Pure Gas Permeation Research Articles

Fabrication and characterization of aging resistant carbon molecular sieve membranes for C3 separation using high molecular weight crosslinkable polyimide, 6FDA-DABA

Although propylene/propane separation remains a challenge for industrial processes, carbon molecular sieve membranes (CMSMs) have the potential to replace traditional separation methods. A high molecular weight crosslinkable polyimide was utilized to fabricate CMSMs, which showed pure gas permeabilities in excess of 400 barrers with propylene/propane selectivities as high as 25. Mixed gas (C3H8:C3H6 50:50) measurements yielded a propylene permeability of 257 barrers and a selectivity of 20. CMSMs from thermally precrosslinked polymer precursors demonstrated a 98% propylene permeability retention after aging for 20 days under vacuum. Active gas flow conditions resulted in slightly lower permeability retention (92.5%) after 15 days of testing.

Synthesis and Gas-Permeation Characterization of a Novel High-Surface Area Polyamide Derived from 1,3,6,8-Tetramethyl-2,7-diaminotriptycene: Towards Polyamides of Intrinsic Microporosity (PIM-PAs).

A triptycene-based diamine, 1,3,6,8-tetramethyl-2,7-diamino-triptycene (TMDAT), was used for the synthesis of a novel solution-processable polyamide obtained via polycondensation reaction with 4,4′-(hexafluoroisopropylidene)bis(benzoic acid) (6FBBA). Molecular simulations confirmed that the tetrasubstitution with ortho-methyl groups in the triptycene building block reduced rotations around the C–N bond of the amide group leading to enhanced fractional free volume. Based on N2 sorption at 77 K, 6FBBA-TMDAT revealed microporosity with a Brunauer–Emmett–Teller (BET) surface area of 396 m2 g−1; to date, this is the highest value reported for a linear polyamide. The aged 6FBBA-TMDAT sample showed moderate pure-gas permeabilities (e.g., 198 barrer for H2, ~109 for CO2, and ~25 for O2) and permselectivities (e.g., αH2/CH4 of ~50) that position this polyamide close to the 2008 H2/CH4 and H2/N2 upper bounds. CO2–CH4 mixed-gas permeability experiments at 35 °C demonstrated poor plasticization resistance; mixed-gas permselectivity negatively deviated from the pure-gas values likely, due to the enhancement of CH4 diffusion induced by mixing effects.

Axial Distribution of Permeance and Selectivity of a Porous Cylindrical Tube for Binary Gas Mixtures (CO2/N2)

In previous studies, the selectivity property of a porous stainless steel cylindrical tube showed different filtration rates of pure carbon dioxide (CO2) and of pure nitrogen (N2) because of the effect of the dynamic boundary layer into the tube. In this study, a binary mixture of CO2 and N2 is considered under three different volumetric compositions (50/50%, 60/40%, and 70/30%) to evaluate the separation property of a porous stainless steel tube (membrane effect). The pure gas permeability, mixture permeability, ideal selectivity, and separation selectivity of this tube are determined for a total mass flow rate ranging from 1 to 2.5 g·s–1 and for an inlet pressure varying from 2 to 3.5 bar accordingly. The factors affecting the distribution of CO2 and N2 inside the porous tube are qualified. It is found that both the ideal and separation selectivity values are close to each other for a 50/50% composition, but the difference between the values increases for different compositions because of the effects of...

Pure - and sour mixed-gas transport properties of 4,4′-methylenebis(2,6-diethylaniline)-based copolyimide membranes

Three aromatic 6FDA-Durene/MDEA random copolyimides with different Durene:MDEA molar ratios (3:1; 1:1 and 1:3) were synthesized, and pure gas permeation properties through their dense films were investigated. Compared to their corresponding homopolymers (6FDA-MDEA and 6FDA-Durene), the copolymers exhibit significant improvement in gas separation performance, as the membranes display improved gas transport properties. For example, for pure gas, the CO2 permeability for 6FDA-Durene/MDEA (3:1) is around 234 Barrer and CO2/CH4 selectivity equal to 17.8 obtained at 22 °C and feed pressure of 100 psi. In addition, for sweet gas mixture consisting of 10, 59, 30 and 1 vol% CO2, CH4, N2 and C2H6, respectively, the 6FDA-Durene/MDEA (1:3) copolyimide membrane shows CO2 permeability of 73 Barrer and CO2/CH4 selectivity of about 24 at an elevated pressure of 800 psi. For a sour gas mixture with high H2S content (20 vol % H2S in the feed gas), the membrane exhibits H2S/CH4 selectivity of 21; and H2S permeability of 112 Barrer. The transport properties of the herein reported membrane are similar to or even better than the performance exhibited by some polymeric membranes reported in the literature.

