Deep extractive and oxidative desulfurization of dibenzothiophene with C5H9NO·SnCl2 coordinated ionic liquid

Efficient and promising oxidative desulfurization of fuel using Fenton like deep eutectic solvent

Oxidative desulfurization (ODS) has emerged as a prominent technique for the removal of sulfur compounds from fuels, aiming to comply with stringent environmental regulations and minimize sulfur dioxide emissions. Herein, Fenton-like deep eutectic solvents (DESs) were synthesized as a catalyst and reaction medium and their application for the ODS process was investigated. The study encompassed the optimization of DES composition, reaction conditions, and the influence of different parameters on the desulfurization efficiency. The experimental findings demonstrated that the Fenton-like DES exhibited outstanding catalytic activity in the oxidative desulfurization of fuel. The optimized conditions involved conducting the reaction at room temperature for 2.5 h, using 200 mg of the prepared DES (HNFM-FeCl4) as both the extraction solvent and catalyst. An oxidant-to-sulfur (O/S) ratio of approximately 3:1 was maintained, with a 30 wt% H2O2 solution utilized as the oxidant. The analysis of the reaction products using GC-MS revealed a remarkable yield of 98% for dibenzothiophene sulfone. The DES provided a suitable medium for the reaction, enhancing the solubility and availability of sulfur compounds. The iron catalyst, in the presence of hydrogen peroxide, facilitated the oxidation of sulfur-containing compounds to their corresponding sulfones, which can be easily separated from the fuel phase. The DES catalysts exhibited stability and recyclability, making them suitable for practical applications in fuel desulfurization processes.

Semiconducting nanomaterials for photocatalytic desulfurization of liquid fuel under sunlight irradiation

Nanomaterials have fascinated the interest of researchers due to their unique electronic, optical, magnetic, and several other properties. Tin sulfide (SnS2) and Zinc oxide (ZnO) have emerged as promising materials for pharmaceutical, textile, environmental remediation, energy conversion, and storage device design. These two compounds were widely used in waste-water treatment for photocatalytic destruction of organic contaminants. However, the degradation of organic sulfur compounds in the liquid fuel desulfurization process has rarely been investigated using such materials. We hereby, present a hydrothermal method for developing the hexagonal lattice structure of SnS2 and ZnO for the deep desulfurization of model liquid fuel. These materials were further characterized through powder X-ray diffraction for phase purity and crystalline, FTIR analysis to validate functional groups, N2 adsorption-desorption isotherm to study surface properties, UV–vis diffuse reflectance spectroscopy for band gap analysis, scanning and transmission electron microscopy for morphology analysis. The optical behavior reveals that the energy gap for SnS2 and ZnO is 2.09 and 3.21 eV, respectively which corresponds to the visible light absorption range. The photocatalysis experiment was carried out in direct sunlight to degrade 10 ppm DBT in iso-octane. The obtained results show that 60% of the DBT degrade with SnS2 and 15% of the DBT degraded with ZnO in 120 min, with a first-order kinetics rate constant of 0.009 and 0.001 min−1 respectively.

Mechanical exfoliation of boron carbide: A metal-free catalyst for aerobic oxidative desulfurization in fuel

Metal-free catalysts have been proved to be a low-cost and environmentally friendly species in aerobic oxidative desulfurization (ODS). In this work, exfoliated metal-free boron carbide with few-layered structure, small size, and abundant defects, was first employed in an aerobic ODS system for ultra-deep desulfurization. The exfoliation process was realized by employing a planetary ball mill strategy. Detailed characterizations showed that the ball milling process not only induces thinner layers and small sizes but also introduces numerous defects into the boron carbide catalysts, which is vital in metal-free catalysis. Furthermore, the exfoliated boron carbide catalyst was applied in aerobic ODS system, and 99.5 % of sulfur removal was obtained. Moreover, the catalyst can be recycled 17 times without a significant decrease in catalytic activity. In particular, it was found that ∼90 % of the sulfur compounds in real diesel oil could be removed by the current aerobic ODS system.

In situ synthesis of Cl-doped Bi2O2CO3 and its enhancement of photocatalytic activity by inducing generation of oxygen vacancies

Cl-Doped Bi₂O₂CO₃ is prepared using ionic liquids as dopants and the oxygen-vacancy-induced photocatalytic mechanism is revealed.

