Dibenzothiophene Conversion Research Articles

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.

Получение экологичного катализатора на основе четвертичной аммониевой соли гетерополикислоты для глубокой окислительной десульфуризации дизельного топлива

Hydrodesulfurization (HDS) is the most widely used method for fuel oil desulfurization, which can easily remove mercaptan and thiophene from diesel oil, but the removal rate of dibenzothiophene (DBT) and its alkylated derivatives is low. Compared with traditional HDS technology, oxidative desulfurization (ODS) technology has the advantages of less investment, mild reaction conditions, and high ODS activity for DBT and its derivatives. Heteropoly acid (salt)/H2O2 system is highly efficient and the oxidation product of hydrogen peroxide is water, making them green catalysts. A new type of polyoxometalates phase transfer catalyst, [(C16H33(CH3)3)N]3-HPW11VO40, was synthesized through ion exchange method. It was applied to the catalytic oxidative desulfurization of model diesel oil using H2O2 as oxidant. The influencing factors of reaction were investigated in detail. The catalyst exhibits the dibenzothiophene conversion rate of 100% and excellent reusability and retrievability with 99.97% conversion after five times reaction in mild reaction conditions of n(catalyst)/n(DBT)=1/80, n(H2O2)/n(DBT)=8/1, 50 °C, and atmospheric pressure in 3 h. The catalyst could be quickly separated and recycled by centrifugation after reaction and hence be promising in the low-sulfur fuel production.

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.

Enhancing oxidative desulfurization using sludge-derived ferrate (VI) for dibenzothiophene: An optimization study

Sulfur emissions pose a substantial threat to human health and the environment. To address this, stringent regulations limit sulfur content in fuels, and innovative desulfurization technologies are under active investigation. Oxidative desulfurization (ODS) employs oxidants to convert sulfur compounds into more readily recoverable sulfones. This study explores high-shear mixing in ODS, known as mixing-assisted oxidative desulfurization (MAOD), focusing on dibenzothiophene (DBT) oxidation in model fuels and pyrolysis oil. Fe(VI) derived from drinking water treatment sludge via wet oxidation is utilized in the MAOD process. The research evaluates the impact of ferrate concentration (400–600 ppm), phase transfer agent (PTA) concentration (100–300 mg per 50 mL of fuel), agitation speed (4,400 to 10,800 rpm), and temperature (40–60 °C) on % DBT conversion. Experimental sulfur conversions range from 63.4 % to 99.6 %. Through response surface methodology, optimal parameters of 537 ppm Fe(VI), 114 mg PTA per 50 mL of model fuel, 8,157 rpm agitation speed, and 41.7 °C are determined. These parameters are applied to pyrolysis oil, achieving a desulfurization efficiency of 53.2 %. Notably, increasing Fe(VI) concentration, agitation speed, and temperature significantly enhances sulfur reduction. The study underscores the potential of using potassium ferrate derived from drinking water treatment sludge in MAOD for effective desulfurization and provides insights into the impact of operating conditions on desulfurization efficiency. Ultimately, the research contributes to advancing environmentally friendly and cost-effective desulfurization technologies.

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.

Flower-like hierarchical TS-1/Al2O3 composite supported NiMo catalysts for efficient hydrodesulfurization of dibenzothiophenes

Flower-like Al2O3 materials were successfully incorporated by TS-1 nanocrystals to synthesize Flower-like TS-1-Al2O3 (FTA) micro-mesoporous composite by a facile nano self-assembly method. FTA supported NiMo bimetallic catalysts (NiMo/FTA) were further constructed and applied to the hydrodesulfurization (HDS) reactions for dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). FTA composites were constructed from flower-like pore structures stacked with nanosheets, which are conducive to the even load and dispersion of active species and the diffusion of macromolecular sulfur-containing compounds with relatively low resistance. The fabrication of TS-1 nanocrystals effectively enhanced the acidic sites, regulated the metal-support interaction, which could increase the stacking layer of MoS2 slabs, and producing more NiMoS-II type active phase. NiMo/FTA-10 presented the excellent HDS conversion of DBT (99.3 %) and 4,6-DMDBT (93.2 %) at 10 h−1, the highest reaction rate constant (2.6 × 10-7 mol g−1 s−1) and turnover frequency values (6.7 × 10-4 s−1) for 4,6-DMDBT HDS reaction. Compared to the direct desulfurization route (DDS), hydrogenation route (HYD) and isomerization route (ISO) can effectively eliminate the steric hindrance of 4,6-DMDBT, which is more conducive to the HDS reaction.