Highly Permeable Matrimid®/PIM-EA(H₂)-TB Blend Membrane for Gas Separation.

The effect on the gas transport properties of Matrimid®5218 of blending with the polymer of intrinsic microporosity PIM-EA(H2)-TB was studied by pure and mixed gas permeation measurements. Membranes of the two neat polymers and their 50/50 wt % blend were prepared by solution casting from a dilute solution in dichloromethane. The pure gas permeability and diffusion coefficients of H2, He, O2, N2, CO2 and CH4 were determined by the time lag method in a traditional fixed volume gas permeation setup. Mixed gas permeability measurements with a 35/65 vol % CO2/CH4 mixture and a 15/85 vol % CO2/N2 mixture were performed on a novel variable volume setup with on-line mass spectrometric analysis of the permeate composition, with the unique feature that it is also able to determine the mixed gas diffusion coefficients. It was found that the permeability of Matrimid increased approximately 20-fold with the addition of 50 wt % PIM-EA(H2)-TB. Mixed gas permeation measurements showed a slightly stronger pressure dependence for selectivity of separation of the CO2/CH4 mixture as compared to the CO2/N2 mixture, particularly for both the blended membrane and the pure PIM. The mixed gas selectivity was slightly higher than for pure gases, and although N2 and CH4 diffusion coefficients strongly increase in the presence of CO2, their solubility is dramatically reduced as a result of competitive sorption. A full analysis is provided of the difference between the pure and mixed gas transport parameters of PIM-EA(H2)-TB, Matrimid®5218 and their 50:50 wt % blend, including unique mixed gas diffusion coefficients.

PDMS/ZIF-8 coating polymeric hollow fiber substrate for alcohol permselective pervaporation membranes

Abstract In order to develop high performance composite membranes for alcohol permselective pervaporation (PV), poly(dimethylsiloxane)/ZIF-8 (PDMS/ZIF-8) coated polymeric hollow fiber membranes were studied in this research. First, PDMS was used for the active layer, and Torlon®, PVDF, Ultem®, and Matrimid® with different porosity were used as support layer for fabrication of hollow fiber composite membranes. The performance of the membranes varied with different hollow fiber substrates was investigated. Pure gas permeance of the hollow fiber was tested to investigate the pore size of all fibers. The effect of support layer on the mass transfer in hydrophobic PV composite membrane was investigated. The results show that proper porosity and pore diameter of the support are demanded to minimize the Knudsen effect. Based on the result, ZIF-8 was introduced to prepare more selective separation layer, in order to improve the PV performance. The PDMS/ZIF-8/Torlon® membrane had a separation factor of 8.9 and a total flux of 847 g·m−2·h−1. This hollow fiber PDMS/ZIF-8/Torlon® composite membrane has a great potential in the industrial application.

Thermally cross-linked diaminophenylindane (DAPI) containing polyimides for membrane based gas separations

This study aims to expand structure-property relationships of diaminophenylindane (DAPI)-containing polyimides and the influence of thermal cross-linking on gas transport properties of such materials. A polyimide synthesized from hexafluoroisopropylidene diphthalic anhydride (6FDA), DAPI, and diaminobenzoic acid (DABA) in a molar ratio of 0.5/0.33/0.17, 6FDA0.5-DAPI0.33/DABA0.17, was crosslinked by thermal decarboxylation. After cross-linking, pure gas permeability of 6FDA0.5-DAPI0.33/DABA0.17 increased with increased cross-linking time; gas permeability increased by about 30% after cross-linking at 353 °C for 40 min. This increase in permeability correlated with an increase in d-spacing measured by wide angle x-ray scattering, suggesting an increase in inter-chain spacing upon cross-linking. Minimal changes in O2/N2 and N2/CH4 selectivities occurred with increased thermal cross-linking time for 6FDA0.5-DAPI0.33/DABA0.17. However, CO2/CH4 and C2H4/C2H6 pure gas selectivities increased with thermal treatment, suggesting a potential narrowing of free volume distribution.

