Application of aluminum-copper bimetallic ionic liquids in 1-hexene/n-hexane separation

doi:10.11949/0438-1157.20241074

Abstract

Abstract:

The separation of olefin/alkane in naphtha is the requirement of feedstock optimization and product purification in petrochemical processes, and liquid-liquid extraction is an important olefin/alkane separation method. This study investigated the feasibility of bimetallic ionic liquids for highly selective extraction of olefins using 1-hexene/n-hexane as a model hydrocarbon mixture. The results showed that the aluminum-copper bimetallic ionic liquid had good separation performance for 1-hexene/n-hexane. Under the conditions of a solvent-oil mass ratio of 2 and an extraction temperature of 10℃, the 1-hexene extraction selectivity is 6.33, which is better than conventional imidazole-type ionic liquids and traditional organic solvents. The aluminum-copper bimetallic ionic liquid had good reusability. The anionic structure of the bimetallic ionic liquid was revealed by synchrotron X-ray absorption fine structure spectroscopy (XAFS) and density functional theory (DFT). The interaction of the ionic liquid with 1-hexene and n-hexane was further analyzed by using quantum chemistry software to explain the selective separation of 1-hexene by the bimetallic ionic liquid.

Key words: extraction, ionic liquids, 1-hexene, n-hexane, separation

摘要：

石脑油中烯烃/烷烃的分离是石油化工过程原料优化和产品精制的需求，液液萃取是烯烃/烷烃分离的重要途径。以1-己烯/正己烷为模型化合物，探讨了铝铜双金属离子液体选择性萃取烯烃的可行性。结果表明，铝铜双金属离子液体对1-己烯/正己烷具有较好的分离性能，在剂油质量比为2、萃取温度10℃的条件下，1-己烯萃取选择性为6.33，优于常规咪唑型离子液体和传统有机溶剂。此外，铝铜双金属离子液体具有良好的重复使用性能。通过同步辐射X射线吸收精细结构光谱（XAFS）和密度泛函理论（DFT）揭示了双金属离子液体阴离子结构。利用量子化学计算手段对离子液体与1-己烯、正己烷相互作用进行计算分析，解释了双金属离子液体选择性分离1-己烯的原理。

关键词: 萃取, 离子液体, 1-己烯, 正己烷, 分离

CLC Number:

TQ 028

Jiaxin CUI, Mengfan YIN, Tao ZHENG, Han LIU, Rui ZHANG, Zhichang LIU, Haiyan LIU, Chunming XU, Xianghai MENG. Application of aluminum-copper bimetallic ionic liquids in 1-hexene/n-hexane separation[J]. CIESC Journal, 2025, 76(2): 686-694.

崔家馨, 殷梦凡, 郑涛, 刘晗, 张睿, 刘植昌, 刘海燕, 徐春明, 孟祥海. 铝铜双金属离子液体在1-己烯/正己烷分离中的应用[J]. 化工学报, 2025, 76(2): 686-694.

