Benzothiophene Research Articles

Theoretical study on the desulfurization mechanisms of thiophene and benzothiophene under inert and oxidative atmospheres

A detailed theoretical study of desulfurization mechanisms of thiophene and benzo thiophene was performed under inert and oxidative atmospheres. Density functional theory (DFT) was used to investigate the 13 reaction pathways of their desulfurization mechanisms under these two atmospheres. The feasibility of each reaction was analyzed thermodynamically and kinetically. The calculated results show that it is thermodynamically and kinetically unfavorable for thiophenes to desulfurize under inert atmosphere, if a H2 directly attacks their S atoms and C-S bonds. This is resulted by their extremely high energy barriers and high reaction energies. However, the desulfurization mechanisms of thiophenes may be thermodynamically dominated by Diels-Alder reaction under inert atmosphere. Compared with inert atmosphere, it is much easier for thiophenes to desulfurize under oxidative atmosphere. The reason is that C-S bond strength of thiophenes-OH and sulfones is much lower than that of thiophenes based on Mayer bond order (MBO) analysis. It is found that thiophenes oxidation desulfurization is very possibly initiated by oxidative agent OH rather than thiophenes C-S bond directly attacked by O2. In addition, Diels-Alder reaction between thiophene sulfones can also possess very low barrier reaction pathways.

Liquid Polymer Eutectic Mixture for Integrated Extractive-Oxidative Desulfurization of Fuel Oil: An Optimization Study via Response Surface Methodology

Hydrodesulfurization (HDS) has been commercially employed for the production of ultra-low sulfur fuel oil. However, HDS is unable to remove sterically hindered sulfur-containing compounds such as dibenzothiophene (DBT) and benzothiophene (BT). An alternative way to remove sulfur is via extractive desulfurization system (EDS) using deep eutectic solvents (DES) as sustainable extractant. In this work, liquid polymer DES was synthesized using tetrabutylammonium chloride (TBAC) and poly(ethylene glycol) 400 (PEG) with different molar ratios. Response surface methodology (RSM) was applied to study the effect of independent variables toward extraction efficiency (EE). Three significant operating parameters, temperature (25–70 °C), DES molar ratio (1–3), and DES volume ratio (0.2–2.0), were varied to study the EE of sulfur from model oil. A quadratic model was selected based on the fit summary test, revealing that the extraction efficiency was greatly influenced by the amount of DES used, followed by the extraction temperature and PEG ratio. Although molar ratio of DES was less sensitive towards EDS performance, the EE was much higher at lower PEG ratio. For the realization of an energy-efficient EDS system, optimization of EDS parameters and EE was carried out via a desirability tool. At 25 °C, 1:1 molar ratio of TBAC to PEG, and DES-to-model-oil-volume ratio of 1, removal of DBT reached as high as 79.01%. The present findings could provide valuable insight into the development of practicable EDS technology as a substitute to previous HDS process.

Homology Modeling and In Silico Docking Studies of DszC Enzyme of Streptomyces sp. VUR PPR 101

Sulfur dioxide released during the combustion of fossil fuels causes hazardous effects to living beings. The traditional hydrodesulfurization (HDS) which is employed to remove sulfur components from fossil fuels is not effective in the reduction in aromatic organosulfur compounds like benzothiophene (BT), dibenzothiophene (DBT) and its derivatives. Biodesulfurization process by microorganisms is considered as an effective one over HDS in the removal of sulfur from fuels. DBT, which is a typical recalcitrant organosulfur compound, is considered as a model compound for biodesulfurization studies. Microbes which employ 4S pathway for the removal of sulfur from DBT are commercially so significant. The 4S pathway encompasses four reactions involving three enzymes. The present work deals with the DszC enzyme which catalyzes the first two reaction steps of 4S pathway. The 3D structure of DszC enzyme protein of Streptomyces sp. VUR PPR 101 was modeled and validated. Four mutant DszC enzyme proteins viz., Q119I, H221L, F161A and N129A, were constructed. Wild and mutant DszC proteins were docked against the substrates, DBT and dibenzothiophene sulfoxide (DBTO). Based on the Libdock scores of the docked complexes, the mutant proteins F161A and H221L were found with the highest affinity toward DBT and DBTO, respectively.