Characterization and optimization of ultrasound assisted oxidative desulfurization of a model fuel using a novel magnetic deep eutectic solvent

ABSTRACT In various studies, researchers have utilised different solvents to extract sulfur compounds from the fuels. This paper introduces a novel magnetic deep eutectic solvent employed in the ultrasound-assisted oxidative desulfurisation of dibenzothiophene within a model fuel. The solvent, synthesised at 85°C by combining choline chloride, p-toluene sulfonic acid, and FeCl₃, underwent characterisation through Fourier transform-infrared, Vibrating-sample magnetometer, and Raman spectrometry. Exploration of the key parameters, including oxidant to model fuel volumetric fraction percentage (0.2–0.3), Iron (III) chloride to choline chloride mole fraction (0.1–0.3), and Magnetic deep eutectic solvent to model fuel volumetric fraction (0.2–0.3), was conducted to assess their impact on dibenzothiophene conversion rates. Employing response surface methodology based on central composite experimental design, optimal operational parameters for the ultrasound-assisted oxidative desulfurisation process were identified, resulting in a sulfur removal rate of 98.7%. The findings highlight the solvent sustained efficiency even at higher dibenzothiophene concentrations. Additionally, the solvent paramagnetic properties facilitated an expedited separation from the fuel, leading to the significantly reduced process times.

MOF-derived CoP/C catalyst for efficient dibenzothiophene hydrodesulfurization

The design of an active and sulfur-resistant catalyst for dibenzothiophene (DBT) hydrodesulfurization (HDS) in crude oil purification is highly desirable but remains a grand challenge. Here, two carbon-supported cobalt phosphide catalysts Co2P/C and CoP/C, and a reference sample Co/C are successfully synthesized using a metal–organic-frameworks (MOFs) precursor. A P/Co ratio dependence on crystal phases is found, leading to the formation of two pure-phase cobalt phosphide catalysts CoP/C and Co2P/C. Catalyst evaluation in HDS of DBT shows that the CoP/C catalyst exhibits a higher activity and stability than Co2P/C and Co/C, giving a 93.7 % DBT conversion with 100 h stability under 3 MPa and 380 ◦C. Moreover, a 67.4 % biphenyl yield characterizes the dominance of the direct desulfurization (DDS) pathway. The obtained catalytic performance over the CoP/C catalyst is also superior to the published cobalt phosphide catalysts. Multiple characterization techniques co-evidence that the copious specific surface area, efficient electron transport from Co to P, high thermal stability of Co nanoparticles (NPs), and strong sulfur resistance account for the enhanced catalytic performance of CoP/C. The findings of this report suggest that phosphorus-modified cobalt over the carbon support can act as a promising catalyst for the HDS of DBT.

Hydrodesulfurization of Dibenzothiophene: A Machine Learning Approach.

The hydrodesulfurization (HDS) process is widely used in the industry to eliminate sulfur compounds from fuels. However, removing dibenzothiophene (DBT) and its derivatives is a challenge. Here, the key aspects that affect the efficiency of catalysts in the HDS of DBT were investigated using machine learning (ML) algorithms. The conversion of DBT and selectivity was estimated by applying Lasso, Ridge, and Random Forest regression techniques. For the estimation of conversion of DBT, Random Forest and Lasso offer adequate predictions. At the same time, regularized regressions have similar outcomes, which are suitable for selectivity estimations. According to the regression coefficient, the structural parameters are essential predictors for selectivity, highlighting the pore size, and slab length. These properties can connect with aspects like the availability of active sites. The insights gained through ML techniques about the HDS catalysts agree with the interpretations of previous experimental reports.

Room Temperature Ultrafast Oxidative Desulfurization with Sodium Hypochlorite in the Presence of Silica-Supported Catalysts.

A series of silica-supported catalysts containing molybdenum, tungsten, and vanadium oxides as the active phase was investigated in the process of oxidative desulfurization with sodium hypochlorite. It was shown for the first time that catalysts containing vanadium oxide as the active phase are more stable under oxidation conditions with sodium hypochlorite and retain their effectiveness at increased dosages of the oxidant and at high initial sulfur contents. The catalysts were characterized in detail by a complex of methods: Fourier transform infrared, X-ray spectral fluorescence, transmission electron microscopy, scanning electron microscopy, and low-temperature nitrogen adsorption/desorption. Key factors affecting the oxidation of dibenzothiophene (DBT) were investigated: oxidant and catalyst amount, oxidation time, initial sulfur content, and acetonitrile amount. Under optimized conditions, the DBT conversion rate was 100% in 5 min at room temperature (25 °C), NaClO/S molar ratio 6:1, catalyst amount 2 wt %. In the real sample of the straight-run diesel fraction, the sulfur content was reduced from 10,100 to 3030 ppm. The V(10%)/SiO2 catalyst retains its activity for 5 oxidation-regeneration cycles.

