide/acetic acid (0.1g, 1g/4ml) at 50 ºC for 60min. NiFe2O4@SiO2-DETA@POM could be recycled for five consecutive oxidation runs without significant deterioration in its catalytic activity. The UHP's safety and efficiency as an oxidant, high removal efficacy, short transformation times, easy workup procedure, catalyst reusability, simple separation of nanocatalyst, green conditions, and environmental compatibility and sustainability. The obtained results prove that NiFe2O4@SiO2-DETA@POM is a suitable and efficient hybrid catalyst for the oxidative desulfurization of simulated and real fuels.

Ionic liquid-derived molybdenum oxide encapsulated in 3D ordered meso/macroporous ZrO2 matrix as promising catalyst for the oxidation of dibenzothiophene in fuel oil

The removal of thiophene-type sulfides in fuel oil still remains a significant challenge to achieve the production of sulfur-free diesel fuel. Herein, an ionic liquid-derived 3D meso/macroporous Mo/ZrO2 (m/M Mo/ZrO2) composite has been prepared by two steps self-assembling process using 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl) and close-packed poly (methyl methacrylate) (PMMA) colloidal crystal as dual-templates. The characterization results demonstrate the existence of interconnected 3D channels, with MoO3 active sites highly dispersed on the tetragonal ZrO2 framework. Moreover, the effects of pore structure, especially mesopores, on the reactivity of as-synthesized m/M Mo/ZrO2 catalyst have been investigated by the addition of different amount of [C16mim]Cl. As-fabricated 3D m/M Mo/ZrO2 catalyst exhibits excellent catalytic activity on dibenzothiophene (DBT) under mild reaction conditions. In addition, the 3D m/M Mo/ZrO2 catalyst demonstrates good cycle stability in the extractive-oxidative desulfurization process with no obvious decrease in activity after 7 cycles, which makes it a promising candidate for deep oxidative desulfurization.

Heteropoly acid-based ionic liquid grafted on hybrid nanomaterial for deep oxidative desulfurization of diesel fuel

Heteropoly acid-based ionic liquid grafted on hybrid nanomaterial for deep oxidative desulfurization of diesel fuel