Removal Of Thiophene Research Articles

Betaine + (Glycerol or Ethylene Glycol or Propylene Glycol) Deep Eutectic Solvents for Extractive Purification of Gasoline

AbstractDeep eutectic solvents (DES), a class of ′green′ solvents, are being tested for extractive desulfurization, denitrification and dearomatization of fuels. Here, three DESs were prepared by combining betaine (B) with glycerol (Gly), ethylene glycol (EG) or propylene glycol (PG) in the molar ratios of 1:3, 1:3 and 1:3.5, respectively. The DESs were used for the removal of thiophene, pyridine and toluene from a 6‐component model gasoline and for the removal of sulfur and nitrogen compounds from a real fluid catalytic cracking (FCC) gasoline. Physical properties of the prepared DESs – density, viscosity, refractive index, specific conductance, thermal conductivity, temperature diffusivity and heat capacity were determined, too. All tested DESs exhibit higher potential for denitrification of model fuel with respect to desulfurization and dearomatization. B‐PG 1:3.5 worked best in one‐stage denitrification of both model gasoline (∼80%) and real FCC gasoline (∼36%). The reuse of solvent without loss in extraction efficiency in four extraction stages was successfully achieved for all three DESs by evaporation purification of DES between the stages.

Removal of low-concentration thiophene by DC corona discharge plasma

This study focuses on the removal of C4H4S using DC corona discharge plasma. The influences of various factors such as C4H4S concentration (ppm), temperature (°C), O2 concentration (%), and dust concentration (mg/m3) on the conversion of C4H4S were studied. Furthermore, gaseous compositions were determined using Fourier transform infrared (FTIR) spectroscopy. Solid products, which were collected from earth and discharge electrodes, were analyzed using X-ray diffraction (XRD). The results showed that, under the condition of DC corona discharge plasma, C4H4S converted to CO, CO2, S, SO2, and SO42-, and that the conversion rate increased with the increase in specific input energy (SIE). The increase of O2 concentration led to further energy consumption that generated O3, which in turn decreased the conversion rate of C4H4S. The increase in temperature exhibited a positive influence on the conversion of C4H4S when the SIE was less than 268J/L. However, above this value of SIE, the temperature affected the conversion of C4H4S negatively with the increase in SIE. When dust was introduced, the conversion of C4H4S was significantly improved and the yield of SO2 reduced due to the reaction which took place among C4H4S, SO2 and dust in the electric field. The results showed that the DC corona discharge plasma exhibited considerable potential to remove C4H4S, while dust contributed positively towards the disposal of C4H4S. Graphical abstract In this work, DC corona plasma was used to remove thiophene (C4H4S) from a dust-containing gas stream. The results showed that electron collision, oxidizability of radicals, and existence of O3 were the main causes of C4H4S decomposition. The electron collision effects, contents of radicals, O3, and the conversion rate of C4H4S were enhanced with the increase in SIE (specific input energy). The main products consisted of CO, CO2, SO2, and solid products. The solid products and dust moved to the earth electrode in the electric field.

The effect of hydrogen on thiophene catalytic removal over Ni/Al2O3

To investigate the essential role of H2 on thiophene removal over supported nickel catalysts, a NiO/Al2O3 catalyst was prepared, and a series of desulfurization reactions were carried out with different H2 feed concentrations. The characterization of fresh and spent catalysts indicated that reduced nickel (Ni0), which showed dependence on the H2 feed concentration, was the key factor to the thiophene reactive adsorption desulfurization (RADS) process. The equilibrium between sulfurization and reduction of nickel species retained the activity of the catalyst. The stability of the formed nickel sulfides was related to the H2 feed concentration. The higher H2 feed concentration favored the RADS process for the positive auto-regeneration of the nickel species.

