Aliphatic–aromatic polyimide blends for H2 separation

In this work the synthesis of a semi aliphatic BTDA-DAH polyimide and their blends with BTDA-ODA and BTDA-DDS polyimides was carried out in order to improve the H₂ permselective properties of polyimides. The syntheses were made using the well-known two steps method and the silylation method. The prepared films were characterized by FTIR, DSC, thermal stability and fluorescence spectroscopy. Intercatenary distances (d-spacing) and gas separation properties were also investigated. PI blend membranes presented only one glass transition temperature (Tg) intermediate between those of the neat polyimides. Fluorescence spectra were a useful tool to recognize electron-donor and electron-acceptor interactions indicating intermolecular charge-transfer complex (CTC) formation which were confirmed by UV–Vis absorptions. As a result, a decrease in the intercatenary distances and a shift for both IR and fluorescence bands of polyimide blends were measured. PI blend membranes showed a permeability decrease with respect to the neat ones, while the selectivity increased according to X-ray diffraction results. To analyze the polyimide blend permselectivities, H₂/CH₄, H₂/CO₂, H₂/O₂ and H₂/N₂ systems were chosen. As a result, H₂/CH₄ separation factor of PI blends was among the highest reported by other authors using traditional membrane materials.     

PVDF/ionic liquid polymer blends with superior separation performance for removing CO2 from hydrogen and flue gas

We have demonstrated, for the first time, a polymer blend comprising poly(vinylidene fluoride) (PVDF) and a room-temperature ionic liquid (RTIL) that shows a high CO₂ permeability of 1778 Barrer with CO₂/H₂ and CO₂/N₂ selectivity of 12.9 and 41.1, respectively. The low viscosity RTIL, 1-ethyl-3-methylimidazolium tetracyanoborate ([emim][B(CN)₄]) possesses a high CO₂ solubility, and plays a significant role in CO₂ separation, whereas PVDF provides the mechanical strength to the blend membranes. A series of PVDF/[emim][B(CN)₄] polymer blends with different compositions were tested for their gas separation performance involving H₂, N₂ and CO₂ in both pure gas and mixed gas conditions. Both optical observation and Maxwell predictions confirm the heterogeneous nature of the PVDF/[emim][B(CN)₄] system. However, compared to miscible ionic liquid based blends, where molecular level interactions may restrain chain flexibility and reduce gas permeability, heterogeneous PVDF/RTIL blend systems show far superior gas transport properties. Most of these blend membranes outperform most reported materials and their gas transport and separation capabilities fall within the attractive region bound by the “2008 Robeson Upper Limit” for CO₂/H₂ and CO₂/N₂ gas pairs, and are also very stable at trans-membrane pressure up to 5 atm. Therefore, they are potential materials for H₂ purification and CO₂ capture from hydrogen production and flue gas.     

Developing cross-linked poly(ethylene oxide) membrane by the novel reaction system for H2 purification

In this study, a ‘green” method has been discovered by utilizing the amino functional poly(ethylene oxide) (PEO) and epoxy functional PEO with low molecular weights to synthesis cross-linked membranes for enhancing H₂ purification and CO₂ capture performance by retarding the crystallinity of semi-crystalline polymer of PEO. The cross-linking reaction can happen simply by mixing two materials without using any solvent. The reaction has been characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), solid-state ¹³C nuclear magnetic resonance (NMR) and the gel content test. Furthermore, X-ray diffraction (XRD) and differential scanning calorimeter (DSC) confirm the amorphous structure of cross-linked PEO membranes, which should benefit the gas transport. The gas transport properties and the plasticizing phenomenon of CO₂ have been examined in detail. Interestingly, the investigation on CO₂ plasticization phenomenon reveals that the cross-linked PEO membrane should be plasticized immediately after the pressure load. The pressure dependence of CO₂ permeability in the pressure range from 0.25 atm to 30 atm can be separated into two stages based on the permeability increment although the CO₂ permeability continuously increases with the loading pressure. The gas transport results illustrate that CO₂ has much larger permeability than that of any tested gas (including H₂, N₂ and CH₄) attributing to the CO₂-philic characteristic of ethylene oxide (EO) groups in the cross-linked PEO membrane. The good permeability and selectivity make the developed PEO membrane promising for H₂ purification and CO₂ capture applications.     

