Desulfurization of Diesel Fuel by Extraction with Lewis-Acidic Ionic Liquid

Abstract

Ionic liquids were found to be highly selective for the extractive removal of aromatic sulfur compounds from fuels at room temperature. The efficiency of ionic liquids for the removal of aromatic sulfur compounds is dependent on the properties and structure of the ionic liquids. In this work, the Lewis-acidic ionic liquid 1-butyl-3-methylimidazolium tetrahalogenoferrate(III) ([BMIM] [FeCl₄]) was synthesized and demonstrated to be more effective for the removal of aromatic sulfur compounds from diesel over ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM] [BF₄]) because of its Lewis-acidic property. The ionic liquids favorably extracted organic compounds with a higher density of aromatic π-electrons. [BMIM][FeCl₄] ionic liquid can be regenerated through reextraction by hexane, and could be used in multiple steps for the removal of sulfur compounds from diesel.     

Preparation of well-defined dendrimer encapsulated ruthenium nanoparticles and their application as catalyst and enhancement of activity when utilised as SCILL catalysts in the hydrogenation of citral

Silica supported dendrimer encapsulated ruthenium nanoparticles were prepared and evaluated as catalysts in the hydrogenation of citral. The dendrimer encapsulated nanoparticles were prepared using the generation 4 (G4), generation 5 (G5) and generation 6 (G6) hydroxyl-terminated poly(amidoamine) (PAMAM-OH) dendrimers as templating agents with different Ru metal:dendrimer ratios. The effects of ionic liquids as catalyst coatings on the catalytic activity were investigated for the ionic liquids [BMIM][NTf₂], [OMIM][NTf₂], [BMIM][BF₄], [BMIM][PF₆], [EMIM][OcS] and [EMIM][EtS]. An enhancement in catalytic activity was observed when utilising [BMIM][NTf₂] as an ionic liquid coating with selectivity towards citronellal.     

Proposed kinetic mechanism of biodiesel production through lipase catalysed interesterification with a methyl acetate acyl acceptor and ionic liquid [BMIM][PF6] co‐solvent

The production of biodiesel was investigated using a lipase‐catalysed (Novozym 435) reaction involving methyl acetate and ionic liquid [BMIM][PF₆] as a co‐solvent to produce an environmentally friendly, “green” process. Experiments were conducted at various amounts of ionic liquid. The reaction mechanism was examined through use of kinetic modelling and the effect of ionic liquid was studied for the first time. Studies indicated that the reaction followed a Ping–Pong Bi–Bi mechanism, and that the ionic liquid present in the system led to reduced initial reaction rates due to mass transfer limitations.     

Improved activity and stability of pseudomonas capaci lipase in a novel biocompatible ionic liquid, 1‐isobutyl‐3‐methylimidazolium hexafluorophosphate

BACKGROUND: Enzymes may exhibit enhanced activity, stability and selectivity in ionic liquids, depending on the properties of the liquid. The physical–chemical properties of ionic liquids, however, may be modified by altering the anion or cation in the ionic liquid. This feature is a key factor for realizing successful reactions. In this work, a new ionic liquid, 1‐isobutyl‐3‐methylimidazolium hexafluorophosphate (abbreviated as [i‐C₄mim][PF₆]), was synthesized and investigated as a novel medium for the transesterification reaction of 2‐phenylethanol with vinyl acetate catalyzed by pseudomonas capaci lipase. As contrasts, the reaction was also carried out in two reference solvents; the isomeric ionic liquid [i‐C₄mim][PF₆], 1‐butyl‐3‐methylimidazolium hexafluorophosphate (abbreviated as [C₄mim][PF₆]), and hexanes. RESULTS: As reaction medium, [i‐C₄mim][PF₆] was best among the three solvents. The initial reaction rate, the equilibrium conversion of 2‐phenylethanol and the half‐lifetime of the lipase in [i‐C₄mim][PF₆] medium were about 1.5, 1.2 and 3‐fold that obtained in [C₄mim][PF₆] medium, respectively. The lipase in [i‐C₄mim][PF₆] medium was recycled 10 times without substantial diminution in activity. CONCLUSION: The ionic liquid [i‐C₄mim][PF₆] has good biocompatibility, and can be used widely as green media in various biocatalysis reactions to improve the activity and stability of enzymes. Besides hydrophobicity and nucleophilicity, the spatial configuration of ionic liquids is also considered a key factor effecting the behaviour of the enzyme in ionic liquids. Copyright © 2008 Society of Chemical Industry     

