Benzothiophene Research Articles

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.

An Innovative Approach for Oxidative Desulfurization Advancement through High Shear Mixing: An Optimization Study on the Application of Benzothiophene.

Alternative fuels are being explored to mitigate the effects of petroleum-based fuels. Pyrolysis oil from waste tires is a promising alternative fuel; however, it contains very high concentrations of benzothiophene (BT) which are beyond the allowable sulfur limits of Taiwan and the Philippines. Mixing-assisted oxidative desulfurization (MAOD) is a method that removes sulfur from fuel oils by utilizing high-shear mixing and oxidants. In this paper, the oxidation of BT in a model fuel was studied to determine optimal process conditions. Crude Fe(VI) prepared from sludge was used as the oxidant. Using the Box-Behnken design under response surface methodology, the significance of the following independent variables was studied: mixing speed (4400-10 800 rpm), phase transfer agent (PTA) amount (100 to 300 mg), Fe(VI) concentration (400-6000 ppm), and mixing temperature (40 to 60 °C). The results from a comprehensive statistical analysis showed the increase of sulfur conversion with high levels of Fe(VI) concentrations and PTA amounts together with low levels of agitation speeds and temperatures. The BT to BT sulfone conversions from experimental runs ranged from 17% to 64%. The optimum sulfur conversion of 88% for the BT model fuel was reached at the maximum levels of Fe(VI) concentration and mixing speed, along with the minimum levels of PTA concentration and temperature. The optimal MAOD variables were applied to a high-sulfur pyrolysis oil sample, which resulted in a sulfur reduction of 55%. The produced fuel oil meets the sulfur requirements of Taiwan and the Philippines for industrial heating oils. Therefore, the findings of the study support the effectiveness of sludge-derived Fe(VI) in the MAOD of BT in the model fuel and pyrolysis oil under mild process conditions.

Optoelectronic properties study of arylamine-functionalized benzothiophenes and benzothiophene S,S-Dioxides. Application in solution-processed organic light-emitting diodes

Conjugated organic molecules based on core benzothiophene (BT) and benzothiophene S,S-dioxide (BTO), substituted with triphenylamines at positions 3,5,6 and 2,4,7, were designed via Suzuki couplings. Optoelectronic properties were studied, and theoretical calculations were carried out to understand the structured absorbance spectra of the various compounds. All compounds exhibited bright emission within the visible region, ranging from blue for BT to yellow-orange for BTO. Organic light-emitting diode (OLED) devices were fabricated through an air-processed spin-coating method where all layers, except the top cathode, were solution-processed. Device luminance exceeded 1000 cd/m2 using 2,4,7-triphenylaminebenzothiophene S,S-dioxide, which in turn was successfully translated to a large-area module slot-die coated on a plastic substrate.

Carboxylic acid-based deep eutectic solvent for efficient desulfurization: Experimental and computational thermodynamics

The improvement of fuel quality requires the reduction of sulfur content. The main challenge of catalytic cracking diesel extraction desulfurization is to find low-price and good-performance extractants. Based on experimental research, this work further explores the separation mechanism of DES for thiophene (TP) and benzothiophene (BTP). First, the COSMOS-RS model was used to predict the separation performance of 10 HBAs and 10 HBDs for TP and BTP. The results showed that the low-cost carboxylic acid based DES had excellent separation performance. Secondly, the effect of experimental conditions on the separation performance of three carboxylic acid based DESs was investigated. When the molar ratio of DES to TP and BTP was 3:1, after three stage extraction, the extraction rates of TP and BTP by TEAC: PrA(1:3) were 98.06 % and 98.53 %, respectively. Finally, the structure–activity relationship was studied by using quantum chemistry and molecular dynamics simulation. It was found that EvdW plays a dominant role in the desulfurization process and does not include H-bond interactions. TEA+ was distributed parallel to the aromatic ring and has a CH···π interaction with thiophene. TP and BTP were distributed in the voids of DES and do not affect the regeneration performance of DES.