Kinetics of Triphase Extractive Oxidative Desulfurization of Benzothiophene with Molecular Oxygen Catalyzed by HPA‐5

AbstractThe triphasic aerobic extractive desulfurization of benzothiophene (BT) using an aqueous H8[PV5Mo7O40] solution as catalyst and O2 as oxidant was investigated. A time‐resolved analysis of all reaction products in the gas, organic and aqueous phase, is given. The organic sulfur in BT is mainly converted to sulfuric acid. Mass transport limitations can be excluded. The reaction orders are 1 with regard to BT, and 0.5 both for HPA‐5 and O2. Calculated data derived from this mechanism with a power law kinetic approach show good agreement to the experimental data for conversions below 60 %. At higher BT conversions, significant deviations are found, suggesting that acidic products formed in the BT oxidation affect the catalyst and therefore the initial kinetics of the BT oxidation.

Tuning the optoelectronic properties of Benzo Thiophene (BT-CIC) based non-fullerene acceptor organic solar cell

Organic solar cells have become a center of attention in the field of research and technology due to its remarkable features. In the current research work, we designed Benzo Thiophene (BT-CIC) based non-fullerene acceptor organic solar cell having A-D-A novel structure. The designed structures D1-D4 were derived from BT-CIC (non-fullerene acceptor) by replacing 2-(5,6-dichloro-2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene)acetonitrile of reference molecule R with different electron withdrawing end-capper acceptor moieties. The effect of end acceptor groups on absorption, energy level, charge transport, morphology, and photovoltaic properties of the designed molecules (D1-D4) were investigated by TD-DFT B3LYP/6-31G basic level of theory and compared with reference molecule R. Among all novel structures, D3 exhibited maximum absorption ([Formula: see text]) of 701.7[Formula: see text]nm and 755.2[Formula: see text]nm in gaseous state anfd chloroform, respectively. The red shift in D3 was due to the presence of strong electron withdrawing acceptor moiety and more extended conjugation as compared to other structures. D3 also displayed lowest values of energy bandgap (1.97 eV), [Formula: see text] (0.0063[Formula: see text]eV) and [Formula: see text] (0.0099[Formula: see text]eV) and which signify its ease electron mobility. Lowest value of binding energy 1.20[Formula: see text]eV of D3 suggested that this molecule could be easily dissociated into charge carriers TDM results revealed that easy exciton dissociation occurred in D3. Overall, designed structure D3 was found to be more effective and efficient acceptor molecule for SMOSCs. The findings provide novel information for the development of non-fullerene acceptors for OPVs.

Highly efficient capture of benzothiophene with a novel water-resistant-bimetallic Cu-ZIF-8 material

A novel water-resistant and bimetallic metal organic frameworks (MOFs), Cu-ZIF-8, was successfully synthesized by a coordination synthesis method for the first time. The structure properties of obtained MOFs can be probed and confirmed with nitrogen adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS), etc. In addition, the pore size can be convenient adjusted by doping amount of Zn(II) and Cu(II) that the body-centered cubic crystal lattice of the parent ZIF-8 framework is continuously maintained. The pseudo-second-order model can make a good description of the adsorption kinetics, while Langmuir model could well express the adsorption isotherms. The Cu-ZIF-8 exhibited a remarkable benzothiophene (BT) uptake capacity compared with those previously reported adsorbents in the literatures. Especially, the Cu-ZIF-8 displayed an outstanding stability in the presence of benzene, octane and water, maintaining more than 95% initial uptake capacity after recycling five times. The as-prepared Cu-ZIF-8 might be a hopeful material for BT capture toward deep desulfurization. Our findings explored a simple and powerful way to incorporate metal ions into the backbones of open framework materials without losing their properties.

Nickel-catalyzed and Li-mediated regiospecific C–H arylation of benzothiophenes

A sustainable nickel-catalyzed direct C–H arylation of benzothiophenes, benzofuran and selenophene is reported for the first time.