Recovery of Furfural from Aqueous Solution by Ionic Liquid Based Liquid–Liquid Extraction

Abstract

Liquid–liquid extraction with imidazolium based ionic liquids ([C₄mim][PF₆], [C₆mim][PF₆], and [C₈mim][PF₆]) is proposed for the separation of furfural or 5-methylfurfural from aqueous solution. Factors affecting the extraction of furfural or 5-methylfurfural have been studied. It was shown that the extraction equilibria can be achieved within 30 min and the process was less affected by the factors such as volume ratio and feed concentration. The partition coefficients of furfural and 5-methylfurfural decreased with increasing temperature. [C₆mim][PF₆] was found to have the best extraction ability among the three ionic liquids studied. Presence of small amount of NaCl or Na₂SO₄ in the aqueous phase results in the considerable increase in the partition coefficients of furfural because of the competitive hydration of the salts with furfural. A thermodynamic study revealed that the extraction process was driven mainly by hydrophobic interactions. Further experimental results indicated that furfural can be separated selectively from aqueous furfural/acetic acid mixtures.     

Ionic liquid effects on the reaction of β-enaminones and tert-butylhydrazine and applications for the synthesis of pyrazoles

In order to evaluate the effect of a series of 10 different ionic liquids ([BMIM][BF₄], [BMIM][Br], [OMIM][BF₄], [BMIM][PF₆], [DBMIM][Br], [DBMIM][BF₄], [BMIM][OH], [BMIM][SCN], [HMIM][HSO₄] and [HMIM][CF₃CO₂]) the cyclocondensation reaction between 4-dimethylamino-1-phenyl-3-alken-2-ones (RC(O)CHCHNMe₂, where R = Ph, 4-Me-Ph, 4-F-Ph, 4-Cl-Ph, 4-Br-Ph, 4-NO₂-Ph, thien-2-yl, fur-2-yl, pyrrol-2-yl, pyrid-2-yl, hexyl, dimethoxymethyl) and tert-butylhydrazine was performed. The effects of each ionic liquid are discussed and the best yields for the cyclocondensation reaction studied were obtained using [BMIM][BF₄].     

Biocatalytic production of ricinoleic acid from castor oil: augmentation by ionic liquid

Abstract

In present study involving castor oil hydrolysis catalyzed by porcine pancreas lipase, organic solvent, and ionic liquid were applied to augment production of ricinoleic acid. Toluene was the best organic solvent (30.18% hydrolysis in 2?h). In presence of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]), an ionic liquid, the optimal conditions were, 0.12?g ionic liquid/g oil, 4?mg enzyme/g oil, 2?g buffer/g oil, pH of 8, and 2.5?h. Under this condition, ricinoleic acid recovery was 43.41 and 52% at 25?°C and 35?°C, respectively. Organic solvent concentration, enzyme concentration, buffer concentration and time had significant impacts on lipase catalyzed hydrolysis in the presence of organic liquid; whereas, pH and speed remained insignificant. In hydrolysis involving ionic liquid, time had most important effect on ricinoleic acid production. Interaction between enzyme and buffer concentration was most significant. Interactions of ionic liquid concentration with all other variables were also significant besides buffer concentration–time interaction.     

Ionic liquid effects on the reaction of β-enaminones and tert-butylhydrazine and applications for the synthesis of pyrazoles

In order to evaluate the effect of a series of 10 different ionic liquids ([BMIM][BF₄], [BMIM][Br], [OMIM][BF₄], [BMIM][PF₆], [DBMIM][Br], [DBMIM][BF₄], [BMIM][OH], [BMIM][SCN], [HMIM][HSO₄] and [HMIM][CF₃CO₂]) the cyclocondensation reaction between 4-dimethylamino-1-phenyl-3-alken-2-ones (RC(O)CHCHNMe₂, where R = Ph, 4-Me-Ph, 4-F-Ph, 4-Cl-Ph, 4-Br-Ph, 4-NO₂-Ph, thien-2-yl, fur-2-yl, pyrrol-2-yl, pyrid-2-yl, hexyl, dimethoxymethyl) and tert-butylhydrazine was performed. The effects of each ionic liquid are discussed and the best yields for the cyclocondensation reaction studied were obtained using [BMIM][BF₄].     

