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1.
The effects of the impregnation of three types of inorganic fillers into polyvinylidene fluoride (PVDF) polymer membranes on the gas permeability and selectivity of these membranes were studied theoretically and experimentally. Permeabilities of He, CO2, O2, and N2 through three types of mixed matrix membranes (MMMs) based on PVDF, that is, PVDF/SiO2, PVDF/MCM‐41, and PVDF/4A MMMs, were experimentally measured and theoretically predicted using Maxwell, Higuchi, Bruggeman, and Bottcher‐Landauer models. Theoretical permeabilities of the PVDF/SiO2 MMMs using the above four models predicted the results in the following order: Maxwell model>Bruggeman model>Bottcher model>Higuchi model. However, this sequence was reversed for PVDF/MCM‐41 MMMs. The nonporous SiO2, mesoporous MCM‐41 and zeolite 4A inorganic fillers had effects on the permeabilities of the challenge gases for the PVDF/SiO2, PVDF/MCM‐41, and PVDF/4A MMMs but had no effects on the selectivities of the MMMs. The experimental permeabilities of the MMMs showed that there were no significant differences among the three types of MMMs despite that the inorganic fillers, that is, SiO2, MCM‐41, and zeolite 4A, had distinct dissimilar properties such as pore structures and particle sizes. Density measurements indicated that some voids were present in the polymer/particle interfaces. Based on the density measurement results, the void volume fractions of the resulting MMMs were calculated. An equation is derived to determine the void thickness of the MMM in terms of its physical properties and hence this proposed equation can substitute the difficult task of measuring such void thickness through any microscopy techniques. The Maxwell, Higuchi, Bruggeman, and Bottcher‐Landauer models could not predict the actual gas permeabilities of the PVDF MMMs. By taking the effects of crystallinity and immobilization factor on gas permeability into consideration, the extended modified Maxwell model showed good agreement with the experimental gas permeabilities of the resulting MMMs, indicating that the model did capture the essence of the gas transport behaviors through the MMMs. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4715–4726, 2013  相似文献   

2.
Polyether‐block‐amide (Pebax)/graphene oxide (GO) mixed‐matrix membranes (MMMs) were prepared with a solution casting method, and their gas‐separation performance and mechanical properties were investigated. Compared with the pristine Pebax membrane, the crystallinity of the Pebax/GO MMMs showed a little increase. The incorporation of GO induced an increase in the elastic modulus, whereas the strain at break and tensile strength decreased. The apparent activation energies (Ep) of CO2, N2, H2, and CH4 permeation through the Pebax/GO MMMs increased because of the greater difficulty of polymer chain rotation. The Ep value of CO2 changed from 16.5 kJ/mol of the pristine Pebax to 23.7 kJ/mol of the Pebax/GO MMMs with 3.85 vol % GO. Because of the impermeable nature of GO, the gas permeabilities of the Pebax/GO MMMs decreased remarkably with increasing GO content, in particular for the larger gases. The CO2 permeability of the Pebax/GO MMMs with 3.85 vol % GO decreased by about 70% of that of the pristine Pebax membrane. Rather than the Maxwell model, the permeation properties of the Pebax/GO MMMs could be described successfully with the Lape model, which considered the influence of the geometrical shape and arrangement pattern of GO on the gas transport. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42624.  相似文献   

3.
Mixed matrix membranes (MMMs), which combine the characteristics of inorganic nanofillers and organic matrices, have received wide attention because of their good permeability and selective performance for separating CO2 from industrial waste gases. In this work, the amino-GO-loaded bentonite (amino GO-Bent) was prepared by loading  NH2 on the GO surface with a large number of functional sites. Firstly, by introducing  NH2 on the surface of GO and then interacting with bentonite (Bent) organically modified by silane coupling agents through amide bonding. Mixed matrix membranes (MMMs) with an area of 623.7 cm2 and homogeneous texture were prepared using amino-GO-Bent as inorganic filler to improve the membrane selectivity for CO2/N2 and CO2/CH4 separation. The results show that the introduction of amino GO-Bent in MMMs can greatly improve the CO2 permeability and obtain high CO2 permeation performance: 2.67945 × 10−7 cm3 (STP)·cm/s/cm2/cmHg, and the selectivity of CO2/N2 and CO2/CH4 can reach 307.28 and 325.97, respectively. The two selective values were 14 and 18 times higher than those of pure PVDF membranes, and the performance of MMMs far exceeded the Robeson upper limit in 2008, respectively.  相似文献   