Sulfur speciation of Kuwaiti crude oils fractions using two-dimensional gas chromatography

The main objective of this study is to develop a methodology for sulfur compounds speciation using two-dimensional gas chromatography coupled with a flame ionization detector and sulfur chemiluminescence detectors. The methodology enhances the ability to detect and quantify the refractory sulfur in petroleum distillates, and it was utilized to screen the molecular differences between distillates of two Kuwaiti heavy crude oils from different reservoirs but with similar physical properties. Despite the similarity in the physical properties, the detailed comparative analysis indicated significant differences in molecular composition, which suggests substantial differences in crude oil processability based on the reactivity of the detected compounds. The distillates that have been considered in this study include heavy naphtha, kerosene, and gas oil. The compositional differences between the distillates were observed using the two-dimensional gas chromatography system with an in-house developed method. This method groups the sulfur compounds into thiols, benzothiophenes (BTs), and dibenzothiophene (DBTs), and it can handle any atmospheric distillate up 365 °C. Furthermore, the method includes the possibility of identifying and quantifying a total number of 44 sulfur species, which covers the previously mentioned sulfur groups.

Synthesis and characterization of new nano organic-inorganic hybrid (TBA)4PW11Fe@TiO2@PVA as a promising phase-transfer catalyst for oxidative desulfurization of real fuel

In this work, an efficient oxidative desulfurization (ODS) process of real gas oil and model oils was introduced using (TBA)4PW11Fe@TiO2@PVA phase-transfer catalyst. The catalyst was successfully prepared by the composition of the quaternary ammonium salt of mono iron-substituted phosphotungstate (abbreviated as (TBA)4PW11Fe), titanium dioxide (TiO2), and polyvinyl alcohol (PVA). The nanocomposite obtained was characterized through FT-IR, UV–vis, XRD, and SEM techniques. The spectroscopic characterization revealed that the (TBA)4PW11Fe was immobilized on the surface of TiO2@PVA. The results of catalytic tests showed the outstanding ODS performance of (TBA)4PW11Fe@TiO2@PVA in the removal of thiophenic compounds. Under optimized reaction conditions, the ODS efficiencies of benzothiophene (BT), dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) reach 96, 99, 97, and 98%, respectively. The desulfurization system can be recycled five times with merely a slight decrease in activity.

Deep oxidative desulfurization of real fuel and thiophenic model fuels using polyoxometalate-based catalytic nanohybrid material

In this paper, a new inorganic-organic nanohybrid material (Cu-SPOM@PbO@PVA) was constructed and used as a catalyst for oxidative desulfurization (ODS) treatment. The hybrid catalyst composed of Cu-substituted polyoxometalate (Cu-SPOM), lead oxide (PbO), and polyvinyl alcohol (PVA) was prepared via sol-gel method. The Cu-SPOM@PbO@PVA composite was characterized by various analytical techniques. The SEM results showed that the Cu-SPOM and PbO particles were well dispersed on the PVA matrix. Also, the mean particle size of the composite was in a range of 30–40 nm. According to the ODS results of real gasoline, the removal efficiency of sulfur content could reach 97 % at 35 °C after 1 h. Under the same reaction conditions, the concentration of some of thiophenic compounds, including, thiophene (Th), benzothiophene (BT), and dibenzothiophene (DBT) was significantly reduced from the model fuels with the efficiency of 97, 98, and 98 %, respectively. In addition, a series of ODS tests were carried out concerning desulfurization effect, kinetic study, and regeneration of the nanohybrid catalyst. The excellent catalytic activity of the Cu-SPOM@PbO@PVA composite suggested a fascinating new field in designing of inorganic-organic nanohybrid catalysts for ODS reactions.

The Gas-Phase Formation Mechanism of Dibenzofuran (DBF), Dibenzothiophene (DBT), and Carbazole (CA) from Benzofuran (BF), Benzothiophene (BT), and Indole (IN) with Cyclopentadienyl Radical.