Novozym 435 catalyzed regioselective acylation of ethane-1,2-diol in the presence of ionic liquids

The acylation of ethane-1,2-diol catalyzed by lipase (Novozym 435) with ethyl acetate in 1-butyl-3-methyl imidazolium hexaflorophosphate [BMIM][PF₆] and 1-butyl-3-methyl imidazolium tetrafloroborate [BMIM][BF₄] was studied. It was demonstrated that the activity of the enzyme in [BMIM][BF₄] was very low for this reaction, while it was very active in [BMIM][PF₆]. Both the equilibrium conversion and the selectivity to ethane-1,2-diol monoacetate (EDMA) in [BMIM][PF₆] could be considerably higher than that at solvent-free condition. The IL and enzyme have synergetic effect to prevent thermal deactivation of the enzyme. Addition of small amount of water in [BMIM][PF₆] could enhance the conversion and selectivity to EDMA.     

Recyclable Selective Palladium‐Catalyzed Synthesis of Five‐, Six‐ or Seven‐Membered Ring Lactones and Lactams by Cyclocarbonylation in Ionic Liquids

The ionic liquids, BMIM PF₆ or BMIM NTf₂, are used successfully for the palladium‐catalyzed cyclocarbonylation of 2‐allylphenols and anilines, 2‐vinylphenols, and 2‐aminostyrenes. The reaction proceeds cleanly and efficiently to afford high yields of lactones or lactams with good or excellent selectivity for one isomer. The ionic liquid containing the palladium catalyst, and ligand, is recyclable in all cases.     

Quantum chemical studies on the simultaneous interaction of thiophene and pyridine with ionic liquid

The simultaneous interaction of thiophene and pyridine with different ionic liquids:1‐butyl‐1‐methylpyrrolidinium tetrafluoroborate([BPYRO][BF₄]),1‐butyl‐1‐methylpyrrolidinium hexafluoro‐phosphate ([BPYRO][PF₆]), 1‐butyl‐4‐methylpyridinium tetrafluoroborate ([BPY][BF₄]), 1‐butyl‐4‐methylpyridinium hexafluorophosphate ([BPY][PF₆]) and 1‐benzyl‐3‐methylimidazolium tetrafluoroborate ([BeMIM][BF₄]) were investigated using quantum chemical calculations. A three‐tier approach comprising of partial charges, interaction energies and sigma profile generation using conductor‐like screening model for real solvents (COSMO‐RS) was chosen to study the systems. A quantitative attempt based on the CH‐π interaction in ionic liquid; thiophene–pyridine complexes gave the interaction energies of ILs in the order: [BPY][BF₄] > [BPYRO][PF₆] > [BeMIM][BF₄] > [BPY][PF₆] > [BPYRO][BF₄]. An inverse relation was observed between the activity coefficient at infinite dilution predicted via COSMO‐RS–based model and interaction energies. The dominance of CH‐π interaction was evident from the sigma profiles of ionic liquid together with thiophene and pyridine. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

疏水性离子液体-中性磷氧萃取剂萃取稀土元素的应用

液液萃取广泛应用于稀土元素的分离回收,为了便于相的分离,通常采用疏水性萃取剂。基于液液萃取的特性,通过微波辅助法合成了疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐（[BMIM][PF₆]）。分别探究了[BMIM][PF₆]搭配不同中性磷氧萃取剂对稀土元素中Nd³⁺和Pr³⁺的萃取研究。结果表明1-丁基-3-甲基咪唑六氟磷酸盐-三正辛基氧化磷（[BMIM][PF₆]-TOPO）为最适宜萃取体系。在最适宜萃取体系下,探究了时间、温度、pH值、V（A）/V（O）（水相稀土离子/有机相萃取体系）和萃取组分体积比对萃取效率的影响。结果表明：萃取时间为20 min、温度为25℃、pH值=6.0、V（A）/V（O）=1.0、V_[BMIM][PF6]：V_TOPO=1：1,体系对于Nd³⁺的萃取效果最佳,萃取率可达97.8%;萃取时间为25 min、温度为25℃、pH值=6.0、V（A）/V（O）=1.0、V_[BMIM][PF6]：V_TOPO=1：1,体系对于Pr³⁺的萃取效果最佳,萃取率可达94.2%;萃取过程为放热反应,反应焓变分别为ΔH（Nd³⁺）=-38.43 kJ·mol^-1,ΔH（Pr³⁺）=-28.76 kJ·mol^-1。     