Fabrication and characterization of poly(phenylene oxide)/SBA-15/carbon molecule sieve multilayer mixed matrix membrane for gas separation

A novel multilayer mixed matrix membrane (MMM), consisting of poly(phenylene oxide) (PPO), large-pore mesoporous silica molecular sieve zeolite SBA-15, and a carbon molecular sieve (CMS)/Al₂O₃ substrate, was successfully fabricated using the procedure outlined in this paper. The membranes were cast by spin coating and exposed to different gases for the purpose of determining and comparing the permeability and selectivity of PPO/SBA-15 membranes to H₂, CO₂, N₂, and CH₄. PPO/SBA-15/CMS/Al₂O₃ MMMs with different loading weights of zeolite SBA-15 were also studied. This new class of PPO/SBA-15/CMS/Al₂O₃ multilayer MMMs showed higher levels of gas permeability compared to PPO/SBA-15 membranes. The permselectivity of H₂/N₂ and H₂/CH₄ combinations increased remarkably, with values at 38.9 and 50.9, respectively, at 10 wt% zeolite loading. Field emission scanning electron microscopy results showed that the interface between the polymer and the zeolite in MMMs was better at a 10 wt% loading than other loading levels. The increments of the glass transition temperature of MMMs with zeolite confirm that zeolite causes polymer chains to become rigid.     

Development of hydrogen-selective CAU-1 MOF membranes for hydrogen purification by ‘dual-metal-source’ approach

Hydrogen provides reliable, sustainable, environmental and climatic friendly energy to meet world's energy requirement and it also has high energy density. Hydrogen is relevant to all of the energy sectors-transportation, buildings, utilities and industry. In all of these sectors, hydrogen-rich gas streams are needed. Thus, hydrogen-selective membrane technology with superior performances is highly demanded for separation and purification of hydrogen gas mixtures. In this study, novel [Al₄(OH)₂(OCH₃)₄(H₂N-BDC)₃]·xH₂O (CAU-1) MOF membranes with accessible pore size of 0.38 nm are evaluated for this goal of hydrogen purification. High-quality CAU-1 membranes have been successfully synthesized on α-Al₂O₃ hollow ceramic fibers (HCFs) by secondary growth assisted with the homogenously deposited CAU-1 nanocrystals with a size of 500 nm as seeds. The energy-dispersive X-ray spectroscopy study shows that the HCFs substrates play dual roles in the membrane preparation, namely aluminum source and as a support. The crystals in the membrane are intergrown together to form a continuous and crack-free layer with a thickness of 4 μm. The gas sorption ability of CAU-1 MOF materials is examined by gas adsorption measurement. The isosteric heats of adsorption with average values of 4.52 kJ/mol, 12.90 kJ/mol, 12.82 kJ/mol and 27.99 kJ/mol are observed for H₂, N₂, CH₄, and CO₂ respectively, indicating different interactions between CAU-1 framework and these gases. As-prepared HCF supported CAU-1 membranes are tested by single and binary gas permeation of H₂/CO₂, H₂/N₂ and H₂/CH₄ at different temperatures, feed pressures and testing time. The permeation results show preferential permeance of H₂ over CO₂, N₂, and CH₄ with high separation factors of 12.34, 10.33, and 10.42 for H₂/CO₂, H₂/N₂, H₂/CH₄, respectively. The temperature, pressure and test time dependent studies reveal that HCFs supported CAU-1 membranes possess high stability, resistance to cracking, temperature cycling, high reproducibility, these of which combined with high separation efficiency make this type of MOF membranes are promising for hydrogen recycling from industrial exhausts.     

