Oxidative Desulfurization Performance Research Articles

Preparation and oxidative desulfurization performances of modified SBA-15 supported polyacid metal oxolates

In this study, eight composite catalysts were prepared by loading (CTAB)3H3[PW9V3O40] (active components) onto amino-functionalized mesoporous titanium silicate Ti-SBA-15(supports). In order to study the effects of different Ti contents and different active components on the catalytic performances of the catalysts, 30 %(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-X (X = 0, 25, 50, 75, 100) and X%(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-50 (X = 20, 40, 50) were obtained and characterized. The oxidative desulfurization performances of the composite catalysts were explored. It was found that catalyst 40 %(CTAB)3H3[PW9V3O40]/NH2–Ti-SBA-50 exhibits the optimal oxidative desulfurization performance. This is because the incorporation of SBA-15 with an appropriate amount of Ti (n(Si)/n(Ti) = 50) can improve the acidity and stability of mesoporous silica. The successful substitution of CTAB (n(CTAB)/n(H6PW9V3O40) = 3) in the active component can reduce the mass transfer resistance and speed up the reaction rate. 3-Aminopropyltriethyl silane (APTES) acts as a silane coupling agent to graft amino groups onto mesoporous molecular sieve SBA-15, which can enhance the interaction between heteropolyacids and carriers. Under the synergistic effect of the active component and the support, the total removal rate of the optimal catalyst with a total concentration of 1000 ppm sulfur compounds in the simulated fuel was 94.44 %. After four cycles, the total desulfurization rate of the catalyst can reach 91.28 %.

Synergistic Palladium Single Sites and Nanoparticles Implanted Into a Novel Zr‐Based Metal–Organic Framework via Solvent‐Free Processing for Upgrading Oxidative Desulfurization Performance

AbstractDesulfurization is a significant approach to producing clean fuel. The design of novel host–guest catalysts with multiple active sites at atomic‐ and nano‐scales, opens a new door to gain an ultrahigh synergistic performance for targeted applications. Herein, an in situ solvent‐free approach is conducted for synchronously implanting Pd single sites (PdSS) and nanoparticles (PdNP) into a novel Zr‐based metal–organic framework (Zr‐MOF). The optimal catalyst exhibits ultrahigh oxidative desulfurization (ODS) performance that can oxidize 1 000 ppm sulfur with diluted oxidant at 40 °C within 5 min. The turnover frequency of the catalyst at 40 °C reaches 774.7 h−1 which is 47.4 times higher than host Zr‐MOF and surpasses the most reported ODS catalysts. A substantial synergistic effect between PdSS and PdNP is responsible for the upgradation of ODS performance. Experimental and theoretical results indicate that PdSS in Zr‐MOF can readily absorb H2O2, and synergistically decompose H2O2 with the assistance of PdNP for accelerated generation of •OH radicals that dominates the ODS performance. This work provides a new solvent‐free way for in situ implanting synergistic catalytic sites into MOFs to upgrade their catalytic performance in targeted reactions.

Isomeric organic ligands directing octamolybdates-linked Copper(II) functionalized complexes as active catalysts in electrochemistry and desulfurization

Two remarkable octamolybdates-based copper-organic complexes, namely, [Cu7(L)4(H2O)7(β-H2Mo8O26)]·7H2O (POM 1) and [Cu6(HX)4(β-Mo8O26)(H2O)6]·3H2O (POM 2) (H3L = 2-(pyridine-4-yl)-1H-imidazole-4,5-dicarboxylic acid; H3X = 2-(pyridine-3-yl)-1H-imidazole-4,5-dicarboxylic acid), were successfully assembled using two isomeric organic ligands under hydrothermal conditions. The two-dimensional metal-organic layers of POMs 1 and 2 were converted into three-dimensional frameworks by hexadentate β-H2Mo8O262− and tetradentate β-Mo8O264− clusters, respectively. The electrocatalytic properties of POM 1 were investigated, revealing its ability to catalyze the reduction of BrO3−, NO2− and H2O2 and the oxidation of ascorbic acid. Notably, POMs 1 and 2 demonstrated exceptional stability in organic solvents and exhibited excellent catalytic performance in oxidative desulfurization. When employed as catalysts for thioanisole oxidation, the conversion rates reached 94.5% after 150 min for POMs 1 and 99.9% after 120 min for POMs 2. In addition, their catalytic performances in model oil remained largely unchanged after five recycling cycles.