A New Strategy for Fuel Desulfurization by Molecular Inclusion with Copper(II)-β-cyclodextrin@SiO2@Fe3O4 for Removing Thiophenic Sulfides

Developing a new and environment-friendly desulfurization strategy for removing thiophenic sulfides from fuel is currently necessary. Fuel desulfurization by molecular inclusion with a novel cyclodextrin-based magnetic nanomaterial copper(II)-β-cyclodextrin@silica@ferroferric oxide (Cu(II)-β-CD@SiO2@Fe3O4) was proposed for the efficient removal of thiophene (T), benzothiophene (BT), and dibenzothiophene (DBT) in fuel. Cu(II)-β-CD@SiO2@Fe3O4 was successfully prepared by the reaction between mono-6-O-toluenesulfonyl-Cu(II)-β-CD and 3-aminopropyltrimethoxysilane functionalized SiO2@Fe3O4, and the structural characterization illustrated that the active desulfurization component Cu(II)-β-CD was evenly immobilized on the surface of SiO2@Fe3O4. Furthermore, Cu(II)-β-CD@SiO2@Fe3O4 showed outstanding desulfurization performance for thiophenic sulfides in the order BT > DBT > T on account of the varying molecular inclusion ability of Cu(II)-β-CD for the three types of thiophenic sulfides. The optimum immobilized lo...

Photo oxidation of DBT using carbon nanotube titania composite as visible light active photo catalyst

Sulfur removal from liquid fuels has increased in importance in recent years. Although hydrodesulfurization is the usual method for removing sulfur, the elimination of thiophene compounds using this process is difficult. Photocatalysis is an alternative method being developed for thiophene removal at ambient conditions. Among semiconductors, titania has shown good potential as a photo-catalyst; however, quick recombination of electron holes hinders its commercial use. One way to decrease the recombination rate is to combine carbon nanotubes with a semiconductor. In this work, multiwall carbon nanotube (MWCNT) / titania composites were prepared with different mass ratios of MWCNT to titania using tetraethyl orthotitanate (TEOT) and titanium tetra isopropoxide (TTIP) as precursors of titania. Dibenzothiophene (DBT) photocatalytic removal from n-hexane was measured in both the presence and absence of oxygen. The results indicated that the best removal occurred when the MWCNT to titania ratio was 1. When the ratio exceeded this number, DBT removal efficiency decreased due to light scattering. Also, the composites prepared by TEOT exhibited better efficiency in DBT removal. The research findings suggested that the obtained composite was a visible light active photocatalyst and exhibited better performance in the presence of oxygen. Kinetics of photocatalytic DBT removal was a first-order reaction with removal rate constant 0.7 h–1 obtained at optimum conditions.

Desulfurization of FCC gasoline by using spiral wound pervaporation module: Removal of different types of sulfur containing species

In last decade, pervaporation has been recognized as a promising novel process for desulfurization of FCC (Fluidized Catalytic Cracking) gasoline. This study deals with the comparison of the removal of different types of sulfur containing species by a spiral wound pervaporation module. For this, different binary systems containing 2-methyl thiophene, 1-butanethiol and diethyl sulfide as solute and n-heptane as solvent are selected as model gasoline. Results reported in our previous study on n-heptane/thiophene systems are also included in the analysis. Experiments were performed on a spiral wound module with PDMS/PI (Polydimethylsiloxane/Polyimide) composite membrane at a variety of operating conditions. A suitable mathematical model was then used to predict the module performance theoretically. Some of the experimental results were used to predict the membrane transport parameters for different sulfur containing compounds, and the remaining experimental results were then used to validate the mathematical model. Comparison of the model predictions and experimental results validated the mathematical model, which suggests that the reported mathematical model can be applied to design the spiral wound pervaporative modules to remove higher molecular weight thiophenes as well as other sulfur containing compounds.The presented results show that the PDMS/PI membrane is selective for all three sulfur containing compounds. However, the pervaporation process is found more suitable for removal of lower molecular weight thiophenes. Results further show that the optimum operating conditions for sulfur removal may depend on the functional groups present and molecular weight of sulfur containing compounds present in the gasoline.

Prediction of thiophene removal from diesel using [BMIM][AlCl4] in EDS Process: GA-ANFIS and PSO-ANFIS modeling

ABSTRACTIn this study, the treatment capability of 1-butyl-3-methylimidazolium tetrachloroaluminate [BMIM] [AlCl4] ionic liquid was investigated in a diesel fuel containing thiophene. The effects of operating parameters including the volumetric ratio of ionic liquid to model fuel, extraction temperature and time have been studied. Then, a neuro-fuzzy inference system (ANFIS) tuned by particle swarm optimization (PSO) algorithm has been developed to predict the sulphur removal from diesel fuel using [BMIM][AlCl4] in EDS process. The outputs were in a good agreement with the experimental data, and the model tuned by PSO predicts the data better than ANFIS and ANFIS tuned by GA.

