Catalyst For Oxidative Desulfurization Research Articles

Constructing frustrated Lewis pairs on Mo-doped Fe2O3 catalyst to enhance oxidative desulfurization efficiency

The emission of sulfur oxides will not only cause a series of environmental pollution but also threaten human health. At present, oxidative desulfurization is considered one of the technologies to achieve high-efficiency conversion of sulfur-containing compounds. Herein, the special frustrated Lewis pairs (FLPs) for efficient oxidative desulfurization are created by regulating surface doping in a redox iron-based oxide. According to experimental results, the Lewis acidic sites can be considered as the iron atoms adjacent to the molybdenum dopant, while the doped metal proximal to the oxygen vacancies serves as Lewis basic sites to create FLPs in redox iron-based oxide. This reactivity of FLPs is further adapted to the chemical activation of molecular oxygen and aromatic sulfur-containing compounds. The Fe2O3-FLP catalyst can achieve 100 % sulfur removal at 3 h and maintains 96.9 % after seven cycles, higher than other previously reported iron-based oxidative desulfurization catalysts. In addition, the design of FLPs offers a promising approach for developing high-efficiency catalysts in the oxidative desulfurization process.

Metal-based Ionic Liquids and Solid-loaded Catalysts in Fuel Oil Desulfurization: A Review

Abstract: Metal-based ionic liquids (MILs) have the advantages of designability, efficiency, stability, and regenerative cycle and can efficiently convert thiophene and its derivatives, which are important for the production of "ultra-low sulfur" oils. This paper provides an overview of the research progress of MILs in the field of fuel desulfurization, focusing on the current status of MILs and solid-loaded MILs catalysts in extractive desulfurization, oxidative desulfurization, extraction-catalyzed oxidative desulfurization, and catalytic-adsorption desulfurization processes. For MILs, the anion and cation can be altered by design so as to impart specific functions. Loading is one of the effective ways to solidify MILs, and the combination of MILs with different carriers can not only reduce the usage while ensuring the catalytic activity but also improve the reusability of the catalyst. The combination of MILs with specially structured carriers also allows solution-free adsorption and removal of oxidation products. Compared with conventional MILs, polymetallic-based ionic liquids (PMILs) exhibit ultrahigh catalytic activity and are one of the most promising materials available, but are still in their infancy in the field of fuel catalysis, and researchers are needed to enrich the gap in this field. Finally, some problems faced by various types of MILs are pointed out in order to design new functional MILs catalysts with better properties in the future and promote the further development of MILs in the field of fuel catalysis.

Atomically Permeated MoP‐WOx Core‐Shell Catalysts for Efficient and Selective Oxidation of Thiophenic Sulfides in Fuels via Direct Electron Transfer Mechanism

AbstractHeterogeneous interfaces designed rationally in catalysts can induce geometrical, compositional, and electronic effects that can be applied to modulate catalytically active sites and consequently accelerate reaction kinetics. Here, a core‐shell heterostructure catalyst consisting of crystalline molybdenum phosphide (MoP) cores and amorphous tungsten oxide (WOx) shells on porous carbon nanosheets (PCN) is developed for oxidative desulfurization (ODS) of fuels. The strongly coupled core‐shell heterogeneous interface triggers a distinctive atomic permeation effect that induces substantial electron transfer from MoP to WOx and subsequent generation of electron‐rich W sites, consequently optimizing the adsorption of intermediates and substrates. The resulting catalyst (WOx@MoP/PCN) demonstrates a turnover frequency as high as 768.1 h−1 for ODS at 60 °C, exceeding that of almost all the state‐of‐the‐art ODS catalysts by 1–2 orders of magnitude. Moreover, a novel surface oxidation pathway based on direct electron transfer is identified in the WOx@MoP/PCN‐H2O2 system, which bypasses the formation of reactive oxygen species, consequently endowing the system with a moderate redox potential. Thus, WOx@MoP/PCN exhibits unprecedented selectivity, achieving 100% removal of thiophenic sulfides from real diesel with minimal consumption of oxidant.

Synthesis of V6O13 Supported Catalyst for Intensive Catalytic Oxidative Desulfurization of Diesel

Synthesis of V₆O₁₃ Supported Catalyst for Intensive Catalytic Oxidative Desulfurization of Diesel

Zeolitic Framework Ta and MoO3 Confined in Beta Zeolite Cooperatively Enhance Activity and Stability for Oxidative Desulfurization.