One-Pot Preparation of Nitro-Functionalized Bimetallic UiO-66(Zr-Hf) with Hierarchical Porosity for Oxidative Desulfurization Performance.

Preparation of multifunctional metal-organic frameworks (MOFs) offers new opportunities to obtain ultrahigh synergistic catalytic performance for heterogeneous reactions; however, the application of a one-pot method for preparing multifunctional MOFs remains challenging. Herein, we develop a one-pot green route for synthesizing bimetallic nitro-functionalized UiO-66(Zr-Hf)-NO2 with hierarchical porosity under solvent-free conditions. The optimal UiO-66(Zr-Hf0.6)-NO2 shows an ultrahigh enhancement of oxidative desulfurization (ODS) efficiency to oxidize sulfur compounds (1000 ppm sulfur) in a model fuel at 40 °C within 12 min due to the introduction of more active Hf sites in the nodes, the increased Lewis acidity of Zr/Hf-O nodes by the electron-withdrawing NO2 group, and the enhanced diffusion rates by the mesopores. The turnover frequency (TOF) over UiO-66(Zr-Hf0.6)-NO2 at 40 or 50 °C reaches 145.3 or 217.0 h-1 that surpasses the TOF of most reported MOF-based catalysts in the ODS reaction. Quenching and electron paramagnetic resonance experiments confirm that the formed Hf-OH on the Zr/Hf-O nodes can easily decompose the oxidant (H2O2) for generating a Hf-OOH-active intermediate and dominate the ODS efficiency. This contribution provides a one-pot solvent-free avenue to synthesize multifunctional MOFs for enhancing their catalytic activities for targeted applications.

The Utilization of Rice Husk as Both the Silicon Source and Mesoporous Template for the Green Preparation of Mesoporous TiO2/SiO2 and Its Excellent Catalytic Performance in Oxidative Desulfurization.

In recent years, TiO2-based catalysts have received extensive attention from researchers for their excellent oxidative desulfurization (ODS) performances. In this paper, a series of mesoporous TiO2/SiO2 catalysts with different TiO2 loadings are prepared, using an incipient wetness impregnation method with agricultural waste rice husk as both the silicon source and mesoporous template and tetrabutyl titanate as the titanium source. The effect of different TiO2 loadings on the ODS performance of the samples is investigated, and the appropriate TiO2 loading is 2.5%. Compared with pure TiO2, the 2.5%TiO2/SiO2 sample exhibits high catalytic activity for oxidative desulfurization. This is, on the one hand, due to the high specific surface area and mesopore volume of the 2.5%TiO2/SiO2 sample. On the other hand, it is due to the uniform dispersion of TiO2 grains with an average diameter of 6.1 nm on the surface of the mesoporous SiO2 carrier, which greatly increases the active sites of the 2.5%TiO2/SiO2 sample, thus improving the catalytic activity of the sample. The recycling performances of the 2.5%TiO2/SiO2 sample are further investigated. The results show that, after fifteen cycles, the 2.5%TiO2/SiO2 sample still maintains high conversions of dibenzothiophene (99.8%) and 4,6-dimethyldibenzothiophene (99.7%) without deactivation. In addition, the 2.5%TiO2/SiO2 sample treated with TBHP aqueous solution is characterized by the technique of UV-Vis, and the Ti-peroxo (Ti-OOtBu) species, the active intermediate for the ODS of bulky organic sulfides, is successfully captured. Finally, a possible reaction mechanism for the ODS process over the 2.5%TiO2/SiO2 sample is proposed.