RETRACTED: Enhanced gas separation performance using carbon membranes containing nanocrystalline cellulose and BTDA-TDI/MDI polyimide

This paper presents the derivation of carbon membranes from BTDA-TDI/MDI polyimide (PI) prepared via a dip-coating technique on an inorganic tubular support surface, followed by a heat treatment (stabilization and carbonization) under N2 gas flow. In order to enhance the gas separation performance of the resultant carbon membrane, a synthesized nanocrystalline cellulose (NCC) using tissue paper as an additive was added into the dope solution at various carbonization temperatures of 600, 700, 800, and 900 °C. The NCC was prepared by extracting the unprinted area of a newspaper and was processed as an additive in the polymer solution. The chemical structure, morphological structure, and gas permeation properties of the resultant membrane were analyzed. Special attention was given to the physicochemical characteristics of the resulting PI/NCC-based carbon membrane and its corresponding gas permeation properties. Pure gas permeation tests were performed using CO2, CH4, O2, and N2 at room temperature. The gas permeation data demonstrated that the carbon membrane exhibited an excellent performance compared to the polymeric membrane. Enhancement in both gas permeance and selectivity were observed in the NCC-containing carbon membranes prepared at carbonization temperature of 800 °C, with the CO2/CH4 selectivity of 68.2 ± 3.3, the CO2/N2 selectivity of 66.3 ± 2.2, and the O2/N2 selectivity of 9.3 ± 2.5, with respect to the neat carbon membrane. By manipulating various carbonization temperatures, carbon membranes with different structures and properties were obtained.

Pebax/ionic liquid modified graphene oxide mixed matrix membranes for enhanced CO2 capture

The development of mixed matrix membranes (MMMs) is mostly challenged by the filler dispersion and the fabrication of defect-free membranes with an ultra-thin selective layer. Graphene oxide based MMMs are promising materials for gas separation application. The low filler content and preference of extended GO lamella to align perpendicular to a membrane surface, and hence the gas flow direction permits the development of thin film composite membrane (TFC). Here, facilitated transport MMMs were fabricated by incorporating ionic liquid functionalized graphene oxide (GO-IL) into poly(ether-block-amide) (Pebax 1657). The 1-(3-aminopropyl)-3-methylimidazolium bromide ionic liquid was reacted to graphene oxide sheets, enhancing the CO2 solubility and CO2/gas selectivity of the MMMs. Moreover, hydrogen bonding interactions between the ionic liquid and amide moieties in Pebax provide a homogeneous dispersion of GO-IL. The pure (H2, CO2, O2, N2, CH4) and mixed (CO2/H2, CO2/N2) gas permeability of the membranes were performed at 25 °C and 4 bar. The gas permeability measurements indicate an improvement of over 90% in CO2/N2 selectivity and 50% in CO2 permeability for the GO-IL MMMs compared to the pure Pebax membrane. The resulting TFC membranes showed high CO2 permeance up to 900 GPU (10−6 cm3 (STP) cm−2 s−1 cm Hg−1) and the CO2/N2 and CO2/H2 selectivities of about 45 and 5.8, respectively. Our finding underlines the importance of GO-IL nanosheet to design high selective thin film membranes, providing a direction to fulfil the concept of mixed matrix membranes for practical applications.

Blending of compatible polymer of intrinsic microporosity (PIM-1) with Tröger's Base polymer for gas separation membranes

The novel gas separation membranes have been prepared by blending highly gas permeable polymer of intrinsic microporosity (PIM-1) and with Tröger's Base polymer (TB). Interestingly, it was found firstly that the PIM-1 polymer was miscible with Tröger's Base polymer in any proportion. It was assumed that the excellent compatibility between two polymers could be attributed to the interaction between CN group in PIM-1 and N atoms in Tröger's Base moieties, as confirmed by ATR-IR results. Thus, flexible, tough and transparent blending membranes (PIM/TB) at different compositions between PIM-1 and TB were obtained by solution casting. The SEM results further confirmed the homogeneous morphology of blending membranes, indicating the excellent compatibility between two polymers. The gas separation performance testing by the volume-constant method suggested that the PIM/TB blending membrane showed lower pure gas permeability but higher ideal permselectivity than that of the pristine PIM-1 membrane, probably due to the lower d-spacing of TB polymers from commercial aromatic diamine which has a rotatable bond as confirmed by XRD results. The highest ideal permselectivity of CO2/CH4 was obtained for PIM/TB (6:4) membranes with CO2 permeability of 2585Barrer. Moreover, the excellent anti-plasticization ability of CO2 was observed for the blending membranes. The temperature dependence of gas separation and ideal permselectivity had also been observed for the membranes. The results suggested that the ideal permselectivity, particularly for the CO2/N2 and CO2/CH4 at lower temperature were much higher than that of the membrane at high temperature in spite of the decreasing permeability of CO2. The highest ideal permselectivity was achieved as high as 54.3 for CO2/N2 at − 25 ℃ for PIM/TB(8:2) membrane. Thus, the strategy of blending Tröger's Base with PIM-1 showed a promising approach for high performance gas separation membrane.

