CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2017
·
IF 1.174
Xingxing Wang,Peng Zhang,Penglei Cui,Weiguo Cheng,Suojiang Zhang
A large number of surplus glycerol from the biodiesel production can be used as renewable feedstock to produce glycerol carbonate. In this paper, a series of guanidine-based ionic liquids were synthesized to catalyze the transesterification of glycerol and dimethyl carbonate. The tunable basicity and the anion–cation cooperative effect were responsible for the obtained results. The [TMG][TFE] showed the best activity (turnover frequency (TOF) of 1754.0 h − 1 , glycerol (GL) conversion of 91.8%, glycerol carbonate (GC) selectivity of 95.5%) at 80 °C with 0.1 mol% catalyst for 30 min. The reaction mechanism of the transesterification was also proposed.
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CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Luhong Zhang,Jingyuan Wang,Yongli Sun,Bin Jiang,Huawei Yang
In this work, a kind of novel, inexpensive and stable superbase-derived Lewis acidic ionic liquids (ILs) with the protonated 1,5-diazabicyclo[4.3.0]-non-3-ene (DBN) cation and the ZnCl 2 -based complex anion have been synthesized for the first time and employed in the extraction combined oxidative desulfurization (ECODS) process of both model oil and real diesel with hydrogen peroxide (H 2 O 2 , 30 wt%) as an oxidant. Comparing the three ILs [HDBN]Cl/nZnCl 2 (n = 1, 2 and 3), the ECODS performance decreased with the increasing of ZnCl 2 proportion, which is quite different from the previous reports. Therefore, detailed characterizations were carried out to research the resonance structures of protonated DBN and the conformation transition related to the ZnCl 2 fraction was revealed. As the [HDBN]Cl/ZnCl 2 performed the best by reaching complete removal of dibenzothiophene in model oil, other important factors were also investigated, including reaction temperature, molar ratio of H 2 O 2 /S, mass ratio of IL/oil and sulfur species. After reused for six cycles, no noticeable changes in both sulfur removal performance and chemical structure were observed. Under the optimal reaction conditions, the S-content of a real diesel could be decreased from 559.7 ppm to 6.5 ppm with 98.8% sulfur removal via only one-step ECODS. Neither the original heterocyclic sulfides nor the oxidation products were detected, which indicated the excellent catalytic activity and extractive capacity of the ILs.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2016
·
IF 2.653
Yunchang Fan,Xing Dong,Xiaojing Li,Yingying Zhong,Jichuan Kong,Shaofeng Hua,Juan Miao,Yan Li
The effects of ionic liquids (ILs) on the lipase activity were studied by UV–Vis spectroscopy and the IL-lipase interaction mechanism at the molecular level was investigated by fluorescence technique. Experimental results indicated that the lipase activity was inhibited by ILs and the degree of inhibition highly depended on the chemical structures of ILs. The inhibitory ability of the Cl − - and Br − -based ILs increased with increasing the alkyl chain length in the IL cation. Thermodynamic parameters, enthalpy change (Δ H ) and entropy change (Δ S ) were obtained by analyzing the fluorescence behavior of lipase with the addition of ILs. Both Δ H and Δ S were positive suggesting hydrophobicity was the major driven force for the Cl − - and Br − -based ILs. For the BF 4 − -, CF 3 SO 3 − -, ClO 4 − - and N(CN) 2 − -based ILs, hydrogen bonding was the main driven force. For a more comprehensive understanding of the effects of ILs on lipase activity, the roles of hydrophobicity and hydrogen bonding must be considered simultaneously. A regression-based equation was developed to describe the relationship of the inhibitory ability of ILs and their hydrophobicity and hydrogen bonding ability.