Role of CO2 in the CH4 oxidation and H2 formation during fuel-rich combustion in O2/CO2 environments

The effect of CO₂ reactivity on CH₄ oxidation and H₂ formation in fuel-rich O₂/CO₂ combustion where the concentrations of reactants were high was studied by a CH₄ flat flame experiment, detailed chemical analysis, and a pulverized coal combustion experiment. In the CH₄ flat flame experiment, the residual CH₄ and formed H₂ in fuel-rich O₂/CO₂ combustion were significantly lower than those formed in air combustion, whereas the amount of CO formed in fuel-rich O₂/CO₂ combustion was noticeably higher than that in air. In addition to this experiment, calculations were performed using CHEMKIN-PRO. They generally agreed with the experimental results and showed that CO₂ reactivity, mainly expressed by the reaction CO₂ + H → CO + OH (R1), caused the differences between air and O₂/CO₂ combustion under fuel-rich condition. R1 was able to advance without oxygen. And, OH radicals were more active than H radicals in the hydrocarbon oxidation in the specific temperature range. It was shown that the role of CO₂ was to advance CH₄ oxidation during fuel-rich O₂/CO₂ combustion. Under fuel-rich combustion, H₂ was mainly produced when the hydrocarbon reacted with H radicals. However, the hydrocarbon also reacted with the OH radicals, leading to H₂O production. In fact, these hydrocarbon reactions were competitive. With increasing H/OH ratio, H₂ formed more easily; however, CO₂ reactivity reduced the H/OH ratio by converting H to OH. Moreover, the OH radicals reacted with H₂, whereas the H radicals did not reduce H₂. It was shown that OH radicals formed by CO₂ reactivity were not suitable for H₂ formation. As for pulverized coal combustion, the tendencies of CH₄, CO, and H₂ formation in pulverized coal combustion were almost the same as those in the CH₄ flat flame.     

Ni/CeO2 catalysts with high CO2 methanation activity and high CH4 selectivity at low temperatures

CO₂ methanation was performed over 10 wt%Ni/CeO₂, 10 wt%Ni/α-Al₂O₃, 10 wt%Ni/TiO₂, and 10 wt%Ni/MgO, and the effect of support materials on CO₂ conversion and CH₄ selectivity was examined. Catalysts were prepared by a wet impregnation method, and characterized by BET, XRD, H₂-TPR and CO₂-TPD. Ni/CeO₂ showed high CO₂ conversion especially at low temperatures compared to Ni/α-Al₂O₃, and the selectivity to CH₄ was very close to 1. The surface coverage by CO₂-derived species on CeO₂ surface and the partial reduction of CeO₂ surface could result in the high CO₂ conversion over Ni/CeO₂. In addition, superior CO methanation activity over Ni/CeO₂ led to the high CH₄ selectivity.     

Carbon dioxide reforming of methane in a SrCe0.7Zr0.2Eu0.1O3−δ proton conducting membrane reactor

Utilizing CO₂ for fuel production holds the promise for reduced carbon energy cycles. In this paper we demonstrate a membrane reactor, integrating catalytic CO₂ reforming of methane with in-situ H₂ separation, that results in increased CO₂ and CH₄ conversion and H₂ production compared to a Ni catalyst alone. The tubular proton-conducting SrCe_0.7Zr_0.2Eu_0.1O_3−δ membrane reactor demonstrates that the addition of the membrane improves CO₂ conversion, due to in-situ H₂ removal, by 10% and 30% at 900 °C for CH₄/CO₂ = 1/1 and CH₄/CO₂/H₂O = 2/1/1 feed ratios, respectively. It also improves total H₂ production at 900 °C by 15% and 18% for CH₄/CO₂ = 1/1 and CH₄/CO₂/H₂O = 2/1/1, respectively. Further, the H₂/CO in the reactor side effluent can be adjusted for subsequent desired Fischer-Tropsch products by combining CO₂ reforming and steam reforming of methane.     

An experimental and kinetic modeling study of premixed NH3/CH4/O2/Ar flames at low pressure

An experimental and modeling study of 11 premixed NH₃/CH₄/O₂/Ar flames at low pressure (4.0 kPa) with the same equivalence ratio of 1.0 is reported. Combustion intermediates and products are identified using tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry. Mole fraction profiles of the flame species including reactants, intermediates and products are determined by scanning burner position at some selected photon energies near ionization thresholds. Temperature profiles are measured by a Pt/Pt-13%Rh thermocouple. A comprehensive kinetic mechanism has been proposed. On the basis of the new observations, some intermediates are introduced. The flames with different mole ratios (R) of NH₃/CH₄ (R0.0, R0.1, R0.5, R0.9 and R1.0) are modeled using an updated detailed reaction mechanism for oxidation of CH₄/NH₃ mixtures. With R increasing, the reaction zone is widened, and the mole fractions of H₂O, NO and N₂ increase while those of H₂, CO, CO₂ and NO₂ have reverse tendencies. The structural features by the modeling results are in good agreement with experimental measurements. Sensitivity and flow rate analyses have been performed to determine the main reaction pathways of CH₄ and NH₃ oxidation and their mutual interaction.     

