电解合成乙醛酸的改进

研究改进了草酸电解还原制备乙醛酸中的阳极材料、隔膜及电解工艺。实验 :本研究选用隔膜电解法。阳极选用在酸性溶液中有良好导电性、有高的析氧过电势及低的阳极极化率 ,同时价格较便宜的钛基氧化铱电极 ,阴极用铅板。隔膜材料直接影响电解反应能否顺利进行及产率大小 ,在全氟、ＨＦ -10 1高性能均相、聚氯乙烯 3种阳离子交换膜中用实验方法进行电解草酸产率比较后选定ＨＦ - 10 1高性能均相阳离子交换膜。通过实验分析确定了电解工艺 :电流密度 5 0 0Ａ ｍ2 ,槽电压 4 5Ｖ ,电解温度2 0℃ ,阳极电压 - 1 32Ｖ ,阳极草酸浓度始终维持质量…     

隔膜法电解基本知识 第三讲 隔膜法电解生产

一、隔膜法电解的原理 1.原理所谓隔膜法电解就是用隔膜电解槽(即在电解槽阴阳极之间设置一层隔膜)进行电解生产,其阳极为石墨阳极,阴极为铁阴极。我们已经知道,当直流电通过氯化钠水溶液时,在阳极产生氯气,在阴极产生氢气及氢氧化钠。即: 在阳极 2Cl~- -2e→Cl_2在阴极总反应式为2NaCl 2H_2O→2NaOH Cl_2 H_2,这是电解过程的主要反应。     

多孔隔膜电阻系数的测定

一、前言由多孔材料(石棉、含氟高分子材料或玻璃、金属等)制成的隔膜在电化工业如电池工业、电解工业中以及在电渗析、电泳等净化分离技术里均获得广泛应用。在氯碱工业中,隔膜在电解槽里用来隔离阴极室及阳极室以便在电解过程中从阴极室及阳极室获得所需的不同产物,而由于隔膜的多孔性,对离子亦即电流提供通路。评价多孔隔膜的好坏,除强度、寿命、透水性等因素外,一项重要的性能指标即为隔膜的电阻系数或膜电阻,即隔膜对电流而呈现的阻力,这对电解过程降低电耗,提高电流效率具有重要意义。     

对氨基苯酚的绿色电化学合成及其工业化

研究了在阴极转动分隔式电解槽中硝基苯电化学还原制备对氨基苯酚（PAP）时阴极转速、反应温度等工艺参数对电解性能的影响,并考察了不同阳极材料的稳定性.实验结果表明,增大阴极转速和升高反应温度有利于反应的进行;自制的Pb-Sb-Sn-Ag-Cu五元合金作为阳极材料具有比Ti/Ir阳极更长的工作寿命.当以铅合金为阳极材料、体系温度为90℃、阴极转速为900 r•min^-1、电解电流为3000 A时,硝基苯的平均转化率为99%,PAP平均收率为69.9%,电解直流电单耗为7.24 kW•h•(kg PAP)^-1,产品纯度大于98%,熔点为186.1～187.3 ℃.     

电脱氧法工艺研究用熔盐电解材料

电脱氧法是在熔盐体系中由金属氧化物直接电解制备金属或合金的工艺。本文介绍了电脱氧法及其发展,并对电脱氧法中熔盐电解材料的特性及应用进行了详细阐述和比较。包括:Ti、刚玉、石墨、不锈钢等坩埚材料的选用;阳极材料和阴极材料的应用以及阴极制备方法的改进;CaCl2、K2TiF6等熔盐体系和导线材料的选择。     

《中国大百科全书·化工》条目

gemo dianjiefa——隔膜电解法(diaphragm cell electrolysis process)利用多孔渗透性的材料作为电解槽内的隔层,以分隔阳极产物和阴极产物的电解方法.氯碱工业利用隔膜电解槽电解食盐水溶液生产烧碱(氢氧化钠)、氯气和氢气.1893年首先在美国用于工业生产.     

电解食盐水溶液生产氯碱基础知识讲座

第四讲隔膜法电解一、隔膜法电解原理1、概述隔膜法电解是用隔膜电解槽进行电化学生产的一种方法。隔膜电解槽是在阳极和固体阴极之间设置了一种多孔性隔膜的电解槽。该隔膜能让电流通过,但它能阻止阴阳极电解产物的混合,从而保证了电化学反应     

电化学合成乙醛酸研究

研究了隔膜电解草酸法生产乙醛酸的工艺 ,首次使用了性能优越的新型阳极材料钽铱电极和HF - 1 0 1型强酸型阳离子交换膜 ,并对电解工艺进行优化 ,结果表明 :在电解温度为 2 0℃ ,电流密度为 35 0A/m2 ,使用HF - 1 0 1型阳离子交换膜和钽铱电极 ,电解草酸饱和溶液 8h后 ,乙醛酸产率达 96 1 3% ,明显高于国内文献值。该法具有电解液不受污染 ,离子交换膜不易中毒且无机械损伤 ,阳极材料使用寿命长 ,产品纯度、产率高等优点 ,具有广阔的工业化前景。     