Removal of thiophene in air stream by absorption combined with electrochemical oxidation

Abstract As typical heteroaromatic compounds, thiophene is an air pollutant that pose serious environmental and health related impacts due to its volatility and toxicity. This work reports a hybrid process of absorption combined with electrochemical oxidation to degrade thiophene. The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) was employed as the absorbent to capture thiophene from air stream. Linear sweep voltammetry (LSV) demonstrated that thiophene could be oxidized on β-PbO2 anode modified with fluoride at 1.28 V versus Ag/Ag + electrode (RE) with a scan rate of 100 mV/s while [BMIM]BF4 was used as the electrolyte. Results of bulk electrolysis showed that thiophene could be thoroughly degraded within 60 min in [BMIM]BF4 under 50 mA/cm2 due to the successive attack of hydroxyl radicals (·OH) produced by electrolysis on the surface of β-PbO2 anode. Acetic acid was determined as the main intermediate and could be further mineralized to fumaric acid, maleic acid and oxalic acid, while sulfur atom in thiophene was finally converted to sulfate ions (SO42−). Based on the HPLC analysis and a precipitation of BaSO4, degradation pathway of thiophene was proposed and the thiophene sulfur could be degraded completely into sulfate. The kinetics of the electrochemical oxidation process for thiophene can be described by the pseudo-first order model. This absorption-electrochemical oxidation method with continuous operation would be a promising way for the clean and safe removal of heteroaromatic compounds from waste gases.

Room Temperature Adsorptive Removal of Thiophene over Zinc Oxide-Based Adsorbents

This study investigated the room temperature adsorptive removal of thiophene over zinc oxide adsorbents in the presence of hydrogen. The bulk zinc oxide was prepared by precipitation method and calcined at different temperatures in the range of 300-550 °C. Supported zinc oxide was prepared by co-precipitation of 30 wt.% ZnO with alumina and calcined at 550 °C. Properties of the adsorbents were determined by various characterization techniques such as surface area and pore volume analysis, XRD, FESEM, EDX and TPR. The desulfurization process was carried out in a down-flow packed bed reactor at room temperature (30 °C). The BET surface area of bulk zinc oxide adsorbents decreased with the increase in calcination temperature from 300 to 550 °C. The surface area of bulk zinc oxide adsorbents was 30.5 and 14.6 m2/g when calcined at 300 and 550 °C, respectively. The surface are of supported zinc oxide adsorbents was 177 m2/g. The highest average pore size was obtained for bulk ZnO calcined at 550 °C (45 nm) compared to that calcined at 300 °C (42 nm) and supported ZnO (27 nm). The XRD peaks corresponded to the hexagonal structure of zinc oxide. The removal of thiophene was most significant for bulk ZnO calcined at 550 °C. The higher removal efficiency for this adsorbent in spite of lower surface area may be attributed to its higher percentage of larger pores and higher average pore size.

High removal of thiophene from model gasoline by porous MIL-101(Cr)/SA hybrid membrane.

Membrane separation technologies have great promising potential for applications in several industries. Metal–organic frameworks (MOFs), for their large surface areas, low framework densities, transition-metal ions in the skeleton and high pore volumes relative to other porous matrices, have great potential for the removal of sulfur from gasoline with high efficiency. In the present study, a novel porous membrane adsorbent MIL-101(Cr)/SA was prepared by immobilizing MIL-101(Cr) onto sodium alginate (SA) matrix, which can combine the size/shape selectivity of MIL-101(Cr) with the processability and mechanical stability of SA polymer. The physico-chemical properties of MIL-101(Cr)/SA were investigated by FT-IR, SEM, BET, XRD and EDX methods. To investigate the effects of some important factors on the adsorption behavior for thiophene, a batch of experiments were performed by changing the concentration of porogen polyethylene glycol in the MIL-101(Cr)/SA, solution temperature, initial thiophene concentration and contact time. Meanwhile, benzothiophene, thiophene and 3-methyl thiophene were used to test the selectivity of MIL-101(Cr)/SA. The MIL-101(Cr)/SA showed an excellent uptake capacity of 671 mg g−1 under the optimal adsorption conditions. Selectivity testing indicated that the uptake capacity of MIL-101(Cr)/SA follows the order of benzothiophene > thiophene > 3-methyl thiophene. Kinetics experiments indicated the pseudo-second-order model displayed good correlation with adsorption kinetics data. The Crank model showed that the intraparticle solute diffusion is the rate-controlling adsorption step. Regeneration experiment result shows that the prepared MIL-101(Cr)/SA has excellent adsorption and desorption efficiencies.