Oxidative desulfurization (ODS), as a novel desulfurization technique of fuel oil, possesses high desulfurization efficiency for aromatic sulfide and low cost, making it a promising approach. The key to the technology lies in the rational design of catalysts with high activity and stability. Polyoxometalates, which are environmentally friendly, cost-effective, and abundantly available, face constraints in the development of ODS applications due to their low specific surface area and difficulty in regeneration. Introducing metal oxides into carriers with large specific surface areas to obtain heterogeneous catalysts is an effective solution to this problem. Beta zeolites, with regular three-dimensional channel systems, large specific surface area, and superior thermal/hydrothermal stability, are usually used as carriers. In this work, we developed a strategy to enhance zeolite carrier utilization efficiency by introducing Ta5+ species into the rigid framework of zeolites containing confined MoO3. The Ta species in the zeolite framework and the confined MoO3 produce a synergistic effect, exhibiting extremely high catalytic activity for the aerobic oxidative desulfurization of various organic aromatic sulfur compounds under mild conditions (90 °C and atmospheric pressure) in a deep eutectic solvent, surpassing common heterogeneous catalysts for oxidative desulfurization. Moreover, it can resist the adverse effects of interferents, such as naphthalene and indole. Additionally, the confined nature of Beta zeolite endows it with exceptional stability, demonstrating distinctive recyclability.

SBA-15 Type Mesoporous Silica Modified with Vanadium as a Catalyst for Oxidative and Extractive Oxidative Desulfurization Processes.

One of the current challenges is the reduction of sulfur emitted into the atmosphere, usually in the form of sulfur oxides generated by fossil fuel combustion. To achieve this goal, the sulfur content should be reduced in fuel. In this context, vanadium-containing materials based on SBA-15 mesoporous silica supports and two different sources of vanadium were prepared, characterized, and applied as catalysts for oxidative desulfurization (CODS) and extractive oxidative desulfurization processes (ECODSs). The novelty of this work was the comparative study of vanadium-containing materials in two desulfurization systems. The properties of the catalysts, the concentration and state of vanadium species, and their role in the catalytic process were examined by low-temperature nitrogen physisorption, XRD, UV-Vis, XPS, and chemisorption of pyridine combined with FTIR spectroscopy. The catalytic performance of the material prepared using ammonium metavanadate was superior to that of the catalyst obtained using vanadium(IV) oxide sulfate, which was explained by a higher concentration of vanadium species on the surface of the support and their lower oxidation state in the former. Both types of catalysts showed high activity and stability in the ECODS process.

A novel MOF-808 derived material for oxidative desulfurization: the synergistic effect of hydrophobicity and electron transfer.

A functionalized modified metal-organic framework material, T-MOF-808, was synthesized through hydrophobic modification with tetraethyl orthosilicate (TEOS) and chlorotrimethylsilane (TMCS). Then a supported oxidative desulfurization catalyst, [C12Py]3(NH4)3Mo7O24/T-MOF-808(s), was prepared by using a heteropoly acid ionic liquid as the active component. The prepared samples were characterized using FT-IR, XRD, SEM, TEM, XPS, etc. [C12Py]3(NH4)3Mo7O24/T-MOF-808(s) was used in the oxidative desulfurization of dibenzothiophene (DBT). At the same time, the effects of different loadings of the active component, oxygen sulfur ratios, reaction temperatures, and reaction time were also investigated. [C12Py]3(NH4)3Mo7O24/T-MOF-808-15%(s) could oxidize 100% of DBT in 40 min at 60 °C. Significantly, the catalyst exhibited no discernible decline in catalytic activity after 14 runs. In addition, the efficiency of sulfur removal was 85.76% in actual diesel oil. It was found that the cooperative impact of hydrophobic modification and electron transfer makes an important contribution to the high activity. The hydrophobic modification provides a novel approach for using MOF materials in the oxidative desulfurization process.

