低黏二氰胺类离子液体乙烯汽液相平衡研究

Vapor-liquid equilibrium of ethylene in low viscous dicyanamide-based ionic liquids

从工业废气中回收分离乙烯(C2H4)具有重要意义,选用了三种低黏度二氰胺类离子液体,分别测定了293.15~333.15K下其密度、黏度等物化性质,研究了其对乙烯(C 2H4)吸收性能。采用非随机(局部)双液体模型(N RTL)关联了三种二元体系溶解度数据,实验值与计算值的平均相对偏差均小于3%。结果表明,低黏度二氰胺类离子液体对C2H4气体吸收性能良好,其中阳离子侧链长度增加和羟基功能团引入可增强对C2H4溶解度。同时,离子液体1-丁基-3-甲基咪唑二氰胺盐([Bmim][DCN])经过3次的吸收解吸循环,仍可以保持较好的C2H4吸收性能,表明该离子液体循环稳定性好,而1-丁基-3-甲基咪唑二氰胺盐([Bmim][DCN])对乙烯吸收量较高,具有作为C2H4吸收剂的潜力。

Three dicyandiamide-based ionic liquids with low viscosity were selected as absorbent for ethylene absorption. The physicochemical properties such as density and viscosity were measured at 293.15-333.15 K, and their properties were studied. The NRTL model was used to correlate the solubility data for the three binary systems. The average relative deviations (ARDs) between the experimental and calculated values of the three binary systems are 2.47%, 2.54% and 1.19%, respectively. The results show that the low viscous dicyandiamide-based ionic liquids presented good C2H4 absorption performance. The solubility of C2H4 in ionic liquids is improved by increasing the length of side-chain and introducing hydroxyl group in the imidazole cation. The C2H4 solubility would increase with decreasing temperature or increasing pressure. Furthermore, these ionic liquids such as [Bmim][DCN] exhibited outstanding reversibility after 3 times of absorption/desorption circulation.[Bmim][DCN] has the better C2H4 solubility than the other two, showing the potential to be C2H4 absorbent.