Facile Combustion Synthesis of ZnFe2O4 for Photocatalytic Oxidative Desulfurization of Thiophene in Model Oil

Nano-ZnFe2O4 photocatalysts are one-step synthesized via solution combustion route, which are characterized by XRD, TEM, and UV-vis DRS. The photocatalytic activity of these samples are evaluated by the removal of thiophene in model oil under visible light irradiation. The influences of fuel amount on the particle size and photocatalytic performance of the as-synthesized catalysts are investigated. The results show that the ZnFe2O4 with the particle size of 21.9 nm exhibits the highest photocatalytic ability, which is acquired using triethylamine hydrochloride as fuel in the fuel-rich combustion condition. The desulfurization yield of model oil can reach 92.5% in 5 h photo-irradiation and the sulfur content can be decreased from 200 ppm to 15 ppm.

Ultra-deep adsorptive desulfurization of fuels on cobalt and molybdenum nanoparticles loaded on activated carbon derived from waste rubber

The role of cobalt and molybdenum nanoparticles loaded on activated carbon (AC) on the adsorptive desulfurization ability of sulfur-containing compounds was investigated under ambient conditions. The AC was first synthesized and activated, followed by incorporation of the cobalt (Co), molybdenum (Mo) and both Co and Mo nanoparticles. The adsorption activity parameters of the developed composites were determined using surface characterization and N2 physisorption techniques. The prepared composites were evaluated for simultaneous adsorption of sulfur compounds from fuels. The AC/CoMo composite showed better adsorption properties than pure AC, AC/Co and AC/Mo composites for the removal of thiophene (T), benzothiophene (BT), dibenzothiophene (DBT), 5-methyl-1-benzothiophene (MBT), 4,6-dimethyldibenzothiophene (DMDBT) and 4-methyldibenzothiophene (MDBT). The order of the thiophene compounds removal was found to be Thiophene < BT < DBT < MBT ≤ MDBT ≤ DMDBT. The enhanced desulfurization performance of the AC/CoMo composite was attributed to the increase in the surface area achieved through impregnation of both Co and Mo.

Synthesis of Cu-BTC/Mt composites porous materials and their performance in adsorptive desulfurization process

This paper highlights the synthesis of Cu-BTC supported on Montmorillonite (Mt) to form Cu-BTC/Mt composite materials and examines their important role in adsorptive desulfurization process of fuel liquids. Cu-BTC/Mt composites were synthesized by solvothermal synthesis using varying Cu-BTC content (30%, 40% and 50%) and a well-known and constant amount of montmorillonite was used as support. The synthesized composites were then characterized using XRD, FT-IR, TEM and BET techniques. The adsorptive desulfurization performance of the as-prepared composite materials was investigated and their ability to remove thiophene from thiophene/n-octane model oil was studied under mild operating conditions namely: temperature near room temperature, atmospheric pressure and at different model oil/adsorbent mass ratio. Investigation results have shown that the 40%Cu-BTC/Mt composite sample has the best desulfurization performance for thiophene removal. After 6 h of desulfurization, under the reaction conditions of temperature of 30 °C and at a model oil/adsorbent mass ratio of 100:1, the percentage of sulfur removal was 76% while the adsorption desulfurization capacity reached 28.95 mgS/gMOF. The 40%Cu-BTC/Mt composite sample could be reused for at least five consecutive rounds. The adsorption kinetics fit well both the pseudo-first order rate equation and pseudo-second order rate equation models.