Toward the design of asymmetric photocatalytic membranes for hydrogen production: Preparation of TiO2-based membranes and their properties

Hydrogen production from water using solar light energy is a significant contribution to green renewable energy economy. Separation of water splitting products is essential for this and approached by creating membrane photocatalytic system (MPS) without macroscopic metallic electrodes. The MPS has a layered structure Pt/chemically loaded TiO₂/filtration loaded TiO₂/porous polymer membrane/support. Influence of MPS preparation conditions on its TiO₂ content, permeability, diffuse reflectance spectra, mechanical stability, Pt loading and membrane morphology was investigated. Chemical bath deposition of TiO₂ followed by aging was found to be essential for mechanical stability and high activity in hydrogen production. Loading TiO₂ by filtration alone is ineffective for achieving low permeability. The detected products of ethanol dehydrogenation in gas phase were H₂, CO₂, CH₄ and C₂H₆ and in liquid phase CH₃COOH and CH₃CHO. Optimum mass of TiO₂ and photodeposited Pt were found for high rate of H₂ generation. The highest quantum efficiency of H₂ production was 13%.     

Hydrogen generation from polyethylene by milling and heating with Ca(OH)2 and Ni(OH)2

A process to produce hydrogen from polyethylene [–CH₂–]_n (PE) is developed by milling with Ca(OH)₂ and Ni(OH)₂ followed by heating the milled product. Characterizations by a set of analytical methods of X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermogravimetry–mass spectroscopy (TG/MS) and gas chromatography (GC) were performed on the milled and heated samples to monitor the process. It has been observed that addition of nickel hydroxide as well as increases in milling time and rotational speed of the mill is beneficial to the gas generation, mainly composed of H₂ and CH₄, CO, CO₂. Gaseous compositions from the milled samples vary depending on the added molar ratio of calcium hydroxide. H₂ emission occurs between 400 and 500 °C, and H₂ concentration of 95% is obtained from the mixture of PE/Ca(OH)₂/Ni(OH)₂ (C:Ca:Ni = 6:14:1) sample, and the concentrations of CO and CO₂ remain below 0.5%. The process offers a novel approach to treat waste plastic by transforming it into hydrogen.     

Reactivity of Ce-ZrO2 (doped with La-, Gd-, Nb-, and Sm-) toward partial oxidation of liquefied petroleum gas: Its application for sequential partial oxidation/steam reforming

Ce-ZrO₂ was found to have useful partial oxidation activity under moderate temperatures. It converted liquefied petroleum gas (LPG) to H₂, CH₄, CO and CO₂ with small amounts of C₂H₆ and C₂H₄ formations depending on the operating temperature and provided significantly greater resistance toward carbon deposition compared to conventional Ni/Al₂O₃. The doping of La, Sm and Gd over Ce-ZrO₂ considerably improved catalytic reactivity, whereas Nb-doping reduced its reactivity. It was found that the impact of doping element is strongly related to the degrees of oxygen storage capacity (OSC) and/or lattice oxygen (O_O^x) of materials. Among all catalysts, La-doped Ce-ZrO₂ was observed to have highest OSC value and was the most active catalyst. Above 850 °C with inlet LPG/O₂ molar ratio of 1.0/1.0, the main products from the reaction over La-doped Ce-ZrO₂ were H₂, CH₄, CO, and CO₂.     

Computational prediction of experimentally possible g-C3N3 monolayer as hydrogen purification membrane

Membrane technology has been used for hydrogen purification. In this work, two-dimensional g-C₃N₃ monolayer was proposed as an effective hydrogen separation membrane on basis of density functional theory computations. The structure of g-C₃N₃ monolayer was optimized first, and the computed phonon dispersion confirmed its stability and supported the experimental feasibility. The permeability of H₂ and impurity gases, including CO, N₂ and CH₄, was investigated. Compared with H₂, it is more difficult for the impurity gases to penetrate through g-C₃N₃ monolayer. The high selectivity of H₂ vs. CO, N₂, and CH₄ ensures a superior capability to conventional carbon and silica membranes. With high H₂ permeability and selectivity, g-C₃N₃ monolayer is a potential H₂ purification membrane.     

