四种烷基咪唑磷酸酯离子液体的热力学性质

针对烷基咪唑磷酸酯离子液体的热物性数据较少的问题,本文在常压下测定了1-乙基-3-甲基咪唑磷酸二氢盐（[EMIM][DHP]）、1-乙基-3-甲基咪唑磷酸二甲酯盐（[EMIM][DMP]）、1-乙基-3-甲基咪唑磷酸二乙酯盐（[EMIM][DEP]）、1-丁基-3-甲基咪唑磷酸二丁酯盐（[BMIM][DBP]）四种烷基咪唑磷酸酯离子液体的密度、黏度（293.15～353.15K）和电导率（293.15～343.15K）,并且测定了四种离子液体的热稳定性。结果表明,离子液体的密度、黏度随温度的升高而减小,而电导率随温度的升高而增大。采用自然对数方程关联四种离子液体的密度,根据实验值计算到了离子液体体积性质;采用VFT方程关联离子液体黏度和电导率,其中密度与电导率的实验值与模型相关系数R2达到0.9999,黏度相关系数R2达到0.99999,实验测定的数据与模型一致;四种离子液体的热稳定性相近,分解温度均在271.9～278.6℃范围内;瓦尔登规则分析表明,四种烷基咪唑磷酸酯离子液体符合Walden规则,而[EMIM][DMP]和[EMIM][DEP]被归类为“good ionic liq...     

乙腈+水+离子液体等压汽液平衡测定与计算

采用改进的Ellis平衡蒸馏仪测定了乙腈+水+1-乙基-3-甲基咪唑磷酸二乙酯盐([EMIM][DEP])、乙腈+水+{1-乙基-3-甲基咪唑醋酸盐([EMIM][OAC])+[EMIM][DEP]}常压(101.3 kPa)等压汽液平衡(VLE)数据。实验结果表明,备选离子液体可促进水+乙腈混合物的分离并消除其共沸点。借助NRTL模型成功关联了含离子液体的三元和四元VLE实验数据,获得了乙腈-[EMIM][DEP]、水-[EMIM][DEP]和[EMIM][OAC]-[EMIM][DEP]二元交互作用参数。应用COSMO-SAC预测了实验VLE,结果令人满意。量化计算表明可与水形成强相互作用的离子液体更易促进乙腈与水的分离。     

乙腈+水+离子液体等压汽液平衡测定与计算

采用改进的Ellis平衡蒸馏仪测定了乙腈+水+1-乙基-3-甲基咪唑磷酸二乙酯盐([EMIM][DEP])、乙腈+水+{1-乙基-3-甲基咪唑醋酸盐([EMIM][OAC])+[EMIM][DEP]}常压(101.3 kPa)等压汽液平衡(VLE)数据。实验结果表明，备选离子液体可促进水+乙腈混合物的分离并消除其共沸点。借助NRTL模型成功关联了含离子液体的三元和四元VLE实验数据，获得了乙腈-[EMIM][DEP]、水-[EMIM][DEP]和[EMIM][OAC]-[EMIM][DEP]二元交互作用参数。应用COSMO-SAC预测了实验VLE，结果令人满意。量化计算表明可与水形成强相互作用的离子液体更易促进乙腈与水的分离。     

离子液体基工质对的吸收制冷循环性能实验研究

分别对以离子液体1-乙基-3-甲基咪唑磷酸二乙酯[Emim][DEP]为吸收剂的二元工质对[Emim][DEP]+H₂O和以[Emim][DEP]+LiBr为吸收剂的三元工质对LiBr+[Emim][DEP]+H₂O的吸收制冷循环性能进行了实验研究,用于评价这种新型的工质对的制冷性能。实验结果表明,二元工质对[Emim][DEP]+H₂O具有吸收制冷性能,但与LiBr+H₂O工质对相比,其制冷系数较低。当发生温度为90℃、循环水温度为30℃、蒸发温度在10～15℃时,制冷系数仅为0.16～0.28。主要原因是[Emim][DEP]+H₂O工质对具有较高的黏度和较低的热导率,导致吸收器降膜吸收传热系数较低,吸收器吸收水蒸气的能力不足。为了强化其制冷效果,在[Emim][DEP]+H₂O工质溶液中加入少量LiBr水溶液,构成三元工质对LiBr+[Emim][DEP]+H₂O。实验结果表明,三元工质对LiBr+[Emim][DEP]+H₂O的制冷性能优于二元工质对[Emim[DEP]+H₂O,在上述蒸发温度范围内,制冷系数能够达到0.17～ 0.34,并且制冷温度更低。     