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.

Facile loading of CuCl on SBA-15 for adsorptive desulfurization

SBA-15 supported CuCl (CuCl/SBA-15) adsorbents were prepared with CuCl2 as precursor via a facile ethylene reduction, where the reduction of CuCl2 was carried out at temperatures ranging from 120 to 220 °C. The prepared adsorbents were characterized by X-ray diffraction, N2 adsorption-desorption, Transmission electron microscopy, and X-ray photoelectron spectroscopy. The characterization reveals that the CuCl2 supported on SBA-15 can be reduced to CuCl, and the ratio of Cu+ to the total copper amount increases with increasing the reduction temperature, reaching 85.7 % at 200 °C. The adsorption capacities of thiophene (TP), benzothiophene (BT) and dibenzothiophene (DBT) over the CuCl/SBA-15(x) were further tested at 30 °C, and the Langmuir equation was used to fit the adsorption isotherms. It shows that their adsorption capacities of desulfurization follow the order of CuCl/SBA-15(200) > CuCl/SBA-15(180) > CuCl/SBA-15(150) > CuCl/SBA-15(120) > CuCl/SBA-15(220). The CuCl/SBA-15 (200) outperforms the other samples, and its adsorption capacities are up to 40.83 mg S/g for TP, 56.10 mg S/g for BT, and 81.23 mg S/g for DBT, respectively. The regeneration experiments for CuCl/SBA-15(200) show that the desulfurization performance was still maintained after four adsorption-desorption cycles.

Removal of thiophene compounds from model fuel with supported copper on active carbon, adsorption kinetics, and isotherms

AbstractIn this study, the adsorption of thiophene compounds (TCs), including thiophene (T), benzothiophene (BT), and dibenzothiophene (DBT), from model fuels was investigated using modified activated carbon (AC). The model fuel, prepared as a single‐solute model at a concentration of 2000 ppm based on a mixture concentration of 3000 ppm, served as the basis for the adsorption experiments. Additionally, an examination of thiophene adsorption from commercial fuels, specifically kerosene, was conducted. Experimental data were used to calculate correlated parameters of adsorption isotherms, kinetic models, and the Fisher factor. The pseudo‐second‐order model demonstrated the best fit to the experimental data. Notably, the adsorbent consisting of 10% Cu+ supported on acid‐washed activated carbon (A1CN10) exhibited the highest adsorption capacity for TCs, achieving removal percentages of 78%, 96%, and 100% for T, BT, and DBT, respectively. Various methods were employed to investigate the physicochemical properties of the adsorbents, including N2 adsorption–desorption surface analysis (BET), scanning electron microscopy (SEM), X‐ray diffraction (XRD), and energy dispersive spectroscopy (EDS). Furthermore, the regeneration of the adsorbent was studied using two techniques: agitation and ultrasound.

Oil extraction desulfurization based on ionic liquid: Back-extractant screening, experiment and process simulation

A comprehensive back-extractant screening method was first developed for regenerating ionic liquids (ILs) after oil extraction desulfurization (EDS). Statistical analysis was performed using the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) with the Entropy Weighting Method (EWM) on screening indices obtained based on the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) and the Quantitative Structure Activity Relationship (QSAR) models. CCl4 was selected as the optimal back-extractant among 196 candidates for regenerating the IL, 1-butyl-3-methylpyridinium dicyanamide ([BMPy][DCA]), targeting the simultaneous removal of thiophene (TS), benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The experimentally measured hexary liquid–liquid equilibrium (LLE) confirmed the satisfactory selectivities and distribution coefficients of CCl4. Based on the NRTL parameters correlated from the LLE data, a complete EDS process including IL-extraction and IL-regeneration was established and evaluated economically based on the total annual cost (TAC). The results demonstrated that this process significantly decreased the sulfur content from 500 ppm to less than 10 ppm. The study results verified the feasibility and effectiveness of the proposed method and showed the excellent industrial performance of the selected IL and back-extractant.

