Dibenzothiophene Research Articles

Hydrophobic Modification of Halloysite Nanotubes Loaded with a Small Amount of Tungsten Oxide for Efficient Oxidative Desulfurization.

Transition metal oxides can be used as efficient multiphase catalysts in the field of catalysis. In this study, a hydrophobic halloysite nanotube (HNT) catalyst was designed and prepared with a low loading. Tungsten oxide was immobilized on the inner surface of the HNT, through electrostatic adsorption and calcination. Furthermore, a dual-functional W/HMT/M catalyst was prepared by hydrophobic modification of the outer surface of HNT through a harmless and nontoxic method. The catalyst was applied in the oxidative desulfurization (ODS) of dibenzothiophene (DBT), and characterized by inductively coupled plasma (ICP), contact angle tests, and other methods. Systematic characterization further confirmed that W/HNT/M has a low loading (0.48 wt %) and a relatively high contact angle of 92.6°. Oxidative desulfurization experiments demonstrated that the high contact angle corresponds to good hydrophobicity. The low loading and high activity of the catalyst enabled it to achieve a removal efficiency of 100% for DBT under conditions of 60 °C and an O/S = 4. The hydrophobic surface of HNT allowed better dispersion in the oil phase, while its hydrophilic inner cavity could adsorb H2O2 and the converted dibenzothiophene sulfoxide, thereby reducing the subsequent extraction steps after oxidative desulfurization and enhancing the reaction environment for reactants and active oxygen. W/HNT/M maintained high activity for at least 5 cycles. Additionally, the potential mechanism of the catalyst in the aqueous ODS reaction was proposed. This study demonstrates that HNT-supported metal oxides have desulfurization potential and provides ideas for improving ODS catalytic activity of the ODS through low loading, high activity, and unique hydrophobicity design.

In situ Cyclization of Aromatic Thioethers in Emissive Materials to Generate Phosphorescent Dibenzothiophenes

AbstractIn this contribution, we explored the photocyclization of thioethers to highly substituted dibenzothiophenes (DBT) using solely UV‐light without any need for additives. This cost‐effective, robust and environmentally friendly approach yielded phosphorescent compounds, which were characterized by X‐ray crystallography and state‐of‐the‐art photophysical methods. The resulting DBTs feature ultralong photoluminescence lifetimes and quantum yields close to unity in frozen glassy matrices. The reaction mechanism was elucidated in detail through a combination of quantum chemical calculations and experimental results, providing evidence that triplet states are involved in the cyclization process. Additionally, the photoreaction can also be induced within materials. For this purpose, the precursors were integrated into polymer films or polymer resins suitable for 3D printing. Irradiation of these polymeric objects allows motifs with ultralong phosphorescence to be irreversibly inscribed through the proceeding photocyclization. The in situ photogeneration of DBTs from aromatic thioethers overcomes the observed incompatibilities regarding solubility in polymer resins for 3D printing.

Genetic and metabolic engineering approaches for enhanced biodesulfurization of petroleum fractions.

Sulfur, an abundant component of crude oil, causes severe damage to the environment, poses risks to human health, and poisons the catalysts used in combustion engines. Hydrodesulfurization, the conventionally used method, is not sufficient to remove thiophenes like dibenzothiophene (DBT) and other aromatic heterocyclic compounds. The push for "ultra-clean" fuels, with sulfur content less than 15 ppm, drives the need for deep desulfurization. Thus, in conjunction with hydrodesulfurization, efficient and eco-friendly methods of deep desulfurization, like biodesulfurization, are desirable. In biodesulfurization, naturally desulfurizing microorganisms are used, with genetic engineering and biotechnology, to reduce the sulfur content of crude oil to below 15 ppm. In this review, we describe genetic and metabolic engineering approaches reported to date to develop more efficient methods to carry out biodesulfurization, making it a practically applicable reality.

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.

