共查询到19条相似文献,搜索用时 140 毫秒
1.
A sulfonated poly(ether ether ketone) (SPEEK) membrane with fairly high degree of sulfonation (DS) swells excessively and even dissolves at high temperature. To solve these problems, sulfonated phenolphthalein poly(ether sulfone) (SPES-C, DS 53.7%) is blended with the SPEEK matrix (DS 55.1%, 61.7%) to prepare SPEEK/SPES-C blend membrane. The decrease in swelling degree and methanol permeability of the membrane is dose-dependent. Pure SPEEK (DS 61.7%) membrane dissolves completely in water at 70ºC, whereas the swelling degree of the SPEEK (DS 61.7%)/SPES-C (40%, by mass) membrane is 29.7% at 80ºC. From room temperature to 80ºC, the methanol permeability of all SPEEK (DS 55.1%)/SPES-C blend membranes is about one order of magnitude lower than that of Nafion®115. At higher temperature, the addition of SPES-C polymer increases the dimensional stability and greater proton conductivity can be achieved. The SPEEK (DS 55.1%)/SPES-C (40%, by mass) membrane can withstand temperatures up to 150ºC. The proton conductivity of SPEEK (DS 55.1%)/SPES-C (30%, by mass) membrane approaches 0.16 S8226;cm-1, matching that of Nafion61650;115 at 140ºC and 100% RH, while pure SPEEK (DS 55.1%) membrane dissolves at 90ºC. The SPEEK/SPES-C blend membranes are promising for use in direct methanol fuel cells because of their good dimensional stability, high proton conductivity, and low methanol permeability. 相似文献
2.
The effect of graft yield on both the thermo-responsive hydraulic permeability and the thermo-respousive diffusional permeability through porous membranes with plasma-grafted poly(N-isopropylacrylamide) (PNIPAM)gates was investigated. Both thermo-respousive flat membranes and core-shell microcapsule membranes with a wide range of graft yield of PNIPAM were prepared using a plasma-graft pore-filling polymerization method. The grafted PNIPAM was formed homogeneously throughout the entire thickness of both the fiat polyethylene membranes andthe microcapsule polyamide membranes. Both the hydraulic permeability and the diffusional permeability were heavily dependent on the PNIPAM graft yield. With increasing the graft yield, the hydraulic permeability (water flux) decreases rapidly at 25℃ because of the decrease of the pore size; however, the water flux at 40℃ increases firstly to a peak because of the increase of hydrophobicity of the pore surface, and then decreases and finally tends to zero because of the pore size becoming smaller and smaller. For the diffusional permeability, the temperature shows different effects on the diffusional permeability coefficients of solutes across the membranes. When the graft yield was low, the diffusional coefficient of solute across the membrane was higher at temperature above the lower critical solution temperature (LCST) than that below the LCST; however, when the graft yield was high, the diffusional coefficient was lower at temperature above the LCST than that below the LCST. It is very important to choose or design a proper graft yield of PNIPAM for obtaining a desired thermo-respousive “on/off“ hydraulic or ditfusional permeability. 相似文献
3.
Proton conducting membranes composed of phosphotungstic acid (PWA) and poly(vinyl alcohol) (PVA) were prepared. Conductivity and Fourier transform infrared spectrometer(FTIR) measurements show that most of the acid embedded are stable in the PVA matrix when the membrane is immerged in water or methanol solution at room temperature. Conductivity of the composite membranes scatters around 10-3S·cm-1 at room temperature. The methanol crossover through the membranes is about an order of magnitude lower than that through Nafion 117 membrane. 相似文献
4.