Diatomite supported bagel-like hydroxylated mesoporous carbon nitride towards the adsorption desulfurization application

The carbon nitride (g-C3N4) nanosheets was apt to occur the donor-acceptor (D-A) interaction with the sulfides via the influence of the electronic structure of C atoms in the ring. Accordingly, we implemented an environmental- friendly approach to raise the electropositivity of the C atoms of N atoms in the ring of g-C3N4 through the hydroxylation treatment of hydrogen peroxide(H2O2), and afterwards constructed a bagel-like morphology composite ((HO)x/g-C3N4@DE) by virtue of the calcined combination of hydroxylated mesoporous g-C3N4 and diatomite (DE). The characterization results showed that the substantial mesoporous structure was produced in the formation of (HO)x/g-C3N4@DE composite. The adsorption desulfurization experiments showed that the bagel-like hydroxylated mesoporous (HO)x/g-C3N4@DE had the optimum adsorption capacity of up to 42.2 mg/g for thiophene (TH) and 30.8 mg/g for benzothiophene (BT), respectively. Moreover, the adsorption capacities of the hydroxylated mesoporous (HO)x/g-C3N4@DE were dramatically higher than the individual (HO)x/g-C3N4 (18.92 mg/g for TH and 15.64 mg/g for BT), suggesting that the occurrence of the secondary stacked mesopores in the formation of the (HO)x/g-C3N4 on the surface and macro-porous structure of DE affected the adsorption capacity. Lastly, the adsorption mechanism of the hydroxylated mesoporous (HO)x/g-C3N4@DE was proposed.

Facile construction of hierarchically porous CPO-27-Ni by mixed ligand strategy towards enhanced adsorption desulfurization from fuels

High-efficiency removal of macromolecular aromatic sulfide from fuel via adsorption technology remains a challenge due to the limited mass-transfer efficiency in traditional microporous materials. Constructing hierarchically porous structure might be an alternative route to overcome the problem. Herein, we propose an approach to prepare rationally defective Nickel(II) 2,5-dihydroxyterephthalate (CPO-27-Ni) using benzoic acid (BA) and 2, 5-dihydroxyterephthalic acid (DHTA) as mixed ligands, aiming at reducing the diffusion resistance of molecules in adsorbents through introducing mesopores and thus enhancing the performance of aromatic sulfide removal. By adjusting the ratio of BA and DHTA (x), CPO-27-Ni (BA-C-x) with rational defects was successfully synthesized. Compared with the single-channel CPO-27-Ni, the penetrating sulfur capacity in the dynamic adsorption experiment was increased by 9.97 times for thiophene (TP), 7.25 times for benzothiophene (BT) and 2.81 times for dibenzothiophene (DBT). After the addition of organic ligand B, additional mesoporous pores were formed in the microporous CPO-27-Ni. The obtained hierarchical structure possessed better textural properties and ensured structural constancy, which improved the utilization rate of high active sites and mass transfer rate of adsorbent, leading to promoted desulfurization performance. The reported method of introducing mesopores into MOFs to construct hierarchically porous structures would provide a meaningful reference for facile preparation of high-efficiency desulfurization adsorbents.

Carbon-sulfur bond elongation as the promoting reaction coordinate in the efficient sub-nanosecond intersystem crossing in thianaphthene derivatives.

