离子液体在车用燃料油脱硫中的应用

综述了离子液体在燃料油脱硫中的应用情况,详细介绍了Lewis酸性离子液体和非Lewis酸性离子液体对各种烃类与含硫化合物的溶解性以及在汽、柴油萃取脱硫和氧化萃取组合脱硫工艺中的应用,并介绍了Lewis酸性离子液体作为催化剂在FCC汽油烷基化脱硫技术中的应用研究。最后,探讨了离子液体在今后燃料油脱硫中的研究方向和工业化前景。     

离子液体在萃取中的应用研究

离子液体具有特殊的物理化学性质,通过选择不同的阳离子和阴离子改变离子液体的物理化学性质,因此离子液体可以取代传统的有机分子溶剂应用于不同的分离过程.本文综述离子液体萃取金属离子、有机化合物、生物分子,脱硫,脱氮及气体分离等的最近研究进展.     

Oxidation desulfurization of fuel using pyridinium-based ionic liquids as phase-transfer catalysts

In this work, several ionic liquids based on pyridinium cations are prepared. The ionic liquids are employed as phase-transfer catalysts (PTCs) for phase-transfer catalytic oxidation of dibenzothiophene (DBT) dissolved in n-octane. The partition coefficients of DBT between ionic liquids and n-octane are investigated. Then H₂O₂-formic acid is used as an oxidant and ionic liquids are used as PTCs. The reaction turns to be heterogeneous and desulfurization rate of DBT increased apparently. When IL ([BPy]HSO₄) is used as PTC, and the condition are: temperature is 60 °C, time is 60 min, H₂O₂/sulfur molar ratio (O/S) is 4, the desulfurization rate reaches the maximum (93.3%), and the desulfurization of the real gasoline is also investigated, 87.7% of sulfur contents are removed under optima reaction conditions. The PTC [BPy]HSO₄ can be recycled for five times without significant decrease in activity.     

离子液体在燃料油脱硫中的应用

室温离子液体作为一类新型绿色介质,近年来在各个领域的应用得到了突飞猛进的发展。作者综述了离子液体用于燃料油和模型油脱硫技术方面的几种方法,包括萃取法、催化氧化法、氧化-萃取法、光化学氧化-萃取耦合法及烷基化法。离子液体由于可以循环使用,必将在燃料油脱硫技术领域发挥重要作用。     

COSMO-RS based predictions for the desulphurization of diesel oil using ionic liquids: Effect of cation and anion combination

Ionic Liquids ILs provide an important alternative in removing aromatic sulphur compounds by Liquid-Liquid Extraction (LLE). A total of 28 anions and 6 cations resulting in 168 possible combinations were screened via COSMO-RS (COnductor Like Screening MOdel for Real Solvents). Initially benchmarking was performed to predict the infinite dilution activity coefficients of thiophene in ionic liquids. Comparison with literature values involving 8 ILs with 20 points gave the average root mean square deviation (RMS) to be 11%. Thereafter artificial simulated diesel, aromatic sulphur compound and the cation and anion combination was used to predict the capacity (C) and selectivity (S) at infinite dilution. In general the selectivities were found to decrease in the following order: thiophene (4-24) > benzothiophene (2-12)> dibenzothiophene (1-7). The different hetero atom (N,S,O) and its location in the cation structure strongly influenced the selectivity and capacity at infinite dilution for all the three aromatic sulphur compounds. It was found that the cation without the aromatic ring combined with anions having sterical shielding effect such as [SCN], [CH₃SO₃], [CH₃COO], [Cl], and [Br] proved to be the most favourable IL for desulphurization. [EMMOR][SCN] proved to be the most viable IL for the removal of all the three aromatic sulphur compounds.     

Separation of m-cresol from aromatic hydrocarbon and alkane using ionic liquids via hydrogen bond interaction

Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes; the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids (ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents (COSMO-RS) model and the liquid–liquid phase equilibrium (LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and n-heptane, 1-ethyl-3-methylimidazolium acetate (emimCH₃COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emimCH₃COO: model oils mass ratio of 0.5 and 298.15 K, emimCH₃COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.     

Extraction of dioxouranium(VI) in small channels using ionic liquids

The extraction behaviour of dioxouranium(VI) from nitric acid solutions with tributylphosphate (TBP) dissolved (30%, v/v) in room temperature ionic liquids (viz. 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide, [C₄mim][NTf₂], 1-decyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide, [C₁₀mim][NTf₂], and trihexyltetradecylphosphonium bis{(trifluoromethyl)sulfonyl}amide, [P_6 6 6 14][NTf₂]) was investigated. The experiments were performed in a capillary (0.5 mm internal diameter) made of Teflon, operated in the plug flow regime. The effects of ionic liquid type, initial nitric acid concentration, and residence time on dioxouranium(VI) extraction were studied. UV–vis spectroscopy was used for the determination of the dioxouranium(VI) concentration in the ionic liquid phase. For increasing [HNO₃]_aq,init, the %extraction decreased and then increased for [C₄mim][NTf₂], while for the other two ionic liquids it increased. The %extraction also increased with residence time in the channel. Overall mass transfer coefficients were about 0.2 s^–1 in all TBP/ionic liquid systems at the initial nitric acid concentration of 3 M when a 10 cm capillary was used.     

