共查询到20条相似文献,搜索用时 31 毫秒
1.
H. SchoemanH.M. Krieg A.J. KrugerA. Chromik K. KrajinovicJ. Kerres 《International Journal of Hydrogen Energy》2012,37(1):603-614
For hydrogen to become a serious contender for replacing fossil fuels, the manufacturing thereof has to be further investigated. One such process, the membrane based Hybrid Sulfur (HyS) process, where hydrogen is produced from the electrolysis of SO2, has received considerable interest recently. Since H2SO4 is formed during SO2 electrolysis, H2SO4 stability is a prerequisite for any membrane to be used in this process. In this study, pure as well as blended polybenzimidazole (PBI), partially fluorinated poly(arylene ether) (sFS) and nonfluorinated poly(arylene ethersulfone) (sPSU) membranes were investigated in terms of their acid stability as a function of acid concentration. Membranes were characterized using weight change, TGA, GPC, SEM/EDX and IEC. While a general stability was observed at 30 and 60 wt% H2SO4, the blended sFS-PBI and sPSU-PBI showed the highest stability throughout. According to the VI curve obtained for the SO2 electrolysis, the sPSU-PBI blend membrane performed slightly better than Nafion®117. 相似文献
2.
Chuan-Yu Yen Chia-Hsun Lee Yu-Feng Lin Hsiu-Li Lin Yi-Hsiu Hsiao Shu-Hang Liao Chia-Yi Chuang Chen-Chi M. Ma 《Journal of power sources》2007
Sulfonated-silica/Nafion® composite membranes were prepared in a sol–gel reaction of (3-Mercaptopropyl)trimethoxysilane (SH-silane) followed by solution casting, and then oxidated using 10 wt% H2O2 solution. The chemical and physical properties of the composite membranes were characterized by using FT-IR, XPS, 29Si NMR and SEM analyses. Experimental results indicated that the optimum oxidation condition was 60 °C for 1 h. The performance of the silica–SO3H/Nafion® composite membranes was evaluated in terms of methanol permeability, proton conductivity and cell performance. The silica–SO3H/Nafion® composite membranes have a higher selectivity (C/P ratio = 26,653) than that of pristine Nafion® (22,795), perhaps because of their higher proton conductivity and lower methanol permeability. The composite membrane with 0.6 wt% silica–SO3H/Nafion® performed better than pristine Nafion®. The current densities were measured as 62.5 and 70 mA cm−2 at a potential of 0.2 V with a composite membrane that contained 0 and 0.6 wt% silica–SO3H, respectively. The cell performance of the DMFC was improved by introducing silica–SO3H. The composite membrane with 0.6 wt% of silica–SO3H yielded the maximum power density of 15.18 mW cm−2. The composite membranes are suitable for DMFC applications with high selectivity. 相似文献
3.
K.B. Kokoh E. Mayousse T.W. Napporn K. Servat N. Guillet E. Soyez A. Grosjean A. Rakotondrainibé J. Paul-Joseph 《International Journal of Hydrogen Energy》2014
Anode catalysts synthesized by the thermal decomposition method were used for splitting water in PEM electrolysis cells. Although the area resistance of the ternary anode materials increased, the Ti content in the ruthenium and iridium based catalysts have led to an energy consumption of 4.5 kWh/Nm3(H2) at 60 °C. The Membrane Electrode Assemblies have given information on the strong dependence of the membrane thickness. The crossover of hydrogen through Nafion®117 is two-fold lower than that measured in the presence of Nafion®115. Life testing was attempted with supplying the electrolyzer by solar power source. Importantly, the proton exchange membrane water electrolyzer (PEMWE) cell has involved a constant cell voltage at 1 A cm−2 over 800 h durability tests. 相似文献
4.