4.
With MOFs of Cu3(BTC)2 and ZIF‐8 as the dispersed phases and four polyimides with CO2 permeabilities ranging from 1.36 to 564 barrer as the continuous phase, the influence of metal organic frameworks on the gas‐separation properties of mixed‐matrix membranes (MMMs) was investigated. The results show that the gas permeabilities of all of the prepared MMMs greatly increased and even largely exceeded the predicted value of the Bruggeman model; for example, with the same Cu3(BTC)2 loading of 21.3 vol %, the O2 permeability increase rate of our prepared Cu3(BTC)2/Matrimide 5218‐20 MMMs was 2.26 times, whereas that predicted by the Bruggeman model was only 1.05 times. In addition, when the gas permeability of the polymeric phase was far lower than the dispersed phase of ZIF‐8 or Cu3(BTC)2 compared with ZIF‐8, which had a particle size (R) around 150 nm, Cu3(BTC)2 of 5–15 µm showed a little better enhancing effect on the gas‐permeation performance of the MMMs. In addition to the properties of the dispersed and continuous phases, we speculated that the ratio between R of the dispersed phase to the membrane thickness (L) played an important role for MMMs; the larger R/L was, the greater the gas permeability of the MMMs was. This speculation was initially evidenced by the ZIF‐8/ODPA/TMPDA‐20 MMMs with different Ls. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45728.  相似文献   

5.
Graphene oxide (GO)‐polyether block amide (PEBA) mixed matrix membranes were fabricated and the effects of GO lateral size on membranes morphologies, microstructures, physicochemical properties, and gas separation performances were systematically investigated. By varying the GO lateral sizes (100–200 nm, 1–2 μm, and 5–10 μm), the polymer chains mobility, as well as the length of the gas channels could be effectively manipulated. Among the as‐prepared membranes, a GO‐PEBA mixed matrix membrane (GO‐M‐PEBA) containing 0.1 wt % medium‐lateral sized (1–2 μm) GO sheets showed the highest CO2 permeation performance (CO2 permeability of 110 Barrer and CO2/N2 mixed gas selectivity of 80), which transcends the Robeson upper bound. Also, this GO‐PEBA mixed matrix membrane exhibited high stability during long‐term operation testing. Optimized by GO lateral size, the developed GO‐PEBA mixed matrix membrane shows promising potential for industrial implementation of efficient CO2 capture. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2843–2852, 2016  相似文献   

6.
Mixed‐matrix membranes (MMMs) have shown great advantages but still face some challenges, such as the trade‐off between permeability and selectivity, stability, and the lack of efficient ways to enhance them simultaneously. Here, the fabrication of MMMs with metal‐organic frameworks derived porous carbons (MOF‐PCs) as fillers which exhibit selective‐facilitating CO2 transport passage originating from interactions between fillers and CO2 is showed. With the aid of the developed multicalcination method, MOF‐PCs with variable N‐contents were prepared and incorporated into PPO‐PEG matrix for the first time to prepare MMMs, which show excellent separation performance for CO2/CH4 mixture with a tunable separation performance by combining different N‐contents and surface areas of MOF‐PCs. Moreover, the developed MMMs have hydrothermal and chemical stability. This work not only presents a series of MMMs with both good separation properties and stability, it also provides useful information for guiding the fabrication of high performance MMMs for practical application. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3400–3409, 2018  相似文献   

7.
Poly vinyl chloride/multi wall carbon nano tubes (PVC/MWCNTs) mixed matrix membranes (MMMs) were prepared for gas separation. Raw and functionalized MWCNTs (R-MWCNTs and C-MWCNTs) were utilized in membranes preparation. The C-MWCNT shows better performance compared to raw ones. Membrane (CO2/CH4) selectivity was increased from 39.21 to 52.18 at 2 bar pressure by MWCNT loading ratio. The modified membranes with styrene butadiene rubber (SBR-MMMs) showed 63.52 and 34.70 selectivity for (CO2/CH4) and (CO2/N2) at 2 bar pressure. Mechanical properties analysis exhibited tensile module improvement utilizing blending modification. Increase of feed pressure led to membrane gas permeability decreasing. But gas pair selectivity follows a nearly constant behavior for MMMs and increasing behavior for blend MMMs.  相似文献   