Ti/SnO_2电极隔膜电解处理氨氮废水技术研究

分别以平板Ti/SnO_2网状电极和石墨为阳极和阴极,制作隔膜和无隔膜电解反应器并对比处理500mg/L自配氨氮溶液。在处理水量为3.6 L,电流密度为10 m A/cm2,有效阳极面积为1 440 cm~2,电流为0.8 A,反应时间70 min条件下,出水氨氮分别为74、222 mg/L,去除率分别为85.2%、55.6%;当两种反应器吨水电耗均为10.5k W·h时,出水氨氮分别为74、153 mg/L,去除率分别为85.2%、69.4%。在出水氨氮相同时,隔膜电解反应器在吨水电耗、电流效率以及反应速率方面均优于无隔膜电解反应器。     

草酸电解还原制备乙醛酸的研究

研究连续草酸电解还原制备乙醛酸的过程和工艺。采用一膜两室电解面积为10cm×10cm的离子膜电解槽进行连续电解实验,比较了电极材料、阳离子交换膜材料、研究了电解液流量对电流效率的影响以及电流密度、电解温度和电解时间对电解过程的影响。结果表明以铅极板作阴极、钽-铱作阳极板、NF-1型含氟磺酸阳离子交换膜时电解的效果较好,得到的优化电解条件为:电流密度1000A.m-2,电解温度25℃,电解时间4.5h,阴极液和阳极液流量均为2L.min-1。在此条件下的电耗为3038.9kWh.t-1产品,研究结果可为工业化设计提供参考数据。     

碳钢/钛合金复合材料在3%NaCl溶液中的电偶腐蚀研究

采用失重方法和电化学方法,研究碳钢/钛合金复合材料在3%NaC l溶液中的电偶腐蚀行为。结果表明,在碳钢/钛合金电偶腐蚀过程中,碳钢为阳极,钛合金为阴极,随着阴/阳面积比的增大,电偶电流增大,碳钢腐蚀速率变大,而电偶电位基本不变。     

电解制备离子水的研究

研制了一种简易的离子水生成器 ,采用电解法制备酸性离子水和碱性离子水。比较分析了电极材料的性能 ,发现阳极和阴极同时采用铂 /钛合金 ,电解性能较好。Na Cl浓度和电解时间不同 ,所制得的离子水强度也不同 ,Na Cl浓度宜选择 0 .5～ 1 .0 g/ L。同时 ,制得的离子水应密封保存     

Galvanic studies related to the use in desalination plant of corrosion-resistant materials

Galvanic currents and potentials have been measured for bimetallic couples involving carbon steel, three grades of stainless steel, 90 Cu/10 Ni and titanium when exposed to seawater in the laboratory at temperatures of 18C and 60C and varying oxygen content. The galvanic currents flowing between couples consisting of two of the corrosion-resistant materials were very small. The galvanic corrosion rate of carbon steel, when connected to one of the other materials, was dependent upon the cathodic-polarisation characteristics of the noble-material surface with indications that, at a given area ratio, the galvanic corrosion of carbon steel was greater when coupled to the 90 Cu/10 Ni alloy than when connected to stainless steel or titanium. The usual effects of increasing the anode/cathode area ratio were observed and data were obtained to demonstrate quantitatively the significant beneficial effect of coating the cathode in a bimetallic couple. Intermediate air exposures were not found to promote any large, long-term, effects on galvanic corrosion. There was evidence that galvanic corrosion rates were very small when the dissolved oxygen content was controlled at low levels and some interesting aspects of galvanic corrosion at the higher temperature were noted.     

Production of NiTi shape memory alloys via electro-deoxidation utilizing an inert anode

NiTi shape memory alloys (SMA) with equiatomic composition of Ni and Ti were prepared by electro-deoxidation, in molten calcium chloride, at 950 °C. Constant voltage electro-deoxidation was conducted using a NiTiO₃ cathode, and either a carbon anode or a novel CaRuO₃/CaTiO₃ composite inert anode. Both anode materials successfully allowed NiTi shape memory alloy to be obtained. The primary difference is that molecular oxygen was produced on the inert anode, instead of environmentally undesired CO₂ greenhouse gases on the carbon anode. Indeed, it was found that carbon could successfully be substituted with conductive calcium titanate-calcium ruthenate composites for electro-deoxidation. Furthermore, DSC was used to analyze the phase transformation of NiTi shape memory alloys, with results revealing the existence of reversible martensite-austenite phase transformations during the cooling and heating process.     

