由氢、氧催化合成过氧化氢新工艺

日本东京工业学院科学家们声称，已开发了一种在燃料电池反应器中由氢、氧催化合成过氧化氢新工艺。已知的氢、氧直接化合法中，反应混合物具有高爆炸性。且生成过氧化氢的选择性低，采用燃料电池体系可防止爆炸，因反应物氢、氧是被隔膜分开的，反应器采用多孔电极将三相隔开，从而防止过氧化氢被竞争还原为水。电极效率随添加剂的介入而得到提高，添加剂可为炭黑。     

固态质子导体型燃料电池反应器

将固态质子导体型燃料电池作为新型反应器用于合成化学品,产物选择性高,能耗低,可以实现电能与化学品共生.通过对反应器操作参数的调变,可以获得预期的化学产品及相应的电化学特性.本工作综述了固态质子导体型燃料电池反应器在简单无机物加氢、具有不饱和键脂肪族和芳香族化职物加氢、醇脱氢以及烷烃脱氢等反应中的应用.随着对该反应过程认...     

由氢、氧催化合成过氧化氢新工艺

日本东京工业学院科学家们声称，已开发出一种在燃料电池反应器中由氢、氧催化合成过氧化氢新工艺。已知的氢、氧直接化合法中，反应剂混合物具有高爆炸性，且生成过氧化氢的选择性低，采用燃料电池体系可防止爆炸，因反应剂氢、氧是被隔膜分开的，反应器采用多孔电极将3相隔开，从而防止过氧化氢被竞争还原成水。电极效率随添加剂的介入而得到提高，添加剂可以为炭黑。     

管式反应器在电化学中的应用

介绍了电化学管式反应器的结构、特点和管式电化学反应系统的组成,综述了电化学管式反应器在工业废水、生活污水等有机废水处理方面的研究与应用,以及在重金属回收处理、燃料电池等领域的研究情况。管式反应器中流体运动规律、电催化反应过程机制、新型高效电极材料的研制和反应器运行模式的研究是今后管式电反应器应用应重点研究解决的问题。     

氢燃料电池中氢氧耦合过程研究

以氢燃料电池低温启动过程模拟为依据,设计微反应器的氢氧催化反应,对氢空混气催化过程状态进行分析.氢燃料电池的低温启动问题体现在:在冰点以下环境中,电池内部的液态水发生冻结,造成启动缓慢甚至启动失败.文中提出了一种新的思路,通过气体流动过程分析反应情况,调节反应中氢空参数,考察上述参数对反应过程和反应效率的影响,用研究数...     

燃料电池电催化剂的研究进展

燃料电池是一种将化学能转化为电能的装置,催化剂的制备方法是燃料电池电极催化剂开发中重要课题之一。将催化剂担载到多孔、大表面积的载体上,或将催化剂制作成纳米结构可极大的提高催化剂利用效率,同时也可防止燃料电池在使用过程中催化剂的团聚。铂是目前为止认为最有效的催化剂,将其制作成纳米中空球结构和纳米线结构,然后负载到碳载体上可显著提高其催化性能和利用效率。     

微生物燃料电池应用及性能优化研究进展

微生物燃料电池作为新型微生物传感器,既能降解水中污染物也可以通过微生物产电输出电能。通常将污染物降解效率和产电功率作为衡量燃料电池性能好坏的重要参数,反应器构型是影响微生物燃料电池产电性能与降解效果的关键。归纳了光电极微生物燃料电池、自分层微生物燃料电池和人工湿地-微生物燃料电池这3种构型的反应器机理及对废水的适用性,总结了电极材料、电子介体、分隔膜材料等因素对燃料电池产电性能影响的研究进展。     

金属卟啉制备及其电化学特性

引　言燃料电池作为环境友好的发电方式已经得到广泛的认同 ,另外 ,燃料电池也可作为氢化反应器实现化学品与电能共生[1,2 ] .燃料电池的核心是膜电极的制备[3,4 ] .如何降低燃料电池成本是研究者关注的焦点 ,开发新型的非贵金属电催化剂是降低成本的途径之一 .金属卟啉化合物具有高的共轭结构和化学稳定性 ,对分子氧表现出良好的电催化还原活性 ,近年来逐渐成为燃料电池氧还原电催化剂的研究热点 ,以期取代贵金属作为燃料电池和金属空气电池氧还原催化剂 .目前 ,四苯基卟啉 (TPP)、四甲氧基苯基卟啉 (TMPP)是研究较多的卟啉化合物 ,而与…     