Hydrogen separation and purification using crosslinkable PDMS/zeolite A nanoparticles mixed matrix membranes

The transport properties of gases in polydimethylsiloxane (PDMS)/zeolite A mixed matrix membranes (MMMs) were determined based on pure gas permeation experiments. MMMs were prepared by incorporating zeolite 4A nanoparticles into a PDMS matrix using a new procedure. The permeation rates of C₃H₈, CH₄, CO₂, and H₂ were evaluated through a dense homogeneous pure PDMS membrane and PDMS/4A MMMs to assess the viability of these membranes for natural gas sweetening and hydrogen purification. SEM investigations showed good adhesion of the polymer to the zeolite in MMMs. Permeation performance of the membranes was also investigated using a laboratory-scale gas separation apparatus and effects of feed pressure, zeolite loading and pore size of zeolite on the gas separation performance of the MMMs were evaluated. The MMMs exhibited both higher selectivity of H₂/CH₄ and H₂ permeability as compared with the neat PDMS membrane, suggesting that these membranes are very promising for gas separations such as H₂/CH₄ separation.     

Quaternized poly(vinyl alcohol)/alumina composite polymer membranes for alkaline direct methanol fuel cells

The quaternized poly(vinyl alcohol)/alumina (designated as QPVA/Al₂O₃) nanocomposite polymer membrane was prepared by a solution casting method. The characteristic properties of the QPVA/Al₂O₃ nanocomposite polymer membranes were investigated using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), micro-Raman spectroscopy, and AC impedance method. Alkaline direct methanol fuel cell (ADMFC) comprised of the QPVA/Al₂O₃ nanocomposite polymer membrane were assembled and examined. Experimental results indicate that the DMFC employing a cheap non-perfluorinated (QPVA/Al₂O₃) nanocomposite polymer membrane shows excellent electrochemical performances. The peak power densities of the DMFC with 4 M KOH + 1 M CH₃OH, 2 M CH₃OH, and 4 M CH₃OH solutions are 28.33, 32.40, and 36.15 mW cm⁻², respectively, at room temperature and in ambient air. The QPVA/Al₂O₃ nanocomposite polymer membranes constitute a viable candidate for applications on alkaline DMFC.     

Thermodynamic equilibrium analysis of combined carbon dioxide reforming with partial oxidation of methane to syngas

The chemical equilibrium analysis on combined CH₄-reforming with CO₂ and O₂ (combined CORM–POM) has been conducted by total Gibbs energy minimization using Lagrange's undetermined multiplier method. The equilibrium compositions of the combined CORM–POM process were considerably influenced by CH₄:CO₂:O₂ feed ratios and operating temperatures. Methane oxidation reaction occurred predominantly at low temperatures, while the CO₂ conversion was strongly influenced by the O₂/CH₄ feed ratio. The addition of O₂ to the CORM process improved the CH₄ conversion, H₂ and H₂O yields and also the H₂/CO product ratio at the expense of CO₂ conversion and CO yield. Accordingly, the optimal equilibrium conditions for the CH₄:CO₂:O₂ ratio were within the range of 1:0.8:0.2–1:1:0.2 and a minimum requirement temperature of 1000 K.     