The role of microwave radiation in extractive desulfurization of real diesel fuel for green environment: an experimental and computational investigation

The process of removing sulfur compounds and aromatic compounds to produce clean fuel is an important and effective contribution to the processes of mitigating and adapting to climate change. In contrast, it is necessary to find an innovative way to remove sulfur and carcinogenic aromatic compounds because clean, low-sulfur diesel is commonly used in all countries of the world at the present time. Therefore, in this work, we have studied the effect of the microwave radiation power and the irradiation time with the use of more than one type of organic solvent; methanol, acetonitrile and ethyl acetoacetate; as an extractant and solvent to feed ratio impact on the removal of sulfur and aromatic compounds of a real diesel fuel feed which has 450 ppm sulfur content and 16 wt% aromatic Content. The results showed that the best solvent used during this work was ethyl acetoacetate. According to the results, high sulfur removal (≈ 92%) was accomplished with microwave-assisted extractive desulfurization technique under the following ideal conditions: the irradiation time is 7 min, the solvent feed ratio is 3:1 and the microwave intensity is 180 W. To reveal the mechanism of microwave-assisted extractive desulfurization via different organic solvents, a theoretical study including structural examination and interaction energy analysis on the interaction between dibenzothiophene (DBT) or dimethyl dibenzothiophene (DMDBT) and the different organic solvents was also conducted.

Desulfurization of simulated and commercial liquid fuel on nano-ZnO fabricated walnut shells.

The current investigation involved the development of activated carbon, juglans regia activated carbon (JRACs), from walnut shells, scientifically known as Juglans regia. The ZnO nanorods were loaded on the activated carbon and referred to as ZnO@JRACs. Desulfurization efficiency was assessed through batch adsorption and compared to commercial activated carbon known as DARCO. The materials were characterized using PXRD (powder X-ray diffraction), FTIR (Fourier-transform infrared spectroscopy), ICP-AES (inductively coupled plasma atomic emission spectroscopy), BET (Brunauer-Emmett-Teller) surface area analysis, TEM (transmission electron microscopy) imaging, and TGA (thermal gravimetric analysis). The findings indicated that the materials have oxygen functionalities, a porous morphology, and a substantial specific surface area (BET) of 1269.92 m2/g for ZnO@JRACs. Zn atom concentration in the ZnO@JRACs surface was determined to be 1.16 atomic percent using ICP-AES. Desulfurization experiments were conducted on three liquid fuels, namely a single component model fuel, MSF (multicomponent simulated fuel), and commercial fuel (kerosene), under optimized conditions (8g/L adsorbent dosage in 10mL of fuel, 15min of contact time at room temperature). The conditions effectively removed ~ 98.9% of dibenzothiophene (DBT) from the single component model fuel. The observed order for adsorption capacity is as follows: ZnO@JRACs (63.6mgg-1) > JRACs (46.3mgg-1) > DARCO (26.1mgg-1). The analysis of multicomponent simulated fuel (MSF) using gas chromatography-flame photometric detector (GC-FPD) revealed significant removal percentages for different types of thiophenic sulfur. Specifically, the removal percentages were ~ 46.2%, 97.6%, and 99.4% for benzothiophene, dibenzothiophene, and 4, 6-dimethyldibenzothiophene, respectively. Kinetic studies have shown that the adsorption process is governed by a pseudo second-order reaction. Additional thermodynamic studies were conducted to further investigate the mechanism of adsorption. The spent synthesized composite ZnO@JRACs were thermally regenerated and can be reused for up to four cycles.

Experimental and ANN modeling of kerosene fuel desulfurization using a manganese oxide-tin oxide catalyst