两种咪唑型离子液体对纤维素的溶解及纺丝性能的比较

以1-乙基-3-甲基咪唑醋酸盐（[EMIM]Ac）和1-丁基-3-甲基咪唑氯盐（[BMIM]CI）两种咪唑型离子液体为溶剂,研究比较了它们对纤维素的溶解性能及其溶液的纺丝加工性能。结果发现：两种离子液体均能在一定条件下溶解纤维素,但[EMIM]Ac较[BMIM]Cl对纤维素具有更低的溶解温度和更快的溶解速率。从流变分析还发现：纤维素/[EMIM]Ac溶液与纤维素/[BMIMCl溶液均为切力变稀流体,相同条件下纤维素/[EMIM]Ac溶液的黏度远低于纤维素/[BMIM]Cl溶液,使其可在相对低的温度下纺丝。此外,GPC分析结果表明：纤维素在用[EMIM]Ac溶解及纺丝过程中降解程度较小,而用[BMIM]Cl进行溶解纺丝时,降解作用则较明显。对纤维结构与力学性能的分析结果进一步表明：与相同喷头拉伸比下制得的[EMIM]Ac法再生纤维素纤维相比,[BMIM]Cl法再生纤维素纤维的聚集态结构相对较完善,结晶度与取向度更高些,从而使其力学性能也相对较好。     

含氰基离子液体的物理性能及其对SO_2的吸收性能

对两种阴离子含氰基的离子液体1-乙基-3-甲基咪唑硫氰酸盐([Emim][SCN])、1-丁基-3-甲基咪唑硫氰酸盐([Bmim][SCN])的密度、粘度及热稳定性等物理性质进行了研究,探讨了离子液体的分子体积V_m、标准熵S~0、晶格能U_(POT)等热力学性能。同时对两种离子液体的脱硫性能进行了研究。结果表明,两种离子液体的热稳定性较高,能够适用于烟气脱硫应用。两种离子液体均表现出良好的脱硫性能,20℃条件下,1 mol[Bmim][SCN]可吸收3.04 mol SO_2,且[Emim][SCN]、[Bmim][SCN]循环脱硫5次脱硫性不变。通过核磁共振H谱和红外光谱对两种离子液体的脱硫机理进行研究,发现离子液体和SO_2的结合主要为物理作用。     

含氰基离子液体的物理性能及其对SO_2的吸收性能

对两种阴离子含氰基的离子液体1-乙基-3-甲基咪唑硫氰酸盐([Emim][SCN])、1-丁基-3-甲基咪唑硫氰酸盐([Bmim][SCN])的密度、粘度及热稳定性等物理性质进行了研究,探讨了离子液体的分子体积V_m、标准熵S⁰、晶格能U_(POT)等热力学性能。同时对两种离子液体的脱硫性能进行了研究。结果表明,两种离子液体的热稳定性较高,能够适用于烟气脱硫应用。两种离子液体均表现出良好的脱硫性能,20℃条件下,1 mol[Bmim][SCN]可吸收3.04 mol SO_2,且[Emim][SCN]、[Bmim][SCN]循环脱硫5次脱硫性不变。通过核磁共振H谱和红外光谱对两种离子液体的脱硫机理进行研究,发现离子液体和SO_2的结合主要为物理作用。     

离子液体用于四氢呋喃-乙醇-水三元共沸物系分离的研究

以离子液体1-丁基-3-甲基咪唑二氰胺（[BMIM] [DCA]）为萃取剂，采用流程模拟和机理分析两种方法，对离子液体用于四氢呋喃（THF）-乙醇-水三元共沸物的分离进行了研究。通过COSMO-RS理论，以选择性为性能指标筛选出合适的离子液体[BMIM][DCA]，并且以[BMIM][DCA]为萃取剂，在适合的操作条件下建立了萃取精馏过程，模拟结果表明THF、乙醇和水的质量分数都接近1。通过对[BMIM][DCA]和三种溶质的σ-谱图分析，发现[BMIM][DCA]可分别与三种溶质形成更强的氢键，从而打破三种溶质间的固有氢键，进而消除它们的共沸现象。     

咪唑类[PF_6]^-型离子液体萃取苯胺

研究了以咪唑类[PF6]-型室温离子液体1-丁基-3-甲基咪唑六氟磷酸盐（[Bmim][PF6]）、1-己基-3-甲基咪唑六氟磷酸盐（[Hmim][PF6]）和1-辛基-3-甲基咪唑六氟磷酸盐（[Omim][PF6]）对苯胺水溶液的萃取平衡。实验结果表明：pH值对分配系数的影响很大,在碱性条件下,分配系数较高;萃取过程属于吸热过程;经过四级错流萃取,废水可达到排放标准,萃取相中的苯胺回收率在90%左右,离子液体回收率〉90%,离子液体可以循环利用。     