Thiophene derivatives have become integral to OLEDs, photovoltaics, and photodynamic therapy research. A deeper understanding of their excited state dynamics and electronic relaxation mechanisms is expected to provide important physical insights of direct relevance for these applications. In this study, thianaphthene (TN), 2-methylbenzothiophene (2MBT), and 3-methylbenzothiophene (3MBT) are investigated using femtosecond broadband transient absorption and steady-state spectroscopy techniques along with time-dependent density functional calculations in cyclohexane and acetonitrile. The photophysical properties and electronic relaxation mechanisms of these derivatives are elucidated. Small fluorescence quantum yields ranging from 0.4 to 1.1% are measured. It is demonstrated that excitation of TN at 290 nm leads primarily to intersystem crossing to the triplet manifold with a lifetime of 400 ± 15 ps in either solvent, whereas four- to twofold shorter intersystem crossing lifetimes are measured for 2MBT and 3MBT depending on whether cyclohexane or acetonitrile is used. Linear interpolation of internal coordinates evidence that elongation of the S-C bonds enables ultrafast intersystem crossing in these thiophene derivatives involving singlet and triplet states with ππ* and πσ* characters. Excitation at 266 nm results in an additional 5 ± 1 ps lifetime, which is assigned to intramolecular vibrational relaxation dynamics occurring in the excited singlet state.

Fabrication of Unique Mixed-Valent CoICoII and CuICuII Metal-Organic Frameworks (MOFs) for Desulfurization of Fuels: A Combined Experimental and Theoretical Approach toward Green Fuel.

Herein, metal-organic framework (MOF)-based adsorbents are designed with distinct hard and soft metal building units, namely, [Co2ICoII(PD)2(BP)] (Co_PD-BP) and [Cu2ICuII(PD)2(BP)] (Cu_PD-BP), where H2PD = pyrazine-1,4-diide-2,3-dicarboxylic acid and BP = 4,4'-bipyridine. The designed MOFs were characterized via spectral and SCXRD techniques, which confirm the mixed-valent states (+1 and +2) of the metal ions. Topological analysis revealed the rare ths and gwg topologies for Co MOF, while Cu-MOF exhibits a unique 8T21 topology in the 8-c net (point symbol for net: {424·64}). Moreover, severe environmental issues can be resolved by effectively removing heterocyclic organosulfur compounds from fuels via adsorptive desulfurization. Further, the developed MOFs were investigated for sulfur removal via adsorptive desulfurization from a model fuel consisting of dibenzothiophene (DBT), benzothiophene (BT), and thiophene (T) in the liquid phase using n-octane as a solvent. The findings revealed that Cu_PD-BP effectively removes the DBT with a removal efficiency of 86% at 300 ppm and an operating temperature of 25 °C, with a recyclability of up to four cycles. The adsorption kinetic analysis showed that the pseudo-first-order model could fit better with the experimental data indicating the physisorption process. Further, the studies revealed that adsorption capacity increased with the increasing initial DBT concentration with a remarkable capacity of 70.5 mg/g, and the adsorption process was well described by the Langmuir isotherm. The plausible reason behind the enhanced removal efficiency shown by Cu_PD-BP as compared to Co_PD-BP could be the soft-soft interactions between soft sulfur and soft Cu metal centers. Interestingly, density functional theory (DFT) studies were done in order to predict the mechanism of binding of thiophenic compounds with Cu_PD-BP, which further ascertained that along with other interactions, the S···π and S···Cu interactions predominate, resulting in a high uptake of DBT as compared to others. In essence, Cu_PD-BP turns out to be a promising adsorbent in the field of fuel desulfurization for the benefit of mankind.

Cu+-Doped PVA-Derived Mesoporous Carbon@Diatomite Adsorbent for Selective Adsorption Desulfurization.

Herein, we successfully constructed a Cu+-doped PVA-derived mesoporous carbon@diatomite (DE) composite by virtue of N2-suffered carbonization and self-reduction at a high temperature. The structure and composition of C/Cu@DE composite adsorbents were determined by a series of characterizations. The results affirmed that Cu+ species are highly scattered in PVA-derived mesoporous carbon, which covered the DE surface. The effect of carbonization temperature on the structure and composition of the C/Cu@DE composite adsorbents were intensively investigated, indicating that the C/Cu@DE composite at an 800 °C carbonization temperature (C/Cu@DE-800 °C) showed the formation of many Cu+ species and preferable hierarchical pore properties. The adsorption experiments of benzothiophene (BT) indicated that C/Cu@DE-800 °C possessed a better adsorption capacity. The adsorption behavior of BT onto C/Cu@DE-800 °C was investigated by a variety of adsorption times, initial concentrations, and recycle times, of which the largest adsorption capacity for BT attained 34.2 mg/g. Furthermore, the adsorption kinetics, intraparticle diffusion, adsorption isotherms, and adsorption thermodynamics of BT onto C/Cu@DE-800 °C was deeply studied, which contributed to the proposed adsorption mechanism.