Benzofuran (BF), benzothiophene (BT), indole (IN), dibenzofuran (DBF), dibenzothiophene (DBT), and carbazole (CA) are typical heterocyclic aromatic compounds (NSO-HETs), which can coexist with polycyclic aromatic hydrocarbons (PAHs) in combustion and pyrolysis conditions. In this work, quantum chemical calculations were carried out to investigate the formation of DBF, DBT, and CA from the reactions of BF, BT, and IN with a cyclopentadienyl radical (CPDyl) by using the hybrid density functional theory (DFT) at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants of crucial elementary steps were deduced over 600−1200 K, using canonical variational transition state theory with a small-curvature tunneling contribution (CVT/SCT). This paper showed that the production of DBF, DBT, and CA from the reactions of BF, BT, and IN with CPDyl involved six elementary steps: the addition reaction, ring closure, the first H shift, C–C cleavage, the second H shift, and elimination of CH3 or H. The cleavage of the C–C bond was regarded as the rate-determining step for each pathway due to the extremely high barrier. The 1-methyl substituted products were more easily formed than the 4-methyl substituted products. The main products were DBF and 1-methyl-DBF, DBT and 1-methyl-DBT, and CA and 1-methyl-CA for reactions of BF, BT, and IN with CPDyl, respectively. The ranking of DBF, DBT, and CA formation potential was as follows: DBT and methyl-DBT formation > DBF and methyl-DBF formation > CA, and methyl-CA formation. Comparison with the reaction of naphthalene with CPDyl indicated that the reactions of CPDyl attacking a benzene ring and a furan/thiophene/pyrrole ring could be inferred to be comparable under high temperature conditions.

Deep eutectic solvents based highly efficient extractive desulfurization of fuels – Eco-friendly approach

The developed process is based on alternative, green and cheap solvents for efficient desulfurization of fuels. Several deep eutectic solvents (DESs) were successfully synthesized and studied as extraction solvents for desulfurization of model fuel containing thiophene (T), benzothiophene (BT) and dibenzothiophene (DBT). The most important extraction parameters (i.e. kind of DES, DES: fuel volume ratio, hydrogen bond acceptor: hydrogen bond donor mole ratio, time of extraction and temperature) were optimized using central composite design model. Furthermore, the mutual solubility of DES and model fuel and influence of multistage extraction, reusability, regeneration of DES and content of aromatic groups in fuel are discussed followed by explanation of desulfurization mechanism, by means of density functional theory (DFT) as well as FT-IR analysis. The studies revealed high desulfurization effectiveness resulting in 91.5%, 95.4% and 99.2% removal of T, BT and DBT respectively in a single stage extraction. A three stage desulfurization provide >99.99% removal of T, BT and DBT. The research on the desulfurization mechanism revealed that π-π interaction is the main driving force for desulfurization process based on DES.

Synthesis and characterization of new sandwich-type polyoxometalate/nanoceramic nanocomposite, Fe2W18Fe4@FeTiO3, as a highly efficient heterogeneous nanocatalyst for desulfurization of fuel

Aiming deep oxidative desulfurization (ODS), Fe2W18Fe4@FeTiO3 composite was constructed as a new heterogeneous nanocatalyst on the basis of nanoceramic iron titanate (FeTiO3) and tetranuclear sandwich-type polyoxometalate (Na9K[(FeW9O34)2Fe4(H2O)2]·32H2O, abbreviated as Fe2W18Fe4). The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis method indicated the successful composition of the materials. The XRD studies showed that the average crystallite size of the composite particles was estimated to be about 42.1 nm, which confirmed by the results of SEM. The catalytic performance of nanocatalyst was investigated in the ODS of real gasoline and model oils. The maximum sulfur removal efficiency was achieved at 35 °C after 60 min using in situ production of peroxyacetic acid (HOOAc) as an oxidant. The heterocyclic organic sulfur compounds such as thiophene (Th), benzothiophene (BT) and dibenzothiophene (DBT) were oxidized with the efficiency of 97, 98 and 99%, respectively. The kinetic studies revealed that the rate of the ODS process obeys the pseudo-first-order model. The superior catalytic activity of the Fe2W18Fe4@FeTiO3 was assessed by the formation of active metal-oxo-peroxo intermediate complexes during the oxidation step. Also, the nanocatalyst exhibited excellent activity and stability even after five times reuse. Therefore, the prepared Fe2W18Fe4@FeTiO3 composite was suggested as a potentially attractive heterogeneous nanocatalyst for application in the ODS process of gasoline.

