不饱和有机酸在Pt-Rh合金电极上的吸附动力学

采用快速动电位扫描方法 ,系统地研究了吸附时间、溶液浓度、温度、吸附电位等因素对在不同组成的Pt-Rh电极上不饱和有机酸吸附过程的影响 .研究结果表明 ,在中等表面覆盖率下 ,所研究的不饱和有机酸在Pt-Rh合金电极上吸附速率都遵循Rogynski-Zilidowicz方程 ,Pt电极上吸附速率最大 ,从Pt电极向Rh电极过渡中 ,吸附速率下降 2 0～ 30倍 .温度升高吸附速率加快 .丙烯酸在Pt-Rh电极表面的吸附速率比其他不饱和有机酸高 ,并按丙烯酸 >丁烯酸 >顺丁烯二酸顺序递减     

贮氢合金电极在山梨醇制备中的应用

用贮氢合金作催化还原电极恒电位电解葡萄糖 ,得出合金的表面处理及电极的活化可提高山梨醇电流效率至 80 %以上的结论。同时贮氢电极与Pb电极及发泡Ni电极作了对比 ,发现电解葡萄糖制备山梨醇过程中 ,贮氢电极是较好的还原电极。用贮氢电极 (2 )做阴极 ,30℃ ,电流密度为 80 0mA/dm2 ,葡萄糖溶液及硫酸钠支持电解质浓度均为 0 .5mol/L ,pH =8的条件下 ,电解葡萄糖制山梨醇电流效率高达 94% ,葡萄糖转化率达 80 %以上。     

铈对Ni-Mo合金电极析氢性能的影响

在Ni-Mo合金镀液中添加Ce盐,制备了Ce盐修饰的Ni-Mo合金电极,研究了Ce对Ni-Mo合金电极析氢催化性能的影响,并测试研究了Ce对Ni-Mo合金镀层结构的影响。实验结果表明,镀液中添加少量的Ce盐并没有改变合金电极的结构,但是使镀层的晶粒细化,从而增大了电极的真实表面积,提高了Ni-Mo合金电极的析氢催化活性。     

La-Mg-Ni系贮氢电极合金的研究进展

综述了La-Mg-Ni系贮氢合金电极的研究进展,包括合金材料的组成、结构、制备方法及表面处理工艺等,着重介绍了AB3型和A2B7型合金的电化学性能,分析讨论了各种替代元素对合金性能影响的原因,提出了未来La-Mg-Ni系贮氢合金应用研究的方向。     

电化学技术制备析氢电极材料的研究进展

电化学方法是制备析氢电极材料最常用、最简单的方法之一。介绍了采用电化学方法制备晶态合金、纳米晶合金、非晶态合金及复合金属等析氢电极材料的研究进展,并对电极催化析氢机理进行了概述。     

氢钼青铜修饰铂电极对甲醇催化剂的电催化作用

利用循环伏安法研究了氢钼青铜在铂电极上的修饰作用和修饰铂电极在c(H2SO4)=0.5mol/L，溶液中对甲醇的催化作用，研究结果表明：铂电极因钼酸盐的还原和钼青铜的氧化而得到修饰，低电位范围内修饰钱电极对甲醇的氧化有催化作用，催化氧化电流是未修饰电极上的1．6倍，酸性条件下，含高价态钼的钼青铜不稳定，会不断溶解对铂失去修饰作用，对甲醇姝氧化效果与未修饰铂电极上的效果相同，而低电位时，钼青铜修饰电极则相对稳定。     