The SO2 transport properties of Nafion® and sPEEK membranes were measured using an electrochemical reaction cell to investigate their application in the electrochemical hybrid sulfur process. The permeability of SO2 in the membranes was determined from a combined theory based on Faraday's law and Fick's law where the electrochemical reaction rate of SO2 in the downstream membrane is the same as its diffusion flux through the membrane. Both Nafion® and sPEEK membranes show higher SO2 diffusion coefficients at higher temperatures. For sPEEK membranes, increasing the degree of sulfonation resulted in increasing permeability, as more water was imbibed in the membranes with higher degrees of sulfonation. Activation energy was extracted from the temperature-dependence of the diffusion coefficients for both membranes. The sPEEK membranes exhibited similar diffusion coefficients to those of Nafion®, even at high sulfonation degrees of 70%. Besides SO2 permeability, proton conductivity and mechanical properties were measured for comparison between the 2 polymer membranes. Although the proton conductivity of the sPEEK was slightly lower than the Nafion® membrane, it was very competitive considering its higher mechanical strength and much lower cost. 相似文献
5.
Yongsheng Wei Saif Matar Liangbo Shen Xinwei Zhang Zhijun Guo Hong Zhu Hongtan Liu 《International Journal of Hydrogen Energy》2012
Systematic experiments have been carried out to study the performance of the novel sodium titanate (Na2Ti3O7) nanotube/Nafion® composite membrane (5 wt% Na2Ti3O7) in a single direct methanol fuel cell (DMFC) at different operating temperatures, methanol concentrations, air flow rates, methanol flow rates, and cathode humidification temperatures. The experimental results showed that the composite membrane outperform pure Nafion® membranes with the same thickness, Nafion®112, under all the operating conditions. Furthermore, under some operating conditions, the new composite membranes even outperform Nafion®117, a much thicker membrane. These experimental results have proved that the new composite membrane is superior to pure Nafion® membrane in DMFCs and the addition of Na2Ti3O7 nanotubes into Nafion® is an effective way to improve membrane performances. 相似文献
6.
Lili Sun Suli Wang Wei Jin Hongying Hou Luhua Jiang Gongquan Sun 《International Journal of Hydrogen Energy》2010
In this paper, Fe2O3–SO42−/Nafion® composite membranes were prepared by a solution casting method. The physico-chemical properties of composite membranes were characterized by X-ray diffraction (XRD), SEM–EDX and thermogravimetric analysis (TGA). The water uptake ability, proton conductivity, and methanol permeability of the composite membranes were evaluated and compared with the recast Nafion® membrane. The results showed that the proton conductivity and the water uptake of the composite membranes were slightly higher than that of the recast Nafion® membrane. The composite membrane containing 5 wt.% Fe2O3–SO42- showed superior ability to suppress methanol crossover, and it further improved the direct methanol fuel cell (DMFC) performances with both 1 M and 5 M methanol feeding, compared with the recast Nafion® membrane. The preliminary 30 h lifetime test of the DMFC with the composite membrane with 5% Fe2O3–SO42− indicated that the composite membrane is stable working at the real DMFC operating conditions at least during the test. These results suggest the applicability of the composite membranes in DMFCs. 相似文献
7.
Yu-Feng Lin Yi-Hsiu Hsiao Chuan-Yu Yen Chin-Lung Chiang Chia-Hsun Lee Ching-Chun Huang Chen-Chi M. Ma 《Journal of power sources》2007
A novel functional poly(propylene oxide)-backboned diamine of Mw 400 (abbreviated as D400) was grafted with sulfonic acid (abbreviated as D400-PS) to improve the performance of Nafion® membranes in direct methanol fuel cells (DMFCs). The interaction of the D400-PS with Nafion® was studied by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The performance of the blend Nafion®/D400-PS membranes was evaluated in terms of methanol permeability, proton conductivity and cell performance. The proton conductivity of the blend membrane was slightly reduced by rendering proton conductivity to D400 by functionalized with an organic sulfonic acid. The methanol permeability of the blend membrane decreased with increasing of D400-PS content. The methanol permeability of the blend Nafion®/D400-PS with the composition 3/1 (–SO3H/–NH2) was 1.02 × 10−6 cm2 S−1, which was reduced 50% compared to that of pristine Nafion®. The current densities that were measured with Nafion®/D400-PS blend membranes in the ratio 1/0 and 5/1 (–SO3H/–NH2), were 51 and 72 mA cm−2, respectively, at a potential of 0.2 V. Consequently, the blend Nafion®/D400-PS membranes critically improved the single-cell performance of DMFC. 相似文献
8.
