基于碳微晶结构的炭膜模型及其气体分离模拟

doi:10.11949/0438-1157.20230249

摘要/Abstract

摘要：

在混合气体的膜分离过程中，组分与膜结构的相互作用直接影响分离效果。采用分子模拟方法，建立基于PEK-C基炭膜结构表征的碳微晶基炭膜模型，探究膜的碳微晶孔径和比表面积对CO₂/CH₄吸附和扩散的影响。结果表明，气体在炭膜内的吸附位点与其微结构有关，碳微晶孔径与比表面积增加时，吸附位点由碳微晶外部孔隙向碳微晶内部转移；炭膜孔隙体积较小时，分子形状为影响扩散的主要因素，其中直线型的CO₂比正四面体型的CH₄更易于扩散；30℃、100 kPa下，碳微晶孔径为0.493 nm时炭膜具有最优的气体分离性能，其吸附分离系数为10.49；炭化温度升高，炭膜比表面积增大，不利于气体分离，表明炭化温度不宜过高。研究结果拓展了炭膜气体分离机理，可为高性能炭膜的制备提供依据。

关键词: 分子模拟, 炭膜, 吸附, 扩散, 微结构, 碳微晶

Abstract:

The interaction between the gas and the membrane structure greatly affects the separation during the membrane separation of mixed gases. A carbon membrane model with carbon microcrystal structure based on PEK-C-based carbon membrane characterization was constructed by using molecular simulation to investigate the effects of carbon microcrystal pore size and specific surface area of the membrane on CO₂/CH₄ adsorption and diffusion. The results show that the adsorption sites of gas inside the carbon membrane are related to its microstructure. Gas molecules will be preferentially adsorbed in the pores formed by the random stacking of carbon microcrystals, while the gas adsorption location shifts to the interior of carbon microcrystals when the pore size of carbon microcrystals increases and the specific surface area increases. The molecular shape is the main factor influencing the diffusion when the pore volume of the carbon membrane is more minor, where the linear CO₂ is more easily diffused inside the carbon membrane than the ortho-tetrahedral CH₄. The carbon membrane has the best gas separation performance with an adsorption separation coefficient of 10.49 when the pore size of carbon microcrystals is 0.493 nm at 30℃ and 100 kPa. As the carbonization temperature increases, the specific surface area of the carbon film increases, which is not conducive to gas separation, indicating that the carbonization temperature should not be too high. The research results not only expand the mechanism of carbon membrane gas separation but also provide a basis for preparing high-performance carbon membranes.

Key words: molecular simulation, carbon membrane, adsorption, diffusion, microstructure, carbon microcrystal

中图分类号:

TQ 423.1

李辰鑫, 潘艳秋, 何流, 牛亚宾, 俞路. 基于碳微晶结构的炭膜模型及其气体分离模拟[J]. 化工学报, 2023, 74(5): 2057-2066.

Chenxin LI, Yanqiu PAN, Liu HE, Yabin NIU, Lu YU. Carbon membrane model based on carbon microcrystal structure and its gas separation simulation[J]. CIESC Journal, 2023, 74(5): 2057-2066.

图/表 13

图1 炭膜模型微晶炭片层结构示意图

Fig.1 Schematic diagram of microcrystal carbon sheet layer structure of carbon membrane model

图2 气体吸附等温线模拟值与实验值的比较

Fig.2 Comparison of simulated and experimental values of gas adsorption isotherms

图3 气体径向分布函数

Fig.3 Gas radial distribution function

图4 气体与炭膜微结构间的相互作用能

Fig.4 The interaction energy between gas and microstructure of carbon membrane

图5 不同碳微晶孔径下CO2/CH4混合气体的吸附等温线与吸附分离系数

Fig.5 Adsorption isotherms and adsorption separation coefficients of CO2/CH4 gas mixtures at different carbon microcrystal pore sizes

图6 不同碳微晶孔径下的气体径向分布函数

Fig.6 The radial distribution function of gas at different carbon microcrystal pore sizes

图7 不同碳微晶孔径下CO2/CH4混合气体与炭膜间的相互作用能

Fig.7 The interaction energy between CO2/CH4 gas mixture and carbon membrane with different carbon microcrystal pore sizes

图8 不同碳微晶孔径下CO2/CH4混合气体的扩散系数与扩散分离系数

Fig.8 The diffusion coefficient and diffusion separation coefficient of CO2/CH4 gas mixture with different carbon microcrystal pore sizes