Effect of Mobile Phase Additives on the Resolution of Four Bioactive Compounds by RP-HPLC

The use of mobile phase additives enhances the separation and resolution of the bioactive compounds on the C₁₈ column. Chlorogenic acid, caffeic acid, rutin, and scoparone from Herba Artemisiae Scopariae were investigated as the target compounds. Acetic acid, triethylamine, inorganic salts, and several ionic liquids were added as mobile phase additives into methanol/water (40:60, v/v). The result revealed that a mobile phase with 0.01 mol/L of ionic liquid [BMIM][BF₄] enabled the optimum separation of the four target compounds.     

Extraction of Azo Dyes from Aqueous Solutions with Room Temperature Ionic Liquids

In this work, ionic liquids/water distribution ratios (D) of azo dyes, including 1-(phenylazo)-2-naphthol, 1-(2-pyridylazo)-2-naphthol, 4-(nitrophenylazo)resorcinol, 4-(2-pyridylazo) resorcinol, and 2-(4-dimethylaminophenylazo) benzoic acid, have been determined experimentally. It was found that the D values are highly influenced by the pH of the water phase and the type of salts added. They increase with increasing alkyl chain length on the cations of the ionic liquids, and the anionic effect follows the order [BF₄]^? > [PF₆]^?. Possible extraction mechanism and selective separation of some azo dyes are also investigated. The results suggest that ionic liquids have potential applications in the removal and selective separation of azo dyes from water.     

Trihexyl(tetradecyl)phosphonium hexafluorophosphate as an promising Extractant for extractive desulfurization from liquid fuels

Experimental data on extractive desulfurization (EDS) of dibenzothiophene (DBT), thiophene, benzothiophene, and other substituted derivatives of sulfur from liquid fuel using trihexyl(tetradecyl)phosphonium hexafluorophosphate ([THTDP][PF₆]) have been presented. The Fourier transform infrared spectrophotometer, ¹H-NMR, ¹³C-NMR, and ³¹P-NMR analysis have been discussed for molecular confirmation, and conductivity, solubility, and viscosity analyses of ([THTDP][PF₆]) were investigated. The effects of time, temperature, S-compounds, ultrasonication, and recycling of ([THTDP][PF₆]) on DBT removal from fuel were examined. Also, desulfurization of real fuels and multistage extraction was also tested. The data and results provided the significant insights of phosphonium ionic liquids as a promising solvent for EDS.     

The Use of an Ionic Liquid in a Karr Reciprocating Plate Extraction Column: Dispersed Phase Hold-up Prediction

The use of ionic liquids (ILs) as alternatives to volatile organic liquids in solvent extraction is being considered in a number of applications. This study presents data on the dispersed phase holdup of the ionic liquid [bmim][PF₆] with water in a Karr extraction column. It was found that this system conforms to the standard slip velocity relationships and that the holdup can be predicted using existing correlations for dispersed phase holdup in Karr reciprocating plate columns. This indicates that the incorporation of ionic liquids into existing processing equipment is relatively straightforward and they behave in a predictable manner.     