Adsorption and Separation Mechanism of Thiophene/Benzene in MFI Zeolite: A GCMC Study

Selective removal of thiophene from aromatic components is one of the key challenges facing the petrochemical industry. The adsorption and separation mechanism from the molecular viewpoint can guide and upgrade the relative adsorption based technology. Therefore, we performed the grand canonical ensemble Monte Carlo (GCMC) simulation to investigate the adsorption performance and mechanism of competitive adsorption. Density distribution and radial distribution functions (RDF) analysis give a more detailed description of the adsorption sites. For pure component adsorption, donut-shaped adsorption sites were obtained for both benzene and thiophene from the straight channel point. From the viewpoint of the zigzag channel, the sorbates follow the straight line shape distribution at low loading and the S shape distribution at high loading. As for the binary component adsorption, more benzene adsorbs in the zeolite than thiophene at low pressure; however, thiophene competes successfully at high pressure. This ca...

Adsorption of thiophene by activated carbon: A global sensitivity analysis

The removal of sulfur compounds in biomass gasification processes is crucial to protect downstream equipment. While conventional sorbent materials can retain H2S, many fail to capture heterocyclic sulfur compounds such as thiophene (C4H4S). This work explored activated carbons (ACs) for the removal of thiophene from the gas phase both experimentally and by employing different models. Experiments were performed in a laboratory packed bed column between 100–200°C at various gas flow-rates and inlet concentrations. Altering the temperature had the strongest effect with breakthrough capacities ranging from 7–138mmolkg−1. The transient adsorption process was described by a 1-D approach, including mass transfer phenomena and axial dispersion. Experimental validation showed good agreement between measured and predicted breakthrough times and capacities. A global sensitivity analysis (GSA) was performed to obtain a ranking of importance of model input factors and gain further process insight. The GSA included 12 model parameters and a selection of axial dispersion correlations and isotherm models. Based on the chosen range of input factors, the GSA indicated that the type of isotherm model, axial dispersion correlation, and temperature have a major effect on the predicted breakthrough time. The calculated slope of the curve is strongly affected by the isotherm model and axial dispersion correlation. Overall, this work showed that ACs are a promising option for thiophene removal and provided a generic approach for the application of GSA to adsorption models. In the given context the analysis demonstrated that the selection of common model assumptions deserves as much attention as the model parameters.

Facile functionalization of 3-D ordered KIT-6 with cuprous oxide for deep desulfurization

Deep desulfurization by π-complexation is an efficient technique for purification of fuels. In π-complexation adsorbents, Cu(I)-based materials are effective due to low cost and high activity. However, the deep desulfurization has been proven to strongly rely on the dispersion extent of Cu species. Herein, for the first time, we report ammonia assisted deposition precipitation one-step N2 reduction strategy to fabricate Cu2O-containing KIT-6. In such strategy, Cu(NO3)2 precursor was directly introduced into the microenvironment exist between template and silica walls of template-P123-containing KIT-6 via ammonia assisted deposition precipitation. The subsequent single step N2 reduction strategy perform three functions in a single mode i.e. decomposition of Cu precursor to CuO, template removal, and conversion of CuO to Cu(I). Our strategy is convenient and efficiently promoted the dispersion of Cu species with high yield (61.84%) of Cu(I). We also demonstrated that the resultant material, as-synthesized KIT-6 supported with an optimal content 20wt% of Cu, can capture 0.28mmol·g−1 thiophene, which is obviously better than its counterpart CuCK-20 synthesized via calcined KIT-6. Furthermore, the thiophene adsorption activity can be recovered well without any obvious loss. Facile synthesis, high thiophene removal, and excellent regeneration ability make Cu/KIT-6 favorable for utilization in adsorptive desulfurization technology.

Adsorption Kinetic and Isotherms Studies of Thiophene Removal from Model Fuel on Activated Carbon Supported Copper Oxide

In the present study, activated carbon supported metal oxides was prepared for thiophene removal from model fuel (Thiophene in n-hexane) using adsorptive desulfurization technique. Commercial activated carbon was loaded individually with copper oxide in the form of Cu2O/AC. A comparison of the kinetic and isotherm models of the sorption of thiophene from model fuel was made at different operating conditions including adsorbent dose, initial thiophene concentration and contact time. Various adsorption rate constants and isotherm parameters were calculated. Results indicated that the desulfurization was enhanced when copper was loaded onto activated carbon surface. The highest desulfurization percent for Cu2O/AC and origin AC at initial thiophene concentration of 500 ppm, adsorbent dose of 0.01 g/ml and equilibrium time of 5 hr were 87.4% and 53.4% respectively, for outlet concentration of 63 mg/L for copper oxide and 236 mg/L for original AC. Generally, the percent removal of thiophene increases with the increase in adsorbent dose and decrease with increase in initial thiophene concentration. The present study was mainly focusing on the kinetics and adsorption isotherms aspect; adsorption kinetics of thiophene onto activated carbon supported Cu2O adsorbent was closely represented by the second order kinetic model and Freundlich isotherms well represented the equilibrium adsorption of thiophene from model fuel.