Electrothermally-Driven Ultrafast Chemical Modulation of Multifunctional Nanocarbon Aerogels.

Ultrahigh-temperature Joule-heating of carbon nanostructures opens up unique opportunities for property enhancements and expanded applications. This study employs rapid electrical Joule-heating at ultrahigh temperatures (up to 3000K within 60s) to induce a transformation in nanocarbon aerogels, resulting in highly graphitic structures. These aerogels function as versatile platforms for synthesizing customizable metal oxide nanoparticles while significantly reducing carbon emissions compared to conventional furnace heating methods. The thermal conductivity of the aerogel, characterized by Umklapp scattering, can be precisely adjusted by tuning the heating temperature. Utilizing the aerogel's superhydrophobic properties enables its practical application in filtration systems for efficiently separating toxic halogenated solvents from water. The hierarchically porous aerogel, featuring a high surface area of 607m2g-1, ensures the uniform distribution and spacing of embedded metal oxide nanoparticles, offering considerable advantages for catalytic applications. These findings demonstrate exceptional catalytic performance in oxidative desulfurization, achieving a 98.9% conversion of dibenzothiophene in the model fuel. These results are corroborated by theoretical calculations, surpassing many high-performance catalysts. This work highlights the pragmatic and highly efficient use of nanocarbon structures in nanoparticle synthesis under ultrahigh temperatures, with short heating durations. Its broad implications extend to the fields of electrochemistry, energy storage, and high-temperature sensing.

Ultra‐deep and fast oxidative desulfurization by IL‐POM immobilized on bar‐shaped green fiber toward the high efficiency

The Keggin‐type P‐Mo‐W polyoxometalate‐based ionic liquids ([VimAm]Br‐POM, POM is PMo6W6O40) were facilely supported on the green fiber (CA) to obtain a kind of bar‐shaped catalyst. The [VimAm]Br‐POM@CA showed an outstanding oxidative desulfurization performance for model oil and real oils with H2O2 as oxidant, mainly due to the dual role of the [VimAm]Br‐POM with the high activity and its excellent dispersion on CA. The dibenzothiophene (DBT) in model oil could be almost completely removed with [VimAm]Br‐POM@CA‐2 in 60 min at 60 °C without adding other extractants, in which [VimAm]Br acts as this role. Meanwhile, the influences of reaction temperature, molar ratio of H2O2/S, catalyst dosage, and different sulfur‐containing compounds were also investigated. Interestingly, the pretty low activation energy (0.1875 kJ/mol) has been achieved, and no significant loss of activity even after being reused for 5 cycles. The combination of IL‐POM and CA is an efficient strategy to obtain a newly kind desulfurization catalyst, with remarkable results on catalytic efficiency and reuse ability at the same time.

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.

Controllable Synthesis of Titanium Silicon Molecular Zeolite Nanosheet with Short b-Axis Thickness and Application in Oxidative Desulfurization.

Titanium silicon molecular zeolite (TS-1) plays an important role in catalytic reactions due to its unique nanostructure. The straight channel on TS-1 was parallel to the orientation of the short b-axis and directly exposed to the aperture of the 10-member ring with a diameter of 0.54 nm × 0.56 nm. This structure could effectively reduce the diffuse restriction of bulk organic compounds during the oxidative desulfurization process. As a kind of cationic polymer electrolyte, polydimethyldiallyl ammonium chloride (PDDA) contains continuous [C8H16N+Cl-] chain segments, in which the Cl- could function as an effective structure-directing agent in the synthesis of nanomaterials. The chain of PDDA could adequately interact with the [0 1 0] plane in the preparation process of zeolite, and then the TS-1 nanosheet with short b-axis thickness (6 nm) could be obtained. The pore structure of the TS-1 nanosheet is controlled by regulating the content of PDDA. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 physical adsorption analysis, infrared absorption spectrum and ultraviolet-visible spectrum were used to determine the TS-1. The thinner nanosheets exhibit excellent catalytic performance in oxidative desulfurization of dibenzothiophene (DBT), in which the removal rate could remain at 100% after three recycles. Here, the TS-1 nanosheet with short b-axis thickness has a promising future in catalytic reactions.