Design of oscillatory helical baffled reactor and dual functional mesoporous catalyst for oxidative desulfurization of real diesel fuel

Enhancing real diesel fuel properties by expelling pollutants using a new design has received considerable interest in the present day. This work investigates the conversion of sulfur compounds via oxidation reaction with peracetic acid as an oxidant. For this purpose, a dual functional mesoporous catalyst was synthesized via loading active metal (iron oxide) nanoparticles over mesopore γ-alumina-anatase titanium oxide prepared via the impregnation procedure (IWI) and precipitation methods, respectively. The novel design of the mesoporous catalyst represents the dual functional catalyst in the oxidative desulfurization process (ODS). The mesoporous catalyst that was formulated underwent a comprehensive analysis using various characterization techniques such as physical adsorption-desorption under N2, X-ray diffraction-XRD, Fourier transforms infrared spectroscopy-FTIR, Field Emission Scanning Electron Microscopy-FESEM, Energy dispersive X-ray analyzer-EDX, and thermogravimetric analysis-TGA. A newly designed laboratory pilot plant for an oscillatory helical baffled reactor (OHBR) was developed and utilized for the ODS process to evaluate the performance of the synthesized mesopore catalyst. The investigated rapid conversion for sulfur removal was found to be 98.42 % under ambient operating conditions such as oscillation of frequency 2 Hz, oscillation of amplitude 8 mm, temperature of oxidation 80°C, and residence time of 9 min. It is clearly observed that the new design of OHBR and mesoporous catalyst highly affected sulfur removal, resulting in a clean diesel.

Boosting tungsten -based catalyst activity for aerobic oxidative desulfurization of gas oil by cerium

This study is aimed at investigating the effect of tungsten-based catalysts for aerobic oxidative desulfurization (AODS) for gas oil. Two catalysts tungsten loaded on activated carbon (W/AC) and cerium-tungsten load on activated carbon (Ce–W/AC) were prepared, and they are characterized by Fourier transform infrared spectroscopy FTIR, X-ray diffraction (XRD), Scanning electronic microscopy (SEM), Energy dispersive spectroscopy EDX, and thermal behavior was examined by thermal graphometry analysis (TGA), the surface area was measure by Brunauer-Emmett-Teller (BET) method. The experiments were conducted in a lab-scale reactor. The primary investigation shows that Ce–W/AC was more active than W/AC. The second part examines the effect of reaction temperature, air flow rate, and catalyst dosage on sulfur removal efficiency by using Ce–W/AC, the ranges for the studied parameter are 150–200 °C, 20–60 mL/min, and 0.5–1 g for reaction temperature, air flow rate, and catalyst dosage respectively. The experiments were designed according to the Taguchi method. The experiments results show the sulfur removal efficiency ranged between 72.3 and 99.9. The findings demonstrate that increasing the reaction temperature leads to an increase in sulfur removal efficiency, while the increase in sulfur removal efficiency with air flow rate and catalyst dosage did not continue because it started decreasing after it reached a maximum value According to analysis variance ANOVA demonstrated that the effect of the studied variables ordered the following: reaction temperature air flow rate and finally catalyst dosage via their F-value where these values are 12.27, 4.09, and 0.16 for reaction temperature, air flow rate, and catalyst dosage respectively.

Tungsten oxide nanoparticles encapsulated by porous carbon for boosting H2S selective oxidation performance

Effective advancements for H2S removal are desperately expected to meet security and ecological necessities as natural guidelines on H2S emissions. Selective catalytic oxidation, as a green technology, has attracted attention owing to its direct conversion of H2S to S without thermodynamic constraints. Herein, we report a carbon-encapsulated WO3 (C@WO3–300) catalyst with nearly 100 % H2S conversion and 99 % S selectivity. Importantly, it likewise accomplishes noteworthy catalytic stability (over 120 h of continuous operation) and water resistance. Excellent durability may be attributed to the ideal porosity of C@WO3, which facilitates the adsorption and activation of H2S and O2. Additionally, the abundant lone pair electrons of carbon support can optimize the chemical environment of WO3-based catalysts and thereby benefit the O2 activation. This study provides a new avenue for the rational design of efficient and durable catalysts for continuous catalytic oxidative desulfurization.