Natural deep eutectic solvents of γ-valerolactone and formic acid for oxidative desulfurization with superior efficiency

Deep eutectic solvents (DESs) are widely used in oxidative desulfurization (ODS) to produce clean fuel. However, some DESs with good ODS efficiencies are generally consisted of harmful components, and the ODS efficiencies of most DESs with green components need to be further improved. Herein, a DES with two natural compounds of γ-valerolactone (γ-Val) and formic acid (FA) was prepared and used in ODS. The hydrogen bond interaction of DES was characterized by FT-IR, 1H NMR, DSC, and calculated by density functional theory (DFT) computation. The radical quenching experiments, EPR, and kinetic study were carried out to investigate the active radical and apparent activation energy of ODS process. The desulfurization efficiencies of γ-Val and FA (molar ratio 1: 4) DES was capable of reaching 100% of dibenzothiophene (DBT) removal within 100 min at an energy saving way of room temperature (25 °C) with a low O/S molar ratio of 2. When the temperature was raised to 70 °C and the O/S molar ratio was raised to 5, 100% sulfur removal of dibenzothiophene, 4,6-dimethyldibenzothiophene (4,6-DMDBT), and benzothiophene (BT) could be achieved in 4 min, 6 min, and 10 min respectively. DFT calculations revealed that the introduction of γ-Val could reduce the transition state energy barrier of ODS compared with a single FA ODS process. This work provides a novel high ODS efficiency DES with natural compounds, indicating the potential application of green DESs in ODS catalysts.

Desulfurization of Diesel Using Ionic Liquids: Process Design and Optimization Using COSMO-Based Models and Aspen Plus.

Sulfur dioxide emissions from fossil fuel combustion have been known to cause detrimental health and environmental effects. The currently used hydrodesulfurization (HDS) method employed by refineries has several drawbacks, such as excessive hydrogen consumption, high energy demand, and inability to remove complex organosulfur compounds, which have limited its ability to produce ultralow sulfur diesel (ULSD) at reasonable operating and capital costs. Ionic liquids (ILs) have been widely studied for their potential to replace conventional HDS. However, while their success has been demonstrated at the laboratory level, studies on industrial-scale feasibility and their integration into process simulators such as Aspen Plus are limited. In this work, 26 commercially available ILs have been screened using COSMO-based models and Aspen Plus for the desulfurization of diesel fuel and several possible process configurations have been examined. In particular, the challenge of ionic liquid regeneration, which has largely been ignored in the literature, has also been addressed and several potential regeneration methods have been proposed including extractive regeneration (E-RE) and stripping regeneration using nitrogen and air as stripping media (S-RE). The results indicate that, among the 26 ILs studied, 1-butyl-3-methylimidazolium thiocyanate is the most promising as a solvent for extractive desulfurization (EDS), E-RE, and S-RE. E-RE was found to be more effective for the removal of dibenzothiophene (DBT), while S-RE is more suited to the removal of thiophene and benzothiophene (BT). As a result, an optimized diesel desulfurization process using 1-butyl-3-methylimidazolium thiocyanate has been proposed that achieves ULSD with <10 ppm total sulfur in simulation studies, with complete recycling of the IL and minimal loss of the model diesel.