Completely Inorganic Deep Eutectic Solvents for Efficient and Recyclable Liquid-Liquid Interface Catalysis.

Organic acid-based deep eutectic solvents (DESs) as catalysts always suffer from weak stability and low recyclability due to the accumulation of organic oxidative products in the DES phase. Herein, a completely inorganic deep eutectic solvent (IDES) ZnCl2/PA with zinc chloride (ZnCl2) and phosphoric acid (PA) as precursors is constructed to realize liquid-liquid interface catalysis for desulfurization of fuel and product self-separation for the first time. Owing to the inorganic nature, the organic oxidative products are accumulated at the interface between the IDES and fuel rather than the IDES phase. With this unique feature, the IDES can be reused for at least 15 times without any further treatment in oxidative desulfurization process, showing a state-of-the-art cycle-regeneration stability. Moreover, compared with the reported organic DESs, the IDES also reveals more attractive catalytic oxidative desulfurization performance. Experimental and theoretical studies indicate that the strong coordination Zn···O═P and the strong adsorption energy between IDES and sulfides enhance the activation of H2O2 to reactive oxygen species, leading to the superior catalytic performance in oxidative desulfurization of fuel.

Constructing interface chemical coupling S-scheme heterojunction MoO3-x@PPy for enhancing photocatalytic oxidative desulfurization performance: Adjusting LSPR effect via oxygen vacancy engineering

Construction of photocatalyst that combines excellent electron transfer and photoresponse capabilities to enhance photocatalytic performance remains a challenging task. In this work, interfacial Mo-N bonds and vacancy engineering collaborative modified MoO3-x@polypyrrole (MP) S-scheme heterojunction is rational designed for efficient photocatalytic oxidative desulfurization. The addition of polypyrrole introduces rich defects which inducing the localized surface plasmon resonance (LSPR) effect and enhancing light absorption. Furthermore, the combination facilitates the formation of Mo-N bonds. The modifications amplify the built-in electric field and conduct the efficacious separation of photogenerated carriers. With the synergism of LSPR effect and interfacial chemical Mo-N bonds, the optimal MP photocatalyst displays attractive desulfurization rate of 100% for dibenzothiophene (DBT) in 60 min under illumination, touching the objective of ultra-deep desulfurization. The study extends a novel understanding of the impact of LSPR effect and heterojunction interface charge transfer on the photocatalytic desulfurization ability.

Exceptional functionalized ionic liquid@metal–organic framework: A high-efficiency desulfurization platform for organic sulfide oxidation by reactive oxygen species

There is a challenge with designing catalysts that simultaneously possess active sites for catalyzing the generation of reactive oxygen species (ROSs) and effectively overcoming mass transfer resistance in oil–water biphasic systems. In this study, a novel, highly efficient oxidative desulfurization (ODS) strategy is proposed that uses an ILs-loaded metal–organic framework (MOF) coupled material as a catalyst. The IL@MOF ([Hnmp]HSO4@MIL-125(Ti)) coupled material prepared by loading [Hnmp]HSO4 onto MIL-125(Ti) has catalytic-adsorption synergistic capability. It demonstrated outstanding oxidative desulfurization performance by achieving nearly a 100 % removal of dibenzothiophene (DBT) from model oil with a dosage of 0.04 g IL@MOF per 10 mL of model fuel under mild conditions (50 °C, 10 min). By comparing the experimental results with the characterization data, it is suggested that [Hnmp]HSO4@MIL-125(Ti) converts superoxide radicals (•O2−) into 1O2 through oxygen vacancies (Ov) and that the catalytic action of Ti on the oxidation of DBT is primarily based on a 1O2-driven non-free radical mechanism. [Hnmp]HSO4@MIL-125(Ti) serves as a favorable medium for contact to be made between ROSs and sulfides, which indicates an efficient catalytic-adsorption synergy.