Direct photo-curing 3D printed bionic multistage Mo-doped tungsten oxide catalysts for static and dynamic oxidative desulfurization of fuels

3D printed monolithic catalysts have attracted increasing attention in the petrochemical industry due to their advantages of the freedom of configuration, the rapidity of fabrication and the control of the fluid properties of the reaction medium. However, this remains challenging in constructing of micromorphology, reliable manufacturing, and adaptive functionality. Herein, inspired by the function of acicular plant fractal structure, we have developed bionic multistage monolithic catalysts based on direct photo-curing 3D printing technology. We also design two configuration strategies for static and dynamic oxidative desulfurization of fuels. Below the catalyst surface, the porous structure prepared by the hard template method can increase the specific surface area of the catalyst to disperse the active center and adsorb organic sulfur to strengthen the oxidation effect. The 3D-MoWO/PC-CE monolithic catalyst shows excellent activity in the static reaction with 100% sulfur removal. Above the catalyst surface, microcrystalline cellulose is introduced in-situ in 3D printed ink to build needle-like structures to enhance mass transfer efficiency and reduce surface pressure in dynamic fixed bed reaction. This work provides valuable ideas for the fabrication of efficient monolithic catalysts in various reactions.

Supported chromium nitride: A new catalyst for oxidative desulfurization of liquid fuel

Desulfurization of fuel is very important for our sound health and environment; oxidative desulfurization (ODS) can be one of the solutions. In this work, ODS or oxidation of thiophenic S-compounds was done firstly with a CrN catalyst, dispersed on carbon, which was prepared via pyrolysis of a MOF (composed of Cr2O3 and melamine), even without ammonia flow. Of note, ODS has been very seldom studied with Cr-based catalysts, so far. One CrN@carbon (named CrN@C-6) was highly effective in ODS with very low Ea (which is not far from that of simple diffusion in the liquid phase). Additionally, the catalyst showed rapid kinetics even at low temperatures (for example, 96 % of dibenzothiophene (1000 mg/L) was oxidized in 30 min at 60 °C; 83 % dibenzothiophene oxidation was possible at 30 °C in 60 min). The oxidation mechanism over the CrN@C-6 catalyst was interpreted with radical scavengers and electron spin resonance; the ODS was carried out through a non-radical mechanism probably through Cr-peroxo species. Calculation also supported that the Cr-nitride was more effective than Cr-oxide (that can be a representative Cr-based catalyst for ODS) in both H2O2 adsorption and ODS. The effective ODS catalysis could be explained with the contribution of well-dispersed active CrN with the electronegative nitrogen atom of the CrN and the high porosity of the catalyst. Finally, the invented CrN@C-6 can be suggested as a promising catalyst for ODS based on its remarkable activity even at low temperatures and ready recyclability (after simple solvent washing).

Eco-friendly catalyst in ultrasonic-assisted oxidative desulfurization of dibenzothiophene compound

10 W t.% WO3@activated carbon was prepared from apple peel and used as a catalyst in ultrasonic-assisted oxidative desulfurization of dibenzothiophene@octane in the presence of H2O2 as an oxidant. The physical characteristics of the prepared catalyst were investigated using X-ray diffraction, N2-adsorption-desorption, and scanning electron microscope. The reaction time, oxidant dose, catalyst dose, and sulfur compound concentration were studied to reach 99 % dibenzothiophene removal at ambient conditions and after four cycles the efficiency of dibenzothiophene removal can reach 97.7 %. The kinetic parameters were studied and indicate the ultrasonic-assisted oxidative desulfurization reaction is pseudo-second order.

Synthesis of boron nitride nanorod and its performance as a metal-free catalyst for oxidative desulfurization of diesel fuel

In order to reduce the sulfur compounds in diesel fuel, boron nitride (BN) has been employed as a novel metal free catalyst in the present research. This nanocatalyst was synthesized via template-free approach followed by heating treatment at 900 °C in nitrogen atmosphere that the characteristics of the sample were identified by the XRD, FTIR, Raman Spectroscopy, FESEM TEM, AFM and N2 adsorption–desorption isotherms. The results of structural and morphological analysis represented that BN has been successfully synthesized. The efficacy of the main operating parameters on the process was studied by using response surface methodology based on the Box–Behnken design (BBD) method. The prepared catalyst showed high efficiency in oxidative desulfurization of diesel fuel with initial sulfur content of 8040 ppm S. From statistical analysis a significant quadratic model was obtained to predict the sulfur removal as a function of efficient parameters. The maximum efficiency of 72.4% was achieved under optimized conditions at O/S molar ratio of 10.2, temperature of 71 °C, reaction time of 113 min and catalyst dosage 0.36 g. Also, the reusability of the BN was studied and the result showed little reduction in activity of the catalyst after 10 times regeneration. Moreover, a plausible mechanism was proposed for oxidation of sulfur compounds on the surface of the catalyst. The present study shows that BN materials can be selected as promising metal-free catalysts for desulfurization process.