Synthesis and characterization of new nanosphere hybrid nanocomposite polyoxometalate@ceramic@polyaniline as a heterogeneous catalyst for oxidative desulfurization of real fuel

In this manuscript, the catalytic oxidative desulfurization (CODS) was proceeded using PMoV@CuO@PAN hybrid nanocatalyst. The nanocatalyst was prepared by the composition of potassium salt of 11-molybdo-1-vanadophosphat (PMoV), copper oxide (CuO), and polyaniline (PAN). The samples were characterized through various methods like FT-IR, XRD, SEM, and EDX. Thiophene (Th), benzothiophene (BT), and dibenzothiophene (DBT) were selected as the target sulfur compounds for CODS of simulated fuel. The oxidation processes were conducted under different conditions to evaluate the effects of individual reaction variables, including reaction time, reaction temperature, and nanocatalyst dosage. Moreover, a kinetic study was carried out and the activation energies for CODS of Th, BT, and DBT were determined. The investigations on CODS of real gasoline revealed that the sulfur content was reduced from 0.4987 to 0.0246 wt% and the mercaptans concentration was lowered from 98 to 5 ppm. Based on experimental results, the PMoV@CuO@PAN nanocatalyst retained a high removal yield of DBT compound after five rounds of reaction cycles and can be used as a reusable hybrid heterogeneous nanocatalyst in CODS treatments.

A Deep Analytical Study in the Oxidation Polymerization Desulfurization Process Using a Keggin-Type Polyoxometalate Catalyst: Characterization of Solid and Liquid Products

In this study, oxidation of a model fuel, benzothiophene (BT) in n-decane, using polyoxometalate catalyst with Keggin structure has been investigated. The solid product evaluation was performed using gel permeation chromatography (GPC), thermal gravimetric analysis (TGA)/(DSC) differential scanning calorimeter, FTIR, proton and carbon nuclear magnetic resonance (1H + 13C NMR) spectrums, elementary (C, H, N and S) analyses. The results showed that the solid product was a polymer with a weighted average molecular weight (Mw) of 183030. In addition, the polymer was found to be sticky, branched and cross-linked. Moreover, for the first time, the role of the different solvents in the formation of the polymer was studied. It was revealed that the solvent intermolecular force plays an important role in polymerization so that the solvent with stronger molecular force did not participant in the polymerization. Ultimately gas chromatography-flame ionization detector (GC-FID) analysis showed the amount of desulfurization was about 81%.

Morphology‐Controlled Synthesis of CuO, CuO Rod/MWW Composite for Advanced Oxidation of Indole and Benzothiophene

AbstractVarious morphologies of copper (II) oxide (CuO) such as dandelion, sea anemone, walnut, leaf, dendrite, rod, fiber, feather, and flake were synthesized and characterized by different methods. The oxidation of indole (IND) and benzothiophene (BT) in mild conditions was studied by various morphologies of CuO. Walnut with the lowest surface area 7.928 (m2g−1) and rod with a high surface area 41.237 (m2g−1) had efficiencies of 5.93% and 91.44% for IND and 0.53% and 88.29% for BT at 4 h, respectively. Zeolite MWW was synthesized by microwave and hydrothermal method on which CuO rod was loaded via wet impregnation method. The results indicated that CuO rod/MWW composite considerably outperformed CuO rod. The oxidations of IND and BT by CuO rod/MWW composite for 75 min was 99.99 and 97.67%, respectively. Based on the results across all experiments, the oxidation of the IND was higher than that of BT. CuO rod/MWW composite was shown to be an efficient catalyst for oxidation of nitrogen and sulfur heterocycles.