Synthesis of TiO2-Modified Y Zeolite and its Adsorption-Catalytic Oxidative Desulfurization Performance

Synthesis of TiO2-Modified Y Zeolite and its Adsorption-Catalytic Oxidative Desulfurization Performance

A linker selective retention strategy to construct hierarchical porous metal-organic frameworks with high catalytic activity for oxidative desulfurization.

In order to improve the oxidative desulfurization (ODS) performance of MOF materials, an effective way is to convert a microporous MOF into a hierarchical porous MOF (HP-MOF) by utilizing the linker selective retention strategy. Herein, UiO-66 with the introduction of an unstable linker ligand (dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate, dhtz) can selectively remove dhtz ligands to form HP-MOF (HP-UiO-66-dhtz) through heat treatment at high temperature. While maintaining the original structure of UiO-66, HP-UiO-66-dhtz features mesopores and abundant Lewis acid sites, showing excellent ODS performance for diphenylthiophene (DBT).

Characterization, oxidative desulfurization performance evaluation and the catalytic reaction mechanism of polyoxometalate-coated, semi-encapsulated heart-shaped metal organic frameworks

The oxidative desulfurisation process is a subject of considerable interest at present due to the mild reaction conditions, good selectivity, and significant removal efficiency for aromatic sulphides and the promise of ultra-deep desulfurisation.

Catalytic oxidative desulfurization performance of a modified nano-sized β zeolite loaded with different structural polyoxometalates

HPW/β-T+S has the best desulfurization activity among the composite catalysts supported by polyoxometalates with different structures.

Upgrading the oxidative desulfurization performance of metal-organic frameworks with proton stimulation

The modification of metal-organic frameworks (MOFs) to achieve desirable performance is attracting extensive investigation in heterogeneous catalysis, however, exploring the potential peculiarity of pristine MOFs for targeted applications is often overlooked. In this work, we developed an efficient approach for upgrading the oxidative desulfurization (ODS) performance of Zr-MOFs with proton stimulation. The ODS performance of pristine Zr-MOFs prepared under solvothermal conditions was commonly very poor at ambient temperature but could be activated when protons were introduced. Moreover, the upgradation of ODS efficiency by protons exhibited a sharply increasing trend (from 0.05 to 17.5 mmol g−1 h−1) with the increased density of defects in Zr-MOFs. The most defective UiO-66(Zr) showed ultrahigh activity in model oil which removed 1000 ppm sulfur after 25 min at 30 °C or after 4 min at 50 °C upon proton stimulation that is better than the sample pre-treated with 1 M HCl, and in multicomponent model oil which removed 972 ppm sulfur after 20 min at 50 °C in the present of proton. The turnover frequency (TOF) could reach 211.6 h−1 at 50 °C, surpassing the most investigated ODS catalysts. Quenching experiments and EPR tests demonstrated that the reaction pathway of UiO-66(Zr) could be altered by protons from free radical (OH• and O2•-) into non-free-radical (Zr–OOH) that manipulate the sulfur removal efficiency. Experimental results indicated that the terminal Zr–OH/OH2 sites could decompose H2O2 with assistance of H+ to form Zr–OOH, which probably accounts for the enhancement of ODS activity. Our work reveals a facile and efficient strategy for upgrading the ODS performance of pristine MOFs.