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Science China-Chemistry
·
2016
·Vol. 59
·期 5
·587-593
·
IF 2.429
Pei Yuanchao,Cao Yuan,Huang Yanjie,Song Xinxin,Wang Huiyong,Zhao Yuling,Wang Jianji
In this work, 16 kinds of [FeCl 4 ] - -based magnetic ionic liquids (ILs) with different cation structures have been designed and synthesized, and their structures are characterized by IR and Raman spectroscopy. Then the lower critical solution temperature (LCST)-type phase behavior of these magnetic ILs in water is investigated as a function of concentration. It is shown that cation structure, alkyl chain length and molar ratio of FeCl 3 /chloride IL have a significant influence on the LCST of the mixtures. The phase separation temperature can be tuned efficiently by these factors. Meanwhile, the LCST-type phase separation process is also investigated by dynamic light scattering. The results support the mechanism that the hydrogen bonds of the [FeCl 4 ] - anion with water have been gradually disrupted to form ILs aggregates with increasing temperature. In addition, the stability of the ILs in water is also examined in some details. These LCST-type phase separation systems may have potential applications in extraction and separation techniques at room temperature.
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ADSORPTION-JOURNAL OF THE INTERNATIONAL ADSORPTION SOCIETY
·
2016
·Vol. 22
·期 7
·871-878
·
IF 1.87
Ge Li,Huang Hao,Qin Yanshu,Xia Fan,Yang Kedi
Ionic liquids (ILs)-bonded silica adsorbents were prepared by chemical modification of the silica surface using N -alkylimidazolium-based ILs with Cl − , BF 4
− , PF 6
− or NO 3
− anion, and applied to selective separation of the model mixture of luteolin and aloe-emodin. Among the investigated ILs-bonded silica materials, the silica grafted with N -octyllimidazolium hexafluorophosphate ([C 8 mim]PF 6 @SiO 2 ) exhibited higher adsorption capacity and selectivity of luteolin from the model mixed solution of luteolin and aloe-emodin. The isotherm data of luteolin on [C 8 mim]PF 6 @SiO 2 correlated better to the Freundlich model than the Langmuir model, and the calculated thermodynamic parameters indicated that the adsorption of luteolin was spontaneous and exothermic. The dynamic adsorption and elution experiments demonstrated that the high adsorption capacity and good desorption efficiency of luteolin on fixed bed packed with the [C 8 mim]PF 6 @SiO 2 . Moreover, the results from batch adsorption and dynamic adsorption showed well selective separation towards the model mixture of luteolin and aloe-emodin.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2016
·
IF 2.567
Jie Fu,XiuXiu Xu,Xilei Lu,Xiuyang Lu
The hydrothermal decomposition reactions of cellulose, glucose, and fructose were catalyzed by ionic liquids (ILs) to produce levulinic acid (LA). Among 18 types of ionic liquids with different anions, the ionic liquids containing haloids and hydrogen sulfates exhibited a universal activity for the conversion of fructose, glucose, and cellulose to produce LA. Reusability tests for [PrSO3HMIm]Cl and [BSO3HMIm]HSO4 were carried out and revealed that [BSO3HMIm]HSO4 can be used over four cycles without a loss of activity. The effects of reactant loading, ionic liquid loading, reaction temperature, and time on the decomposition of glucose and cellulose were investigated with [BSO3HMIm]HSO4. The optimum reaction conditions were obtained as a [BSO3HMIm]HSO4 loading of 0.5 g, a reactant loading of 0.05 g, a temperature of 180 °C, and a reaction time of 1 h. Yields of 60.8% from glucose and of 54.5% from cellulose were obtained for the catalysis with [BSO3HMIm]HSO4. Kinetics studies of the decomposition of glucose and cellulose were conducted. The rate constants at each temperature were obtained. For the decomposition of glucose, the activation energies for the conversion of glucose to LA and conversion of glucose to humins were determined as 121.1 ± 4.7 kJ/mol and 114.6 ± 6.1 kJ/mol, respectively. For the decomposition of cellulose, the activation energies for the conversion of cellulose to glucose, conversion of glucose to LA, and conversion of glucose to humins were determined as 186.8 ± 7.4 kJ/mol, 114.0 ± 2.7 kJ/mol, and 148.3 ± 11.2 kJ/mol, respectively.