Controlled construction of Co3S4@CoMoS yolk-shell sphere for efficient hydrodesulfurization promoted by hydrogen spillover effect

A yolk-shell structured Co3S4@CoMoS catalyst was prepared through Oswald ripening method and subsequently used for hydrodesulfurization (HDS) reaction. The shells, constructed from Co-promoted MoS2 nanosheets, possess abundant active sites and facilitate the adsorption of reactants through the development of pore channels. The MoS2 sheets are arranged in a staggered and convoluted manner, creating numerous defect sites. The shorter MoS2 slabs provide a wide distribution of reactive sites, ensuring efficient reactions. The Co3S4 species within the inner core acts as an auxiliary active phase, inducing the hydrogen spillover effect in the HDS system. This facilitates the transfer of active hydrogen species to the CoMoS shell, where both CoMoS and Co3S4 phases synergistically enhance the HDS reaction. The Co3S4@CoMoS catalyst achieved up to 99.2% dibenzothiophene (DBT) conversion and 94.9% 4,6-dimethyldibenzothiophene conversion at the lower dosage (30 mg). The structure-activity relationships between active phase and HDS activity were investigated via in-situ infrared spectroscopy and other characterizations as well as density functional theory calculations.

On the effect of hafnium loading and location in mesoporous silica on the activity of catalysts in oxidation of dibenzothiophene

Oxidation of thiophenes to sulfones (easily extracted from fuel) is of crucial importance in petrochemical and automotive industry. The rational design and synthesis of stable catalysts of this process still remains one of the biggest challenges. In this work, a series of HfSBA-15 mesoporous materials with different hafnium content (3, 5 or 10 wt.%) has been prepared and studied in the liquid phase oxidation of dibenzothiophene (DBT) with H2O2. The activity of HfSBA-15 samples prepared by one-pot method was compared to that of Hf/SBA-15 synthesized by impregnation and that of HfMCF type of silica. It has been shown that hafnium loading and its location in the silica structure (framework and/or extra-framework positions) affect the efficiency of DBT oxidation. Moreover, the reaction conditions (i.e. oxidation temperature, reaction time, oxidant/sulfur ratio and catalyst amount) were optimized to achieve maximum conversion of dibenzothiophene (99 %). The location of hafnium species in SBA-15 and MCF materials was influenced by the loading of the metal and the type of silica structure (determined by the preparation method). Hafnium located in the framework of SBA-15 promoted generation of a higher number of active Lewis acid sites (LAS) and higher activity in oxidation of dibenzothiophene compared to extra-framework HfO2 species anchored in HfMCF material. It indicates that the location (framework vs extra-framework) and formation of isolated Hf4+ species are decisive for high activity of hafnium-doped mesoporous molecular sieves. This finding opens up a pathway for the development of highly efficient, stable and relatively cheap solid acid catalyst for oxidation of thiophenes to sulfones.

Multi-objective optimization of simultaneous oxidative desulfurization and denitrogenation of model fuel

Petroleum fractions are accompanied with sulfur and nitrogen compounds, and nitrogen compounds tend to compete for the catalyst active sites, reducing desulfurization efficiency. They can be removed by oxidative desulfurization and denitrogenation, wherein the sulfur and nitrogen compounds are converted into corresponding oxides with higher polarity than their parent forms, thus favoring their extractive or adsorptive removal from the oil phase. The introduction of ultrasound into the oxidation system can significantly improve the process efficiency and oxidation kinetics through strong cavitation phenomena involving physical and chemical effects. In this work, ultrasound-assisted simultaneous oxidation of pyridine and dibenzothiophene (DBT) contained in a model fuel was performed. Response surface methodology (RSM) was employed to study the effect of six parameters, viz., catalyst dose (5–12.5 g/L), reaction time (5–60 min), ultrasonic amplitude (10–60 %), volume of hydrogen peroxide (0.5–2 mL), volume of acetic acid (0.5–2 mL) and reaction temperature (40–60 °C) on the conversion of DBT and pyridine. A face-centered central composite design was employed as the RSM tool, and the effect of the parameters and their interactions on the two responses was investigated. The two responses were simultaneously optimized via desirability functions and overlaying individual contour plots. The results revealed that sonication significantly enhanced the conversion of both compounds. All six factors significantly influenced the oxidation of pyridine, while DBT conversion was mainly affected by four factors. The desirability for the process under consideration ranged from 0.85 to 0.89, and at the optimum conditions, 100 % conversion of pyridine and 46.06 % conversion of DBT were obtained. Two-staged oxidation of the fuel at optimum conditions resulted in 100 and 93.7 % conversion of pyridine and DBT, respectively.