Extractive desulfurization of fuels using trialkylamine-based protic ionic liquids

Despite the extraction desulfurization of fuel oils using ionic liquids (ILs) as promising alternatives to traditional extractants has attracted worldwide attention, the drawbacks of ILs, such as poor extraction efficiency, high cost and complex preparation, have limited their further application in industrial scale. In this study, a series of trialkylamine-based protic ionic liquids (PILs) were synthesized and characterized, and their extraction desulfurization for thiophene (TH), benzothiophene (BT), and dibenzothiophene (DBT) in model oil was carried out. Effects of PIL species, extraction time, temperature, PIL dosage, and initial sulfuric concentration on desulfurization efficiency were investigated. Experimental results showed that the PILs exhibited higher extraction ability for TH, BT, and DBT as compared to the reported ILs. Under optimal conditions, the removal efficiency of TH, BT, and DBT using tris(3,6-dioxaheptyl) ammonium salicylate ([TDA][SA]) as extractant was 72.68%, 76.31%, and 83.94%, respectively. Finally, the suggested PIL can be easily regenerated and reused via a back extraction process. After 5 extraction cycles, the removal efficiency has no noticeable decrease. With advantages such as higher desulfurization efficiencies, cheap and easily obtained raw materials and simple synthetic process, this study will provide new green solvents for extraction desulfurization process of fuels.

A sustainable peroxophosphomolybdate/H2O2 system for the oxidative removal of organosulfur compounds from simulated and real high-sulfur diesels

Highly efficient, deep desulfurization of a multi-component model diesel containing benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) has been achieved by using the peroxophosphomolybdate [(n-C4H9)4N]3{PO4[MoO(O2)2]4} (Q3PMo4) directly as catalyst, and aqueous H2O2 as oxidant. Q3PMo4 behaves as a heterogeneous catalyst in the complete oxidation of the various sulfur compounds to the corresponding sulfones within 3 h at 70 °C, using a relatively low H2O2/S molar ratio of 3.7, and could be recycled for ten times with only a minimal decrease in activity. A study was performed to adapt the catalyst Q3PMo4 for the removal of sulfur from a real untreated diesel while maintaining a low, economically desirable, H2O2/S molar ratio of 3.7. The highest desulfurization performance was achieved in the presence of an extraction solvent during the catalytic oxidative stage, reinforced by two extraction steps before and after sulfur oxidation. Under these conditions, the sulfur content of the real diesel was reduced from 2300 to 500 ppm (78% desulfurization efficiency) after 3 h.

Cellulose nanocrystal shelled with poly(ionic liquid)/polyoxometalate hybrid as efficient catalyst for aerobic oxidative desulfurization

Immobilization of polyoxometalates (POMs) plays significant roles in their industrial applications. In this work, POM-supported catalyst has been developed with cellulose nanocrystal (CNC) as a sustainable carrier and employed in the aerobic oxidative desulfurization (AODS) of fuels. The catalyst was constructed by grafting a poly(ionic liquid) (PIL) onto CNCs and subsequently exchanging the counterions of the PIL into [Co(OH)6Mo6O18]3−, a kind of POM anionic clusters. The resulting CNC@PIL@POM was systematically characterized and utilized as a catalyst in the AODS of thiophenic compounds including benzothiophene (BT), dibenzothiophene (DBT), and 4, 6-dimethyldibenzothiophene (4, 6-DMDBT), with oxygen contained in air as oxidizing agent. The catalyst could achieve complete conversion of DBT in model diesel under mild condition and be reused five times without apparent losing of activity. As for the desulfurization of a real diesel, it was demonstrated that almost all of the original sulfides were completely converted. Based on these results, it is expected that the core-shell POM-supported catalyst may serve as an efficient, separable and sustainable catalyst for AODS of fuels.

High Electron Mobility in [1]Benzothieno[3,2-b][1]benzothiophene-Based Field-Effect Transistors: Toward n-Type BTBTs

The first example of an n-type [1]benzothieno[3,2-b][1]benzothiophene (BTBT)-based semiconductor, D(PhFCO)-BTBT, has been realized via a two-step transition-metal-free process without using chromat...