Performance of non-porous graphite and titanium-based anodes in microbial fuel cells

Four non-porous materials were compared for their suitability as bio-anode in microbial fuel cells (MFCs). These materials were flat graphite, roughened graphite, Pt-coated titanium, and uncoated titanium. The materials were placed in four identical MFCs, of which the anode compartments were hydraulically connected in series, as well as the cathode compartments. The MFCs were operated with four resistors. The anode kinetics at these electrode materials were studied by means of dc-voltammetry and electrochemical impedance spectroscopy (EIS). Both techniques were compared and showed that the bio-anode performance decreased in the order roughened graphite > Pt-coated titanium > flat graphite > uncoated titanium. Uncoated titanium was unsuitable as anode material. For the other three materials, specific surface area was not the single variable explaining the differences in current density for the different materials. All polarization curves showed a clear limiting current. This limit could not be attributed to mass transfer of the substrate and reflected the maximum biomass activity. The current density of the non-porous bio-anodes, except for the uncoated titanium anode, was comparable to the reported current densities of porous materials when normalized to the projected surface area. The high current densities that were recorded by dc-voltammetry, however, could not be maintained in a stable way for a longer period. This shows that polarization curves of MFCs should be evaluated critically.     

TiCN and metallic coatings for corrosion protection of separator plates in MCFCs

Stainless steel 304 substrates were coated with different materials in order to find a suitable coating material for corrosion protection of separator plates in molten-carbonate fuel cells (MCFCs). Five titanium carbonitride coatings differing in composition and morphology and a titanium monoxide coating were deposited with chemical vapour deposition techniques. Also double-layer coatings of TiN/Au and TiN/Ni were prepared. The coatings were tested on their corrosion protection of separator plates in four different environments: under MCFC-cathode or anode gas, at load or at open circuit conditions. The corrosion behaviour was characterized using cyclic voltammetry. Corrosion rates were determined with electrochemical methods and cross-section analyses of corrosion layers. Titanium nitride coatings showed the best corrosion protection. The titanium carbide and titanium monoxide coating showed respectively less and no protection. The thin gold and Ni-coatings were unstable. Under cathode gas, the most important corrosion protection is given by keeping the cell at load, and then a titanium nitride coating might provide lifetime protection. Under anode gas, corrosion is most severe at load conditions. A titanium nitride coating also gives corrosion protection, but not enough for lifetime protection.     

SiO2对CaCl2熔盐电解还原钛铁矿精矿制备FeTi合金的影响

在不同电解时间和槽电压下,添加SiO2电解还原钛铁矿精矿制备钛铁合金. 结果表明,以添加一定量SiO2的钛铁矿精矿为阴极,控制阴极中主要组元的摩尔比Ti:Fe:Si=1.2:1:0.2,以石墨棒为阳极、CaCl2熔盐为电解质,在槽电压3.2 V、温度900℃下电解2 h,可制得疏松多孔、颗粒尺寸较均匀的FeTi合金粉体. 钛铁矿精电解还原过程中会生成CaTiO3和Fe?Ti?O等中间产物,添加的SiO2在电解时会优先还原生成单质Si,并参与CaTiO3等中间产物的还原反应,降低中间产物电解还原生成FeTi合金的理论电压,有利于加快电解还原钛铁矿精矿制备钛铁合金的速率.     

A study of the potentials achieved during mechanical abrasion and the repassivation rate of titanium and Ti6Al4V in inorganic buffer solutions and bovine serum

Titanium alloys in orthopaedic implants are susceptible to mechanical disruption of the passive film (fretting corrosion). To study this effect, open-circuit potential (ocp) measurements before, during and after mechanical disruption of the passive film in a tribo-electrochemical cell on commercial pure titanium and Ti6Al4V alloy in inorganic buffer solutions in the pH range from 2.0 to 12.0 and calf bovine serum at pH 4.0 and 7.0 are reported. Additionally, the effect of pH, electrolyte and sample composition on the repassivation rate has been investigated. The potentials achieved during the abrasion of Ti6Al4V are the same as those characterizing pure titanium, which indicates that the corrosion current of both materials in the active state is due to the oxidation of titanium. However, commercial pure titanium displays a tendency to repassivate faster than Ti6Al4V in inorganic buffer solutions thanks to the lower critical current density and the higher catalytic activity towards the hydrogen evolution reaction observed on the pure metal in comparison with the alloy.Proteinaceous solutions like bovine serum, significantly slow down the anodic dissolution and the cathodic reactions both on titanium and the alloy. However, the repassivation rate of the Ti6Al4V is not affected by serum, while that of cp titanium significantly decreases both at pH 4.0 and 7.0.