Three-layer coated composite materials PMoV2@UiO-66-X@mSiO2: Efficient oxidative desulfurization catalysts

In this article, composite materials PMoV2@UiO-66-X (X = H, NH2, NO2, SO3H) are prepared by using hydrothermal synthesis method, and then the surfaces of the composite materials are coated with mSiO2 shell to obtain three-layer coated catalysts PMoV2@UiO-66-X@mSiO2. The prepared catalysts were characterized by FT-IR, XRD, N2 adsorption desorption isotherms, SEM, and TEM. The catalytic oxidation desulfurization performance of the catalyst was studied using GC–MS, and the optimal reaction conditions of the catalysts were explored, including temperature, stirring rate, catalyst dosage, and oxidant dosage. The results indicate that at 800 ppm of simulated fuel, PMoV2@UiO-66-NO2@mSiO2 has the highest catalytic activity, with a total desulfurization efficiency of 98 % under optimal conditions. After eight cycles, the efficiency can still reach 94 %, which is attributed to the strong acidity provided by PMoV2, the electron donating effect of the –NO2 group, and the stable core–shell structure after coating with mSiO2.The paper further confirmed the high catalytic activity of the catalyst through UV–Vis analysis.

Magnetically recyclable high-entropy metal oxide catalyst for aerobic catalytic oxidative desulfurization

High-entropy metal oxide catalysts have demonstrated exceptional performance in activating oxygen for catalytic oxidation reactions. However, ensuring their ease of cyclic usage is crucial to broadening their applications. To address this challenge, a magnetic and recyclable high-entropy metal oxide catalyst is designed and its potential in catalytic oxidative desulfurization of fuel oils with oxygen as the oxidant is also investigated. Through a mechanochemical-assisted calcination method, the magnetic high-entropy metal oxide catalyst (HEMO-900) is successfully synthesized, and the structure of the HEMO-900 catalyst is comprehensively characterized. In addition, it is found that the high-entropy structure facilitates charge modulation of the active components, thereby enhancing the oxygen activation performance. The HEMO-900 catalyst exhibits exceptional oxygen activation ability and catalytic oxidative desulfurization performance, and 96.9% of sulfur removal is achieved under optimal conditions. In addition, it achieves profound desulfurization of various fuel samples by efficiently oxidizing and eliminating diverse aromatic sulfur compounds. Additionally, the catalyst demonstrates outstanding magnetically recyclable properties, enabling rapid separation and recovery from the fuel oil phase through the application of an external magnetic field, making the HEMO-900 catalyst maintained a remarkable sulfur removal efficiency of 91.1% even in the 5th cycle. Therefore, this magnetically recyclable HEMO-900 catalyst possesses significantly promising research and application prospects in the field of catalytic oxidative desulfurization of fuel oils with oxygen as the oxidant, as well as some other heterogeneous catalysis.

Oxidative desulfurization of fuel oil and molecular characterization of the sulfone compound distribution in the different extractants

PMoA/G5 catalyst was synthesized, and its oxidative desulfurization (ODS) performance on model oil was studied. The catalyst and oxidation-extraction-adsorption system was used for the ODS of Arabian Extra light oil (AXL). Acetonitrile and methanol were chosen as different extractants for the extraction of sulfones (O2S and O2S4). The distribution of sulfone was first reported in detail at each of the three-stage extraction solvents at the molecular level analyzed by the Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), proton, and 13C nuclear magnetic resonance (1H NMR,13C NMR). The FT-ICR MS results show that the extracted proportion of macromolecular sulfone compounds increases with the extraction stages. Acetonitrile exhibited better selectivity than methanol for polyaromatic sulfone with a high carbon number for the O2S species with double bond equivalent (DBE) = 12–15 and O2S2 species with DBE = 11–16. The NMR results reveal that polyaromatics with naphthenic rings and a low carbon number (<30) can be easily extracted due to their high polarity. The excellent performance of the PMoA/G5 catalyst makes it a promising candidate in the ODS reaction, and the research results give guidelines for ODS technology.