Catalyst, Emulsion Stabilizer, and Adsorbent: Three Roles In One for Synergistically Enhancing Interfacial Catalytic Oxidative Desulfurization

A Pickering emulsion catalytic system was proposed to reduce the transfer limitation between two immiscible reactant phases for enhancing the kinetics of heterogenetic oxidative desulfurization (ODS). By loading phosphotungstic acid (HPW) nanoparticles on a novel pyridine-based porous organic polymer of P[tVPB-VP _x], the amphiphilic catalysts were produced and used as the stabilizer for Pickering emulsions. Specifically, an ultrafast ODS rate was realized in the HPW/P[tVPB-VP₁]-stabilized Pickering emulsion catalytic system, and just within 15 min, 100 ppm dibenzothiophene (DBT) was completely oxidized by H₂O₂. Because the obtained hierarchical porous HPW/P[tVPB-VP _x] catalysts showed both high adsorption capacity of DBT and excellent catalytic ODS performance, the catalysts assembling at the interface of emulsions provided this fastest reaction dynamics. Playing three roles of catalyst, emulsion stabilizer, and adsorbent, the synergistic functional catalytic emulsions can be a promising approach to significantly boost the heterogeneous catalytic ODS performance.

A Comprehensive Review on Catalytic Oxidative Desulfurization of Liquid Fuel Oil

The production of green fuel oil is of the utmost importance for maintaining a healthy life and environment in the current world. Effective and complete removal of sulfur refractory compounds (such as 4,6-dimethyldibenzothiophene and other alkyl-substituted thiophene derivatives) from fuel oil is essential to meet the new requirements of sulfur standards. Several techniques have been proposed for desulfurization of fuel oil, such as hydrodesulfurization (HDS), selective adsorption, extractive distillation, biodesulfurization, and oxidative desulfurization (ODS). The removal of sulfur by the HDS process requires higher investment costs, high reaction temperature (up to 400 °C), and high pressure (up to 100 atm) reactors. On the other hand, studies have shown that the ODS process is remarkably successful in the removal of sulfur under mild reaction conditions. This review article presents a comparative analysis of various existing catalytic oxidation techniques: acetic acid/formic acid catalytic oxidation, heteropolyacid (HPA) catalytic oxidation, ionic liquid catalytic oxidation, molecular sieve catalytic oxidation, polyoxometalates catalytic oxidation, titanium catalytic oxidation, and ultrasound-assisted oxidation systems, as well as discusses research gaps, and proposes important recommendations for future challenges.

Extractive/catalytic oxidative mechanisms over [Hnmp]Cl·xFeCl3 ionic liquids towards the desulfurization of model oils

A highly efficient extractant of an FeCl₃-based ionic liquid is prepared and its extractive/catalytic oxidative mechanisms for sulfur removal are proposed.

TiO2-Containing Carbon Derived from a Metal-Organic Framework Composite: A Highly Active Catalyst for Oxidative Desulfurization

A new metal-organic framework (MOF) composite consisting of Ti- and Zn-based MOFs (ZIF-8(x)@H₂N-MIL-125; in brief, ZIF(x)@MOF) was designed and synthesized. The pristine MOF [H₂N-MIL-125 (MOF)]- and an MOF-composite [ZIF(30)@MOF]-derived mesoporous carbons consisting of TiO₂ nanoparticles were prepared by pyrolysis (named MDC-P and MDC-C, respectively). MDC-C showed a higher surface area, larger pore sizes, and larger mesopore volumes than MDC-P. In addition, the TiO₂ nanoparticles on MDC-C have more uniform shapes and sizes and are smaller than those of MDC-P. The obtained MDC-C and MDC-P [together with MOF, ZIF(30)@MOF, pure/nanocrystalline TiO₂, and activated carbon] were applied in the oxidative desulfurization reaction of dibenzothiophene in a model fuel. The MDC-C, even with a lower TiO₂ content than that of MDC-P, showed an outstanding catalytic performance, especially with a very low catalyst dose (i.e., a very high quantity of dibenzothiophene was converted per unit weight of the catalyst), fast kinetics (∼3 times faster than that for MDC-P), and a low activation energy (lower than that for any reported catalyst) for the oxidation of dibenzothiophene. The large mesopores of MDC-C and the well-dispersed/small TiO₂ might be the dominant factors for the superior catalytic conversions. The oxidative desulfurization of other sulfur-containing organic compounds with various electron densities was also studied with MDC-C to understand the mechanism of catalysis. Moreover, the MDC-C catalyst can be reused many times in the oxidative desulfurization reaction after a simple washing with acetone. Finally, composing MOFs and subsequent pyrolysis is suggested as an effective way to prepare a catalyst with well-dispersed active sites, large pores, and high mesoporosity.