A novel technique for separating glycerine from palm oil-based biodiesel using ionic liquids

Biodiesel production from abundant bio-sources has drawn the attention of the academic as well as the industrial communities in recent years. However, one of the most serious obstacles for using biodiesel as an alternative fuel is the complicated and costly purification processes involved in its production. The difficulties involved in the separation of glycerine and other un-reacted reactants and by-products necessitate the development of new competent low cost separation processes for this purpose. In this work, a low cost quaternary ammonium salt-glycerine-based ionic liquid is proposed as a solvent for extracting glycerine from the transesterification biodiesel product. The separation technique was tested on palm oil-based produced biodiesel with KOH as a reaction catalyst. The study investigated the effect of DES:biodiesel ratio and the DES composition on the efficiency of the extraction process. The lab scale purification experiments proved the viability of the separation technique with a best DES:biodiesel molar ratio of 1:1 and a DES molar composition of 1:1 (salt:glycerine). The purified biodiesel fulfilled the EN 14214 and ASTM D 6751 standard specifications for biodiesel fuel in terms of glycerine content. A continuous separation process is suggested for industrial scale application.     

Solution spinning of cellulose carbon nanotube composites using room temperature ionic liquids

Multiwall carbon nanotube (MWCNT)/cellulose composite fibers were processed from solutions in ethyl methylimidazolium acetate (EMIAc). Rheological percolation in MWCNT/Cellulose/EMIAc solution was observed above 0.01 mass fraction of MWCNT, while electrical percolation in oriented fibers was observed above 0.05 mass fraction of MWCNTs with respect to the weight of the cellulose. Cellulose orientation and crystal size were significantly higher in the composite than in the control cellulose fiber. In addition, in the composite fiber, carbon nanotube orientation was higher than cellulose orientation. At 0.05 mass fraction MWCNT, fiber tensile strength increased by about 25%, strain to failure increased by 100%, and modulus essentially remained unchanged. The composite fibers showed lower thermal shrinkage than the control cellulose fiber. The axial electrical conductivity at 0.1 mass fraction MWCNTs in these oriented fibers was more than 3000 S/m.     

Electrochemical synthesis of polypyrrole in ionic liquids

Electrochemical synthesis of inherently conducting polymers such as polypyrrole is traditionally performed in a molecular solvent/electrolyte system such acetonitrile/lithium perchlorate. We report the use of ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) amide and N,N-butylmethylpyrrolidinium bis(trifluoromethanesulfonyl) amide, both as the growth medium and as an electrolyte for the electrochemical cycling of polypyrrole films. Use of the ionic liquid as the growth medium results in significantly altered film morphologies and improved electrochemical activities.     

功能化离子液体萃取分离甘氨酸

以结构和功能可设计的离子液体为萃取剂,通过液–液萃取分离甘氨酸,考察了不同结构的咪唑和季铵离子液体萃取分离甘氨酸的效果,研究了pH值、萃取温度、萃取时间、甘氨酸初始浓度和二环己基-18-冠醚-6(DCH18C6)浓度等工艺参数对甘氨酸分配系数和萃取率的影响,考察了胆碱双三氟甲磺酰亚胺盐([N1112(OH)][NTf2])的循环利用性,通过FT-IR和量子化学计算探究了[N1112(OH)][NTf2]和DCH18C6萃取甘氨酸的机理。结果表明,[N1112(OH)][NTf2]的萃取率高于其它离子液体,加入DCH18C6可提高萃取率,[N1112(OH)][NTf2]–DCH18C6复配体系中,甘氨酸萃取率可达85.4%。在最优条件下,分配系数和萃取率分别为10.9和94.4%。离子液体循环利用5次,甘氨酸萃取率仍保持90%。[N1112(OH)][NTf2], DCH18C6和甘氨酸之间存在的强氢键作用为萃取分离的关键。因此,[N1112(OH)][NTF2]?DCH18C6可有效萃取分离甘氨酸,为甘氨酸的绿色分离新工艺奠定基础。     

