低共熔法分离油酚混合物的相平衡及传质动力学研究

发布时间：2018-06-22 07:03

本文选题：低共熔溶剂 + 季铵盐　；参考：《北京化工大学》2015年硕士论文

【摘要】：酚类物质是一种重要的有机化工原料,其广泛应用于农药、香料、医药、合成纤维、消毒剂、防腐剂、酚醛树脂等化工产品及中间体的合成,有巨大的市场需求。煤焦油和煤液化油中含有丰富的酚类物质,从这些油中提取高附加值的酚类物质具有重要意义。目前从油中分离酚类化合物主要采用NaOH洗脱法,这也是唯一大规模工业化应用的方法。其本质是碱洗和酸洗过程,需用大量酸碱溶液,并产生需再次处理的含酚废水。因此有必要寻找一种新型分离方法进行油酚混合物的分离。为解决上述问题,本课题组发现一系列季铵盐能与油中酚类物质形成低共熔溶剂(DES),进而从油中萃取酚类物质。此法操作简单,分离率高,萃取剂低廉易得、无毒且可循环使用,有着诱人的工业应用前景。众所周知,新工艺的应用需要大量热力学及动力学基础数据,本文针对低共熔溶剂法分离油酚混合物过程中的相平衡及传质动力学内容展开研究,论文的主要内容和结果如下：1.本文首先对季铵盐萃取苯酚的相平衡过程进行研究,考察温度及季铵盐含量对平衡的影响。结果表明：随着温度升高,达到萃取平衡后,苯酚的分配系数减小,选择性降低,不利于油酚分离过程,且达到分离饱和时所需季铵盐的量变大,不利于从DES中反萃出季铵盐。在一定温度下,季铵盐的量加到某一值后,平衡时的上下相组成不发生变化。2.通过对不同比例DES的傅里叶红外光谱与氢核磁谱图的分析,进一步验证了低共熔溶剂中氢键的存在。3.考察了温度及苯酚浓度对氯化胆碱、四甲基氯化铵、四乙基氯化铵、1-丁基-3-甲基咪唑氯盐、1-乙基-3-甲基眯唑氯盐五种萃取剂在甲苯中溶解度影响。结果表明：溶解度均随着温度的升高而升高,其中氯化胆碱与四乙基氯化铵的溶解度最小。在25℃下,五种萃取剂在纯甲苯中的溶解度均很小,在20-50μg/mL范围内。苯酚浓度对其溶解度影响很大,苯酚浓度越大,萃取剂溶解度越大。4.为了深入了解低共熔法分离油酚混合物过程中的动力学特征,本文以氯化胆碱与苯酚形成低共熔溶剂,采用恒界面池法测定了苯酚在模拟油/DES界面的传质系数与萃取速率。分别考察了搅拌速度、温度、接触面积、季铵盐种类及浓度对萃取过程的影响。结果表明：苯酚的萃取速率随着搅拌速度的增加而增大。苯酚萃取的传质阻力主要存在于DES相,即苯酚向DES相扩散是萃取的速控步骤；萃取速率随着温度的升高而升高,在所研究体系中根据阿伦尼乌斯方程得出苯酚萃取过程的正向表观活化能为8.9 kJ·mol-1,苯酚的萃取为扩散控制过程。界面传质系数不随接触面积和萃取剂浓度的的改变而发生变化,但萃取通量随着接触面积的增大而增大；传质系数和萃取速率与季铵盐种类有关,季铵盐与苯酚形成的DES黏度越小,越有利于传质过程。
[Abstract]:Phenolic compounds are an important organic chemical material. They are widely used in the synthesis of chemical products and intermediates, such as pesticides, spices, medicines, synthetic fibers, disinfectants, preservatives, phenolic resins and other chemical products and intermediates. There are abundant phenolic substances in coal tar and coal liquefaction oil, and high value-added phenolic compounds are extracted from these oils. It is of great significance. NaOH elution is mainly used to separate phenolic compounds from oil, which is the only method of large-scale industrial application. The essence is alkali washing and acid washing process. It is necessary to use a large amount of acid and alkali solution and produce the wastewater that needs to be retreated again. Therefore, it is necessary to find a new separation method for the mixture of petroleum phenol. In order to solve the above problems, we found that a series of quaternary ammonium salts can form a low eutectic solvent (DES) with phenolic compounds in oil, and then extract phenolic compounds from oil. This method is easy to operate, high separation rate, cheap and easy to obtain, nontoxic and recyclable, and has a promising industrial application prospect. It is well known that the application of the new process is well known. The main contents and results of this paper are as follows: 1. firstly, the phase equilibrium process of quaternary ammonium salt extraction of phenol was studied, and the balance of temperature and quaternary ammonium salt content was investigated. The results show that with the increase of temperature, the distribution coefficient of phenol decreases and the selectivity decreases, which is not conducive to the separation process of phenol, and the quantitative change of quaternary ammonium salt needed when the separation is saturated is not favorable to the stripping of quaternary ammonium salt from DES. At a certain temperature, the amount of quaternary ammonium salt is added to a certain value and the balance is in the upper and lower levels. The phase composition did not change.2. through the analysis of Fourier transform infrared spectra and hydrogen magnetic spectra of different proportions of DES, the existence of hydrogen bonds in the low eutectic solvent.3. was further verified by the investigation of the temperature and the concentration of phenol to choline, four methyl ammonium chloride, four ethyl ammonium chloride, 1- butyl -3- methyl imidazolium chloride, 1- ethyl -3- methyl methazolium chloride. The solubility of five kinds of extractants in toluene shows that the solubility increases with the increase of temperature, and the solubility of choline chloride and four ethyl ammonium chloride is the smallest. At 25, the solubility of five extractants in pure toluene is very small, in the range of 20-50 mu g/mL. The concentration of phenol has a great influence on its solubility and the concentration of phenol is strong. The greater the degree of degree, the greater the solubility of the extractant.4. in order to understand the kinetic characteristics of the mixture of oil and phenol in the low eutectic process. In this paper, the mass transfer coefficient and extraction rate of phenol in the simulated oil /DES interface were determined by the formation of the low eutectic solvent of choline and phenol. The stirring speed, temperature and contact were investigated respectively. The effect of the area and the type and concentration of quaternary ammonium salt on the extraction process. The results show that the extraction rate of phenol increases with the increase of stirring speed. The mass transfer resistance of phenol is mainly in the DES phase, that is, the diffusion of phenol to DES phase is the speed control step of extraction; the extraction rate increases with the increase of temperature, and is based on the study system. The Arrhenius equation shows that the positive apparent activation energy of the phenol extraction process is 8.9 kJ. Mol-1, the extraction of phenol is the diffusion control process. The interfacial mass transfer coefficient does not change with the change of the contact area and the concentration of the extractant, but the extraction flux increases with the increase of the contact area; the mass transfer coefficient and extraction rate and quaternary ammonium salt The smaller the DES viscosity of quaternary ammonium salt and phenol, the better the mass transfer process.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028.32

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