图9 不同表观密度下炭膜的孔径分布

Fig.9 Pore size distribution of carbon membrane at different apparent densities

图10 不同比表面积下CO2/CH4混合气体的吸附等温线与吸附分离系数

Fig.10 Adsorption isotherms and adsorption separation coefficients of CO2/CH4 gas mixtures at different specific surface area

图11 不同比表面积下的气体径向分布函数

Fig.11 The radial distribution function of gas at different specific surface area

图12 不同比表面积下CO2/CH4混合气体与炭膜间的相互作用能

Fig.12 The interaction energy between CO2/CH4 gas mixture and carbon membrane with different specific surface area

图13 不同比表面积下CO2/CH4混合气体的扩散系数与扩散分离系数

Fig.13 The diffusion coefficients and diffusion separation coefficients of CO2/CH4 gas mixture with different specific surface area

参考文献 33

1	Farnam M, bin Mukhtar H, bin Mohd Shariff A. A review on glassy and rubbery polymeric membranes for natural gas purification[J]. ChemBioEng Reviews, 2021, 8(2): 90-109.
2	Feng S C, Du X B, Luo J Q, et al. A review on facilitated transport membranes based on π-complexation for carbon dioxide separation[J]. Separation and Purification Technology, 2023, 309: 122972
3	徐瑞松,李琳,侯蒙杰,等.新型炭基膜材料前驱体聚合物的研究进展[J].膜科学与技术,2020, 40(1): 250-259.
	Xu R S, Li L, Hou M J, et al. Development of polymeric precursor for the fabrication of carbon molecular sieve membrane[J]. Membrane Science and Technology, 2020, 40(1): 250-259.
4	Salinas O, Ma X H, Litwiller E, et al. High-performance carbon nolecular sieve membranes for ethylene/ethane separation derived from an intrinsically microporous polyimide[J]. Journal of Membrane Science, 2016, 500: 115-123.
5	Adams J S, Itta A K, Zhang C, et al. New insights into structural evolution in carbon molecular sieve membranes during pyrolysis[J]. Carbon, 2019, 141: 238-246.
6	Swaidan R, Ma X H, Litwiller E, et al. High pressure pure- and mixed-gas separation of CO₂/CH₄ by thermally-rearranged and carbon molecular sieve membranes derived from a polyimide of intrinsic microporosity[J]. Journal of Membrane Science, 2013, 447: 387-394.
7	Zhu Y D, Lu X H, Xie W L, et al. The progress of quantitatively description of membrane process based on the mechanism of nanoconfined mass transfer[J]. Chinese Science Bulletin, 2017, 62(2/3): 223-232.
8	MacElroy J M D, Friedman S P, Seaton N A. On the origin of transport resistances within carbon molecular sieves[J]. Chemical Engineering Science, 1999, 54(8): 1015-1027.
9	曹伟,吕玲红,黄亮亮,等.不同管径碳纳米管中CO₂/CH₄分离的分子模拟[J].化工学报, 2014, 65(5): 1736-1742.
	Cao W, Lü L H, Huang L L, et al. Molecular simulations on diameter effect of carbon nanotube for separation of CO₂/CH₄ [J]. CIESC Journal, 2014, 65(5): 1736-1742.
10	Yeganegi S, Gholampour F. Simulation of methane adsorption and diffusion in a carbon nanotube channel[J]. Chemical Engineering Science, 2016, 140: 62-70.
11	赵昊瀚,潘艳秋,何流,等.炭膜分离CO₂/CH₄混合气的分子模拟[J].化工学报, 2016, 67(6): 2393-2400.
	Zhao H H, Pan Y Q, He L, et al. Molecular simulation on separation of CO₂/CH₄gas mixture with carbon membrane[J]. CIESC Journal, 2016, 67(6): 2393-2400.
12	Di Biase E, Sarkisov L. Systematic development of predictive molecular models of high surface area activated carbons for adsorption applications[J]. Carbon, 2013, 64: 262-280.
13	Wang S S, Lu L, Wu D, et al. Molecular simulation study of the adsorption and diffusion of a mixture of CO₂/CH₄ in activated carbon: effect of textural properties and surface chemistry[J]. Journal of Chemical & Engineering Data, 2016, 61(12): 4139-4147.
14	Li S, Song K L, Zhao D F, et al. Molecular simulation of benzene adsorption on different activated carbon under different temperatures[J]. Microporous and Mesoporous Materials,2020, 302: 110220.
15	Widiastuti N, Widyanto A R, Caralin I S, et al. Development of a P84/ZCC composite carbon membrane for gas separation of H₂/CO₂ and H₂/CH₄ [J]. ACS Omega, 2021, 6 (24): 15637-15650.