Conceptual process design for aromatic/aliphatic separation with ionic liquids

Presently, there are no processes available to separate low concentration (<20%) aromatic hydrocarbons from mixed aromatic aliphatic hydrocarbon streams, such as a feed stream to naphtha crackers, which may contain 10–25% of aromatic components, depending on the source of the feed (naphtha or gas condensate). Present practice is removal of the aromatic hydrocarbons from the C₅⁺-stream in the naphtha cracker by extractive or azeotropic distillation. If a major part of the aromatic compounds present in the feed to the crackers could be separated upstream of the furnaces, it would offer several advantages: higher capacity, higher thermal efficiency and less fouling. The improved margin will be around €20/t of feed or €48 million per year for a naphtha cracker with a feed capacity of 300 t/h, due to lower operational costs.Extraction with sulfolane will result in a negative margin of €10 million per year. Therefore, a conceptual process for the extraction of aromatic hydrocarbons with the ionic liquid 4-methyl-N-butylpyridinium tetrafluoroborate was developed using ASPEN. The investment costs are estimated to be €56 million and the annual costs about €28 million per year, resulting in a positive margin of about €20 million per year.     

Separation of heterocyclic nitrogen compounds from coal tar fractions via ionic liquids: COSMO-SAC screening and experimental study

Ionic liquids (ILs) have been applied as a promising solvent for the separation of different kinds of compounds. But the enormous combination possibilities of the cations and anions make it a challenging task to screen an appropriate IL for a specific application. Thus, the method for screening IL candidates based on the COSMO-SAC model is presented and illustrated to extract heterocyclic nitrogen compounds, indole and carbazole, from coal tar fractions. Also, the σ-profile analysis is used to evaluate the effect of different types of cations and anions, and systematically confirmed the structure–activity relationships for the extraction process. Then, 22 cations and 19 anions are screened as the initial structures of the potential extractants from a σ-profile database (containing 39 cations and 29 anions). Along with the rigorous evaluation criterion proposed in this work, three IL extractants are adopted. Afterwards, the extractive ability of the candidates is experimentally investigated.     

Imidazolium-based alkylphosphate ionic liquids - A potential solvent for extractive desulfurization of fuel

N-ethyl-imidazolium-based alkylphosphate ionic liquid (IL), viz. N-ethyl-N-methyl-imidazolium dimethylphosphate ([EMIM][DMP]), N-ethyl-N-ethyl-imidazolium diethylphosphate ([EEIM][DEP]) and N-butyl-N-ethyl-imidazolium dibutylphosphate ([BEIM][DBP]) were demonstrated to be effective for the removal of aromatic sulfur compounds (S-compound) 3-methylthiophene (3-MT), benzothiophene (BT) and dibenzothiophene (DBT) from fuel oils in terms of sulfur partition coefficients (K_N) at 298.15 K. It was shown that the extractive ability of the alkylphosphate ILs was dominated by the structure of the cation and followed the order [BEIM][DBP] > [EEIM][DEP] > [EMIM][DMP] for each S-compound studied with their K_N-value being 1.72, 1.61 and 1.17, respectively for DBT. For a specified IL the sulfur selectivity followed the order DBT > BT > 3-MT with their K_N-value being 1.61, 1.39 and 0.78, respectively for [EEIM][DEP]. The alkylphosphate ILs are insoluble in fuel while the fuel solubility in ILs varies from 20.6 mg(fuel)/g(IL) for [EMIM][DMP] to 266.9 mg(fuel)/g(IL) for [BEIM][DBP]. The results suggest that [EEIM][DEP] might be used as a promising solvent for the extractive desulfurization of fuel, considering its higher sulfur extractive ability, lower solubility for fuel and thus negligible influence on the constituent of fuel, and the ease of regeneration for the spent IL via water dilution process.     

离子液体的应用进展

离子液体由于具有独特的物理化学性质而成为一种新型的绿色介质,近年来成为国际上研究的前沿和热点。它为开发新型绿色工艺,实现将传统重污染、高能耗工业过程的升级换代提供了新机遇。对离子液体应用的研究进展进行了综述,详细介绍了离子液体在催化科学、电化学、材料科学、环境科学和分离技术等领域的应用,并对其发展方向进行了展望。     

Phosphonium cation-containing polymers: From ionic liquids to polyelectrolytes

Phosphonium cation-based ionic liquids (ILs) are a readily available family of ILs that often offer superior properties compared to ammonium cation-based ILs. Recently investigated applications include extraction solvents, electrolytes in batteries and super-capacitors, and corrosion protection. At the same time, the range of cation–anion combinations available commercially has also increased in recent years. Polymerized ionic liquids and polyelectrolytes play major roles in a broad range of biological applications including antimicrobials, non-viral gene delivery, synthetic enzymes, metal chelation, and drug delivery. Ammonium- and phosphonium-containing macromolecules will be reviewed with a focus on structure–property relationships of these polyelectrolytes and ionic liquids. Phosphonium-containing macromolecules often display enhanced performance compared to ammonium analogs.     