La-Mg-Ni系贮氢合金相结构及电化学性能

采用感应熔炼法制备La0.75Mg0.25Ni3.4-xAl0.1Cox (x=0.0, 0.5, 1.0)贮氢合金,研究了合金元素Co对Ni部分替代对合金相结构及电化学性能的影响. 结果表明,合金由La2Ni7相、LaNi5相及LaMg2Ni9相组成. 随Co含量的增加,合金电极活化次数变化不大,最大放电容量、循环稳定性呈现先增后减的趋势. 合金的最大放电容量和循环保持率分别由x＝0时的316.92 mA.h/g和61.83%增加到x＝0.5时的340.31 mA.h/g和75.21%,而后减少到x＝1.0时的333.22 mA.h/g和66.70%. 而合金的高倍率放电性能降低,当放电电流密度为900 mA/g时,其倍率放电性能由62.49% (x=0)减小到53.68% (x=1.0). 合金电极的极限电流、贮氢合金电化学反应电阻逐渐增大,其高倍率放电性能的降低源于电极表面的电子迁移速率和氢在合金体相中扩散速率的共同作用.     

铂铑网及铂铑网灰中铬的原子吸收光谱分析

建立了用空气-乙炔火焰原子吸收光谱分析铂铑网及铂铑网灰中铬的分析方法。研究了样品的处理,样品处理液中共存元素的干扰和抑制。该方法灵敏度高、准确度好,在最佳实验条件下,测定铂铑网及铂铑网灰中铬的最小检测限为0．1μg／g,变异系数≤1％,加标回收率为93％～98％。     

电沉积Ni-S、Ni-P-S合金析氢阴极的研究

在电沉积法制备Ni-S合金电极的基础上,向镀液中添加次亚磷酸钠制备了Ni-P-S合金电极。电化学测试结果表明,Ni-P-S和Ni-S合金电极的催化性能都要好于其它电极,Ni-P-S合金电极的性能随着次亚磷酸钠质量浓度的升高而降低。计算了电极的电极反应动力学参数(包括Tafel斜率b、交换电流密度0ρ和过电位η),解释了Ni-P-S合金电极和Ni-S合金电极在不同电流密度区活性不同的原因。恒电流电解表明,Ni-P-S合金电极具有较高的稳定性。电极的微观形貌用SEM进行表征,成份用能谱进行分析,通过X射线衍射分析电极的晶型结构。     

Pitting and repassivation processes of Al---Zn---Mg alloys in chloride solutions containing sulphate

The mechanism of localized corrosion of Al—5.03%Zn—1.67%mg—0.23%Cu alloy submitted to different heat treatments (annealed (A); cold-rolled (ST); quenched (F); quenched and aged (B); and quenched in two stages and aged (C)) in NaCl, Na₂SO₄ and in NaCl---Na₂SO₄ solution has been studied by cyclic polarization (CP), open circuit potential measurements, chronocoulometry, SEM and EDX. The electrochemical results in NaCl were consistent with the assays of SCC resistance of alloys B and C previously reported in the literature. Sulphate addition to chloride solutions produced a considerable shift of the breakdown potential in the positive direction. However, the repassivation potential, much more reproducible than the latter, was only slightly shifted in the negative direction. The role of sulphate was related with the oxide presence, its incorporation in the film precluding significant chloride penetration. However, the film conductivity apparently increased with potential in the presence of sulphate, finally making pit propagation possible and resulting in a much more intense pitting attack.     

Induced electrodeposition of tungsten with nickel from acidic citrate electrolyte

Induced electrodeposition of Ni–W alloys was carried out onto steel substrates from acidic citrate baths (pH 4.5) under different conditions of concentration of electrolyte, current density and temperature. Bright and highly adherent Ni–W deposits were successfully obtained with a relatively high cathodic current efficiency CCE (80–85%). The CCE increases greatly with increasing pH and Ni²⁺ ion content in the bath. The W% in the alloy deposits is in the range of 4–20 wt% depending on the operating condition. The W content in the deposit was found to increase with an increase in Ni²⁺ ion content, pH and temperature. The surface morphology was examined by scanning electron microscopy while the structure of the alloy was examined by X-ray diffraction analysis.     