8.
Modified ultra-porous ZIF-8 particles were used to prepare novel ZIF-8/Pebax 1657 mixed matrix membranes (MMMs) on PES support for separation of CO2 from CH4 using spin coating method. TEM and SEM were used to characterize modified ZIF-8 particles. SEM was also used to investigate the morphology of synthesized MMMs. The MMMs with thinner selective layer showed higher CO2 permeability and lower CO2/CH4 selectivity in permeation tests compared to MMMs with thicker selective layer. The plasticization was recognized as the main reason for rise in CO2 permeability and drop in CO2/CH4 selectivity of thinner MMMs. The gas sorption results showed that the high permeability of CO2 in MMMs is mainly due to the high solubility of this gas in MMMs, leading to high CO2/CH4 solubility selectivity for MMMs. The fractional free volume and void volume fraction of MMMs increased as the thickness of membrane decreased. Applying higher mixed feed pressures and permeation tests temperatures resulted in increase in CO2 permeability and decrease in CO2/CH4 selectivity. At highest testing temperature (60 °C), the CO2 permeability of synthesized MMMs with thinner selective layer remarkably increased.  相似文献   

9.
Mixed matrix membranes (MMMs) were prepared by solvent evaporation method using Pebax-1074 polymer as matrix and inorganic zeolite SAPO-23 as dopant. The morphology, surface functional groups, microstructure, thermal stability, and separation performance of MMMs were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and gas permeation, respectively. The effects of dopant loading amount, permeation temperature, and permeation pressure on the structure and properties of MMMs were investigated. The results showed that the introduction of SAPO zeolite reduced the crystallinity of the MMMs and improved the CO2/N2 selectivity. Under the conditions of 30°C and 0.15 MPa, the MMMs prepared by incorporating with 5% SAPO zeolite in content exhibited the highest CO2/N2 selectivity of 72.0 together with the CO2 permeability of 98.2 Barrer.  相似文献   

10.
We prepared mixed‐matrix membranes (MMMs) composed of carboxylated single‐walled carbon nanotubes (f‐SWCNTs) and a sulfonated biphenyl poly(ether sulfone) (S‐PPSU) polymer matrix. The thermal stability and properties of the pores of the S‐PPSU and f‐SWCNTs were characterized by thermogravimetric analysis and sorption isotherm curves, respectively; these showed that the surface and pore diameter decreased after the introduction of carboxyl groups to the single‐walled carbon nanotubes (SWCNTs), and the pore properties did not restore original values even when the f‐SWCNTs were preheated to 350 °C to remove carboxyl groups. The gas‐separation measurement showed that the MMMs comprised of the S‐PPSU and f‐SWCNTs possessed better gas‐separation properties than the ones composed of biphenyl poly(ether sulfone) and SWCNTs. The permeability for N2, O2, He, and CO2 and the selectivity for O2/N2 and O2/CO2 were enhanced simultaneously because of the good dispersion of f‐SWCNTs and the improved interaction between the two phases. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44995.  相似文献   

11.
This work elucidates the influence of graphene (G) and graphene oxide (GO) content on the desalination performance and scaling characteristics of G/polyvinylidene fluoride (G/PVDF) mixed matrix and GO/PVDF composite‐skin membranes, applied in a direct contact membrane distillation process (DCMD). Inclusion of high quality, nonoxidized, monolayered graphene sheets as polymer membrane filler, and application of a novel GO/water‐bath coagulation method for the preparation of the GO/PVDF composite films, took place. Water permeability and desalination tests via DCMD, revealed that the optimal G content was 0.87 wt%. At such concentration the water vapor flux of the G/PVDF membrane was 1.7 times that of the nonmodified reference, while the salt rejection efficiency was significantly improved (99.8%) as compared to the neat PVDF. Similarly the GO/PVDF surface‐modified membrane, prepared using a GO dispersion with low concentration (0.5 g/L), exhibited twofold higher water vapor permeate flux as compared to the neat PVDF, but however, its salt rejection efficiency was moderate (80%), probably due to pore wetting during DCMD. The relatively low scaling tendency observed for both G and GO modified membranes is primarily attributed to their smoother surface texture as compared to neat PVDF, while scaling is caused by the deposition of calcite crystals, identified by XRPD analysis. POLYM. ENG. SCI., 59:E262–E278, 2019. © 2018 Society of Plastics Engineers  相似文献   

12.
Interfacial void‐free mixed‐matrix membranes (MMMs) of polyimide (PI)/zeolite were developed using 13X and Linde type A nano‐zeolites and tested for gas separation purposes. Fabrication of a void‐free polymer‐zeolite interface was verified by the decreasing permeability developed by the MMMs for the examined gases, in comparison to the pure PI membrane. The molecular sieving effect introduced by zeolite 13X improved the CO2/N2 and CO2/CH4 selectivity of the MMMs. Separation tests indicated that the manufactured nanocomposite membrane with 30 % loading of 13X had the highest permselectivity for the gas pairs CO2/CH4 and CO2/N2 at the three examined feed pressures of 4, 8 and 12 atm.  相似文献   