Development of hybrid models for prediction of gas permeation through FS/POSS/PDMS nanocomposite membranes

The present paper aims to use intelligent methods for prediction of gas permeation in binary-filler nanocomposite membranes containing fumed silica (FS) and octatrimethylsiloxy polyhedral oligomeric silsesquioxane (POSS) nanoparticles incorporated within a polymer matrix of polydimethylsiloxane (PDMS). Two reliable and rigorous hybrid models, i.e., differential evolution-adaptive neuro-fuzzy inference system (DE-ANFIS) and coupled simulated annealing-least square support vector machine (CSA-LSSVM) were developed in order to predict pure gas permeability of including H2, CH4, CO2, and C3H8 through the nanocomposite membranes. The coupled simulated annealing (CSA) optimization algorithm was also used for tuning of the model parameters. The impacts of several key parameters such as pressure, FS nanoparticles loading as well as the kinetic diameter of gases on permeation were investigated. The experimental data were randomly divided into two main groups, namely training (70%) and testing (30%) sets. The results of the study suggested that DE-ANFIS model is a more robust and accurate model than the CSA-LSSVM with the R2 values of 0.9981 and 0.9689, respectively.

CO2 Selective Carbon Tubular Membrane: The Effect of Stabilization Temperature on BTDA-TDI/MDI P84 co-polyimide

Membranes offer remarkable attributes such as possessing small equipment footprints, having high efficiency and are environmentally friendly, with carbon membranes progressively investigated for gas separation applications. In this study, carbon tubular membranes for CO2 separationare prepared via the dip-coating method with P84 co-polyimide as the carbon precursor. The prepared membranes were characterized using Thermogravimetric Analysis (TGA), pore structure analysis Brunauer-Emmett-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and pure gas permeation system. The permeation properties of the carbon membranes are measured and analyzed by using CO2, CH4 and N2 gases. The P84-based carbon tubular membrane stabilized at 300°C and featured excellent permeation properties with permeance range of 2.97±2.18, 3.12±4.32 and 206.09±3.24 GPU for CH4, N2 and CO2 gases, respectively. This membrane exhibited the highest CO2/CH4 and CO2/N2 selectivity of 69.48±1.83 and 65.97±2.87, respectively.

Membrane modeling using CFD: Combined evaluation of mass transfer and geometrical influences in 1D and 3D

In current literature two main approaches are used for the simulation of membrane contactors. One route considers membrane modules only in 1D for process simulation applications, the other route focuses on 3D simulation of modules using Computational Fluid Dynamics to provide very detailed information about membrane mass transfer or geometrical influences on the module performance.A new CFD algorithm is introduced in the current work. It is capable of performing both 3D and 1D simulations using the same code – 1D to be used in fast process simulation applications whereas the 3D method can be applied for fully resolved CFD applications. Using experimental results from pure gas permeation of a hollow fiber module, it was demonstrated that 1D and 3D simulations compare with less than 2% deviation on a global scale. Based on the 3D simulations, it was found that the arrangement of the fibers can lead to high velocity zones close to the module walls. It was demonstrated that the 1D CFD method performs well even for almost pure gases like CH4 at retentate side, by running simulations of a pilot scale biogas separation module in co- and counter-current configurations.