This research pioneered the use of a nanocatalyst composed of manganese oxide (MnO2) and stannic oxide (SnO2) to effectively remove dibenzothiophene (DBT) from kerosene fuel through the catalytic oxidative desulfurization (ODS) process, using hydrogen peroxide (H2O2) as the oxidant. Impregnating SnO2 with varying amounts of MnO2 was used to manufacture the catalyst. The oxidation experiment ran in a batch reactor with varying reaction times and temperatures to determine optimal conditions. High MnO2 dispersion over SnO2 was shown by catalyst characterization data. Under optimal operating parameters (catalyst type: 5 % MnO2/SnO2, reaction temperature: 75 °C, and reaction duration: 100 min), the results demonstrated a maximum DBT removal efficiency of 82.84 % from kerosene fuel. This research also provides the construction of Artificial Neural Network (ANN) model to simulate the upgrading of kerosene fuel via desulfurization process. There has been a growing trend toward the diversified use of ANN to represent steady state systems in chemical engineering. MATLAB's code was employed for matching the experimental data to the artificial neural network (ANN) model. The resulted data showed significant agreement between the experimental and predicted outcomes, with regression coefficients (R2) of 0.99902, 0.99986, and 0.99961 and mean square errors (MSE) of 0.266, 0.272, and 0.104 for 0 % MnO2/SnO2, 1 % MnO2/SnO2, and 5 % MnO2/SnO2 respectively. This interactive model provided a solid foundation for understanding the novel behavior of the oxidation process.

Carboxyl carbon nanotubes strengthened tailorable chitosan imprinted polymers for selective adsorption of dibenzothiophene in hydrogenated diesel

Selectively capturing and adsorbing high-valued dibenzothiophene (DBT) from hydrogenated diesel is a meaningful and economic tactic for sulfide resource recovery. The design of efficient adsorbents with desirable adsorption capacity, high selectivity and simple retrieval is still challenging. In this work, an imprinting polymerization coupling freeze-drying approach was adopted to elaborately prepare carboxyl carbon nanotubes (CCNT) strengthened chitosan (CS) molecularly imprinted polymers (MIPs-CCNT/CS) for non-destructive adsorption of DBT. The introduction of CCNT into CS-based imprinted matrix improved thermal and mechanical stability and enriched adsorption sites of MIPs-CCNT/CS, thus enhancing DBT adsorption ability with the maximum adsorption capacity of 30.58 ± 1.24 mg/g under the optimized adsorption conditions. The Langmuir isotherm and pseudo-second-order kinetics models were verified to fit satisfactorily with the adsorption procedures of MIPs-CCNT/CS towards DBT. Benefiting from the presence of plentiful DBT imprinted cavities, MIPs-CCNT/CS maintained a superior recognition for DBT in the quaternary stimulated diesel, and the relative selectivity coefficients of DBT for benzothiophene (BT), indole, and fluorene with respect to the control non-imprinted adsorbent (NIPs-CCNT/CS) were 2.19, 2.34, and 2.10, respectively. After six adsorption–desorption experiments, the adsorption capacity of MIPs-CCNT/CS toward DBT remained stable (20.67 ± 0.53 mg/g). The preliminary exploration for actual hydrogenated diesel demonstrated that MIPs-CCNT/CS has benign industrial application prospect in the separation and recycling of high value-added DBT.

Biomimetic supported polyoxometalate structures designed and its applications for the ultra-deep oxidative desulfurization of fuels

Inspired by the fact that human nose cilia can effectively contact with particles to prevent their entry into our body, this kind novel biomimetic structures are designed and synthesized to enable the loading efficiency between the polyoxometalate catalytic species (POMs) and the carrier, thereby improving their loading rate and promoting their catalytic performance. The mullite whiskers-uniformed cordierite (CMW) is used as a carrier to support POMs, in which mullite whiskers regarding as the cilia in our nose, this kind catalyst could not only overcome the shortcomings of simple POMs with low specific surface and easy to self-agglomerate, but also could greatly increase their contact probability with the carrier. At the same time, the advantage of the cordierite block structure also greatly conducive to their actual application value on the reusing operation. A series of Keggin-type POM-loaded bulk materials, POM@CMW, [VimAm]Br@POM@CMW, [DVim]Br@POM@CMW, have been developed with various ionic liquid-based POMs (ionic liquid = ILs, chosen these two kinds of [VimAm]Br and [DVim]Br) to a comparative study. The oxidative desulfurization reaction (ODS) for fuels was performed using the obtained materials as catalysts and H2O2 as oxidant, without the additional extractants for the existing of ILs in catalyst. Through experimental evaluations, [DVim]Br@POM@CMW was found the excellent efficiency on the Sulfur removal, with an DBT removal of 96.34 % at 70 °C for 120 min. According to the FT-IR and SEM results after the reaction, the catalyst could retain their original structure and the dibenzothiophene (DBT) removal could still be maintained above 95 % after 7 reuses. Furthermore, the oxidation reactivity of different substrates was in the following order: DBT > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > thiophene (BT) and the high activity in actual diesel oil could be also exhibited. The enhanced reaction activity, excellent structural stability, and recyclability can be attributed to the abundance of active sites and outstanding mechanical properties provided by cordierite/mullite whiskers as a carrier, indicating their potential in the novel biomimetic-structured POMs-loaded catalysts.