An improved solution-cast method is presented to prepare multi-wall carbon nanotubes (MWCNTs)/Nafion® reinforced membrane with different MWCNTs content (from 1 to 4 wt.%). MWCNTs were oxidized by H2O2 and sodium hydroxide (NaOH) was added into the MWCNTs/Nafion®/N,N-dimethylacetamide (DMAC) solution. The long-term stability of the resulting dispersions was much better than the unmodified dispersions. The as-cast membrane was observed by scanning electron microscope (SEM). The MWCNTs were uniformly dispersed in the Nafion® resin. The tensile strength and the elongation at break were greatly improved for the reinforced membranes compared to the recast Nafion® membranes (54 and 27%, respectively). The fuel cell performance of the reinforced membranes with different MWCNTs contents was also tested at 80 °C under fully humidified conditions. By comparing the mechanical properties, proton conductivity and fuel cell performance of the reinforced membranes, we concluded that the content of MWCNTs in the reinforced membranes should not exceed 3 wt.%. The MWCNTs/Nafion® reinforced membrane with 3 wt.% MWCNTs content showed the best mechanical characteristics and excellent fuel cell performance. 相似文献
9.
Yongsheng WeiLiangbo Shen Zhongming WangWein-Duo Yang Hong Zhu Hongtan Liu 《International Journal of Hydrogen Energy》2011,36(8):5088-5095
In this study, novel sodium titanate (Na2Ti3O7) nanotube/Nafion® composite membranes were prepared by a solution casting method. The properties of these composite membranes were studied using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Additionally, the water uptake, methanol permeability, proton conductivity, and selectivity of the composite membranes were measured to evaluate the applicability of these membranes in DMFCs. It was found that the addition of Na2Ti3O7 nanotubes enhanced the water uptake and reduced the methanol permeability of the composite membranes. The proton conductivity and methanol permeability depend on the Na2Ti3O7 nanotube content. Using the selectivity, the optimal nanotube contents was found to be 5 wt%. The new composite membrane was found to have significantly higher selectivity than a pure Nafion® membrane and thus has good potential to outperform Nafion® in DMFCs. 相似文献
10.
Andries J. Krüger Henning M. Krieg Jan van der Merwe Dmitri Bessarabov 《International Journal of Hydrogen Energy》2014
Membrane electrode assembly (MEA) manufacturing parameters such as hot pressing pressure and pressing time were investigated for the use in a SO2 electrolyser. The SO2 electrolysis was optimised in terms of cell temperature, membrane thickness and catalyst loading. The electrolysis efficiency was evaluated using polarisation curves while electrochemical impedance spectroscopy (EIS) was used to determine the membrane resistance, activation energy and mass transport limitations. An electrical circuit, which included inductance, ohmic resistance, charge transfer, constant phase and Warburg elements, was used to fit the experimental data. The optimum hot pressing conditions were 50 kg cm−2 for 5 min at 120 °C. Increased cell temperature (80 °C) resulted in a reduction of mass transport, while thicker membranes resulted in an increased mass transport due to lower water transport through the membrane. Increased catalyst loading (from 0.3 to 1 mgPtC.cm−2) improved the cell performance due to improved kinetics confirmed by the EIS data. 相似文献
11.
Ki Tae Park Un Ho JungDong Woong Choi Kook ChunHyang Mee Lee Sung Hyun Kim 《Journal of power sources》2008
Recast Nafion® composite membranes containing ZrO2–SiO2 binary oxides with different Zr/Si ratios are investigated for polymer electrolyte membrane fuel cells (PEMFCs) at temperatures above 100 °C. Fine particles of the ZrO2–SiO2 binary oxides, same as an inorganic filter, are synthesized from a sodium silicate and a carbonate complex of zirconium by a sol–gel technique. The composite membranes are prepared by blending a 10% (w/w) Nafion®-water dispersion with the inorganic compound. All composite membranes show higher water uptake than unmodified membranes, and the proton conductivity increases with increasing zirconia content at 80 °C. By contrast, the proton conductivity decreases with zirconia content for the composite membranes containing binary oxides at 120 °C. The composite membranes are tested in a 9-cm2 commercial single cell at both 80 °C and 120 °C in humidified H2/air under different relative humidity (RH) conditions. Composite membrane containing the ZrO2–SiO2 binary oxide (Zr/Si = 0.5) give the best performance of 610 mW cm−1 under conditions of 0.6 V, 120 °C, 50% RH and 2 atm. 相似文献
12.