Figures/Tables 14

References 31

1	石博文, 朱楠, 海红莲, 等. 煤制油费托α-烯烃增值利用及发展展望[J]. 合成材料老化与应用, 2023, 52(5): 113-116.
	Shi B W, Zhu N, Hai H L, et al. Value-added utilization and development prospect of Fischer-α-olefin from coal to oil[J]. Synthetic Materials Aging and Application, 2023, 52(5): 113-116.
2	白玫. ACO技术制备烯烃工艺研究及展望[J]. 化工与医药工程, 2017, 38(3): 18-23.
	Bai M. Research of ACO technique used in preparation of olefins and expectation[J]. Chemical and Pharmaceutical Engineering, 2017, 38(3): 18-23.
3	Lin Y H, Yu L, Ullah S, et al. Temperature-programmed separation of hexane isomers by a porous calcium chloranilate metal-organic framework[J]. Angewandte Chemie International Edition, 2022, 61(50): e202214060.
4	Sholl D S, Lively R P. Seven chemical separations to change the world[J]. Nature, 2016, 532(7600): 435-437.
5	Zhu L, Li F F, Zhu J Q, et al. Liquid-liquid equilibria of ternary systems of 1-hexene/hexane and extraction solvents[J]. Chemical Papers, 2016, 70(5): 585-593.
6	容凡丁, 丁泽相, 曹义风, 等. 离子液体强化不饱和键差异化合物分离的研究进展[J]. 化工进展, 2024, 43(1): 198-214.
	Rong F D, Ding Z X, Cao Y F, et al. Progress in enhanced separation of compounds differing in unsaturated bonds by ionic liquids[J]. Chemical Industry and Engineering Progress, 2024, 43(1): 198-214.
7	吴沛文, 荀苏杭, 蒋伟, 等. 离子液体反应型萃取燃油脱硫研究进展[J]. 化工学报, 2021, 72(1): 276-291.
	Wu P W, Xun S H, Jiang W, et al. Recent progress on extractive desulfurization of fuel oils through reactions based on ionic liquids as solvents and catalysts[J]. CIESC Journal, 2021, 72(1): 276-291.
8	吕玉苗, 陈伟, 王艳磊, 等. 离子液体二维结构制备及其特性研究进展[J]. 化学学报, 2021, 79(4): 443-458.
	Lyu Y M, Chen W, Wang Y L, et al. Research progress on the preparation and properties of two dimensional structure of ionic liquids[J]. Acta Chimica Sinica, 2021, 79(4): 443-458.
9	李瑞, 崔现宝, 吴添, 等. 基于COSMO-SAC模型的离子液体萃取剂的选择[J]. 化工学报, 2013, 64(2): 452-469.
	Li R, Cui X B, Wu T, et al. Selection of ionic liquid solvent for liquid-liquid extraction based on COSMO-SAC model[J]. CIESC Journal, 2013, 64(2): 452-469.
10	Xing H B, Zhao X, Li R L, et al. Improved efficiency of ethylene/ethane separation using a symmetrical dual nitrile-functionalized ionic liquid[J]. ACS Sustainable Chemistry & Engineering, 2013, 1(11): 1357-1363.
11	Wang Y, Hao W Y, Jacquemin J, et al. Enhancing liquid-phase olefin-paraffin separations using novel silver-based ionic liquids[J]. Journal of Chemical & Engineering Data, 2015, 60(1): 28-36.
12	Li H, Zhang Z S, Sun G L, et al. Performance and mechanism of the separation of C₈ α-olefin from F-T synthesis products using novel Ag-DES[J]. AIChE Journal, 2021, 67(8): e17252.
13	Yu G R, Deng L Y, Abdeltawab A A, et al. Functional solution composed of Cu(Ⅰ) salt and ionic liquids to separate propylene from propane[J]. Industrial & Engineering Chemistry Research, 2014, 53(34): 13430-13435.
14	Yu G R, Zhang L, Alhumaydhi I A, et al. Separation of propylene and propane by alkylimidazolium thiocyanate ionic liquids with Cu⁺ salt[J]. Separation and Purification Technology, 2015, 156: 356-362.
15	张睿, 董淑媛, 伍洛, 等. 小分子烷烃与烯烃在离子液体中的溶解性能[J]. 化工学报, 2020, 71(10): 4674-4687.
	Zhang R, Dong S Y, Wu L, et al. Solubility of light alkanes and alkenes in ionic liquids[J]. CIESC Journal, 2020, 71(10): 4674-4687.
16	Chen X C, Ming S M, Wu X Y, et al. Cu(Ⅰ)-based ionic liquids as potential absorbents to separate propylene and propane[J]. Separation Science and Technology, 2013, 48(15): 2317-2323.
17	Wentink A E, Kockmann D, Kuipers N J M, et al. Effect of C₆-olefin isomers on π-complexation for purification of 1-hexene by reactive extractive distillation[J]. Separation and Purification Technology, 2005, 43(2): 149-162.
18	Capracotta M D, Sullivan R M, Martin J D. Sorptive reconstruction of CuMCl₄ (M = Al and Ga) upon small-molecule binding and the competitive binding of CO and ethylene[J]. Journal of the American Chemical Society, 2006, 128(41): 13463-13473.
19	Anantharaj R, Banerjee T. COSMO-RS-based screening of ionic liquids as green solvents in denitrification studies[J]. Industrial & Engineering Chemistry Research, 2010, 49(18): 8705-8725.
20	Adamo C, Barone V. Toward reliable density functional methods without adjustable parameters: the PBE0 model[J]. Journal of Chemical Physics, 1999, 110(13): 6158-6170.
21	Neese F. Software update: the ORCA program system, version 4.0[J]. WIREs Computational Molecular Science, 2018, 8(1): e1327.
22	Grimme S, Ehrlich S, Goerigk L. Effect of the damping function in dispersion corrected density functional theory[J]. Journal of Computational Chemistry, 2011, 32(7): 1456-1465.
23	Grimme S, Antony J, Ehrlich S, et al. A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu[J]. The Journal of Chemical Physics, 2010, 132(15): 154104.
24	倪清, 来锦波, 彭东岳, 等. 离子液体萃取分离烃类化合物的研究进展[J]. 化工进展, 2022, 41(2): 619-627.
	Ni Q, Lai J B, Peng D Y, et al. Progress in extraction separation of hydrocarbons by ionic liquids[J]. Chemical Industry and Engineering Progress, 2022, 41(2): 619-627.
25	Sasaki T, Tada M, Zhong C M, et al. Immobilized metal ion-containing ionic liquids: preparation, structure and catalytic performances in kharasch addition reaction and suzuki cross-coupling reactions[J]. Journal of Molecular Catalysis A: Chemical, 2008, 279(2): 200-209.
26	Fulton J L, Hoffmann M M, Darab J G. An X-ray absorption fine structure study of copper(Ⅰ) chloride coordination structure in water up to 325℃[J]. Chemical Physics Letters, 2000, 330(3/4): 300-308.
27	Schäafer H, Binnewies M, Laumanns R, et al. CuAl₂Cl₈. Darstellung und kristallstruktur[J]. Zeitschrift Für Anorganische und Allgemeine Chemie, 1980, 461(1): 31-34.
28	Safarik D J, Eldridge R B. Olefin/paraffin separations by reactive absorption: a review[J]. Industrial & Engineering Chemistry Research, 1998, 37(7): 2571-2581.
29	Bader R F W. Atoms in molecules[J]. Accounts of Chemical Research, 1985, 18(1): 9-15.
30	Lipkowski P, Grabowski S J, Robinson T L, et al. Properties of the C—H…H dihydrogen bond: an ab initio and topological analysis[J]. The Journal of Physical Chemistry A, 2004, 108(49): 10865-10872.
31	Cremer D, Kraka E. Chemical bonds without bonding electron density—Does the difference electron-density analysis suffice for a description of the chemical bond?[J]. Angewandte Chemie International Edition in English, 1984, 23(8): 627-628.