咪唑类离子液体脱除气体中有机硫化物的研究

以1-丁基-3-甲基咪唑为阳离子制备了[BMIM]Ac、[BMIM]HSO₄、[BMIM]DBP、[BMIM]SCN等4种脱有机硫咪唑类离子液体,通过FT-IR和¹HNMR等表征验证了其分子结构特征,考察了不同咪唑离子液体对硫醇的脱除效果。结果表明,4种离子液体中[BMIM]Ac可与硫醇形成稳定的氢键,表现出较优的脱硫能力,常压下当含硫醇的原料气流量为100 mL/min时,吸收2 min后可脱除83%的甲硫醇和乙硫醇,丙硫醇的脱硫率可达到92%;另外,该离子液体脱硫性能稳定、再生循环性能优异,可推广用于天然气中有机硫的脱除。     

Surface tension and viscosity of 1-butyl-3-methylimidazolium iodide and 1-butyl-3-methylimidazolium tetrafluoroborate, and solubility of lithium bromide+1-butyl-3-methylimidazolium bromide in water

The surface tension and viscosity of 1-butyl-3-methylimidazolium iodide ([bmim][I]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) were measured over a temperature range of 298. 15 to 323.15 K. It was found that both the viscosity and surface tension decrease with increasing temperature and that the surface tension and viscosity values of [bmim][I] were higher than those of [bmim][BF₄]. Additionally, the solubility of lithium bromide (2)+1-butyl-3-methylimidazolium bromide ([bmim][Br]) (3) in water (1) was measured at three different mass ratios (w₂/w₃=4 and 7, w₃=0) by using a visual polythermal method. The solubility of the suggested systems was better than that of lithium bromide in water.     

基于COSMO-RS模型研究基团修饰[EMIM][OAC]的离子液体对乙腈-水汽液平衡的影响

以1-乙基-3-甲基咪唑醋酸盐([EMIM][OAC])为基准,通过分别在阴阳离子上修饰胺基(-NH₂)、羟基(-OH)、腈基(-CN)、卤素(Br、F)等,虚拟设计了15 种阳离子和21 种阴离子组成的离子液体(IL)。采用基于COSMO-RS 模型的COSMOthermX 软件计算了所设计的离子液体对乙腈-水混合物恒压汽液相平衡的影响,探索了修饰基团的种类、离子液体结构对乙腈相对挥发度的影响规律。研究发现,在阳离子碳链上修饰-NH₂,阴离子(醋酸根和丙酸根)羰基的邻碳上进行单一的-OH 修饰能促进乙腈与水的分离,且阳离子修饰的-NH₂ 数越多,促进分离的效果越明显,其他嫁接方式未取得好的分离效果。虚拟设计的两种阳离子(1-胺乙基-3-甲基咪唑、2,2,2-三胺乙基-3-甲基咪唑)与3 种阴离子(羟基乙酸、2-羟基丙酸、2-羟基-3-胺基丙酸)组合的离子液体分离效果明显比[EMIM][OAC]好。     

Ionic liquids and nanotechnology: Synthesis of WO3 nanostructures by anodization as photoelectrocatalysts

Two ionic liquids, [BMIM][BF4] and [EMIM][BF4], have been used for the first time to synthesize ordered and well-defined WO₃ nanoplates by electrochemical anodization. Different amounts of these ionic liquids have been added to the electrolytes and their influence on the morphological, structural and photoelectrocatalytic properties of the WO₃ nanoplates has been extensively studied. The resulted nanostructures, especially those synthesized in the presence of 5%–10% ionic liquids, showed excellent photoelectrocatalytic performances under irradiation, due to their better morphology, size and arrangement. These results confirm the potentiality of ionic liquids, such as [BMIM][BF4] and [EMIM][BF4], in the synthesis by anodization of high-efficiency photoelectrocatalysts, which could be used in the energy and environmental fields.     

萃取精馏分离甲醇-丁酮萃取剂的选择

为了解决工业生产中甲醇-丁酮共沸体系难分离的问题,本研究采用一步法合成了N-乙基吡啶溴盐([EPy][Br])、N-丁基吡啶溴盐([BPy][Br])和N-己基吡啶溴盐([HPy][Br])3种离子液体(IL),测定了101.3 kPa下这3种离子液体对甲醇-丁酮共沸物系的溶剂选择性,并考察了溶剂比对其选择性的影响,同时将离子液体的分离性能与有机溶剂进行了比较。实验结果表明:合成的3种离子液体都可提高甲醇对丁酮的相对挥发度,它们的选择性大小顺序为[EPy][Br]> [BPy][Br]> [HPy][Br],同时,它们的选择性随溶剂比的增加而增大,与常规有机溶剂相比,离子液体作为萃取剂具有显著优势。因此,可以选用[EPy][Br]作为分离甲醇-丁酮共沸物系的萃取剂。     

Ionic liquids as entrainer in extractive distillation for effectively separating 1-propanol–water azeotropic mixture