Development and optimization of a sustainable polyoxometalate-kaolinite-based catalyst for efficient desulfurization of model and real fuel using Box-Behnken design.

The oxidative desulfurization of dibenzothiophene in model and real fuel has been investigated by developing an environmentally sustainable catalyst H4SiW12O40@f-kaolinite. The catalyst was synthesized by modifying kaolinite clay with (3-aminopropyl)triethoxysilane (f-kaolinite) followed by immobilizing silicotungstic acid hydrate (H4SiW12O40) onto its surface. The successful synthesis of the catalyst was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, UV-visible spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The influence of variables i.e., catalyst dosage, temperature, and oxidant concentration on the conversion of dibenzothiophene was optimized by Box-Behnken design. The highest sulfur reduction (from 1000 to 78.3 ppm, with a conversion rate of 92.17%) was achieved at 70 °C, using a catalyst dosage of 70 mg and 8 mL of H2O2 in a model fuel. ANOVA analysis indicated that the quadratic model (R 2 = 0.99) was well-fitted for dibenzothiophene conversion, with a p-value of 0.2302 suggesting no statistically significant lack of fit compared to pure error. Furthermore, the H4SiW12O40@f-kaolinite demonstrated a reduction of dibenzothiophene concentration from 354 ppm to 224 ppm in a real fuel oil sample. The heterogeneous nanocatalyst showed remarkable stability, maintaining its elemental structure after five cycles without significant efficiency loss, promoting environmental sustainability.

Citric acid and temperature programming assisted synthesized Vanadium Silicate-1 for oxidative desulfurization of dibenzothiophene

Vanadium-MFI zeolites possess phenomenal potential for catalytic oxidation, while their application is constrained by vanadium content and species distribution. Here, we constructed Vanadium Silicate-1 (VS-1) with enhanced content and preferable distribution by the addition of citric acid in tandem with a temperature-program strategy. Citric acid could modulate the pH in the initial gel and coordinate with vanadium, inhibiting the hydrolysis of vanadium and promoting vanadium incorporation. Moreover, a temperature program was employed to generate unsaturated silicon species, overcoming the tendency of aggregation in vanadium precursor and further promoting vanadium insertion. Furthermore, the effects of the first-stage crystallization temperature and time on the properties of zeolite have been investigated in detail. The sample synthesized through the optimal temperature program achieved 99.9 % dibenzothiophene conversion in 2 h, 10.4 times that of conventional synthesis. To explain the excellent reaction activity, the relationship between different vanadium species and reaction results was investigated. Through linear fitting, V=O(OSi)2(OH) was considered as the dominant active species in oxidative desulfurization (ODS) reaction. Notably, the recycled zeolite proved good reusability, further enhancing its promising application prospect.

The Effect of Mesoporous Structure of the Support on the Oxidation of Dibenzothiophene

A source of Brønsted acid centers, generated on the surface of two mesoporous silica supports of different structures (SBA-15 and MCF), was 3-(trihydroxysilyl)-1-propanesufonic acid (TPS). The materials obtained were characterized and applied as catalysts for the oxidative desulfurization of dibenzothiophene (DBT) with hydrogen peroxide as a model ODS (oxidative desulfurization) process. The properties of the materials were examined via nitrogen physisorption, XRD (X-ray Diffraction) and elemental analysis showing the preservation of the support structure after modification with organosilane species. Due to the aggregation of catalyst particles in the reaction mixture, the SBA-15 based catalyst was not very effective in DBT oxidation. Contrary, TPS/MCF catalyst exhibited a very good activity (almost total conversion of DBT after 1 h in optimized reaction conditions) and stability in dibenzothiophene oxidation in mild reaction conditions.