David AiliMartin Kalmar Hansen Chao PanQingfeng Li Erik ChristensenJens Oluf Jensen Niels J. Bjerrum 《International Journal of Hydrogen Energy》2011,36(12):6985-6993
Proton exchange membrane steam electrolysis at temperatures above 100 °C has several advantages from thermodynamic, kinetic and engineering points of view. A key material for this technology is the high temperature proton exchange membrane. In this work a novel procedure for preparation of Nafion® and polybenzimidazole blend membranes was developed. Homogeneous binary membranes covering the whole composition range were prepared and characterized with respect to chemical and physiochemical properties such as water uptake, phosphoric acid doping, oxidative stability, mechanical strength and proton conductivity. An MEA based on phosphoric acid doped Nafion® was operated at 130 °C at ambient pressure with a current density of 300 mA cm−2 at 1.75 V, with no membrane degradation observed during a test of 90 h. The PBI based MEAs showed better polarization curves (500 mA cm−2 at 1.75 V) but poor durability. 相似文献
13.
Chao JinChenghao Yang Fei ZhaoDaan Cui Fanglin Chen 《International Journal of Hydrogen Energy》2011,36(5):3340-3346
La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) has been applied as hydrogen electrode (cathode) material in solid oxide electrolysis cells operating with different steam concentrations (20, 40, 60 and 80 vol.% absolute humidity (AH)) using 40 sccm H2 carrier gas at 800, 850 and 900 °C, respectively. Impedance spectra and voltage-current curves were measured as a function of cell electrolysis current density and steam concentration to characterize the cell performance. The cell resistance decreased with the increase in electrolysis current density while increased with the increase in steam concentration under the same electrolysis current density. At 1.6 V applied electrolysis voltage, the maximum consumed current density increased from 431 mA cm−2 for 20 vol.% AH to 593 mA cm−2 for 80 vol.% AH at 850 °C. Polarization and impedance spectra experiments revealed that LSCM-YSZ hydrogen electrode played a major role in the electrolysis reaction. 相似文献
14.
Zhimou Wu Gongquan Sun Wei Jin Qi Wang Hongying Hou Kwong-Yu Chan Qin Xin 《Journal of power sources》2007
Commercial Nafion®-115 (trademark registered to DuPont) membranes were modified by in situ polymerized phenol formaldehyde resin (PFR) to suppress methanol crossover, and SO3− groups were introduced to PFR by post-sulfonatation. A series of membranes with different sulfonated phenol formaldehyde resin (sPFR) loadings have been fabricated and investigated. SEM-EDX characterization shows that the PFR was well dispersed throughout the Nafion® membrane. The composite membranes have a similar or slightly lower proton conductivity compared with a native Nafion® membrane, but show a significant reduction in methanol crossover (the methanol permeability of sPFR/Nafion® composite membrane with 2.3 wt.% sPFR loading was 1.5 × 10−6 cm2 s−1, compared with the 2.5 × 10−6 cm2 s−1 for the native Nafion® membrane). In direct methanol fuel cell (DMFC) evaluation, the membrane electrode assembly (MEA) using a composite membrane with a 2.3 wt.% sPFR loading shows a higher performance than that of a native Nafion® membrane with 1 M methanol feed, and at higher methanol concentrations (5 M), the composite membrane achieved a 114 mW cm−2 maximum power density, while the maximum power density of the native Nafion® was only 78 mW cm−2. 相似文献
15.