Application of hydrophobic ionic liquid [Bmmim][PF6] in solvent extraction for oily sludge

In this study, an ionic liquid (IL), 1-butyl-2,3-dimmmethylimidazolium hexafluorophosphate ([Bmmim][PF₆]), was used in combination with a composite solvent of methyl acetate and n-heptane to enhance the oil extraction from oily sludge. The oil recovery increased by approximately 15% compared with that of solvent extraction without [Bmmim][PF₆] at the optimal ratios of IL to sludge and solvents to sludge, which were at 2:5 (M/M) and 4:1 (V/M), respectively. The saturate, aromatic, resin and asphaltene (SARA) analysis revealed that the recovery of resins and asphaltenes was increased by 14% and 38%, respectively, in the solvent extraction with the addition of [Bmmim][PF₆]. [Bmmim][PF₆] maintained a good performance after its reuse four times. The addition of [Bmmim][PF₆] changed the adhesion forces between oil and soil. The IL-assisted solvent extraction procedure followed the pseudo second-order kinetic model, while the unassisted solvent extraction procedure followed the pseudo first-order kinetic model. The results also demonstrated that [Bmmim][PF₆] decreased the solvent consumption by approximately 60% each time. Additionally, [Bmmim][PF₆] can be easily separated. The results suggested that enhancing the solvent extraction with this IL is a promising way to recover oil from oily sludge with a higher oil recovery rate and lower organic solvent consumption than those with the unassisted solvent extraction method.     

Simple, efficient and recyclable palladium catalytic system for Heck reaction in functionalized ionic liquid network

In functionalized ionic liquid network of [BMIM][TPPMS] and [BMIM][OAc], PdCl₂(CH₃CN)₂ efficiently catalyzed the Heck reaction of bromobenzene to ethyl cinnamate with yield of 60% and without the activity loss even after 11 recycling uses. The beneficial influences of this ionic liquid network on activity and stability were explained in terms of synergic ligand effects of [BMIM][TPPMS] and [BMIM][OAc], no accumulation of sodium or ammonium bromides by using [BMIM][OAc] as base, and the positive effect of [BMIM]Br by avoiding the formation of palladium black. The generality of this ionic liquid system to the different substrates also gave the pleasing results.     

Purification of ionic liquids by supercritical CO2 monitored by infrared spectroscopy

Transmission infrared and Attenuated Total Reflection (ATR) in situ infrared spectroscopies were combined for the time-resolved monitoring of both liquid and supercritical phases during extraction of water and other impurities from ionic liquids with supercritical carbon dioxide (scCO₂). Cleaning and drying by scCO₂ at 100 bar and 40 °C proved to be efficient for all ionic liquids tested, including 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), and 1-butyl-3-methylimidazolium trifluoromethansulfonate ([bmim][TfO] or [bmim] triflate). Despite the moderate solubility of water in scCO₂ compared to other classical solvents, the amount of water decreased continuously during the drying. The extraction could be followed by simple transmission IR spectroscopy of the supercritical phase. During the extraction, organic impurities and water were removed rapidly from the ionic liquid phase as scCO₂ improved the transport properties in the ionic liquids.     

Negative effect of [bmim][PF6] on the catalytic activity of alcohol dehydrogenase: mechanism and prevention

BACKGROUND: [bmim][PF₆] is a hydrophobic ionic liquid which could be considered as an environmentally friendly solvent for biocatalysis. In pure [bmim][PF₆], however, alcohol dehydrogenase from yeast (YADH) has no catalytic activity. The aim of the present work was (1) to quantitatively study the negative effect of [bmim][PF₆] on the catalytic activity of YADH and the related mechanism and (2) to made an attempt to lessen the negative effect of [bmim][PF₆] on YADH by microemulsifying [bmim][PF₆]. RESULTS: The activity of YADH in the homogeneous solution formed by H₂O, CH₃CH₂OH and [bmim][PF₆] decreased rapidly with the increase of the molar fraction of [bmim][PF₆]. The inhibitory effect of [bmim][PF₆] on YADH was probably caused by the competition of the imidazole group of [bmim][PF₆] with the coenzyme NAD⁺ for the binding sites on YADH. In a water‐in‐[bmim][PF₆] microemulsion, YADH was catalytically active due to the formation of the interfacial membrane of the nonionic surfactant TritonX‐100, which separated YADH from [bmim][PF₆] and avoided the direct inactivation of [bmim][PF₆] on YADH. Under optimal conditions, the activity of YADH was as high as 51 µmol L^?1 min^?1. CONCLUSION: [bmim][PF₆] was an inhibitor of YADH and its negative effect on YADH could be lessened by its microemulsification. Copyright © 2008 Society of Chemical Industry