16	Rezlerová E, Jain S K, Lísal M. Adsorption, diffusion, and transport of C₁ to C₃ alkanes and carbon dioxide in dual-porosity kerogens: insights from molecular simulations[J]. Energy Fuels, 2023, 37(1): 492-508.
17	Caro J. Diffusion coefficients in nanoporous solids derived from membrane permeation measurements[J]. Adsorption, 2021, 27(3): 283-293.
18	Chokbunpiam T, Fritzsche S, Parasuk V, et al. Molecular simulations of a CO₂/CO mixture in MIL-127[J]. Chemical Physics Letters, 2018, 696: 86-91.
19	Sun H. COMPASS: an ab initio force-field optimized for condensed-phase applications overview with details on alkane and benzene compounds[J]. The Journal of Physical Chemistry B, 1998, 102(38): 7338-7364.
20	何流. 炭分子筛膜微结构及其对气体分离性能的影响机制研究[D].大连: 大连理工大学, 2021.
	He L. Microstructure of carbon molecular sieve membrane and its influence mechanism on gas separation performance[D]. Dalian: Dalian University of Technology, 2021.
21	Di Biase E, Sarkisov L. Molecular simulation of multi-component adsorption processes related to carbon capture in a high surface area, disordered activated carbon[J]. Carbon,2015, 94: 27-40.
22	Morris J R, Contescu C I, Chisholm M F, et al. Modern approaches to studying gas adsorption in nanoporous carbons[J], Journal of Materials Chemisty A, 2013, 1(33): 9341-9350.
23	Xu R S, He L, Li L, et al. Ultraselective carbon molecular sieve membrane for hydrogen purification[J]. Journal of Energy Chemistry, 2020, 50: 16-24.
24	Suzuki T, Kobori R, Kaneko K. Grand canonical Monte Carlo simulation-assisted pore-width determination of molecular sieve carbons by use of ambient temperature N₂ adsorption[J]. Carbon, 2000, 38(4): 630-633.
25	李秉繁,刘刚,陈雷.基于分子动力学模拟的CH₄溶解对原油分子间作用的影响机制研究[J].化工学报, 2021, 72(3): 1253-1263.
	Li B F, Liu G, Chen L. Study on the influence mechanism of CH₄dissolution on the intermolecular interaction between crude oil molecules based on molecular dynamics simulation[J]. CIESC Journal, 2021, 72(3): 1253-1263.
26	张兵. 分子筛炭膜的制备、微结构及气体分离性能[D].大连: 大连理工大学,2007.
	Zhang B. Preparation, microstructure and gas separation performance of molecular sieving carbon membranes[D]. Dalian: Dalian University of Technology, 2007.
27	池君杰,梁晓怿,余青霓,等.分子模拟研究活性炭表面官能团对丙酮吸附的影响[J].航天医学与医学工程, 2015, 28(4): 284-287.
	Chi J J, Liang X Y, Yu Q N, et al. Molecular simulation study on influence of surface functional groups of activated carbon on acetone adsorption[J]. Space Medicine & Medical Engineering, 2015, 28(4): 284-287.
28	稻垣道夫. 膜技术基本原理[M]. 康飞宇, 译. 2版. 北京: 清华大学出版社, 2014: 93.
	Michio I. Materials Science and Engineering of Carbon: Fundamentals[M]. Kang F Y, trans. 2nd ed. Beijing: Tsinghua University Press, 2014: 93.
29	Sarkisov L, Harrison A. Computational structure characterisation tools in application to ordered and disordered porous materials[J]. Molecular Simulation, 2011, 37 (15): 1248-1257.
30	Li S, Yu L, Song K L, et al. Study on microscopic mechanism of activated carbon adsorption of benzene by molecular simulation technology[J]. Chemistry Letters, 2020, 49(12): 1452-1455.
31	Wu Q Y, Liang H Q, Li M, et al. Hierarchically porous carbon membranes derived from PAN and their selective adsorption of organic dyes[J]. Chinese Journal of Polymer Science, 2016, 34(1): 23-33.
32	Ye Z Y, Zhang Y, Hou L, et al. Preparation of a GO/PB-modified nanofiltration membrane for removal of radioactive cesium and strontium from water[J]. Chemical Engineering Journal, 2022, 446: 137143.
33	Bai K, Fan S Q, Chen Y, et al. Membrane adsorber with hierarchically porous HKUST-1 immobilized in membrane pores by flowing synthesis[J]. Journal of Membrane Science, 2022, 650: 120424.

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