Quantification of polycyclic aromatic sulfur heterocycles in fine airborne urban particles (PM2.5) after multivariate optimization of a green procedure

Polycyclic aromatic sulfur heterocycles (PASHs), such as benzothiophenes (BT), dibenzothiophenes (DBT) and benzonapthothiophenes (BNT), can be emitted from vehicular traffic and deposited in fine particles matter (PM2.5). The presence of these compounds in PM2.5 is an environmental concern due to air pollution and its toxic properties. In this study, a green microscale solid–liquid extraction method was developed to determine twenty-three PASHs in PM2.5. A simplex-centroid mixture design was applied to optimize the extraction solvent. A full factorial design was used for preliminary evaluation of the factors that influence the extraction process (extraction time, sample size, and solvent volume) and then a Doehlert design for the significant parameters. The optimal extraction conditions based on the experimental design were: sample size, 4.15 cm2; 450 μL of toluene:dichloromethane (80:20,v/v); and extraction duration, 24 min. High sensitivity (LOD < 0.66pg m−3 and LOQ < 2.21 pg m−3) and acceptable recovery (82.8–120 %), and precision (RSD 3.6–14.0 %) were obtained. The greenness of the method was demonstrated using the Analytical GREEnness (AGREE) tool. The method was applied for analyzing PASHs in PM2.5 samples collected in three time intervals per day from years with different sulfur contents in the diesel: S-500 (≤500 ppm sulfur) and S-50 (≤50 ppm sulfur). Fourteen PASHs were quantified with the highest concentrations observed for 2,8-DMDBT and 4,6-DMDBT, which are recalcitrant compounds. The ANOVA test indicated significant differences between sampling periods during the day. The reduction of diesel S-500 to S-50 corresponded to a 28 % decrease in the total sum of PASHs (∑PASHs) evaluated. Spearman's rank correlations allowed for verifying that BTs and DBTs were highly correlated, suggesting that they were derived from similar sources. A weak correlation of 2,1-BNT and 2,3-BNT with BTs and DBTs indicates that these compounds are a chemical proxy for the emission of diesel engines during the combustion process.

Intensification of extractive desulfurization in micro-channels using triethylamine/propionic acid as deep eutectic solvent

In this study, the extractive desulfurization from the model fuel was investigated in different micro-channels using triethylamine/propionic acid with the molar ratio of 1 to 3 ([TEA:3Pr]) as DES. In this regard, the effect of operating parameters (i.e., extraction time, temperature, and fuel to DES volume ratio) and micro-channel geometrical parameters (i.e., the diameter of the micro-channel, and length of the micro-channel) on the sulfur removal and volumetric mass transfer coefficient was investigated. Moreover, the effect multiple extractive desulfurization cycles, regeneration of spent [TEA:3Pr] has been also investigated. It was found that the best geometry for the micro-channel is 0.6 mm in the diameter and 20 cm in length considering the sulfur removal and mass transfer. The slug and throat-annular flow regimes were observed in the different micro-channels through two-phase flow visualization. The achieved sulfur removal was 70.8%, 68.7%, and 44.4% from the model fuels containing dibenzothiophene (DBT), benzothiophene (BT), and thiophene (Th) in a very short residence time of 17 s, respectively. The overall volumetric mass transfer coefficient in the micro-channel was 0.679 s−1 in the fuel to DES volume ratio of 5. It was also found that deep sulfur removal can be achieved using multiple-extraction cycles.

Robust mechanical-performance core-shell nanostructured HNTs/PAN-supported Cu(I)/UIO-66 composite nanofibers towards selective adsorption removal of benzothiophene