13.
In this study, new monomers having silica groups were synthesized as an intermediate for the preparation of poly(imide siloxane)-zeolite 4A and 13X mixed matrix membranes (MMMs). The effects of membrane preparation steps, zeolite loading, precursor’s composition, and pore size of zeolite on the gas separation performance of these mixed matrix membranes were studied. The new diamine monomer was prepared from 3,5-diaminobenzoic acid (3,5-DABA), 3-aminopropyltrimethoxysilane (3-APTMS), and zeolite 4A and zeolite 13X in N-methyl-2-pyrollidone (NMP) at 180 °C. Poly(imide siloxane)-zeolite 4A and 13X MMMs were synthesized from pyromellitic dianhydride (PMDA) and 4,4-oxydianiline (ODA) in NMP using a two-step thermal imidization. SEM images of the MMMs show the interface between polymer and zeolite phases getting closer when surface modified zeolite is used. The increase in glass transition temperature (T g) confirms the polymer chain becoming more rigid induced by the presence of zeolite. The experimental results indicated that a higher zeolite loading resulted in a decrease in gas permeability and an increase in gas pair selectivity. In terms of O2 and N2 permeance and ideal selectivity, the separation performances of poly(imide siloxane)-zeolite MMMs were related to the zeolite type and zeolite pore dimension.  相似文献   

14.
Cu(I) impregnated MIL‐100(Cr) [denoted Cu@MIL‐101(Cr)] is fabricated by a facile method and utilized in mixed matrix membranes (MMMs) for propylene/propane separation. Cu(I) is prepared from a CuCl2 solution via mild reduction process using sodium sulfite as the reducing agent. The filler is incorporated into a polystyrene‐b‐polybutadiene‐b‐polystyrene (SBS) block copolymer matrix to form MMMs. As a result, both the permeability and selectivity of propylene/propane are improved after Cu(I) impregnation. The best performance is obtained for SBS/Cu@MIL‐101(Cr) MMM, and these values represent 17% and 54% improvements compared to those of SBS/MIL‐101(Cr) MMM, respectively. This result is attributed to the π‐complexation of the loaded Cu(I) by propylene gas, indicating that Cu@MIL‐101(Cr) with internal Cu(I) and a high pore volume acted as an effective filler to aid propylene/propane separation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46545.  相似文献   

15.
Mixed Matrix Membranes (MMMs) of UiO-66-NH2 nanoparticles dispersed in Cellulose Acetate (CA) were prepared with filler loading of 2–20 wt%. MMMs were tested for the upgradation of model biogas (60%–40%) mixture of CH4/CO2 at a feed pressure of 2 bar and 1.5 bar. Detailed characterization of MMMs was performed with Fourier transform infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), Differential scanning calorimetry (DSC), and Field emission scanning electron microscopy (FESEM) to investigate the physical and thermal properties. MMMs formed are defects-free, voids-free, and without polymer rigidification, indicating a better filler polymer interface. MMMs showed improved CO2 permeability while retaining the CO2/CH4 selectivity. The 10 wt.% UiO-66-NH2/CA MMM showed optimum gas separation performance with CO2 permeability of 11 Barrer and CO2/CH4 selectivity of 10. The UiO-66-NH2/CA MMMs performed better when compared to the pure CA membrane. The experimental permeability and selectivity data were compared with the predicted data using Maxwell, Lewis–Nielsen, Higuchi, and Bruggeman's model.  相似文献   

16.
Polysulfone (PSf)‐based mixed matrix membranes (MMMs) with the incorporation of titanium dioxide (TiO2) nanoparticles were prepared. Distribution and agglomeration of TiO2 in polymer matrix and also surface of membranes were observed by scanning electron microscopy, transmission electron microscopy, and energy dispersive X‐ray. Variation in surface roughness of MMMs with different TiO2 loadings was analyzed by atomic force microscopy. Physical properties of membranes before and after cross‐linking were identified through thermal gravimetric analysis. At low TiO2 loadings (≤3 wt%), both CO2 and CH4 permeabilities decreased and consequently gas selectivity improved and reached to 36.5 at 3 bar pressure. Interestingly, PSf/TiO2 3 wt% membrane did not allow to CH4 molecules to pass through the membrane and this sample just had CO2 permeability at 1 bar pressure. Gas permeability increased considerably at high filler contents (≥5 wt%) and CO2 permeance reached to 37.7 GPU for PSf/TiO2 7 wt% at 7 bar pressure. It was detected that, critical nanoparticle aggregation has occurred at higher filler loadings (≥5 wt%), which contributed to formation of macrovoids and defects in MMMs. Accordingly, MMMs with higher gas permeance and lower gas selectivity were prepared in higher TiO2 contents (≥5 wt%). POLYM. ENG. SCI., 55:367–374, 2015. © 2014 Society of Plastics Engineers  相似文献   