This paper reports on ¬¬¬a new microporous composite silica membrane prepared via acid-catalyzed polymeric route of sol-gel method with tetraethylorthosilicate (TEOS) and a bridged silsesquioxane [1, 2-bis(triethoxysilyl)ethane, BTESE] as precursors. A stable nano-sized composite silica sol with a mean volume size of ~5 nm was synthesized. A 150 nm-thick defect-free composite silica membrane was deposited on disk support consisting of macroporous α-Al2O3 and mesoporous γ-Al2O3 intermediate layer by using dip-coating ap-proach, followed by calcination under pure nitrogen atmosphere. The composite silica membranes exhibit molecular sieve properties for small gases like H2, CO2, O2, N2, CH4 and SF6 with hydrogen permeances in the range of (1-4)107 mol•m2•s1•Pa1 (measured at 200 C, 3.0×105 Pa). With respect to the membrane calcined at 500 C, it is found that the permselectivities of H2 (0.289 nm) with respect to N2 (0.365 nm), CH4 (0.384 nm) and SF6 (0.55 nm) are 22.9, 42 and >1000, respectively, which are all much higher than the corresponding Knudsen values (H2/N2 3.7, H2/CH4 2.8, and H2/SF6 8.5). 相似文献
5.
Hydrophobic ZSM-5 zeolite filled polydimethylsiloxane(PDMS) composite membranes with Nylon micro-filtration membrane as the support layer were prepared to separate acetaldehyde from its aqueous solution.The composite membranes were characterized by Fourier transform infrared spectroscopy and X-ray diffraction.Their structural morphology and thermal stability were also examined.The swelling study showed that the composite membranes presented higher degree of swelling in aqueous solution of acetaldehyde than in pure water at 25 C,suggesting that the membranes have stronger sorption capacity in acetaldehyde solution.The effects of ZSM-5 filling content and acetaldehyde concentration on pervaporation performance of composite membranes were investigated.The permeation experiments at different temperatures showed that both selectivity and permeation flux of composite membranes increased with temperature.With 5%ZSM-5-PDMS/Nylon membrane at acetaldehyde mass concentration of 8% and 25℃,the separation factor of acetaldehyde/water achieved 35 and the permeation flux was 233.3 g·m-2·h-1. 相似文献
6.
Proton conducting membranes composed of phosphotungstic acid (PWA) and poly(vinyl alcohol) (PVA)were prepared. Conductivity and Fourier transform infrared spectrometer(FTIR) measurements show that most ofthe acid embedded are stable in the PVA matrix when the membrane is immerged in water or methanol solution atroom temperature. Conductivity of the composite membranes scatters around 10-3 S.cm-1 at room temperature.The methanol crossover through the membranes is about an order of magnitude lower than that through Nafion117 membrane. 相似文献
7.
Polybenzimidazole(PBI) is a kind of proton transport membrane material, and its ion conductivity is a key factor affecting its application in vanadium redox flow batteries(VRFBs). The casting solvent of PBI has a significant influence on the acid doping level of PBI membranes which is closely related to ionic conductivity. In this paper, 3,3′-diaminobenzidine(DABz) and 4,4′-Dicarboxydiphenylether(DCDPE) were used as raw materials by solution condensation to prepare the PBI with ether bond groups. The chemical structure of PBI was determined by1~H NMR and FT-IR, and the prepared PBI had good solubility which can be dissolved in a variety of solvents. The PBI proton exchange membranes were prepared by solution coating with 5 different solvents of N,N-dimethylformamide(DMF), N,N-dimethylacetamide(DMAc), dimethyl sulfoxide(DMSO), 1-methyl-2-pyrrolidone(NMP), methane sulfonic acid(MSA). The effects of different solvents on the ion conductivity and physicochemical properties were discussed in detail. The results showed that the PBI membrane prepared by using MSA as solvent(the PBI + MSA membrane) exhibits high water uptake, acid doping level and low vanadium ion permeability. The VRFB assembled with the PBI + MSA membrane exhibited higher coulombic efficiency(CE) 99.87% and voltage efficiency(VE) 84.50% than that of the commercial Nafion115 membrane at100 m A·cm~(-2), and after 480 cycles, the EE value can still be maintained at 83.73%. The self-discharge time of a single battery was recorded to be as long as 1000 h. All experimental data indicated that MSA is the best solvent for casting PBI membrane. 相似文献
8.