Carboxylated Carbon Nanotubes/Polyethersulfone Hollow Fiber Mixed Matrix Membranes: Development and Characterization for Enhanced Gas Separation Performance

ABSTRACTCarboxylated carbon nanotubes (C or cCNTs) were incorporated in polyethersulfone hollow fiber membranes (P HFMs) to improve the gas separation performance, i.e., pure gas permeability and ideal gas selectivity. The developed CP HFMs showed the remarkable improvement in thermal stability and mechanical strength as compared to that of the pristine P HFMs. The pure gas permeability of CO2, CH4, O2, and N2 gases for the HFMs were measured at 3 bar feed pressure and room temperature. It was observed that the presence of cCNTs in HFMs significantly improved the CO2 and O2 permeability for CP HFMs by 10.8-and 11.7- fold, respectively, as compared to that measured for P HFMs. Furthermore, the ideal gas selectivity for CO2/CH4, O2/N2, and CO2/N2 gas pairs for CP HFMs was also remarkably enhanced by almost 8.6-, 10.7-and 9.9-times, respectively, as compared to that measured for P HFMs. CP HFMs exhibited gas separation performance better than or comparable to that of the literature-reported CNTs-based membranes. Remarkably, the gas separation performance of CP HFMs crossed Robeson’s 2008 upper bound curve for O2/N2 gas-pair and was almost closer to the upper bound curves drawn by Robeson in 2008 for CO2/CH4 and CO2/N2 gas pairs. The improved separation performance can be attributed to the presence of cCNTs in HFMs. Thus, the results obtained in this study clearly showed that the CP HFMs can potentially be used as a membrane material for the industrially relevant gas separations.

Effect of stabilization temperature during pyrolysis process of P84 co-polyimide-based tubular carbon membrane for H2/N2 and He/N2 separations

In this study, the effect of stabilization temperature on the performance of tubular carbon membrane was being investigated. P84 co-polyimide-based tubular carbon membrane will be fabricated through the dip-coating technique. The tubular carbon membrane performance can be controlled by manipulating the pyrolysis conditions which was conducted at different stabilization temperatures of 250, 300, 350, 400, and 450°C under N2 environment (200 ml/min). The prepared membranes were characterized by using scanning electron microscopy (SEM), x-ray diffraction (XRD), and pure gas permeation system. The pure gas of H2, He, and N2 were used to determine the permeation properties of the carbon membrane. The P84 co-polyimide-based tubular carbon membrane stabilized at 300°C demonstrated an excellent permeation property with H2, He, and N2 gas permeance of 1134.51±2.87, 1287.22±2.86 and 2.98±1.28GPU, respectively. The highest H2/N2 and He/N2 selectivity of 380.71±2.34 and 431.95±2.61 was obtained when the stabilization temperature of 450°C was applied. It is concluded that the stabilization temperatures have protrusive effect on the carbon membrane properties specifically their pore structure, and eventually their gas separation properties.

CO 2 /N 2 gas separation using Fe(BTC)-based mixed matrix membranes: A view on the adsorptive and filler properties of metal-organic frameworks

Abstract The incorporation of a Metal-Organic Framework (MOF), Fe(BTC), into a polymeric membrane was assessed for CO2/N2 gas separation. The adsorptive and filler properties of the MOF in the Mixed Matrix Membranes (MMMs) produced were investigated as a strategy to separate CO2 from N2 and contribute to reduce CO2 emissions. Therefore, Fe(BTC) was firstly characterized by single-component adsorption equilibria measurements of CO2 and N2, to evaluate the MOF performance as an adsorbent for CO2/N2 separation and its adsorption role in the MMMs performance. Fe(BTC) was then incorporated in Matrimid®5218 at different loading percentages, and the MMMs produced were characterized by distinct techniques (SEM, TGA, puncture tests and contact angle essays). Finally, pure gas permeation experiments were carried out for CO2 and N2 at 303 K, 323 K and 353 K, to evaluate the temperature impact on both gas permeability and CO2/N2 ideal selectivity. The results show that an increase in CO2 permeability and CO2/N2 ideal selectivity can be advantageously achieved, especially at the higher operating temperature of 353 K. At these conditions, the Robeson upper-bound is surpassed, which is a clear indication of the high potential of using Matrimid®5218/Fe(BTC) MMMs in post-combustion streams at high-temperatures.

Enhancing the CO2 plasticization resistance of PS mixed-matrix membrane by blunt zeolitic imidazolate framework

A novel design to synthesize a defect-free mixed-matrix membrane (MMM) exhibiting superior gas separation performance via fully dispersed blunt zeolitic imidazolate framework (ZIF-8) in polymer matrix has been proposed for the first time. The sphericity and interconnected six-membered-ring (6-MR) pore porosity of ZIF-8 was controlled through an aqueous synthetic process by using a non-ionic surfactant (Pluronics, P123) and deionized water as solvent. The use of surfactant in ZIF-8 synthesis resulted in blunt nanocrystals with increased sphericity and 6-MR pore volume as confirmed by scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherm measurements. Subsequent pure gas permeation tests showed that blunt ZIF-8 increased CO2/N2 separation performance through “ideal morphology” in MMMs as a result of the excellent dispersion of ZIF-8 and good ZIF-8-polymer interfacial adhesion within the polymer matrix. A significant increase in CO2/N2 separation results were obtained with the MMM containing 10wt% loading of blunt ZIF-8 (P51), CO2 permeability of 21.5 Barrer (172.6%), and mixed-gas CO2/N2 selectivity of 43.9 (205.6%). The MMMs further displayed good aging-resistance properties for over 40 days, with considerable potential for long-term operation.