17.
Using porous materials to selectively adsorb H2O from natural gas is a promising method to dehydrate methane (CH4). The structure of a Zirconium metal-organic framework (Zr-MOF), namely, MIP-202, features a high density of amino groups, which can produce strong hydrogen bonding with H2O molecules. MIP-202 is cost-effective, green and scalable, and it exhibits good chemical stability under various conditions. This work incorporated MIP-202 nanoparticles into the high permeability polymer polyetherimide (PEI), and the obtained Mixed Matrix Membranes (MMMs) was used for the gas separation of H2O/CH4. It is found that MMMs loaded with 20 wt% of MIP-202 demonstrated a high H2O/CH4 selectivity of 832.2, which was about 760 times of that of the pure PEI. This approach offers a new route to fabricate functional membranes for energy-efficient gas separations.  相似文献   

18.
This study investigated the effect of annealing time and temperature on gas separation performance of mixed matrix membranes (MMMs) prepared from polyethersulfone (PES), SAPO‐34, and 2‐hydroxy 5‐methyl aniline (HMA). A postannealing period at 120°C for a week extensively increased the reproducibility and stability of MMMs, but for pure PES membranes no post‐annealing was necessary for stable and reproducible performance. The effect of operation temperature was also investigated. The permeabilities of H2, CO2, and CH4 increased with increasing permeation temperature from 35°C to 120°C, yet CO2/CH4 and H2/CH4 selectivities decreased. PES/SAPO‐34/HMA ternary and PES/SAPO‐34 binary MMMs exhibited the highest ideal selectivity and permeability values at all temperatures, respectively. For H2/CO2 pair, when temperature increased from 35°C to 120°C, selectivity increased from 3.2 to 4.6 and H2 permeability increased from 8 to 26.5 Barrer for ternary MMM, demonstrating the advantage of using this membrane at high temperatures. The activation energies were in the order of CH4 > H2 > CO2 for all membranes. PES/SAPO‐34/HMA membrane had activation energies higher than that of PES/SAPO‐34 membrane, suggesting that HMA acts as a compatibilizer between the two phases. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40679.  相似文献   

19.
To construct rapid C3H8 transport pathways in polymer matrix, alkyl chain‐functionalized graphene oxide (GO) was prepared via grafting octadecylamine (ODA) molecules and then embedded into polydimethylsiloxane (PDMS) matrix to obtain high‐efficiency mixed matrix membranes (MMMs). The incorporation of alkyl chains contributes to lowering the surface energy of GO nanosheets and providing higher affinity with PDMS matrix. Additionally, the alkyl chains on the surface of ODA‐functionalized GO nanosheets (ODA‐GO) are in favor of C3H8 adsorption, thus conferring continuous and specific transport pathways for C3H8. The optimized membrane with ODA‐GO loading of 0.3 wt% exhibits the C3H8 permeance of 1897 GPU and the C3H8/N2 ideal selectivity of 67, which are 50.2 and 72.5% higher than those of bare PDMS membrane, respectively. The simultaneous enhancement of C3H8 permeance and C3H8/N2 ideal selectivity indicates that ODA‐GO is an effective filler applied in MMMs for C3H8 recovery. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3501–3510, 2017  相似文献   

20.
Mixed matrix membranes (MMMs) containing fluorinated‐sulfonated poly(ether ether ketone) (F‐SPEEK) and zeolite 4A filler, were prepared by solution casting. F‐SPEEK with a fixed degree of sulfonation (40%) was used for membrane synthesis. The SEM pictures showed good interfacial adhesion between filler particles and polymer, which was also confirmed by the increase in glass transition temperature of MMMs with increase in filler particles. Pure and mixed gas permeation experiments were carried out to investigate the potential of this membrane material. The results revealed that addition of zeolite 4A fillers enhanced both permeability and selectivity owing to the intrinsic nature of polymer and modified membrane morphology due to filler. The highest permeability obtained for CO2 at 30% filler loading was 49.2 Barrer, while highest selectivities obtained for CO2/CH4 and CO2/N2 were 55 and 58 compared to 47 and 51 for the unfilled polymer, respectively. Intrinsic CO2 solubility of F‐SPEEK was observed to be decreased from 10.7 to 1.9 (10?2) cm3 (STP)/cm3 cmHg with the addition of Zeolite 4A. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45952.  相似文献   

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