Effect of Ce on 5 wt% Ni/ZSM-5 catalysts in the CO2 reforming of CH4 reaction

The aim of this study is to investigate the promotional effect of Ce on Ni/ZSM-5 catalysts in the CO₂ reforming of CH₄ reaction. The evaluation of the catalytic performances of the composite catalysts was conducted in a fixed-bed reactor at atmospheric pressure. The influencing factors, including temperature, Ni and Ce loadings, molar feed ratio of CO₂/CH₄, and time-on-stream (TOS), were investigated. The characteristics of the catalysts were checked with Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The reduction and the basic properties of the composite catalysts were elucidated by temperature-programmed reduction by H₂ (H₂-TPR) and temperature-programmed desorption of CO₂ (CO₂-TPD), respectively. The reactivity of deposited carbon was studied by sequential temperature-programmed surface reaction of CH₄ (CH₄-TPSR) and temperature-programmed oxidation using CO₂ and O₂ (CO₂-TPO and O₂-TPO). Results indicate that higher CH₄ conversion, H₂ selectivity, and desired H₂/CO ratio for 5 wt% Ni & 5 wt% Ce/ZSM-5 could be achieved with CO₂/CH₄ feed ratio close to unity over the temperature range of 500–900 °C. Moreover, the addition of Ce could not only promote CH₄ decomposition for H₂ production but also the gasification of deposited carbon with CO₂. The dispersion of Ni particles could be improved with Ce presence as well. A partial reduction of CeO₂ to CeAlO₃ was observed from XPS spectra over 5 wt% Ni & 5 wt% Ce/ZSM-5 after H₂ reduction and 24 h CO₂–CH₄ reforming reaction. Benefiting from the introduction of 5 wt% Ce, the calculated apparent activation energies of CH₄ and CO₂ over the temperature range of 700–900 °C could be reduced by 30% and 40%, respectively.     

Molecular-level mixed matrix membranes comprising Pebax and POSS for hydrogen purification via preferential CO2 removal

The molecular-level mixed matrix membranes (MMMs) comprising Pebax^® and POSS have been developed by tuning the membrane preparation process in this work. They exhibit a simultaneous enhancement in CO₂ permeability and CO₂/H₂ selectivity by optimizing the POSS content at extremely low loadings. This is mainly attributed to the large cavity of POSS itself and its effect on the segmental-level polymeric chain packing. More interestingly, the Pebax^®/POSS MMMs reveal a much higher separation performance in the mixed gas test than that in the pure gas test. The highest CO₂/H₂ selectivity reaches 52.3 accompanied by CO₂ permeability of 136 Barrer at 8 atm and 35 °C. This is due to the CO₂-induced plasticization that improves the free volume and polymer chain mobility, hence benefiting the interaction between the polymer matrix and penetrant CO₂. These features may ensure the superiority of Pebax^®/POSS molecular-level MMMs as CO₂-selective membranes in the industrial application of hydrogen purification.     

Thermally rearranged (TR) HAB-6FDA nanocomposite membranes for hydrogen separation

Thermally rearranged (TR) polymers exhibited a good balance of high permeability and high selectivity. For this purpose HAB-6FDA polyimide was synthesized from 3,3 dihydroxy-4,4-diamino-biphenyl (HAB) and 2,2-bis-(3,4-dicarboxyphenyl) hexafluoro propane dianhydride (6FDA) by chemical imidization. Initially, the sample was modified from pure polymer to silica nanofiller doped polymer membrane. Further the modification was done by thermal rearrangement reaction at 350 °C temperature. This modification causes a mass loss in polymer structure and therefore enhances the fractional free volume (FFV). The gases used for the permeation test were H₂, CO₂, N₂ and CH₄. Selectivity was calculated for H₂/CO₂, H₂/N₂ and H₂/CH₄ gas pairs and plotted in the Robeson's 2008 upper bound and compared with reported data. The transport properties of these gases have been compared with the unmodified membrane. Permeability of all the gases has increased to that of unmodified polymer membrane. Thermally rearranged polymer nanocomposite exhibits higher gas permeability than that of silica doped and pure polymer. Also the selectivity for H₂/CO₂ and H₂/N₂ gas pairs exceeds towards Robeson's upper bound limit. It crosses this limit dramatically for H₂/CH₄ gas pair. Polymer nanocomposite can be utilized to obtain high purity hydrogen gas for refinery and petrochemical applications.     

Preparation and characterization of multi-walled carbon nanotube/PBNPI nanocomposite membrane for H2/CH4 separation

By combining organic polymers normally used to make membrane filters with inorganic substances, multi-walled carbon nanotube (MWCNTs), an extraordinary ability to separate H₂ from CH₄ was developed in this study. A series of MWCNTs/PBNPI nanocomposite membrane with a nominal MWCNTs content between 1 and 15 wt% were prepared by solution casting method, in which the very fine MWCNTs were embedded into glassy polymer membrane. Detailed characterizations, such as morphology, thermal stability and crystalline structure have been conducted to understand the structures, composition and properties of nanocomposite membranes. The results found that this new class of membrane had increased permeability and enhanced selectivity, and a useful ability to filter gases and organic vapours at the molecular level.