Liu Yunfeng, Qiu Zhengsong, Zhong Hanyi, Zhao Xin, Huang Weian, Xing Xijin
School of Petroleum Engineering, China University of Petroleum (East China) Qingdao 266580 China
CNOOC Research Institute Co. Ltd. 100028 Beijing China.
RSC Adv. 2020 Mar 31;10(22):12953-12961. doi: 10.1039/d0ra00615g. eCollection 2020 Mar 30.
Solvent extraction is commonly used to separate mixtures of hydrocarbons and their derivatives, and solvent choice is strongly influenced by the affinity to the target component, cost and safety. Nitrogen-containing switchable solvents can switch from water-immiscible form to water-miscible bicarbonate salts when CO is injected and back to water-immiscible form when N is injected. Switchable solvents, as a type of recyclable green solvent, can be used not only to separate such mixtures but also to reduce process costs. Herein, four switchable solvents, namely, dipropylamine, di--butylamine, ,-dimethylcyclohexylamine (CyNMe), and ,,','-tetraethyl-1,3-propanediamine (TEPDA), were employed to separate benzene/cyclohexane, ethyl acetate/acetonitrile, and ethyl acetate/-heptane mixtures, and the corresponding partition and selectivity coefficients were determined. In all cases, separation selectivity increased in the order of dipropylamine < di--butylamine < CyNMe < TEPDA, , TEPDA was best suited for the separation of hydrocarbons and their derivatives. In addition, cycling experiments revealed that the TEPDA can be re-used at least 15 times and was well suited for industrial applications. In the end, the mechanism of the separation was put forward.
溶剂萃取常用于分离碳氢化合物及其衍生物的混合物，溶剂的选择受对目标组分的亲和力、成本和安全性的强烈影响。当注入CO时，含氮可切换溶剂可从与水不混溶的形式转变为与水混溶的碳酸氢盐，而当注入N时又变回与水不混溶的形式。可切换溶剂作为一种可回收的绿色溶剂，不仅可用于分离此类混合物，还可降低工艺成本。在此，使用了四种可切换溶剂，即二丙胺、二丁胺、N,N-二甲基环己胺（CyNMe）和N,N,N',N'-四乙基-1,3-丙二胺（TEPDA）来分离苯/环己烷、乙酸乙酯/乙腈和乙酸乙酯/正庚烷混合物，并测定了相应的分配系数和选择性系数。在所有情况下，分离选择性按二丙胺＜二丁胺＜CyNMe＜TEPDA的顺序增加，即TEPDA最适合分离碳氢化合物及其衍生物。此外，循环实验表明，TEPDA可重复使用至少15次，非常适合工业应用。最后，提出了分离机理。