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JOURNAL OF MOLECULAR LIQUIDS
·
2016
·
IF 2.74
Min Lin,Zheng B. Hou,Shun Yao,Zhi X. Wang,Hang Song
A new series of chiral dicationic ionic liquids (DILs) were successfully synthesized and characterized by IR and NMR . The density of the whole family of ILs was measured and related physical properties including thermal expansion coefficient , molecular volume, standard molar entropy, and crystal energy were estimated by theoretical methods. Moreover, the viscosity, conductivity of DILs and the binary mixtures of ionic liquid + water were determined. The data were correlated with Arrhenius equation and VogeL-Fulcher-Tamman (VFT) equation and the results were discussed subsequently. Furthermore, the molar conductivity , dissociation equilibrium constant and critical micelle concentration of DIL solution were deduced by experimental or theoretical methods. At last, the influences of the carbon chain of ILs and temperature on density, viscosity and conductivity were discussed.
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ChemSusChem
·
2016
·Vol. 9
·期 23
·3307-3316
·
IF 7.116
Changhua Song,Sijie Liu,Xinwen Peng,Jinxing Long,Wenyong Lou,Xuehui Li
Graphical Iconic ionic : Heteropolyanion-based ionic liquids are used as catalysts for the conversion of renewable carbohydrates to levulinate esters. The process can be operated under mild conditions, and the catalyst can be recovered readily by self-separation through temperature control. The catalyst shows excellent reusability, and a satisfactory yield can be obtained even after the 10th run. An efficient one-pot approach for the production of levulinate ester from renewable carbohydrates is demonstrated over heteropolyanion-based ionic liquid (IL-POM) catalysts with alcohols as the promoters and solvents. The relationships between the structure, acidic strength, and solubility of the IL-POM in methanol and the catalytic performance were studied intensively. A cellulose conversion of 100 % could be achieved with a 71.4 % yield of methyl levulinate over the catalyst [PyPS] 3 PW 12 O 40 [PyPS=1-(3-sulfopropyl)pyridinium] at 150 °C for 5 h. This high efficiency is ascribed to the reasonably high activity of the ionic liquid (IL) catalyst and reaction coupling with rapid in situ esterification of the generated levulinic acid with the alcohol promoter, which allows the insolubility of cellulose encountered in biomass conversion to be overcome. Furthermore, the present process exhibits high feedstock adaptability for typical carbohydrates and handy catalyst recovery by a simple self-separation procedure through temperature control.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2017
·
IF 3.359
Yunchang Fan,Xiaojing Li,Ping Shen,Hongxin Cai,Feifei Li,Yongxiang Wang
In this work, imidazolium-based ionic liquids (ILs) were used to extract hydroxycinnamic acids from water. Experimental results indicated that the ILs with CF 3 SO 3 − anion had higher extraction ability for hydroxycinnamic acids because of the stronger hydrogen-bonding strength of CF 3 SO 3 − . The combination of cation and anion, both of which have strong hydrogen-bonding ability, generates a hydrogen-bonding-functionalized IL, 1-butyl-3-(11-hydroxyundecyl)imidazolium trifluoromethanesulfonate ([C 4 C 11 OHim]CF 3 SO 3 ) which has strongest hydrogen-bonding ability and strongest extraction ability for hydroxycinnamic acids. Thermodynamic analysis suggested that hydrogen-bonding interaction was the major driving force; meanwhile, the influence of hydrophobic interaction and steric hindrance between ILs and hydroxycinnamic acids should be considered when interpreting the extraction behavior of ILs. The extraction ability of the ILs was strongly influenced by the aqueous pH; it decreased with increasing pH in the range of pH > p K a (dissociation constant). The stronger extraction ability of ILs at lower pH values could be interpreted by the strong hydrogen-bonding interaction between ILs and the undissociated hydroxyl and carboxyl groups of the hydroxycinnamic acids. Preliminary results suggested that [C 4 C 11 OHim]CF 3 SO 3 may be applied to the process of the recovery of hydroxycinnamic acids from aqueous media.
