低碳烷烃在离子液体和低共熔溶剂中的溶解性能研究

发布时间：2018-11-26 07:13

【摘要】：甲烷、乙烷、丙烷等低碳烷烃是十分重要的基础化学品,对其分离技术的研究十分必要。本文利用离子液体和低共熔溶剂蒸汽压极低、结构和性质可设计等特点,结合COSMO-RS模拟计算,设计合成一系列新型离子液体和低共熔溶剂,研究低碳烷烃和氮气在其中的溶解性能,得到兼具高容量、高选择性和较低粘度的吸收介质,为开发清洁、高效的低碳烷烃分离新方法提供必要的基础数据和初步的理论依据。利用COSMO-RS方法计算了 308.1 K下丙烷、乙烷和甲烷在364种离子液体和70多种低共熔溶剂中的亨利系数,研究了溶剂结构对气体溶解度和分离选择性的影响规律。结果表明不同碳数低碳烷烃之间选择性以及低碳烷烃的溶解度整体上都随溶剂分子结构中碳原子数量的增加而增加。在此基础上,设计合成了 3种三丁基乙基鳞长链羧酸离子液体,测定了20～150kPa下丙烷、乙烷、甲烷和氮气在其中的溶解度,考察了离子液体结构和温度等因素对气体溶解度和选择性的影响,同时也对吸收热力学和动力学进行了初步探讨。结果表明,引入不对称的三丁基乙基擕阳离子能显著降低离子液体粘度,而增加阴离子碳链长度能提高气体的溶解度。在298.1 K、150kPa下,C3H8、C_2H_6 和 CH_4 在[P4442][C17H35COO]中的溶解度分别高达 0.408、0.133 和 0.029 mmol/g,几乎达到所有已报道离子液体的最高值,而粘度显著更低。C3H8对CH_4、CH_4对N_2的选择性分别为16.9、2.7。进一步设计合成了 12种低共熔溶剂吸收低碳烷烃、乙烯和氮气,研究了组分结构、混合比例以及温度等因素对气体溶解度和选择性的影响,并初步探究了吸收热力学。结果表明,所合成的低共熔溶剂对低碳烃和氮气均展现出很高的溶解度和分离选择性。308.1 K、150kPa下,C3H8和CH_4在这些DES中的溶解度分别为0.308～0.516 mmol/g和0.024～0.035 mmol/g,高于所有已报道的离子液体中的溶解度。丙烷/甲烷选择性和丙烷/氮气选择性分别为14.4～21.0和30.9～90.8,也普遍高于离子液体体系。此外,乙烷/乙烯选择性也较高,308.1 K下可高达2.0。
[Abstract]:Low-carbon alkanes such as methane, ethane and propane are very important basic chemicals, so it is necessary to study the separation technology of methane, ethane and propane. In this paper, a series of new ionic liquids and low eutectic solvents are designed and synthesized by using the characteristics of low vapor pressure, structure and properties of ionic liquids and eutectic solvents, and COSMO-RS simulation. The solubility of low carbon alkanes and nitrogen was studied. The absorbent medium with high capacity, high selectivity and low viscosity was obtained, which provided the necessary basic data and preliminary theoretical basis for the development of a clean and efficient new method for the separation of low carbon alkanes. The Henry coefficients of propane, ethane and methane at 308.1 K in 308.1 K ionic liquids and more than 70 low eutectic solvents were calculated by COSMO-RS method. The influence of solvent structure on gas solubility and separation selectivity was studied. The results show that the selectivity of low carbon alkanes with different carbon numbers and the solubility of low carbon alkanes increase with the increase of the number of carbon atoms in the molecular structure of solvents. On this basis, three triDing Ji ethyl long chain carboxylic acid ionic liquids were designed and synthesized. The solubility of propane, ethane, methane and nitrogen in 20~150kPa was determined. The effects of the structure and temperature of ionic liquids on the solubility and selectivity of gases were investigated, and the absorption thermodynamics and kinetics were also discussed. The results show that the viscosity of ionic liquids can be significantly reduced by introducing asymmetric triDing Ji ethyl cations, while the solubility of gases can be improved by increasing the length of anionic carbon chains. The solubility of C _ 3H _ 8C _ 2H _ 6 and CH_4 in [P4442] [C17H35COO] reached the highest values of nearly all reported ionic liquids in [P4442] [C17H35COO] at 298.1 KG 150kPa, respectively. However, the viscosity was significantly lower. The selectivity of C3H8 to CH_4,CH_4 for N2 was 16.9m2.7. Twelve kinds of eutectic solvents were further designed and synthesized to absorb low carbon alkanes, ethylene and nitrogen. The effects of composition, mixing ratio and temperature on the solubility and selectivity of the gas were studied, and the absorption thermodynamics was preliminarily investigated. The results show that the synthesized low eutectic solvents exhibit high solubility and separation selectivity for both low carbon hydrocarbons and nitrogen. The solubility of C3H8 and CH_4 in these DES were 0.308 mmol/g and 0.024 mmol/g, respectively, which were higher than those in all reported ionic liquids. The selectivity of propane / methane and propane / nitrogen were 14.4U 21.0 and 30.9N 90.8 respectively, which were also higher than those of ionic liquid system. In addition, the selectivity of ethane / ethylene was also higher, up to 2.0 at 308.1 K.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O645.12

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