Effect of ionic liquid inclusion and amino–functionalized SAPO-34 on the performance of mixed matrix membranes for CO2/CH4 separation

Surface voids and filler agglomeration affect the membrane’s structure and gas separation which limits the use of mixed matrix membranes (MMM) for carbon dioxide (CO2) separation in industry. Therefore, synthesis of MMM with ionic liquid and modified inorganic fillers had improved performance and morphologies. In this regards the filler surface (SAPO-34) was modified by introducing organic amino cation, namely ethylenediamine (EDA) and hexylamine (HA). Four (04) mixed matrix membranes were synthesized by the incorporation of un-modified and modified filler along with ionic liquid (IL) in polyethersulfone (PES) matrix. The effects of IL addition and filler functionalization on morphology, thermal and mechanical stability were investigated; while pure gas permeation test using carbon dioxide (CO2) and methane (CH4) was carried out at 4 bar pressure to analyze the membrane gas transport properties. Characterization showed that surface voids and hard agglomerations disappeared by the addition of modified SAPO-34 and ionic liquid [emim][Tf2N]. Moreover, membranes were thermally and mechanically stable after the addition of IL and modified SAPO-34. Synergetic effect of IL and modified filler exhibited excellent CO2/CH4 selectivity (37.23) for PES + IL + modified SAPO-34 + HA MMM.

Separation of CO2 and N2 from CH4 using modified DD3R zeolite membrane: A comparative study of synthesis procedures

The SiO2/H2O ratio of the synthesis solution has high importance in the synthesis of selective DD3R zeolite membrane. A DD3R membrane (M1) has been synthesized by procedure with a defined low SiO2/H2O ratio used mostly for the synthesis of DD3R powder. Another membrane (M2) has been synthesized by procedure with a defined high SiO2/H2O ratio that the synthesis of high selective DD3R membrane with this method is limited to NGK11Nippon (Japan) Gaishi (insulator) Kaisha (company).-insulators. XRD and SEM confirmed the formation of DD3R layer on the support with both methods. The surface of membranes were treated with polydimethyl siloxane solution. The results of pure gas permeation of CO2, N2 and CH4 and CO2/CH4 equimolar mixture showed that using the synthesis procedure with the low SiO2/H2O ratio leads to DD3R membrane with less defects, while the obtained membrane with the high SiO2/H2O ratio was so thick with low performance. Also, high separation performance of the membrane M1 (selectivity of 290 and 9 for CO2/CH4 and N2/CH4) reveals that the procedure with the low SiO2/H2O ratio following by the surface treatment with PDMS solution can be used as a high potential procedure to synthesize a selective DD3R zeolite membrane for separation of CO2 and N2 from CH4.

Integration of molecular dynamic simulation and free volume theory for modeling membrane VOC/gas separation

Gas membrane separation process is highly unpredictable due to interacting non-ideal factors, such as composition/pressure-dependent permeabilities and real gas behavior. Although molecular dynamic (MD) simulation can mimic those complex effects, it cannot precisely predict bulk properties due to scale limitations of calculation algorithm. This work proposes a method for modeling a membrane separation process for volatile organic compounds by combining the MD simulation with the free volume theory. This method can avoid the scale-up problems of the MD method and accurately simulate the performance of membranes. Small scale MD simulation and pure gas permeation data are employed to correlate pressure-irrelevant parameters for the free volume theory; by this approach, the microscopic effects can be directly linked to bulk properties (non-ideal permeability), instead of being fitted by a statistical approach. A lab-scale hollow fiber membrane module was prepared for the model validation and evaluation. The comparison of model predictions with experimental results shows that the deviations of product purity are reduced from 10% to less than 1%, and the deviations of the permeate and residue flow rates are significantly reduced from 40% to 4%, indicating the reliability of the model. The proposed method provides an efficient tool for process engineering to simulate the membrane recovery process.