In this work, a novel core-shell nanostructured coaxial nanofiber membranes (CFMs) were successfully produced by the coaxial electrospinning. The structure and composition of CFMs were probed by a series of characterizations. The results demonstrated that the CFMs were comprised of the versatile core-shell structure nanofibers, therein Cu(I)/UIO-66 scattered in the shell layer and HNTs dispersed in the core layer. As applied in the selective adsorption desulfurization, the Cu(I)/UIO-66 embedded on the surface of the nanofiber undertook the adsorption active sites, while HNTs in core layer served as enhancing the mechanical performance of PAN nanofibers. The CFMs had the superior adsorption performance in the batch adsorption (maximum:40.14 mg·g−1) and fixed-bed adsorption (maximum: 47.43 mg·g−1) capacities for benzothiophene (BT) from fuel oil, respectively. Furthermore, due to having the robust mechanical performance, the CFMs exhibited the preferable recycling adsorption and mechanical stability. The adsorption mechanism of BT molecules on CFMs was explored by the kinetics, isotherms and thermodynamic models, indicating the existence of the synergistic effect of physical adsorption and chemical adsorption.

Ozonation/extraction coupled non‐catalytic desulphurization of VGO/natural gas condensate

AbstractThe desulphurization of hydrocarbon fuels with high sulphur content and a wide variety of sulphur‐containing compounds brings significant challenges. In the present work, the non‐catalytic desulphurization of vacuum gas oil (VGO) and natural gas condensate mixed fuel has been investigated. In this regard, ozone was employed as the oxidant in a bubble column gas–liquid contactor, and an extraction step was further incorporated. The effects of the oxidation reactor scheme, ozonation time, and extraction with different solvents, applying pre‐ and post‐extraction strategies (i.e., ozonation/extraction/extraction and extraction/ozonation/extraction), have been studied. It was found that pre‐extraction of mixed fuel increases the oxidative desulphurization (ODS) efficiency due to the removal of light sulphur‐containing compounds (SCCs). N‐methyl‐2‐pyrrolidone (NMP) has been found to be the most effective extraction agent, removing 44% of sulphur by pure extraction and 77.4% by ozonation + extraction. However, in terms of fuel loss, dimethylformamide (DMF) performs better than NMP, and it has been shown to be the most appropriate solvent for achieving a 90% desulphurization ratio. Finally, it was found that the applied procedure could effectively remove the wide range of SCCs, especially refractive components such as benzothiophene (BT) and dibenzothiophene (DBT).

Polycyclic aromatic sulfur heterocycles used as molecular markers in crude oils and source rocks

Polycyclic aromatic sulfur heterocycles (PASHs), such as benzothiophenes (BTs), dibenzothiophenes (DBTs), and benzonaphthothiophenes (BNTs), are found in crude oil and source rocks and have been extensively studied in the last decades. PASHs play a significant role in organic geochemistry as molecular markers (S-markers) because they are common in a variety of both oils and source rocks and mainly due to their thermal stability. Furthermore, relative to other hydrocarbon groups such as alkanes and many aromatic compounds, S-markers are highly stable and degradation-resistant. Thus, S-markers have been studied to obtain important information about thermal evolution, depositional environment, maturity as well as about petroleum migration and biodegradation. DBT-related markers, such as 4-MDBT/1-MDBT, 4,6-DMDBT/1,4-DMDBT, and benzonaphtho[2,1-d]thiophene/benzonaphtho[1,2-d]thiophene ([2,1]BNT/[1,2]BNT) are good maturity indicators, particularly for high to over-mature oil. The application of these S-markers overcomes the limitation of hopane and sterane maturity indicators which are restricted to a relatively low maturation range. S-markers are also related to the type of source rock where oils derived from siliceous rocks are rich in BT, DBT, DMDBT, and TMDBT and their relative concentrations are lower than those in carbonate-sourced oils. Individual DBTs are used to indicate susceptibility to biodegradation in the following order: DBT > 4-MDBT > 2-+3-MDBT > 1-MDBT. In this study, PASHs used as S-markers individually or through diagnostic ratios in crude oils and source rocks were reviewed. Different analytical techniques (including classical and innovative approaches) used to quantify and characterize S-markers, are discussed. According to our knowledge, this article is the first overview of PASHs employed as geochemical markers and provides an overview of the different alternatives for sample preparation, instrumental analysis, identification, and quantification of these compounds.