【作者】 王国平；

【导师】 林金清；

【作者基本信息】 华侨大学 ， 物理化学， 2008， 硕士

【摘要】 离子液体因其独特的理化性质已成为人们研究的热点。目前在各类离子液体的研究和应用中以烷基取代的咪唑离子液体的研究最多。而在咪唑类离子液体中对于亲水性离子液体[Bmim]BF₄的研究和应用较为常见。离子液体[Bmim]BF₄在其合成的过程存在的问题是:纯化的过程中涉及H₂O-CH₂Cl₂-[Bmim]BF₄-盐体系液液相平衡的问题,缺少该体系的相平衡数据会造成离子液体[Bmim]BF₄不必要的损失,这对于大规模的合成离子液体[Bmim]BF₄是不利的。同时,对于离子液体[Bmim]BF₄回收工艺的优化也是其作为绿色溶剂的内在要求。本文合成了离子液体[Bmim]BF₄,较为详细的研究了H₂O-CH₂Cl₂-[Bmim]BF₄三元体系的液液相平衡关系,并以H₂O-CH₂Cl₂-[Bmim]BF₄三元体系的相平衡数据为指导,在考察了纯化及回收过程中不同因素对离子液体[Bmim]BF₄产率的影响后,得到了水洗过程较为合理的CH₂Cl₂及H₂O用量。同时对不同温度下[Bmim]BF₄-H₂O体系的超额摩尔体积进行了研究。主要内容如下:1.合成了离子液体[Bmim]BF₄,采用红外光谱、核磁共振光谱、元素分析、ICP、密度等手段对产物进行表征,结果表明产物为目标产物[Bmim]BF₄且纯度在99%以上。2.采用浊点法测定常压30℃下H₂O（w1）-CH₂Cl₂（w2）-[Bmim]BF₄（w3）体系的溶解度曲线和密度曲线并对曲线进行关联;采用浊点-密度法测定常压30℃下H₂O（w1）-CH₂Cl₂（w2）-[Bmim]BF₄（w3）体系的相平衡数据。结果表明,该体系一相以H₂O为主,CH₂Cl₂、[Bmim]BF₄的含量很少,另一相以[Bmim]BF₄、CH₂Cl₂为主,H₂O的含量很少。随着体系中CH₂Cl₂含量的增加上相中[Bmim]BF₄的含量从0.1665下降到0.1032。由此可见在纯化离子液体[Bmim]BF₄时适量的增加体系中CH₂Cl₂的含量便可以减少[Bmim]BF₄的损失,从而起到优化纯化工艺的目的。3.采用Othmer-Tobias和Bancroft提出的经验方程对30℃下的H₂O（w1）-CH₂Cl₂（w2）-[Bmim]BF₄（w3）体系液液相平衡数据进行关联,计算结果表明,关联最大相对误差为84.5%,最大相对平均误差为61.47%,关联精度不高,结果不理想。采用Othmer-Tobias经验方程+溶解度方程法对其关联,计算结果表明,关联最大相对误差为4.43%,最大平均相对误差为3.03%,关联精度较高,该方法可适用于有一组分含量较低的体系的液液相平衡的关联计算。4.以H₂O-CH₂Cl₂-[Bmim]BF₄三元体系的液液相平衡数据为指导,对合成离子液体[Bmim]BF₄的纯化过程中所涉及的影响因素进行考察。在综合考察了纯化时CH₂Cl₂用量及H₂O用量等因素对离子液体[Bmim]BF₄得率的影响后,得到了水洗时较为合理的CH₂Cl₂用量及H₂O用量,质量比为:未水洗的[Bmim]BF₄: CH₂Cl₂: H₂O=10:7:3。其中H₂O采用多次加入方式进行水洗。纯化后离子液体[Bmim]BF₄得率为93.15%,得率较高。5.对回收离子液体[Bmim]BF₄的影响因素进行考察。实验中对比考察了在常温常压下二氯甲烷、水、盐和离子液体[Bmim]BF₄的比例不同时对回收率的影响。综合考察各种影响因素后,得出较为合理的的比例为[Bmim]BF₄:CH₂Cl₂:H₂O=10:6:3,其回收率可达到93%以上。对回收的离子液体用红外谱图和密度两种方法表征,结果表明回收的离子液体[Bmim]BF₄纯度符合实验要求,可以循环利用。6.测定了[Bmim]BF₄-H₂O体系不同温度下的超额摩尔体积VmE,在所有组成范围内的超额摩尔体积VmE为正值,且在不同的温度下的等温线都存在一极大值点,同时所有等温线的极值点所对应的H₂O的摩尔分数x2的值基本聚集在x2=0.50附近。不同温度下超额摩尔体积VmE的变化趋势相似,在组成相同的情况下随着温度的增加VmE总趋势变大。按Redlich-Kister方程对[Bmim]BF₄-H₂O体系的超额摩尔体积进行关联,关联后的最大标准偏差低于1.4%,关联精度较高,说明该体系适合用Redlich-Kister方程关联。更多还原