低浓度瓦斯燃料电池发电技术研究

为了解决我国矿井风排瓦斯因浓度低、不易利用而直接排放,污染空气这一难题,提出了低浓度、超低浓度瓦斯燃料电池中发生氧化还原反应产生电能的瓦斯利用新技术。该技术是将低浓度瓦斯与氧气分别从燃料电池的不同电极充入池内,发生得失电子的化学反应,将化学能转化为电能,可以将这部分电能加以储存利用。分析表明:瓦斯在燃料电池中氧化产生的电能比其经过其他形式产生的电能高50%。此外,瓦斯燃料电池发电利用技术还具有不受瓦斯浓度、湿度、杂质等因素制约的优点,有效地克服了低浓度瓦斯在内燃机中燃爆发电等技术的弊端。     

组合式再生燃料电池双效氧电极催化剂制备与表征

介绍了组合式再生燃料电池基本特点,简要回顾了组合式再生燃料电池中双效氧电极催化剂研究现状。利用还原沉积法制备了PtIr／C双效氧电极催化剂,对催化剂进行了XRD表征。以三电极体系对催化剂进行了析氧和溶氧双反应的催化活性评价,结果表明：Pt主要催化燃料电池模式下的溶氧反应,而Ir主要催化水电解模式下的析氧反应。     

Nafion modified with simple bases and amino acid derivatives: Survey of physical properties and search for effective pervaporation membranes

Nafion, a solid perfluorinated polymeric sulfonic acid, reacts readily with bases and can thus be converted to a tremendous number of individual modifications. A survey of spectral, mechanical, thermal, and pervaporation characteristics of Nafion modified with simple inorganic and organic bases and with the derivatives of amino acids is thus reported. The spectral characteristics, thermal stability, and T_g changed pronouncedly for Nafion modified with the stronger bases, such as ammonium or tris(hydroxymethyl)aminomethane, while minor changes were observed for Nafion modified with the derivatives of amino acids. Permeability and selectivity of Nafion observed for the pervaporation of methanol–dimethyl carbonate and methanol–methyl acetate mixtures were mainly influenced by the modification with amines bearing hydroxyl and, most pronouncedly, sulfo groups. Importantly, the pervaporation membrane from Nafion modified with taurine appeared similarly permeable and hygroscopic but more methanol-selective than that from pure Nafion.     

Novel anion exchange membranes having fluorocarbon backbone: Preparation and stability

Anion exchange membranes with excellent durability were prepared by chemical modification of Nafion. The modification was achieved by transformation of the sulfonic acid group into quaternary ammonium group. Namely, Nafion membrane was first converted into an amide-type membrane. Reduction of the carbonxyl group to methylene followed by quaternarization with alkyl iodide resulted in the formation of an anion exchange membrane. The electric resistance of the resulting membranes depends on the equivalent weight of the starting membranes (4.4–6.0 Ω cm² in 0.5N NaCl). The characteristics of the membranes are the excellent stability toward chemical substances such as organic solvents, oxidizing agents, acids, etc. For example, the membranes are stable in aqueous saturated chlorine solution at 60°C for 1000 hr.     

The electrochemical hydrogenation of edible oils in a solid polymer electrolyte reactor. I. Reactor design and operation

A new electrochemical method has been devised and tested for the moderate temperature/atmospheric pressure hydrogenation of edible oils, fatty acids, and fatty acid methyl esters. The method employed a solid polymer electrolyte (SPE) reactor, similar to that used in H₂/O₂ fuel cells, with water as the source of hydrogen. The key component of the reactor was a membrane-electrode-assembly, composed of a RuO₂ powder anode and either a Pt-black or Pd-black powder cathode that were hot-pressed as thin films onto the opposing surfaces of a Nafion cation-exchange membrane. During reactor operation at a constant applied current, water was back-fed to the RuO₂ anode, where it was oxidized electrochemically to O₂ and H⁺. Protons migrated through the Nafion membrane under the influence of the applied electric field and contacted the Pt or Pd cathode, where they were reduced to atomic and molecular hydrogen. Oil was circulated past the back side of the cathode and unsaturated triglycerides reacted with the electrogenerated hydrogen species. The SPE reactor was operated successfully at a constant applied current density of 0.10 A/cm² and a temperature between 50 and 80°C with soybean, canola, and cottonseed oils and with mixtures of fatty acids and fatty acid methyl esters. Reaction products with iodine values in the range of 60–105 were characterized by a higher stearic acid content and a lower percentage of trans isomers than those produced in a traditional hydrogenation process.     