Integrated oxidative-adsorptive desulfurization of model and real fuel oils over a Zn-impregnated hydroxyapatite-activated carbon (Zn/HA-AC) composite

Herein, a Zn-impregnated hydroxyapatite-activated carbon (Zn/HA-AC) composite catalyst was fabricated and was, in turn, applied for the desulfurization of a model and real oil samples via the integrated adsorptive-oxidative desulfurization strategy. Activity results revealed that Zn/HA and AC (25:75) realized 76.7% dibenzothiophene (DBT) adsorptive desulfurization at 50 °C in 60 min reaction time at an adsorbent dose of 0.14 g/20 mL of feed. Zn/HA-AC(25:75) composite catalyst was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray analysis, and scanning electron microscopy analysis. In the oxidative desulfurization (ODS) combined with adsorptive desulfurization experiments, under the optimum conditions of 45 oC temperature for 60 min and a catalyst dose of 0.1 g/20 mL of feed using H2O2 and HCOOH, Zn/HA-AC (25:75) achieved 93% DBT conversion. Under these optimized experimental parameters, the adsorptive desulfurization and catalytic ODS performance (% DBT conversion) of Zn/HA-AC (25:75) for real gasoline, kerosene, and diesel oil reached 18, 31 and 15%, and 31.66, 55.31 and 11.19%, respectively. Contrary to this, under the integrated catalytic-oxidative-adsorptive experiments, the desulfurization performance of Zn/HA-AC (25:75) for gasoline, kerosene, and diesel oil reached 61, 41, and 34%, respectively.

Synthesis of POM@Porphyrin COF heterogeneous catalyst for oxidative desulfurization of thio compounds

Sulfur compounds cause substantial environmental pollution problems, and their immediate removal is urgently needed to keep the environment clean. Fuel desulfurization is necessary due to the severe impacts of sulfur on humans, wildlife, and crops when emitted into the atmosphere during fuel combustion. Fuels with high sulfur contents used in automobiles and factories are the primary source of atmospheric sulfur. A new covalent organic framework (COF) MnTP@ZnAdCOF [(N(C4H9)4]12[{NHC(CH2O)3}4(CO)4C44H24N4Mn(OCOCH3)][ZnMo6O18]4 is synthesized and characterized thoroughly using FT-IR, UV/visible, 1HNMR, TGA, PXRD, SEM-EDX, cyclic voltammetry and fluorescence spectroscopy. Herein, an environmentally safe and cost-effective approach for the ODS of thiobenzoic acid is reported using H2O2 as an oxidant and MnTP@ZnAdCOF as a heterogenous catalyst under mild reaction conditions. Desulphurization results of the catalyst are confirmed by the RP-HPLC technique using acetonitrile and water in a 50:50 M ratio as a mobile phase. Active intermediates [(Por)(OAc)Mn-OOH]−, [(Por)(OAc)MnIVO] and Mo(O2) are formed due to oxidation of Mn and Mo metal in the presence of H2O2 considered responsible for the excellent catalytic efficiency of MnTP@ZnAdCOF catalyst up to 98% desulphurization efficiency was observed. Incredible catalytic conversion of dibenzothiophene, thiobenzoic acid and the mixture of different Sulphur containing compounds to sulfoxide is observed at 25 ℃ temperature. The H2O2/S molar ratio of 5:1 is an outstanding achievement that can be utilized for the oxidation of sulfur compounds present in diesel to reduce the sulfur contents of fuel.

Bimetallic Heterogeneous Catalysts for the Oxidation of Sulfur-Containing Compounds with Hydrogen Peroxide

Bimetallic heterogeneous catalysts based on SBA-15 containing molybdenum and iron oxides were studied in the oxidation reactions of model mixtures of organosulfur compounds. Iron additive (in the form of iron(III) oxide) in the amount of 0.05 wt % to the catalyst 5%Mo/SBA-15 turns out to be the most effective. The catalysts were confirmed by a complex of physicochemical methods: low-temperature adsorption-desorption of nitrogen, X-ray phase analysis, transmission electron microscopy, X-ray photoelectron spectroscopy. The influence of the main oxidation parameters (reaction time, temperature, composition and amount of catalyst, amount of oxidizer) on the conversion of dibenzothiophene as a component of the model mixture weas investigated. Optimal oxidation conditions that allow to achieve total transformation of the substrate were selected: H2O2 : S = 2 : 1, 0.5 wt % of the catalyst FeMo/SBA-15, 60 min, 60°C; catalysts can be used for at least 5 cycles without loss of activity during their intermediate washing from oxidation products.