One-dimensional heterogeneous plug flow model was employed to model an adiabatic fixed-bed reactor for the catalytic dehydration of methanol to dimethyl ether. Longitudinal temperature and conversion profiles predicted by this model were compared to those experimentally measured in a bench scale reactor. The reactor was packed with 1.5 mm γ-Al2O3 pellets as dehydration catalyst and operated in a temperature range of 543-603 K at an atmospheric pressure. Also, the effects of weight hourly space velocity (WHSV) and temperature on methanol conversion were investigated. According to the results, the maximum conversion is obtained at 603.15 K with WHSV of 72.87 h-1. 相似文献
9.
Several pervaporation membranes, cellulose acetate (CA), polyvinylbutyral (PVB), poly(MMA-co-AA), MMA-AA-BA, CA/PVB blend and CA/poly(MMA-co-AA) blend, were prepared, and their pervaporation properties were evaluated by separation of methanol/C5 or methanol/MTBE (methyl tert-butyl ether). The results shows that the CA composite membrane has a high separation performance (flux Jmenthanol =350g.m-2.h-1 and separation factor a > 400) for methanol/C5 mixtures, and the pervaporation characteristics of MMA-AA-BA copolymer membranes changes with the ratio of copolymer. For CA/poly(MMA-co-AA) blend membrane, the pervaporation performance is improved in comparison with CA or poly(MMA-co-AA) membrane. From the experiment of CA/PVB blend membranes for methanol/MTBE mixture, it is found that the compatibility of blends may affect the separation features of blend membrane. 相似文献
10.
Pervaporation has attracted considerable interest owing to its potential application in recovering biobutanol from biomass acetone-butanol-ethanol (ABE) fermentation broth. In this study, butanol was recovered from its aqueous solution using a polydimethylsiloxane (PDMS)/ceramic composite pervaporation membrane. The effects of operating temperature, feed concentration, feed flow rate and operating time on the membrane pervaporation per-formance were investigated. It was found that with the increase of temperature or butanol concentration in the feed, the total flux through the membrane increased while the separation factor decreased slightly. As the feed flow rate increased, the total flux increased gradually while the separation factor changed little. At 40 C and 1% (by mass) butanol in the feed, the total flux and separation factor of the membrane reached 457.4 g•m2•h1 and 26.1, respec-tively. The membrane with high flux is suitable for recovering butanol from ABE fermentation broth. 相似文献
11.
Qijun GAO Mianyan HUANG Yuxin WANG Yuquan CAI Li XU 《Frontiers of Chemical Engineering in China》2008,2(1):95-101
Sulfonated poly(ether ether ketone) (SPEEK) is a very promising alternative membrane material for direct methanol fuel cells.
However, with a fairly high degree of sulfonation (DS), SPEEK membranes can swell excessively and even dissolve at high temperature.
This restricts membranes from working above a high tolerable temperature to get high proton conductivity. To deal with this
contradictory situation, insolvable zirconium tricarboxybutylphosphonate (Zr(PBTC)) powder was employed to make a composite
with SPEEK polymer in an attempt to improve temperature tolerance of the membranes. SPEEK/Zr(PBTC) composite membranes were
obtained by casting a homogeneous mixture of Zr(PBTC) and SPEEK in N,N-dimethylacetamide on a glass plate and then evaporating
the solvent at 60°C. Many characteristics were investigated, including thermal stability, liquid uptake, methanol permeability
and proton conductivity. Results showed significant improvement not only in temperature tolerance, but also in methanol resistance
of the SPEEK/Zr(PBTC) composite membranes. The membranes containing 30 wt-% ∼ 40 wt-% of Zr(PBTC) had their methanol permeability
around 10−7 cm2·s−1 at room temperature to 80°C, which was one order of magnitude lower than that of Nafion?115. High proton conductivity of
the composite membranes, however, could also be achieved from higher temperature applied. At 100% relative humidity, above
90°C the conductivity of the composite membrane containing 40 wt-% of Zr(PBTC) exceeded that of the Nafion?115 membrane and
even reached a high value of 0.36 S·cm−1 at 160°C. Improved applicable temperature and high conductivity of the compositemembrane indicated its promising application
inDMFC operations at high temperature.