萃取剂	S	D	PI
N-甲酰基吗啉	2.12	0.046	0.10
N-甲基吡咯烷酮	1.31	0.301	0.39
乙二醇	2.25	0.028	0.06
[Bmim]Cl-1.0FeCl₃	2.40	0.041	0.10
[Bmim]Cl-1.0AlCl₃	2.39	0.036	0.09
[Bmim]Cl-1.0CuCl [Bmim]Cl-1.5CuCl [Bmim]Cl-2.0CuCl	2.96 4.39 6.41	0.034 0.034 0.039	0.10 0.15 0.25
[Bmim]NTf₂	1.82	0.142	0.26
[Bmim]BF₄	2.45	0.032	0.08
[Bmim]PF₆	2.53	0.042	0.11
[Bmim]Cl-1.0AlCl₃+[Bmim]Cl-2.0CuCl	3.24	0.040	0.13
[Bmim]Cl-0.6AlCl₃-1.0CuCl	6.33	0.073	0.46

萃取剂	S	D	PI
N-甲酰基吗啉	2.12	0.046	0.10
N-甲基吡咯烷酮	1.31	0.301	0.39
乙二醇	2.25	0.028	0.06
[Bmim]Cl-1.0FeCl₃	2.40	0.041	0.10
[Bmim]Cl-1.0AlCl₃	2.39	0.036	0.09
[Bmim]Cl-1.0CuCl [Bmim]Cl-1.5CuCl [Bmim]Cl-2.0CuCl	2.96 4.39 6.41	0.034 0.034 0.039	0.10 0.15 0.25
[Bmim]NTf₂	1.82	0.142	0.26
[Bmim]BF₄	2.45	0.032	0.08
[Bmim]PF₆	2.53	0.042	0.11
[Bmim]Cl-1.0AlCl₃+[Bmim]Cl-2.0CuCl	3.24	0.040	0.13
[Bmim]Cl-0.6AlCl₃-1.0CuCl	6.33	0.073	0.46

Path	N	R/Å	σ²/Å²
Cu—Cl	2.00	2.21	0.013
Cu—Al	1.45	2.93	0.024

Path	N	R/Å	σ²/Å²
Cu—Cl	2.00	2.21	0.013
Cu—Al	1.45	2.93	0.024

离子液体+1-己烯/正己烷	ΔE/(kJ/mol)
[Bmim][CuCl₂]+1-己烯	-89.79
[Bmim][CuAlCl₅]+1-己烯	-138.08
[Bmim][CuCl₂]+正己烷	-24.89
[Bmim][CuAlCl₅]+正己烷	-19.99