Liliane C. Battirola José F. Schneider Íris C.L. Torriani Germano Tremiliosi-Filho Ubirajara P. Rodrigues-Filho 《International Journal of Hydrogen Energy》2013
Nafion® 117 membranes doped with Pt (4 × 10−4 mol L−1 or 8 × 10−4 mol L−1 H2PtCl6 solution), and with Pt–Ru (4 × 10−4 mol L−1 H2PtCl6 and 2 × 10−4 mol L−1 RuCl3 solutions) nanoparticles have been synthesized using a simple and scalable absorption-reduction method. The chemical integrity of the membranes was confirmed by 13C and 19F solid-state NMR. The pore microstructure of the membranes was preserved after the doping process, according to SAXS measurements. The tests of the direct ethanol fuel cells (DEFC) performance at 90 °C exhibited up to 38% and 56% increase at the maximum power densities for Pt doped-Nafion® membrane from lower and higher concentration of H2PtCl6 solution, respectively, compared to bare Nafion® membranes. Additionally, a Pt–Ru doped-membrane tested at 110 °C exhibited the highest power density. Such superior performances may be attributed to a synergistic effect between the extra amount of active catalytic sites inside the pore structure for the electrochemical oxidation of ethanol, thus preventing ethanol crossover, and the excellent proton migration properties conferred by the pore microstructure of Nafion®. These results demonstrate that the doped-Nafion® membrane has a good capacity to improve the performance of DEFC, and provided further clarification on the synthesis process of polymer electrolyte doped-membranes in fuel cell technology. 相似文献
16.
The chemical stability, sulfur dioxide transport, ionic conductivity, and electrolyzer performance have been measured for several commercially available and experimental proton exchange membranes (PEMs) for use in a sulfur dioxide depolarized electrolyzer (SDE). The SDEs function is to produce hydrogen by using the Hybrid Sulfur (HyS) Process, a sulfur-based electrochemical/thermochemical hybrid cycle. Membrane stability was evaluated using a screening process where each candidate PEM was heated at 80 °C in 60 wt% H2SO4 for 24 h. Following acid exposure, chemical stability for each membrane was evaluated by FTIR using the ATR sampling technique. Membrane SO2 transport was evaluated using a two-chamber permeation cell. SO2 was introduced into one chamber whereupon SO2 transported across the membrane into the other chamber and oxidized to H2SO4 at an anode positioned immediately adjacent to the membrane. The resulting current was used to determine the SO2 flux and SO2 transport. Additionally, membrane electrode assemblies (MEAs) were prepared from candidate membranes to evaluate ionic conductivity and selectivity (ionic conductivity vs. SO2 transport) which can serve as a tool for selecting membranes. MEAs were also performance tested in a HyS electrolyzer measuring current density vs. a constant cell voltage (1 V, 80 °C in SO2 saturated 30 wt% H2SO4). Finally, candidate membranes were evaluated considering all measured parameters including SO2 flux, SO2 transport, ionic conductivity, HyS electrolyzer performance, and membrane stability. Candidate membranes included both PFSA and non-PFSA polymers and polymer blends of which the non-PFSA polymers, BPVE-6F and PBI, showed the best selectivity. 相似文献
17.
A novel functional organoclay was prepared using POP-backboned quaternary ammonium salts that contained sulfonic acid (–SO3H) to improve the performance of Nafion® membranes used in direct methanol fuel cells. Modified layered silicate clays were cast with Nafion®. The performance of the Nafion®/MMT-POPD400-PS composite membranes was evaluated in terms of methanol permeability, proton conductivity and cell performance. The methanol permeability of the composite membrane declined as the MMT-POPD400-PS content increased. The MMT was functionalized using organic sulfonic acid to enhance proton conductivity. The proton conductivity of the composite membrane exceeded that of pristine Nafion®. These effects essentially improved the single-cell performance of DMFC. 相似文献
18.
