Efficient ethane and methane separation using ZIF-8/DMPU slurry

doi:10.11949/0438-1157.20241172

Abstract

Abstract:

Ethane is an important raw material in petrochemical production and can be used to produce chemicals such as ethylene. Separating ethane from natural gas can achieve effective utilization of resources. In this study, the methane/ethane mixture was separated by a new absorption-adsorption hybrid separation method. The separation medium was created by suspending ZIF-8 particles into N,N-dimethylpropyleneurea(DMPU). The results indicate that the slurry have a significantly higher absorption capacity for ethane than methane. The sorption rate in ZIF-8/DMPU slurry was fast, especially ethane reached adsorption equilibrium in 3—5 minutes. When the temperature was 283.15 K and the initial gas-liquid ratio was about 52.46, the separation factor of C₂H₆/CH₄ in ZIF-8/DMPU slurry could reach 9.26. In the column breakthrough tests, the slurry also showed excellent dynamic separation performance. In addition, the regeneration conditions of the slurry were mild and the structure of the recovered ZIF-8 material did not change. Continuous absorption-desorption cycle separation of C₂H₆/CH₄ can be achieved.

Key words: ZIF-8, ethane, methane, absorption, adsorption

摘要：

乙烷是石油化工生产中的重要原料，可用于生产乙烯等化学品。从天然气中分离出乙烷，可以实现资源的有效利用。采用吸收-吸附耦合分离法分离甲烷/乙烷混合气，通过将ZIF-8颗粒分散到N， N-二甲基丙烯基脲（DMPU）中形成悬浮浆液，以制备的浆液作为分离介质。研究结果表明，该浆液对乙烷的吸收容量明显高于甲烷；此外，该浆液的吸着速率快，乙烷在3~5 min即达到吸着平衡。283.15 K、初始气液比52.46左右时，ZIF-8/DMPU浆液体系对C₂H₆/CH₄的分离因子可以达到9.26。在混合气动态穿透实验中，浆液也表现出出色的动力学分离性能。此外，该浆液的再生条件温和，回收的ZIF-8材料结构保持完整，可以实现C₂H₆/CH₄的连续吸收-解吸循环分离。

关键词: ZIF-8, 乙烷, 甲烷, 吸收, 吸附

CLC Number:

TE 645

Ruijie MA, Zixuan HUANG, Xueqian GUAN, Guangjin CHEN, Bei LIU. Efficient ethane and methane separation using ZIF-8/DMPU slurry[J]. CIESC Journal, 2025, 76(5): 2262-2269.

马瑞洁, 黄子轩, 关雪倩, 陈光进, 刘蓓. ZIF-8/DMPU浆液分离C₂H₆/ CH₄混合气研究[J]. 化工学报, 2025, 76(5): 2262-2269.

Figures/Tables 10

Fig.1 Schematic diagram of the experimental device

Fig.2 Schematic diagram of the breakthrough experimental apparatus

Fig.3 The viscosity-temperature curves of ZIF-8/DMPU slurry with different ZIF-8 contents

Fig.4 Sorption isotherms of (a) C2H6 and (b) CH4 in ZIF-8［30%(mass)］/DMPU slurry and pure DMPU solvent

Fig.5 Kinetic curves of (a) C2H6 and (b) CH4 in ZIF-8 powder, ZIF-8/water, and ZIF-8/DMPU at a temperature of 293.15 K and an initial pressure of ∼1 MPa.

Table 1 Separation results for C2H6 （1）/CH4 （2）［5.5/94.5（mol）］ mixture by ZIF-8/DMPU slurry at various temperatures

Gas mixtures	T/K	ϕ	P_E/MPa	S_v1/（mol·L^-1）	y₁/%（mol）	x₁/%（mol）	β	S_c1/（mol·L^-1·MPa^-1）
C₂H₆/CH₄	283.15	52.46	0.43	0.09	2.20	17.24	9.26	9.3
	293.15	53.50	0.47	0.09	2.45	17.49	8.44	7.4
	303.15	52.92	0.50	0.08	2.83	18.39	7.75	5.4

Table 2 Separation results for C2H6 （1）/CH4 （2）［5.5/94.5（mol）］ mixture by ZIF-8/DMPU slurry at 293.15 K and various initial gas-liquid volume ratios

Gas mixtures	ϕ	P_E/MPa	S_v1/（mol·L^-1）	y₁/%（mol）	x₁/%（mol）	β	S_c1/（mol·L^-1·MPa^-1）
C₂H₆/CH₄	53.5	0.47	0.09	2.45	17.49	8.44	7.4
	80.1	0.71	0.12	2.65	18.10	8.13	6.4
	111.3	1.00	0.16	2.83	18.52	7.81	5.6
	142.5	1.29	0.19	2.99	18.73	7.47	5.0
	217.5	1.99	0.26	3.32	19.41	7.01	3.9

Fig.6 Breakthrough curve for C2H6/CH4［6.1/93.9（mol）］ mixture in ZIF-8 /DMPU slurry at 293.15 K, 0.6 MPa and 49.5 ml/min inlet flow rate

Table 3 Separation results for C2H6 （1）/CH4 （2）［5.5/94.5 （mol）］ mixture using regenerated slurry at 293.15 K

Gas mixtures	Rused times	ϕ	P_E/MPa	S_v1/（mol·L^-1）	y₁/%（mol）	x₁/%（mol）	β
CH₄/C₂H₆	0	53.50	0.47	0.09	2.45	17.49	8.44
	41	53.34	0.47	0.08	2.52	17.79	8.37
	49	52.23	0.46	0.08	2.52	17.81	8.38

Fig.7 XRD patterns of fresh ZIF-8 and that recovered from ZIF-8/DMPU slurry after 50 cycle sorption-desorption experiments

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