【Abstract】 Ionic liquid has become a hot research because of its unique physical and chemical properties. At present, the research and application of the alkyl imidazole is a large majority during various types of ionic liquids. And the research and application of the hydrophilic ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate （[Bmim]BF₄） is more common. The problem exist during the systhesis of [Bmim]BF₄ is: purification of the process involving the H₂O-CH₂Cl₂-[Bmim]BF₄-salt liquid-liquid equilibrium problems, lack of equilibrium data of the system will cause [Bmim]BF₄’s unnecessary losses, it is negative to the large-scale synthesis of ionic liquids [Bmim]BF₄. Contemporary, the recovery process optimization of the ionic liquids [Bmim]BF₄ is as an intrinsic requirement of green solvents.This paper prepared ionic liquids [Bmim]BF₄, more detailed studied the H₂O -CH₂Cl₂-[Bmim]BF₄ ternary system of liquid-liquid equilibrium,and take the equilibrium data of the system as a guide, after inspecting different factors impact on the ionic liquid [Bmim]BF₄ yield during the process of purification and recycling of it,gained more reasonable amount of CH₂Cl₂ and H₂O during washing process. At the same time, the excess molar volume of [Bmim]BF₄-H₂O system at different temperatures was studied. Main content is as following:1. Synthesize the ionic liquids [Bmim]BF₄, characterize it by means of infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analysis, ICP and density, results show that the product is the target product [Bmim]BF₄ and purity is more than 99%.2. The solubility curve and density curve of H₂O （w1）-CH₂Cl₂（w2）-[Bmim]BF₄ （w3） system was measured according to the turbidity analysis method at 30℃under atmospheric pressure and were correlated with experiential equations. The liquid-liquid equilibrium data of the systems were measured according to the turbidity-density method under the same condition. As shown by experimental results, the light phase was composed mainly of water whereas the methylene chloride and [Bmim]BF₄ concentration was very low, the heavy phase was composed mainly of methylene chloride and [Bmim]BF₄ whereas the water concentration was very low. The concentration of [Bmim]BF₄ descend from 0.1665 to 0.1032 with the concentration of methylene chloride increase in the system. Thus it can be seen that add CH₂Cl₂ properly can lessen the loss of the [Bmim]BF₄ when purify the ionic liquid, and Optimiza the purification process.3.Othmer-Tobias and Bancroft empirical equations were used for correlation of the liquid-liquid equilibrium data at 30℃, but the result was not satisfactory, The maximum relative error was about -84.5%, and the maximum average relative error was about 61.47%. A new method for the correlation by using Othmer-Tobias and solubility equations was proposed. The maximum relative error was about 4.43%, and the maximum average relative error was about 3.03%. There is a good precision, which shows that the method is appropriate to the correlation of containing low composition system.4. According to the equiribrium data of H₂O-CH₂Cl₂-[Bmim]BF₄ ternary system, Inspected different factors impact on the ionic liquid [Bmim]BF₄ yield during the process of purification and recycling of it. Comprehensively studied the factors such as dosages of CH₂Cl₂ and H₂O impact on the [Bmim]BF₄ yield, acquired a more reasonable amount of CH₂Cl₂ and H₂O dosage during washing process.the mass ratio is: unwashed [Bmim]BF₄: CH₂Cl₂: H₂O is 10:7:3. Wash by adding water by several times. The yield of ionic liquid [Bmim]BF₄ is as high as 93.15%.5. Studied the factors of recovery hydrophilic ionic liquids [Bmim]BF₄. Experimental study in contrast the different ratios of dichloromethane under normal temperature and pressure, water, salt and ionic liquids [Bmim]BF₄ impact on the recovery. After comprehensive survey of various factors, a more reasonable ratio of [Bmim]BF₄: CH₂Cl₂: H₂O is 10:6:3, the recovery rate could reach 93%. Characterize the recovery ionic liquid[Bmim]BF₄ by means of infrared spectra and density, the results showed that the recoveried ionic liquids [Bmim]BF₄ can be recycled.6. Mesured the excess molar volume VmE of [Bmim]BF₄-H₂O system at different temperature, in the composition range excess molar volume VmE is positive, and there is a maximum on the isotherm at different temperature, simultaneity, the molar percent of H₂O （x2） corresponding to the extremum on the isotherm assemble around 0.50. The change trend of excess molar volume VmE at different temperature is resemble, it increased with the temperature at the same composition. The correlation of excess molar volume VmE by using Redlich-Kister equation was proposed, The maximum standard deviation was less than 1.4%, there is a good precision, which shows that Redlich-Kister equation is appropriate to the correlation of this system.更多还原