Preparation of novel silver-based deep eutectic solvent and its application in separation of 1-hexene/n-hexane

doi:10.11949/0438-1157.20201680

Abstract

Abstract:

Normal alkenes and normal alkanes with the same carbon number are similar in structure, which makes their relative volatility less and more difficult to separate. As a designable green separating agent, deep eutectic solvent (DES) is widely used in the separation of such mixtures recent years. Additionally, the complexation between transition metal ions and double bond of olefin is focused on the separation of olefins and paraffins. In view of the above two aspects, a novel silver-based deep eutectic solvent (Ag-DES) was prepared and used in the separation of 1-hexene and n-hexane. The separation performance of 1-hexene was investigated systematically by a series of reactive extraction experiments on the effect of olefin concentration in the initial feed, molar ratio of silver ion to olefin and separating temperature. The results showed that Ag-DES had significant effect on the separation selectivity of 1-hexene to n-hexane within the range of 3.5—18 and exhibited excellent circulation stability. Furthermore, the chemical complexation and strong hydrogen bonds between Ag-DES with 1-hexene rather than n-hexane investigated by FT-Raman and quantum mechanical calculation are the essential reasons for the separation of 1-hexene and n-hexane. The study indicates that the reactive extraction separation intensification process using Ag-DES is of great significance for the efficient and green separation of 1-hexene from Fisher-Tropsch synthesis products.

Key words: silver-based deep eutectic solvent, reactive extraction, 1-hexene, n-hexane

摘要：

相同碳数的正构烯烃与正构烷烃因其结构相似，使其相对挥发度较小、分离难度较大。低共熔溶剂（DES）作为一种可设计的绿色分离介质被广泛应用于该类混合物的分离中，此外过渡金属与烯烃双键之间的化学络合作用是促进正构烯烃/烷烃分离的一个重要方法。鉴于此，开发了新型银基低共熔溶剂（Ag-DES），并将其应用于1-己烯/正己烷的分离，系统探究了原料中烯烃浓度、银离子与烯烃摩尔比、分离温度等对1-己烯分离性能的影响，结果显示Ag-DES具有良好的1-己烯/正己烷分离选择性，选择性在3.5~18之间，并具有出色的循环稳定性。进一步通过FT-Raman表征和量化计算揭示了Ag-DES与烯烃之间的化学络合作用和较强氢键作用是实现其与烷烃分离的本质原因，表明应用Ag-DES的反应萃取分离强化方法可实现从F-T合成油中绿色高效分离C₆α-烯烃。

关键词: 银基低共熔溶剂, 反应萃取, 1-己烯, 正己烷

CLC Number:

TQ 028.8

Hu LI, Zisheng ZHANG, Jiuzhou CHEN, Haoliang SHI, Yongjie SHI, Hong LI, Xingang LI, Xin GAO. Preparation of novel silver-based deep eutectic solvent and its application in separation of 1-hexene/n-hexane[J]. CIESC Journal, 2021, 72(8): 4204-4214.

李虎, 张自生, 陈久洲, 石好亮, 石永杰, 李洪, 李鑫钢, 高鑫. 新型银基低共熔溶剂制备及其在1-己烯/正己烷分离中的应用[J]. 化工学报, 2021, 72(8): 4204-4214.

Figures/Tables 16

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影响因素	各因素对1-己烯分离性能影响探究实验条件
影响因素	Ag-DES质量/ g	C₆质量/ g	1-己烯进料质量分数/%	Ag⁺与1-己烯摩尔比	温度/℃
原料中烯烃浓度	11.106	4.48	10/30/50/70/90	—	25
银离子与烯烃摩尔比	11.106	5.04	50	1∶1/1∶1.5/1∶2/1∶2.5/1∶3	25
分离温度	11.106	5.04	50	1∶1.5	0/10/20/25/30/40
循环稳定性	11.106	5.04	50	1∶1.5	25

影响因素	各因素对1-己烯分离性能影响探究实验条件
影响因素	Ag-DES质量/ g	C₆质量/ g	1-己烯进料质量分数/%	Ag⁺与1-己烯摩尔比	温度/℃
原料中烯烃浓度	11.106	4.48	10/30/50/70/90	—	25
银离子与烯烃摩尔比	11.106	5.04	50	1∶1/1∶1.5/1∶2/1∶2.5/1∶3	25
分离温度	11.106	5.04	50	1∶1.5	0/10/20/25/30/40
循环稳定性	11.106	5.04	50	1∶1.5	25

原料中烯烃浓度（质量分数） x₀	有机相组成（摩尔分数）			溶剂相组成（摩尔分数）			分配系数		选择性 S_1,2	1-己烯收率 η₁
原料中烯烃浓度（质量分数） x₀	x₁	x₂	x₃	x₁	x₂	x₃	D₁	D₂	选择性 S_1,2	1-己烯收率 η₁
0.1	0.037	0.962	0.000	0.126	0.180	0.693	0.706	0.039	17.967	0.686
0.3	0.128	0.871	0.002	0.311	0.140	0.550	0.614	0.040	15.183	0.696
0.5	0.273	0.726	0.001	0.427	0.106	0.467	0.440	0.041	10.712	0.689
0.7	0.513	0.486	0.001	0.535	0.068	0.397	0.328	0.044	7.454	0.697
0.9	0.829	0.170	0.001	0.617	0.036	0.347	0.256	0.074	3.477	0.731

原料中烯烃浓度（质量分数） x₀	有机相组成（摩尔分数）			溶剂相组成（摩尔分数）			分配系数		选择性 S_1,2	1-己烯收率 η₁
原料中烯烃浓度（质量分数） x₀	x₁	x₂	x₃	x₁	x₂	x₃	D₁	D₂	选择性 S_1,2	1-己烯收率 η₁
0.1	0.037	0.962	0.000	0.126	0.180	0.693	0.706	0.039	17.967	0.686
0.3	0.128	0.871	0.002	0.311	0.140	0.550	0.614	0.040	15.183	0.696
0.5	0.273	0.726	0.001	0.427	0.106	0.467	0.440	0.041	10.712	0.689
0.7	0.513	0.486	0.001	0.535	0.068	0.397	0.328	0.044	7.454	0.697
0.9	0.829	0.170	0.001	0.617	0.036	0.347	0.256	0.074	3.477	0.731

E	Ag-DES-1-己烯	Ag-DES-正己烷
E_A/(kJ/mol)	-5431268.05	-5431268.05
E_B/(kJ/mol)	-619411.70	-622637.68
E_AB/(kJ/mol)	-6050813.59	-6053982.20
E_BSSE/(kJ/mol)	3.09	4.22×10^-4
E^c_intAB/(kJ/mol)	-130.75	-76.47
?E^c_intAB/(kJ/mol)	54.28