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Translated from Acta Polymerica Sinica, 2007, (4): 337–342 [译自:高分子学报] 相似文献
12.
GAO Qijun HUANG Mianyan WANG Yuxin CAI Yuquan XU Li 《Frontiers of Chemical Science and Engineering》2008,2(1):95
Sulfonated poly(ether ether ketone) (SPEEK) is a very promising alternative membrane material for direct methanol fuel cells. However, with a fairly high degree of sulfonation (DS), SPEEK membranes can swell excessively and even dissolve at high temperature. This restricts membranes from working above a high tolerable temperature to get high proton conductivity. To deal with this contradictory situation, insolvable zirconium tricarboxybutylphosphonate (Zr(PBTC)) powder was employed to make a composite with SPEEK polymer in an attempt to improve temperature tolerance of the membranes. SPEEK/Zr(PBTC) composite membranes were obtained by casting a homogeneous mixture of Zr(PBTC) and SPEEK in N,N-dimethylacetamide on a glass plate and then evaporating the solvent at 60°C. Many characteristics were investigated, including thermal stability, liquid uptake, methanol permeability and proton conductivity. Results showed significant improvement not only in temperature tolerance, but also in methanol resistance of the SPEEK/Zr(PBTC) composite membranes. The membranes containing 30 wt-% ∼ 40 wt-% of Zr(PBTC) had their methanol permeability around 10-7 cm2·s-1 at room temperature to 80°C, which was one order of magnitude lower than that of Nafion ¯115. High proton conductivity of the composite membranes, however, could also be achieved from higher temperature applied. At 100% relative humidity, above 90°C the conductivity of the composite membrane containing 40 wt-% of Zr(PBTC) exceeded that of the Nafion ¯115 membrane and even reached a high value of 0.36 S·cm-1 at 160°C. Improved applicable temperature and high conductivity of the composite membrane indicated its promising application in DMFC operations at high temperature. 相似文献
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15.
Fuqiang Hu Fei Zhong Jie Wang Ting Qu Jing Ni Genwen Zheng Chunli Gong Hai Liu 《大分子材料与工程》2021,306(6):2100053
New types of metal–organic framework based hybrid materials are designed and prepared, which involving the hybridization of various content of boron phosphate (BPO4) with the precursor of HKUST-1. The structure of obtained HKUST-1/BPO4 hybrid materials (HB) is fully investigated, and then applied to construct sulfonated poly (ether ether ketone) (SPEEK) based proton exchange membranes (SPEEK/HB). Owing to effective interactions between hybrid materials and SPEEK matrix, the achieved composite membranes reflect a considerable improvement in mechanical and thermal stability, oxidative stability, methanol permeation, and proton conductivity. In particular, the tensile strength of SPEEK/HB-20 composite membrane is 41.3 MPa, which is 1.5 times higher than pristine SPEEK, and the methanol permeability reduced to one-third of SPEEK at the same time. The SPEEK/HB-10 displays the highest proton conductivity of 37.4 mS cm−1 at 80 °C, which is obviously higher than pristine SPEEK. These results reveal that the hybridization of HKUST-1 with BPO4 provide a promising candidate in the modification of proton exchange membranes (PEMs), and this strategy also possess great application potential in other types of MOFs-based hybrid materials. 相似文献
16.