固体电解质膜对PEMFC电极动力学的影响

研究了不同种类的固体电解质膜对质子交换膜燃料电池性能的影响,采用相同组成的气体扩散电极与制作工艺,分别用Nafion 111、Nafion 112、Nafion 1135、Nafion 115、Dow 800固体电解质膜制成MEA,并组装成单电池,用极化曲线法与交流阻抗法研究了单电池的极化行为与电气特性,并用zsimwin软件模拟了电气特性参数。结果表明,随着固体电解质膜变薄,电池内阻变小,但电池开路电压却反而降低,固体电解质膜的厚度较大(如Nafion 115)或较小(如Nafion 111)都会使电极双电层微分电容变小,使电极电化学反应动力学变差,离子交换容量大的电解质膜电导率大,电极电荷传递阻力较小,反应阻抗小。     

Recast Nafion‐117 thin film from water solution

Perfluorosulfonated ionomer (PFSI) dispersions in various solvents, usually mixtures of organic compounds and water, were used to prepare the membrane‐electrode system in polymer electrolyte membrane fuel cells (PEMFC), the aim being to increase performance by improving the triple contact of graphite (electron conducting material), Pt (hydrogen dissociation catalyst) and ionomeric membrane (proton conducting). When using PFSI dispersions in water‐organic solvent mixture, care must be taken not to poison the Pt catalyst through organic decomposition products, a consequence of the thermal treatment of the electrode‐polymer system bonded with PFSI dispersion. In the present study some procedures for preparing Nafion water dispersion, starting from a Nafion‐117 membrane, are described. The morphological characteristics of the prepared dispersions were compared with Nafion commercial dispersion (NCD). Moreover, membranes with a thickness of 5–20 μm were prepared and characterised, using both the obtained and the NCD dispersions. The obtained data showed that Nafion water dispersion, which can be used to prepare the membrane/electrode system, results in thin membranes that absorb more water than NCD membranes, and have equal and/or higher proton conduction than the NCD.     

微反应器控制的化学反应的选择性

研究利用分子筛、Ｎａｆｉｏｎ薄膜、低密度聚乙烯薄膜和囊泡作为微反应器控制有机光化学反应的方向,提高反应的选择性和可能性。在ＮａＹ沸石或低密度聚乙烯薄膜中,带有长烷基链或醚链的二芳基化合物光二聚只生成分子内的加成产物,而不生成分子间的加成产物,从而在底物浓度很大的情况下,高选择性地合成了大环化合物。通过控制底物和敏化剂分子在ＺＳＭ－５沸石、Ｎａｆｉｏｎ薄膜和囊泡中的分布高选择性地控制烯烃光敏氧化反应     

多孔有机笼在聚丙烯腈纳米纤维表面固载及其复合质子交换膜

质子交换膜（PEM）是质子交换膜燃料电池的核心部件,需具备选择性地快速传递质子的特性。多孔有机笼具有高比表面积、良好的化学稳定性和高吸水特性以及三维连通的质子传递路径,可提升PEM的质子传导性能。本文将多孔有机笼（CC3）原位固载到聚丙烯腈（PAN）纳米纤维表面,与Nafion复合制备了CC3/PAN-Nafion复合质子交换膜,对其结构和性能进行了研究,结果表明：CC3的固载改变了纤维的微观形貌,增加了纤维直径,使纳米纤维比表面积从9.57m²/g增加到113.6m²/g;将CC3/PAN引入复合膜显著提升了CC3/PAN-Nafion的热稳定性、吸水性、阻醇性以及质子传导性能,其中CC3/PAN-Nafion12在100%RH,80℃时质子传导率可达0.165S/cm,较Nafion膜提升了一倍。     

膜反应的应用

介绍了多孔质无机膜、金属膜、固体电解质膜、有机膜等在脱氢、加氢、氧化、甲烷化、NO分解、水蒸气改质及有机合成中的应用情况。     

A design of Nafion-coated bilayered quasi-solid electrolyte for lithium-O2 batteries with high performance

Lithium-air(also known as lithium-oxygen) batteries have attracted considerable global attention in recent years due to their extremely high energy density(11,140 W·h·kg~(-1)).The electrolyte is a key element in lithium-air batteries and the traditional organic electrolyte has great safety risk due to leakage.On the contrary,the polymer electrolyte has the advantages of high safety,high stability and easy processing comparing with the organic liquid electrolytes.In this paper,a new idea was proposed to coat the Nafion membrane on a layer of polymer for blocking the oxidation reduction electric(RM) and Li based on the selective permeability on lithium ion of the Nafion membrane.Self-made thicknesscontrollable Nafion membrane,polyvinylidene fluoride-hexafluoropropylene copolymer(PVDF-HFP)and 2,2,6,6-tetramethylpiperidinooxy(TEMPO) were used to prepare a quasi solid polymer electrolyte(NSPE).Electrochemical workstation and LAND battery testing system were used to perform a galvanostatic charge/discharge test on Li-O_2.The ionic conductivity of NSPE was 4.3 × 10~(-4) S·cm~(-1) at room temperature and the discharge platform was 2.6 V and the charging voltage was 3.7 V after 50 cycles with the cut-off capacity of 500 mA·h·g~(-1).     

戈尔膜过滤器盐水过滤运行状况总结

阐述了戈尔膜过滤器运行参数的设定依据及其设定方法,分析了戈尔膜过滤盐水的质量状况,认为戈尔膜过滤器完全可以替代离子膜烧碱中二次盐水过滤器.