Solvent-free synthesis of highly dispersed zinc-doped porous carbons as efficient dibenzothiophene adsorbents

Designing efficient adsorbents for the deep removal of refractory dibenzothiophene (DBT) from fuel oil is vital for addressing environmental issues such as acid rain. Herein, zinc gluconate and urea-derived porous carbons SF-ZnNC-T (T represents the carbonization temperature) were synthesized without solvents. Through a temperature-controlled process of “melting the zinc gluconate and urea mixture, forming H-bonded polymers, and carbonizing the polymers,” the optimal carbon, SF-ZnNC-900, was obtained with a large surface area (2280 m2 g), highly dispersed Zn sites, and hierarchical pore structures. Consequently, SF-ZnNC-900 demonstrated significantly higher DBT adsorption capacity of 43.2 mg S g−1, compared to just 4.3 mg S g−1 for the precursor. It also demonstrated good reusability, a fast adsorption rate, and the ability for ultra-deep desulfurization. The superior DBT adsorption performance resulted from the evaporation of residual zinc species, which generated abundant mesopores that facilitated DBT transformation, as well as the formation of Zn-Nx sites that strengthened the host-guest interaction (ΔE = −1.466 eV). The solvent-free synthesized highly dispersed Zn-doped carbon shows great potential for producing sulfur-free fuel oil and for designing metal-loaded carbon adsorbents.

Sulfur oxidation of ferrate synthesized from sludge in the aspect of desulfurization: A parametric study

Abstract The emission of sulfur in the atmosphere poses a significant threat to human health and the environment. To address this issue, stringent regulations have been implemented to limit the sulfur content in diesel, and novel desulfurization technologies are being developed. One notable technology is oxidative desulfurization (ODS), which employs oxidants to transform sulfur compounds into their corresponding sulfones, which are relatively easier to recover. The application of high-shear mixing in ODS has been studied to increase sulfur-to-sulfone conversion by creating smaller droplets and reducing mass transfer resistance. This research investigates the application of potassium ferrate derived from drinking water treatment sludge (DWTS), in the mixing-assisted oxidative desulfurization (MAOD) of a dibenzothiophene (DBT) model fuel. Potassium ferrate was synthesized using the wet oxidation method. The study evaluated the effects of ferrate concentration (400 to 600 ppm), agitation speed (4,400 to 10,800 rpm), and temperature (40 to 60 °C) on the efficiency of DBT conversion. The results revealed that 493.2 ppm DBT conversion was achieved at 550 ppm Fe(VI) concentration, 7,600 rpm agitation speed, and 50 °C temperature. Notably, increasing Fe(VI) concentration, agitation speed, and temperature had significant effects on sulfur reduction. This study demonstrates the potential of using potassium ferrate derived from DWTS in MAOD for effective desulfurization and discusses insights into the effects of operating conditions to enhance desulfurization efficiency. Ultimately, the study contributes to the development of environmentally friendly and cost-effective desulfurization technologies.

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.