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ChemSusChem
·
2024
·
IF 7.5
Zhaowei Zhang,Weiqi Mao,Kaili Wang,Lili Jiang,Shenyao Wang,Haoran Li,Congmin Wang
Due to the active unstable nature of carbon anions, it is challenging to develop carbanion-functionalized ionic liquids (ILs) for efficient and reversible carbon dioxide (CO2) capture. Here, a series of carbanion-based ILs with large conjugated structures were designed and a promising system was achieved through tuning the nucleophilicity of carbanions and screening the cation. The ideal carbanion-functionalized IL trihexyl(tetradecyl)phosphonium N,N-diethycyanoacetoamide ([P66614][DECA]) showed equimolar chemisorption of CO2 (up to 0.98 mol CO2 /mol IL) under ambient pressure and excellent absorption rate. What’s more, the combined CO2 can be released easily, leading to excellent reversibility due to high stability of anion conjugated structures. More importantly, the presence of water had negligible effect on the absorption capacity, which makes it potential to be applied to the CO2 capture in industrial flue gas. The chemisorption mechanism of the carbanion and CO2 was confirmed by spectroscopic investigations and DFT calculations, where carboxylic acid product was formed through proton transfer after the carbanions reacted with CO2. Considering that high capacity, quick rate as well as excellent reversibility, these carbanion-functionalized IL should certainly represent competitive candidates for further scale up and practical application in CO2 capture.
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JOURNAL OF MOLECULAR LIQUIDS
·
2018
·
IF 4.513
Yuanchao Pei,Lihui Hao,Jie Ru,Yuling Zhao,Huiyong Wang,Guangyue Bai,Jianji Wang
Self-assembly of ionic liquids (ILs) surfactants in ILs solvents is important from the viewpoint of both scientific research and practical application because of the advantages of high ionic nature and possible application at high temperature. In this work, the aggregation behavior of long-chain ionic liquids 1-alkyl-3-methylimidazolium chloride [C n mim]Cl ( n = 12, 14, 16) and N -alkyl- N , N -dimethylethanolammonium [C n DMEA]Cl (n = 12, 14, 16) in a protic ionic liquid, ethanolammonium nitrate (EOAN), is investigated by surface tension measurements. The variation of micellization parameters with alkyl chain length and head group type of the ILs surfactants is analyzed and compared with that in water and in ethylammonium nitrate (EAN). It is found that the critical micelle concentration (cmc) values of the IL surfactants, such as [C 12 mim]Cl, in EOAN are 27 times smaller than those in EAN, and 4 times smaller than those in water. This suggests that EOAN is a better self-assembly medium for the ILs surfactants. It is also found that the contribution of head groups of the ILs surfactants to the cmc values is different in EOAN, water and EAN, while the contribution of CH 2 group in the alkyl chain of the ILs surfactants is generally independent of the solvents nature.
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CHEMOSPHERE
·
2018
·
IF 4.427
Yue Li,Li Wei,Wen Zhang,Zhiqiang Dong,Yuping Qiu
Sorption of ionic liquids (ILs) to soil and porous materials as affected by anions was observed, but scarce effort has been focused on addressing the role of counteranions in sorption and the associated underlying mechanisms. In this work, two series of 1-butyl-3-methylimidazolium- (Bmim-) and N -butyl, methyl-benzimidazolium-based (Bmbim-based) ILs coupled with different counteranions were prepared to investigate the effect of anions on IL sorption by soot. The octanol–water partition coefficient ( K ow ) and the ion-pair formation constant at infinite dilution in water ( K IP ° ) of ILs were independently measured to explore the contribution of counteranion-dependent hydrophobicity and ion-pair. A wide range of sorption coefficients ( K d ) of ILs were achieved with values varying from 59.8 to 344.3 L·kg −1 for Bmbim-based ILs and from 253.4 to 489.7 L kg −1 for Bmbim-based ILs. Compared with other anions, bis(trifluoromethanesulphonyl)imide ([Tf 2 N] – ) and hexafluorophosphate ([PF 6 ] − ) exhibit tighter association with IL cations in aqueous solution due to their larger K ow and higher K IP ° . Positive linear relationships between log K IP ° and K d and between log K ow and K d evidenced that the counteranion-dependent sorption of ILs relies on the association strengths of IL cations and counteranions, which further influence the hydrophobicity/hydrophilicity of ion pairs. Compared with that of strongly coordinating anions (such as [CH 3 SO 3 ] − , [CF 3 COO] − , [BF 4 ] − , [CF 3 SO 3 ] − , and [Cl] − ), the addition of weakly coordinating anions (such as [Tf 2 N] – and [PF 6 ] – ) in solution contributes to markedly large sorption enhancement of ILs. Consequently, the contribution of different counteranions on IL sorption is essentially based on the formation of ion pair with different K IP ° and K ow in aqueous solution.
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