Tiezhu Fu Shuangling Zhong Zhiming Cui Chengji Zhao Yuhua Shi Wenzhi Yu Hui Na Wei Xing 《应用聚合物科学杂志》2009,111(3):1335-1343
A crosslinked epoxy [4,4′‐diglycidyl‐(3,3′,5,5′‐tetramethylbiphenyl) epoxy resin (TMBP)], cured by phenol novolac (PN), was introduced into a sulfonated poly(ether ether ketone) (SPEEK) membrane (ion‐exchange capacity = 2.0 mequiv/g) with a casting‐solution, evaporation, and heating crosslinking method to improve the mechanical properties, dimensional stability, water retention, and methanol resistance. By Fourier transform infrared analysis, the interactions between the sulfonic acid groups and hydroxyl groups in the blend membranes were confirmed. The microstructure and morphology of the blend membranes were investigated with atomic force microscopy. As expected, the blend membranes showed excellent mechanical properties, good thermal properties (thermal stability above 200°C), lower swelling ratios (1.4% at 25°C and 7.0% at 80°C), higher water retention (water diffusion coefficient = 9.8 × 10?6 cm2/s), and a lower methanol permeability coefficient (3.6 × 10?8 cm2/s) than the pristine SPEEK membrane. Although the proton conductivity of the blend membranes decreased, a higher selectivity (ratio of the proton conductivity to the methanol permeability) was obtained than that of the pristine SPEEK membrane. The results showed that the SPEEK/TMBP/PN blend membranes could have potential use as proton‐exchange membranes in direct methanol fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
17.
The ethylenediamine-modified graphite oxide (EGO)-doped sulfonated poly (arylene ether ketone) (SPEEK) composite membranes have been prepared and developed for fuel cell applications in the present work. The base-modified EGO improves the dispersion of inorganic nanosheet in the polymer matrix and enhances proton conductivity by creating continuous conduction pathways. Furthermore, the methanol barrier property also be enhanced due to the nanosheet block the methanol-transport channels. EGO-filled membranes display improved dimensional stability, proton conductivity, and ethanol permeability than those using SPEEK control and graphite oxide (GO)-filled membranes. In the direct methanol fuel cells (DMFCs), the SPEEK/EGO-1.5 membrane displays the highest current density of 395.9 mA/cm2 at 60°C, which is 1.6- and 1.4-fold higher than that of SPEEK (254.0 mA/cm2) and SPEEK/GO membrane (292.6 mA/cm2). 相似文献
18.
Sulfonated poly(ether ether ketone) (SPEEK)/clay hybrid membranes were prepared using three types of commercially available clays, the sodium montmorillonite (IC), hydrophobic organo‐clay with long alkyl chains (OC), and organo‐clay with carboxylic acid end groups (HC). It was found that the SPEEK/HC hybrid membranes achieved the best clay dispersion, with the exfoliation of the clay nano‐platelets when the filler loading was < 10 wt%. The incorporation of the carboxylic acid groups in clay layers also improved the connectivity between the ionic clusters in the membrane, resulting in higher proton conductivity without compromising the dimensional stability of membranes. The selectivity higher than the pristine SPEEK membranes was obtained for the SPEEK/HC hybrid membranes at low filler loading (<10 wt%), with higher proton conductivity and similar methanol permeability. POLYM. COMPOS., 37:2632–2638, 2016. © 2015 Society of Plastics Engineers 相似文献
19.
Mixed matrix membranes based on zeolite 4A‐methane sulfonic acid (MSA)‐sulfonated poly(ether ether ketone) (SPEEK) are evaluated as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cells (DMFCs). Ion‐exchange capacity, sorption of water, and water–methanol mixture, proton conductivity, and methanol permeability for the mixed‐matrix membranes have been extensively investigated. The mixed‐matrix membranes are also characterized for their cross‐sectional morphology, mechanical, and thermal properties. DMFCs employing SPEEK‐MSA (20 wt.%) blend, zeolite 4A (4 wt.%)‐SPEEK‐MSA (20 wt.%) mixed matrix membranes deliver peak power densities of 130 and 159 mW cm–2, respectively; while a peak power density of only 95 mW cm–2 is obtained for the DMFC employing pristine SPEEK membrane at 70 °C. The results showed that these SPEEK based mixed matrix membranes exhibit higher DMFC performance and lower methanol permeability in comparison to Nafion‐117 membrane. 相似文献