Direct synthesis of Cu-TiO<sub>2</sub>-SBA-16 photocatalysts and its application for the oxidative desulfurization of fuel oil model

In this study, the Cu-TiO2-SBA-16 photocatalytic materials were successfully prepared by direct hydrothermal synthesis method. The products were characterized by X-ray diffraction (XRD), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), N2 adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS) methods. The analysis illustrated that Cu-TiO2 nanocrystals were successfully incorporated into the SBA-16 mesopores. The photocatalytic activity of these Cu-TiO2-SBA-16 mesoporous materials have been tested by the oxidative desulfurization reaction of dibenzothiophene (DBT) using H2O2 as an oxidant under UV light irradiation. The results showed that the Cu-TiO2-SBA-16 mesoporous materials prepared at the Cu/Ti mole ratios of 0.05 showed higher photocatalytic activity than the rest due to the decrease in band gap energy.

Adsorption desulphurization performance of biochar that derived from eucalyptus waste

In this paper, microporous biochar materials with large specific surface area (2592.2 m2/g) and pore volume (1.15 cm3/g) was prepared by eucalyptus waste, and was successfully used for adsorption desulfurization (ADS) where it showed high dibenzothiophene (DBT) adsorption capacity (172.5 mg/g). The biochar materials were characterized by scanning electron microscopy (SEM), N2 adsorption-desorption isotherms and various spectroscopies (Raman, XRD, FTIR) analyses. The adsorption process was well consistent with the pseudo-second-order kinetic model and Langmuir isothermal model. ADS behavior was explained by the intraparticle diffusion model. The adsorption energies of DBT in carbon nanotubes with different pore sizes were calculated by using the density functional theory. It is finally concluded that ADS mainly attributed to π-π interactions between DBT with biochar materials, also includes hydrogen bonding, acid-base interactions and van der Waals force. The present work provides a new idea of ADS, using waste biomass materials to prepare biochar materials.

Atomic decoration of MoS2 using Fe, Co or Ni for highly efficient and selective hydrodesulfurization

Hydrodesulfurization (HDS) is one of the most efficient processes for removing sulfur-containing molecules such as dibenzothiophene (DBT) from oil, whatever fossil based or bio-based. However, hydrodesulfurization using molybdenum sulfides (MoS2) as catalytic active centers and transition metals (X) as promoters is seriously challenged by the insufficient catalytic activity and selectivity because of the separate phases of sulfides, and sparse X-Mo-S active sites, leading to poor synergistic effect between the X promoter and MoS2 active centers. Herein, atomically doped MoS2 catalysts (denoted as XMo, X = Fe, Co or Ni) were synthesized by using polyoxometalate template-based synthetic strategy were proposed. The pre-organized Anderson-type POMs, [XMo6O24H6]n− (X = Fe, Co or Ni), acted as a pre-assembled molecular platform with intimate X-Mo interactions, ensure the uniform formation of X-Mo-S active sites after sulfuration. The promoter atoms, including Fe, Co and Ni, enhanced the efficiency of hydrodesulfurization of MoS2. Particularly, NiMo exhibits the highest HDS activity, while CoMo shows a moderate HDS activity with the highest DDS selectivity (∼85 %). Despite the lowest HDS activities, FeMo with the cheapest Fe promoter, shows good DDS selectivity (∼70 %). Further study reveal NiMo has the most laminated morphology and highest stacking slabs, resulting in the highest HDS activity. Benefiting from the Co(Fe)-Mo-S structure and abundant sulfur vacancy, CoMo and FeMo showed great enhancement in the DDS selectivity. Moreover, the DDS selectivity of these designed catalysts were supported energetically by first principle calculations. This research will expand on the ability to improve the HDS activities and DDS selectivity by precisely engineering catalytic active sites to achieve significant synergistic effect in atomic scale.

Polycyclic aromatic hydrocarbon derivatives onto polar microplastics of polyurethane: equilibrium, thermodynamics, and kinetics of monolayer-multilayer adsorption.