Yu-Feng Lin Chuan-Yu Yen Chen-Chi M. Ma Shu-Hang Liao Chia-Hsun Lee Yi-Hsiu Hsiao Hong-Ping Lin 《Journal of power sources》2007
A novel organic–inorganic mesoporous silica (L64 copolymer-templated mesoporous SiO2), functionalized with perfluoroalkylsulfonic acid groups analogous to that of Nafion®, was prepared. A condensation reaction between the surface silanol groups of the mesoporous silicas and 1,2,2-trifluoro-2-hydroxy-1-trifluoromethylethane sulfonic acid Beta-sultone was conducted. High proton-conducting Nafion®/functionalized mesoporous silica composite membranes were prepared via homogeneous dispersive mixing and the solvent casting method. In this investigation, the proton conductivity (σ) of the composite membrane is increased from 0.10 to 0.12 (S cm−1) as the modified mesoporous silica content is increased from 0 to 3 wt%. The methanol permeability of the composite membrane declined as the sulfonic mesoporous silica content increased. The methanol permeability of the composite membrane that contained 3 wt% M–SiO2–SO3H was 4.5 × 10−6 cm2 S−1—30% lower than that of pristine Nafion®. Results of this study demonstrate a significant improvement in the performance of DMFCs. 相似文献
19.
Chen-Chi M. Ma Yi-Hsiu Hsiao Yu-Feng Lin Chuan-Yu Yen Shu-Hang Liao Cheng-Chin Weng Ming-Yu Yen Min-Chien Hsiao Fang-Bor Weng 《Journal of power sources》2008
Various molecular weights of poly(propylene oxide) diamines oligomers/Nafion® acid–base blend membranes were prepared to improve the performance of Nafion® membranes in direct methanol fuel cells (DMFCs). The acid–base interactions were studied by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The performance of the blend membranes was evaluated in terms of methanol permeability, proton conductivity and cell performance. The proton conductivity was slightly reduced by acid–base interaction. The methanol permeability of the blend D2000/Nafion® was 8.61 × 10−7 cm2 S−1, which was reduced 60% compared to that of pristine Nafion®. The cell performance of D2000/Nafion® blend membranes was enhanced significantly compared to pristine Nafion®. The current densities that were measured with Nafion® and 3.5 wt% D2000/Nafion® blend membranes were 62.5 and 103.5 mA cm−2, respectively, at a potential of 0.2 V. Consequently, the blend poly(propylene oxide) diamines oligomers/Nafion® membranes critically improved the single-cell performance of DMFC. 相似文献
20.
Sergio MolláVicente Compañ 《Journal of power sources》2011,196(5):2699-2708
This work has been focused on the characterization of the methanol permeability and fuel cell performance of composite Nafion/PVA membranes in function of their thickness, which ranged from 19 to 97 μm. The composite membranes were made up of Nafion® polymer deposited between polyvinyl alcohol (PVA) nanofibers. The resistance to methanol permeation of the Nafion/PVA membranes shows a linear variation with the thickness. The separation between apparent and true permeability permits to give an estimated value of 4.0 × 10−7 cm2 s−1 for the intrinsic or true permeability of the bulk phase at the composite membranes. The incorporation of PVA nanofibers causes a remarkable reduction of one order of magnitude in the methanol permeability as compared with pristine Nafion® membranes. The DMFC performances of membrane-electrode assemblies prepared from Nafion/PVA and pristine Nafion® membranes were tested at 45, 70 and 95 °C under various methanol concentrations, i.e., 1, 2 and 3 M. The nanocomposite membranes with thicknesses of 19 μm and 47 μm reached power densities of 211 mW cm−2 and 184 mW cm−2 at 95 °C and 2 M methanol concentration. These results are comparable to those found for Nafion® membranes with similar thickness at the same conditions, which were 210 mW cm−2 and 204 mW cm−2 respectively. Due to the lower amount of Nafion® polymer present within the composite membranes, it is suggested a high degree of utilization of Nafion® as proton conductive material within the Nafion/PVA membranes, and therefore, significant savings in the consumed amount of Nafion® are potentially able to be achieved. In addition, the reinforcement effect caused by the PVA nanofibers offers the possibility of preparing membranes with very low thickness and good mechanical properties, while on the other hand, pristine Nafion® membranes are unpractical below a thickness of 50 μm. 相似文献