Economically separating 1-propanol (NPA) from water is an emergent issue for producing pharmaceutical intermediates such as n-propyl acetate, n-propylamine and so on. In this work, fourionic liquids (ILs) 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]), 1,3-dimethylimidazolium methylsulfate ([MMIM][MS]), 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) were introduced as potential entrainers for separating NPA–water azeotropic mixture. The results show that [MMIM][MS] is the most suitable entrainer compared with other ILs from the analysis of vapor–liquid equilibrium and relative volatilities. The extractive distillation process with the entrainer regeneration system of flash tank and stripper was employed and optimized by the two-step optimization method. The results show that total annual cost and energy consumption per product flow rate were reduced by 39.79% and 60.47% compared with literature. In addition, the efficiency indicator of extractive section, efficiency indicator of per tray in extractive section, carbon dioxide emissions were also selected as the evaluation index for selection of operating parameters and calculated for different cases. The CO₂ emissions of the optimal design can be reduced by 60.98% from environmental aspect.     

Thermodynamic properties of 1‐ETHYL‐3‐methylimidazolium methanesulphonate with aromatic sulphur,nitrogen compounds at T = 298.15–323.15 K and P = 1 bar

This work investigates the ability of 1‐ethyl‐3‐methylimidazolium methanesulphate ([EMIM][MeSO₃]) as a green and tuneable solvent for denitrification and desulphurisation studies. Experimental density, surface tension and refractive index data have been measured for the following systems: [EMIM][MeSO₃] (1) + pyridine (2), [EMIM][MeSO₃] (1) + pyrrole (2), [EMIM][MeSO₃] (1) + quinoline (2), [EMIM][MeSO₃] (1) + indoline (2), [EMIM][MeSO₃] (1) + thiophene (2) and [EMIM][MeSO₃] (1) + water (2) over the entire mole fraction of [EMIM][MeSO₃] at T = 298.15–323.15 K and P = 1 bar. Further from experimental density, surface tension and refractive index, coefficient of thermal expansivity, excess molar volume, deviation of surface tension and refractive index deviation were also calculated. It was found that the heteroaromatic nitrogen/sulphur compounds are completely miscible in [EMIM][MeSO₃]. The surface tension values were found to increase while the refractive index decreases with increasing mole fraction of [EMIM][MeSO₃]. The experimental values for surface tension increased in the order: pyridine > thiophene > pyrrole > indoline > quinoline > water and for refractive index: pyridine > pyrrole > indoline > quinoline > thiophene > water. It was found that the composition of [EMIM][MeSO₃] has a greater influence than temperature in deciding the surface, optical and thermodynamic properties for similar molecular interaction such as IL–thiophene and IL–pyrrole than dissimilar molecules such as IL–water. Further quantum chemical‐based COSMO‐RS tool was used to estimate the activity coefficient at different composition. © 2012 Canadian Society for Chemical Engineering     

Physical and electrochemical properties of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium iodide,and 1-butyl-3-methylimidazolium tetrafluoroborate

The density, viscosity, refractive index, heat capacity, heat of dilution, ionic conductivity, and electrochemical stability of 1-butyl-3-methylimidazolium bromide ([bmim][Br]), 1-butyl-3-methylimidazolium iodide ([bmim][I]), and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) were measured at room temperature or over a temperature range of 293.2 to 323.2 K. The density and refractive index values of [bmim][I] appeared to be the highest among three ionic liquids (ILs). However, the experimental viscosity values of [bmim][Br] were higher than those of [bmim][BF₄], while the heat capacities and heats of dilution of [bmim][BF₄] were higher than those of [bmim][Br]. The cyclic voltammogram of [bmim][br] and [bmim][BF₄] indicated electrochemical windows in the stability range from 2.7 V of [bmim][[Br] to 4.7 V of [bmim][BF₄].     

Measurement of thermal conductivity,viscosity and density of ionic liquid [EMIM][DEP]-based nanofluids☆

This article studied experimentally the effect of multi-wall carbon nanotubes(MWCNTs)on the thermo physical properties of ionic liquid-based nanofluids.The nanofluids were composed of ionic liquid,1-ethyl-3-methylimidazolium diethylphosphate [EMIM][DEP],or its aqueous solution[EMIM][DEP](1)+ H_2O(2)and MWCNTs without any surfactants.The thermal conductivity,viscosity and density of the nanofluids were measured experimentally.The effects of the mass fraction of MWCNTs,temperature and the mole fraction of water on the thermo physical properties of nanofluids were studied.Results show that the thermal conductivity of nanofluids increases within the range of 1.3%–9.7% compared to their base liquids,and have a well linear dependence on temperature.The viscosity and density of the nanofluids exhibit a remarkable increase compared with those of the base liquids.Finally,the correlation of the effective thermal conductivity and viscosity of the nanofluids was made using the models in the literatures.