The study of the adsorption of polycyclic aromatic hydrocarbons on microplastics (MPs) has attracted much attention as to how microplastics can act as carriers of these pollutants. Polyurethane (PU) is one of the MPs found in aquatic environments, containing different functional groups it can interact with polar and nonpolar molecules. PAH derivatives (dPAHs) present different properties and thus can be adsorbed by different interactions; thus, this study investigated the adsorption of fluorene (FLN), dibenzothiophene (DBT), dibenzofuran (DBF), and carbazole (CBZ) onto PU MP. The Langmuir, Freundlich, and BET isotherm models were examined, and the BET model best fitted. The adsorption was a nonspontaneous process, exothermic for mono- and multilayer formation for FLN, DBT, and CBZ, and endothermic for DBF monolayer formation. The adsorption monolayer was formed by van der Waals forces, H─bonding, and π─π interactions, while the formation of the multilayer can be explained by π─π and hydrophobic interactions. The pseudo-second-order model proved to be more consistent for the adsorption of dPAHs. The adsorption in artificial seawater shows no significant differences for the monolayer but favored the adsorption multilayer due to the salting-out effect. Due to the existence of several adsorption mechanisms, PU MP interacts with dPAHs in greater quantities when compared to a MP with a simpler structure.

Removal of sulphur and nitrogen compounds from model fuel by adsorption of modified activated carbon

This study aimed to achieve the highest percentage removal of dibenzothiophene (DBT), quinoline (QUI), and indole (IND) adsorbed by double-impregnated modified activated carbon (MAC). Modification of commercial activated carbon (AC) by sulphuric acid (H2SO4) of 15%, 30%, 45%, 60%, and 75% w/v followed by subsequent 1 zinc chloride (ZnCl2): 1 AC impregnation ratio and activated at 500 oC in a muffle furnace under self-generated atmosphere for an hour. The determination of optimized MAC was identified through the highest removal rate of DBT, QUI, and IND from adsorption experiments which were analysed using an ultraviolet-visible (UV-Vis) spectrophotometer. It was found that DBT and IND showed a removal high percentage of up to 86.23% and 82.77% respectively by using 75% H2SO4 with ZnCl2 MAC. Meanwhile, QUI favoured 30% H2SO4 with ZnCl2 MAC with a removal percentage of 33.17% which was still higher than unmodified AC. Physical and chemical properties such as the morphological structure, elemental analysis, porosity, pore size, surface functional group, percentage yield, pH, bulk density, content, ash content, and iodine number were studied for the optimized MAC. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to characterize the MAC. Both MACs showed high percentage yields of 72.08% and 71.13% for 30% and 75% H2SO4 and ZnCl2 MAC respectively. Meanwhile, the pH was between the ranges of 5.36-5.53 for both MACs. Bulk densities were also favourable while the moisture and ash content were within acceptable limits. Iodine numbers for 30% and 75% H2SO4 and ZnCl2 MAC were 857 and 861 mg/g respectively, hence indicating that the MAC achieved high porosity and good adsorption performance. Langmuir, Freundlich, and Temkin adsorption isotherm models as well as pseudo-first order (PFO) and pseudo-second order (PSO) kinetic models were considered for understanding the adsorption mechanisms. The study revealed that DBT, QUI, and IND removal processes, followed the Langmuir adsorption isotherm model with correlation coefficients, R2 of 0.9905, 0.9791, and 0.9964 respectively. Moreover, the adsorption kinetic data of DBT, QUI, and IND provided a better fitting to the PSO kinetic model with R2 of 0.9992, 0.9987, and 0.9998 respectively. According to the Langmuir isotherm model and PSO kinetic model, the adsorption mechanisms of DBT QUI and IND were chemisorbed under monolayer formations.