Implementation of ionic liquids as activating media for polycondensation processes

Ionic Liquids (ILs) have been used for polycondensation processes, especially for polyimide synthesis. The influence of various reaction parameters including IL's cations and anions nature, monomer structure and concentration, reaction temperature, upon polyimide molecular weight (η_inh) was investigated. The possibility of process activation by the application of IL's small additives in one step polyimide synthesis in common organic solvents was demonstrated. The peculiarities of C-H?Br contacts in solid state were carried out using single crystal X-ray diffraction data. Various high molecular weight polyimides including commercial and sulfonated ones have been obtained in quantitative yields with inherent viscosities ranging from 0.10 to 2.17 dl g⁻¹.     

Prediction and verification of heat capacities for pure ionic liquids

The heat capacity of ionic liquids is an important physical property,and experimental measuring is usually used as a common method to obtain them.Owing to the huge number of ionic liquids that can be potentially synthesized,it is desirable to acquire theoretical predictions.In this work,the Conductor-like Screening Model for Real Solvents(COSMO-RS) was used to predict the heat capacity of pure ionic liquids,and an intensive literature survey was conducted for providing a database to verify the prediction of COSMO-RS.The survey shows that the heat capacity is available for 117 ionic liquids at temperatures ranging 77.66-520 K since 2004,and the 4025 data points in total with the values from 76.37 to 1484 J·mol~(-1)·K~(-1) have been reported.The prediction of heat capacity with COSMO-RS can only be conducted at two temperatures(298 and 323 K).The comparison with the experimental data proves the prediction reliability of COSMO-RS,and the average relative deviation(ARD) is 8.54%.Based on the predictions at two temperatures,a linear equation was obtained for each ionic liquid,and the heat capacities at other temperatures were then estimated via interpolation and extrapolation.The acquired heat capacities at other temperatures were then compared with the experimental data,and the ARD is only 9.50%.This evidences that the heat capacity of a pure ionic liquid follows a linear equation within the temperature range of study,and COSMO-RS can be used to predict the heat capacity of ionic liquids reliably.     

High-efficiency separation and extraction of naphthenic acid from high acid oils using imidazolium carbonate ionic liquids

N-alkyl imidazolium carbonate ionic liquids were employed to separate and recover naphthenic acid from model oils.The effects of the cationic and anionic structures of ionic liquids and operating condi-tions on the deacidification performance were investigated.The deacidification performance of tradi-tional organic solvents was also investigated for comparison.The results indicated that the naphthenic acid could be completely removed from the model oil with a small mass ratio of ionic liquid to oil.The extracted naphthenic acid was regenerated with a recovery of up to 92％.In addition,imidazolium carbonate ionic liquids could be successfully regenerated and recycled.The mechanism of interaction between imidazole ionic liquids and the naphthenic acid molecules were explained by Gauss calculation.     

Ultra-purification of ionic liquids by melt crystallization

Ionic liquids (ILs) have received a great deal of attention in the field of engineering during the last decade due to their unique properties. ILs are a very important new class of non-volatile solvents (T_m < 100 °C) in (bio)catalysis applicable to many ionic, polar and non-polar structure groups and as efficient electrolytes [Wasserscheid, P., and Welton, T., 2003, Ionic Liquids in Synthesis (Wiley–VCH, Weinheim, Germany)]. The applications range from electrochemistry, sensors, analysis, and separation techniques to catalysis and reaction engineering. Given their growing importance, it is vital to develop low cost production methods for ionic liquids including efficient techniques for purification and ultra-purification.This paper will present results of purification and ultra-purification of EMIM-chloride and EMIM-bromide (EMIM, 1-ethyl-3-methyl-imidazolium) by melt crystallization. Different techniques for purification are discussed including zone melting, layer crystallization and dry sweating in lab scale [König, A. and Wasserscheid, P., Ultra Purification of Ionic Liquids by Melt Crystallization, Proceedings of the 13th International Workshop on Industrial Crystallization BIWIC 2006, September 13–15, 2006, Delft, The Netherlands, pp. 79–84] and layer crystallization for static and dynamic crystallization conditions in pilot scale. In the case of EMIM-chloride, segregation coefficients are in the range of 0.05 < k_seg < 0.6 depending on crystallization rate, yield, feed impurity concentration and techniques used. The crystallization behavior of purified ionic liquids is discussed in detail relative to those of organic substances with similar melting points. Purification potential of EMIM-chloride is discussed with respect to different crystallization techniques and different scales used for crystallization.The excellent purification results of EMIM-chloride suggest melt crystallization techniques offer purification potential for other ionic liquids, creating a new innovative class of solvents and reactants. Melt crystallization can be used as a very efficient method to purify ionic liquids at different scales from 0.5 g up to 1000 kg with purity of w_IL>99.99%.