Pervaporative performance of PEBA and PDMS based commercial membranes in thiophene removal from its binary mixtures with hydrocarbons

This work describes vacuum pervaporation tests which were performed to identify the influence of five hydrocarbons typically presented in gasoline, i.e. n-hexane, n-heptane, n-octane, isooctane (2,2,4-trimethylpentane), and 1-octene on thiophene removal efficiency from hydrocarbon/thiophene binary mixtures. Commercial hydrophobic PEBA-based and PDMS-based composite membranes were applied. The impact of process parameters such as feed temperature and feed composition was examined. Experiments performed with various hydrocarbon confirmed, that the membrane performance and overall separation efficiency is influenced by the physiochemical properties of the mixture components (solute and solvent) and the differences in the affinities towards a given membrane. Permeate fluxes and corresponding separation factors presented typical trade-off regardless the type of membrane and solvent. The separation factors were higher in the case of the PEBA membrane which corresponded with the Hansen's Solubility Parameters Theory. The batch pervaporation removal of thiophene from isooctane was also modeled, proving that the PEBA membrane is more effective than the PDMS one. Solvents fluxes were 3 orders of magnitude higher than solute ones, therefore Pervaporation Separation Index (PSI) should be used only as a preliminary assessment of the membrane performance.

Adsorptive Desulfurization of Model Gasoline by Using Different Zn Sources Exchanged NaY Zeolites.

A series of Zn-modified NaY zeolites were prepared by the liquid-phase ion-exchange method with different Zn sources, including Zn(NO3)2, Zn(Ac)2 and ZnSO4. The samples were tested as adsorbents for removing an organic sulfur compound from a model gasoline fuel containing 1000 ppmw sulfur. Zn(Ac)2-Y exhibited the best performance for the desulfurization of gasoline at ambient conditions. Combined with the adsorbents’ characterization results, the higher adsorption capacity of Zn(Ac)2-Y is associated with a higher ion-exchange degree. Further, the results demonstrated that the addition of 5 wt % toluene or 1-hexene to the diluted thiophene (TP) solution in cyclohexane caused a large decrease in the removal of TP from the model gasoline fuel. This provides evidence about the competition through the π-complexation between TP and toluene for adsorption on the active sites. The acid-catalyzed alkylation by 1-hexene of TP and the generated complex mixture of bulky alkylthiophenes would adsorb on the surface active sites of the adsorbent and block the pores. The regenerated Zn(Ac)2-Y adsorbent afforded 84.42% and 66.10% of the initial adsorption capacity after the first two regeneration cycles.

Dispersion of nickel nanoparticles in the cages of metal-organic framework: An efficient sorbent for adsorptive removal of thiophene

Nickel NPs (<2nm) were confined in highly porous metal organic framework (MOF; here, MIL-101(Cr)) via a facile strategy at ambient conditions. With the characterization of HRTEM, XRD, N2 physisorption, SEM, XPS, TPR, FT-IR, NH3-TPD, ICP-OES, and TG-DTG, the resulting nickel NPs up to 20wt% first-ever were detected to be uniformly dispersed, smaller in size and easily reducible in MIL-101(Cr) cages retaining their original crystal structure. The efficiencies of the new sorbents in adsorptive removal of thiophene were investigated. Compared with pristine MIL-101, the capacity of sulfur adsorption of modified MIL-101 enhanced for thiophene, and obey the order 20Ni-MIL-101>10Ni-MIL-101>30Ni-MIL-101>MIL-101. The improved adsorption properties were linked with surface chemistry and texture of MIL-101 support. Pseudo second-order kinetic and Langmuir models showed best fit of thiophene adsorption on MIL-101 and Ni-containing MIL-101 samples. Moreover, the rate controlling step for thiophene adsorption was intraparticle diffusion.