Study on extraction desulfurization of road-paving asphalt by deep eutectic solvents

During the hot mixing process of road-paving asphalt, odorous substances are released, primarily consisting of sulfur-containing compounds that are regarded as atmospheric pollutants, negatively impacting both human quality of life and the eco-environment. In the paper, a kind of simulated asphalt solution was designed with two sulfur-containing compounds, dibenzothiophene (DBT) and benzothiophene (BT), as well as n-eicosane dissolved in cyclohexane. DBT and BT were extracted with deep eutectic solvent (DES) of tetrabutylammonium bromide and polyethylene glycol (TBAB/PEG). The effects of different molecular weight of PEG as donor on desulfurization efficiency were investigated. The effects of DES donor/receptor ratio, extraction temperature and time, solvent oil ratio, mixing speed, recycling performance of DES on desulfurization efficiency were also studied and optimized. The results indicated that the maximum desulfurization efficiency of BT reached 89.40 % at room temperature with a ratio of agent to oil of 2:1, reaction time of 30 min, and mixing speed of 600 rpm. Similarly, the desulfurization efficiency of DBT achieved 95.54 % when the ratio of agent to oil was 3.5:1, with reaction time of 30 min and mixing speed of 600 rpm. After being recycled eight times, the extraction efficiencies of DBT and BT remained at 85.3 % and 65.2 %, respectively. Under optimized conditions, the extraction efficiency of petroleum asphalt exceeded 23 %. Fourier Transform Infrared (FTIR) analysis indicated that the sulfur-containing compounds found in the saturates and aromatics of road-paving asphalt were extracted by DESs, which are generally more volatile than those found in asphaltenes during hot-mixing. Additionally, minimal changes were observed in the structural composition of the four fractions of desulfurized asphalt.

In situ Cyclization of Aromatic Thioethers in Emissive Materials to Generate Phosphorescent Dibenzothiophenes.

In this contribution, we explored the photocyclization of thioethers to highly substituted dibenzothiophenes (DBT) using solely UV-light without any need for additives. This cost-effective, robust and environmentally friendly approach yielded phosphorescent compounds, which were characterized through X-ray crystallography and state-of-the-art photophysical methods. The resulting DBTs feature ultralong photoluminescence lifetimes and quantum yields close to unity in frozen glassy matrices. The reaction mechanism was investigated in detail through a combination of quantum chemical calculations and experimental results, providing evidence that triplet states are involved in the cyclization process. Additionally, the photoreaction can also be induced within materials. For this purpose, the precursors can be integrated into polymer films or polymer resins suitable for 3D printing. Irradiation of these polymeric objects allows motifs with ultralong phosphorescence to be irreversibly inscribed through the proceeding photocyclization. The in situ photogeneration of DBTs from aromatic thioethers overcomes the observed incompatibilities regarding solubility in polymer resins for 3D printing.

Enhanced oxidative desulfurization of dibenzothiophene under visible light using carbon quantum dot-decorated novel Z-scheme BiVO4/MOF-808/CN photocatalyst: Mechanism, performance and stability

BackgroundPhotocatalytic oxidative desulfurization technology enabling the facile oxidation of these compounds to sulfones, deep desulfurization, operation at ambient temperature and pressure, and minimal energy consumption. MethodsThis study introduces a novel photocatalyst, BiVO4/MOF-808/CN integrated with carbon quantum dots (BMC-CQD), designed for the oxidative desulfurization of dibenzothiophene (DBT) under visible light irradiation. Significant findingsNovel approach was undertaken by integrating the photocatalyst BiVO4, g-C3N4 with MOF-808 and carbon quantum dots to enhance the interaction between semiconductors. This innovative photocatalyst addresses several limitations associated with MOF-808, including enhanced visible light absorption (2.21–2.60 eV), reduced electron-hole recombination, rapid charge transfer, high surface area (1370 m2/g), large pore volume (0.908 cm3/g). Under optimized conditions of a catalyst dosage of 1.5 g/L, a reaction temperature of 50 °C, an O/S molar ratio of 6, and an initial DBT concentration of 500 mg/L, the 10 %BMC-CQD photocatalyst achieved an impressive 99.5 % DBT removal efficiency in just 25 min. Incorporating CQD into the BMC framework significantly amplifies the removal rate of the DBT by 10.69, 2.13 and 8.7 times compared to the BiVO4, MOF-808 and CN, respectively. The radical trapping experiments have shown that the •OH and •O2− radicals play a key role in the DBT removal process.