Heterogeneous oxidative desulfurization of diesel fuel catalyzed by mesoporous polyoxometallate-based polymeric hybrid

In this work, the simple preparation of novel polymer supported polyoxometallates (POMs) catalysts has been reported. Soluble task-specific cross-linked poly (ionic liquid) (PIL) was prepared with N,​N-​dimethyl-​dodecyl-​(4-​vinylbenzyl) ammonium chloride and divinylbenzene as co-monomers. The as-prepared cationic PILs were assembled with different commercial POMs to form the interlinked mesoporous catalysts, and the formation mechanism was provided. The catalytic oxidation activities of the catalysts were closely related to the formation pathway of their corresponding peroxide active species. The catalyst with H₂W₁₂O₄₂^10- as counterion, which exhibited the best activity in the oxidation of benzothiophene (BT) and dibenzothiophene (DBT) to sulfones in model oil with hydrogen peroxide (H₂O₂, 30wt%) as oxidant, was characterized by different techniques and systematically studied for its sulfur removal performance. As for the oxidative desulfurization of a real diesel, it was observed that almost all of the original sulfur compounds could be completely converted, and the catalyst could be reused for at least eight cycles without noticeable changes in both catalytic activity and chemical structure. In the end, a catalytic mechanism was put forward with the assistant of Raman analysis.

Heterogenization of homogenous oxidative desulfurization reaction on graphene-like boron nitride with a peroxomolybdate ionic liquid

Heterogenization of homogenous oxidative desulfurization reaction on graphene-like BN with a novel peroxomolybdate ionic liquid.

TiO2 microspheres supported polyoxometalate-based ionic liquids induced catalytic oxidative deep-desulfurization

A series of TiO₂ microspheres supported [SiW₁₂O₄₀]⁴⁻-based ionic liquids were successfully prepared and used as catalysts in oxidative desulfurization system. DBT was oxidized to DBT sulfone (DBTO₂) efficiently with the help of the catalyst and H₂O₂.

Oxidative Desulfurization of Fuels Using Ionic Liquids: A Review

Extractive oxidation, wherein aromatic sulfur compounds are extracted and subsequently oxidized to their corresponding sulfones, has proven to be one of the most effective desulfurization methods for producing ultra-low sulfur content fuels. As non-volatile and highly designable solvents, ionic liquids (ILs) have attracted considerable attention for the oxidative desulfurization of fuels. In this review, we systematically discuss the utility of ILs in catalytic extractive oxidation, including their roles as extractants, catalysts, or dual extracting/catalytic species for this application. We also discuss the challenges facing the use of ILs in this regard, including their relatively high costs and excessive viscosities, as well as the efficiencies and stabilities of catalysts presently being considered within them.

Supported ionic liquid [Bmim]FeCl4/Am TiO2 as an efficient catalyst for the catalytic oxidative desulfurization of fuels

Supported ionic liquid catalyst [Bmim]FeCl₄/Am TiO₂ was synthesized and showed excellent desulfurization efficiency and reuseable performance in the ECODS system.

Extractive desulfurization of dibenzothiophene by a mixed extractant of N,N-dimethylacetamide, N,N-dimethylformamide and tetramethylene sulfone: optimization by Box–Behnken design

In this paper, the performance of extractive desulfurization (EDS) from gasoline was studied using a mixed solvent, which consisted of N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF) and tetramethylenesulfone (TMS).

Light irradiation induced aerobic oxidative deep-desulfurization of fuel in ionic liquid

One-pot extraction combined with metal-free photochemical aerobic oxidative deep desulfurization of fuels in ionic liquid was successfully achieved.

Oxidative desulfurization of model diesel via dual activation by a protic ionic liquid

A novel and green carboxylate-anion-based protic ionic liquid (PIL), [Hnmp]HCOO, was prepared through a simple and atom economic neutralization reaction between N-methyl-2-pyrrolidonium (NMP) and formic acids. Both FT-IR spectra and (1)H NMR confirmed its simple salt structure. [Hnmp]HCOO exhibited so high catalytic activity that the dibenzothiophene (DBT) removal reached 99% at 50°C in 3h under conditions of VPIL/Vmodel oil=1:10 and H2O2/DBT (O/S, molar ratio)=5. The catalytic oxidation reactivity of S-compounds was found to be in the order of DBT>4,6-dimethyldibenzothiophene (4,6-DMDBT)>benzothiophene (BT). The investigation on mechanism showed that oxidative desulfurization was realized through dual activation of PIL. Moreover, [Hnmp]HCOO can be recycled for five times with an unnoticeable decrease in desulfurization activity.

A review of extractive desulfurization of fuel oils using ionic liquids

Extractive desulfurization of fuel oils using ionic liquids as extractive reagents.