Preparation of Anderson-type CoMo6-2NH2@ECOF for highly active catalysis on aerobic oxidative desulfurization of fuel under O2

Deep desulfurization with high-efficiency is imperia for environmental demands with increasing stringent standard of sulfur content in fuels. To develop high efficiency heterogeneous catalyst for aerobic oxidative desulfurization (AODS) of fuel, an Anderson-type CoMo6-2NH2 (POM) as active site, which was considered to be very effective in catalyzing the activation of O2, was successfully anchored on the sub-stoichiometric ECOF as a carrier by Schiff-base condensation reaction between –NH2 groups in CoMo6-2NH2 and –CHO groups in ECOF. The anchoring of CoMo6-2NH2 on ECOF by covalent bond resulted in the heterogenization of CoMo6-2NH2 enabled CoMo6-2NH2@ECOF to be recyclable during the AODS process. When CoMo6-2NH2@ECOF was applied as catalyst for AODS of fuel with surfactant (OTAC) under O2, it exhibited excellent catalytic activity with almost 100 % removal rates under 95 °C for 6 h. Moreover, the catalyst can be recycled 7 times without significant loss of catalytic activity. Further, the structure-activity relationship was investigated and the reaction mechanism of AODS of fuel was verified by ESR, XPS analysis and selective quenching experiments.

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.

Agricultural waste-based microporous catalysts for oxidative desulfurization of highly sour heavy gas oil

In recent years, the use of abundant and low-cost biomaterials such as agricultural wastes in the preparation of activated carbon has been receiving a lot of attention. Besides, the conventional middle and heavy fuel cuts require a substantial and cost-effective sweetening process because sulfur in transportation fuel was found as one of the main causes of air pollution. The present work explored the preparation and characterization of microporous activated carbon (AC) catalysts prepared from olive stone by tubular furnace (Fe/AC1) and microwave (Fe/AC2) heating methods using H3PO4 (85 wt%) as chemical activating agents. The kinetics of the oxidative desulfurization process (ODS) of a highly sour diesel fuel (sulfur content = 7361 ppm) was determined. The effect of the heating method on the texture and morphological structure, surface area, and surface chemistry of the carbons produced was investigated. Fe/AC1 was prepared in a horizontal tabular furnace at 650 °C calcination temperature and 90 min residence time under a nitrogen atmosphere, while Fe/AC2 was performed in a microwave reactor with 565 W and 7 min microwave power and irradiation time respectively. The catalysts were characterized by N2- adsorption-desorption, SEM-EDX, FTIR, XRD, XRF, TGA, PSD, and elemental analysis. It was found that the use of a tubular furnace for heating the olive seeds resulted in a higher surface area and yield. Also, the characterizations of the Fe/AC1 catalyst showed that it has a large surface area of 1175 m2/g and micropore volume of 0.6954 cm3/g whereas Fe/AC2 had a surface area of 854 m2/g and micropore volume of 0.6936 cm3/g. Moreover, SEM-EDX results indicated that Fe/AC1 was dispersed uniformly better than Fe/AC2. Also, TGA/DTA results revealed better results for Fe/AC1 than Fe/AC2 making it favorable in ODS experiments. The difference in texture and chemical properties is caused by the heating methods. The desulfurization removal was investigated under different temperatures (80, 90, 100, 110 °C) and reaction time (30–90 min). The kinetics of the ODS were conducted over the efficient Fe/AC1 catalyst prepared. It was shown that the ODS reaction followed pseudo-first-order kinetics with a fairly low activation energy over the catalyst was 40.71 kJ/mol.

Boron Nitride Nanofibers as Catalysts for High-Efficiency Aerobic Oxidative Desulfurization

Boron Nitride Nanofibers as Catalysts for High-Efficiency Aerobic Oxidative Desulfurization

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.

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.