Thiazoles as corrosion inhibitors for mild steel in formic and acetic acid solutions

2-(N,N-dimethylamino) benzylidene imino-4-(4-methyl phenyl)-1,3-thiazole (DIMPT), 2-benzylidene imino-4-(4-methyl phenyl)-1,3-thiazole (BIMPT), 2-salicylidene imino-4-(4-methyl phenyl)-1,3-thiazole (SIMPT) and 2-cinnamylidene imino-4-(4-methyl phenyl)-1,3-thiazole (CIMPT) were synthesized in the laboratory and their influence on the inhibition of corrosion of mild steel in 20 formic acid and 20 acetic acid was investigated by weight loss and potentiodynamic polarization techniques. The inhibition efficiency of these compounds was found to vary with their nature and concentration, temperature, immersion time and acid concentration. The values of activation energy and free energy of adsorption of the thiazoles were calculated to investigate the mechanism of corrosion inhibition. The adsorption of all the thiazoles on mild steel surface was found to obey Langmuir adsorption isotherm. The potentiodynamic polarization result revealed that the compounds studied are mixed type inhibitors. Electrochemical impedance spectroscopy was used to investigate the mechanism of corrosion inhibition.     

硝酸装置铂铑催化剂使用情况统计分析

根据硝酸装置铂铑催化剂使用情况进行统计分析,以实际生产数据分析铂耗高的原因,验证了铂铑催化剂使用时间、氨氧化温度和机械振动是影响铂耗的主要原因。根据硝酸装置生产经验,提出相应措施以降低铂耗,即选择合理的铂铑催化剂更换时间、设定适宜的氧化温度及减少非计划停车次数。     

Cathodic inhibition and anomalous electrodeposition of Zn-Co alloys

The electrodeposition of Zn-Co alloys from chloride electrolytes was studied on steel substrate. Electrodeposition of Zn-Co alloys is usually divided into two potential regions, i.e. normal (positive to Zn deposition potential versus SCE) and anomalous (negative to ). In order to elucidate the deposition mechanism a complementary approach was used based on the combination of various electrochemical techniques. The morphology of the deposits and elemental composition analysis were determined by using SEM/EDX. It was found that the presence of Zn²⁺ in electrolyte inhibited Co²⁺ and H⁺ reductions in normal region. A critical potential was also noticed in the so-called normal deposition range above which a Co-enriched phase of Co-Zn alloy was favored and below that a severe mitigation to deposition occurred that was considered due to underpotential deposition (UPD) of Zn on the substrate and on active Co sites at either nucleation or growth stage. Beyond the deposition is considered anomalous due to the fact that Zn deposits preferentially compared to the more noble Co. This anomalism was explained by the faster deposition kinetics of Zn as compared to Co on steel and could be overcome by either increasing the Co²⁺/Zn²⁺ ratios in the electrolyte or by carrying out the deposition at higher temperature.     

氢能利用与碳质材料吸附储氢技术

氢能作为一种洁净的可再生能源,对整个世界经济的可持续发展具有重要的战略意义。碳质材料具有比表面积高,吸/脱附速度快,可循环使用,寿命长,容易实现规模化生产等优点,可显著促进低成本、规模化储氢技术的发展,对未来的能源、交通、环保而言具有非常重要的意义。综述了氢能开发利用的最新研究动态,展望了氢能利用和储存的发展趋势,在简要介绍氢能的制备方法、储氢材料和储氢技术的基础上,重点介绍了碳质材料吸附储氢技术。     

产氢用铝镓合金的制备技术

为了探索一种新型、快捷、安全的制氢途径,实验以铝、镓为原材料,采用综合热分析仪、温控仪等设备,通过控制保护气体流量、保温时间、降温速率等工艺参数,进行了mg量级和g量级的产氢用铝镓合金的制备;并对合金样品进行了化学成分、熔点等分析.实验结果表明:综合热分析仪制备获得的铝镓合金性能优于温控仪获得的合金性能;采用综合热分析...     

氢在多壁碳纳米管上的等量吸附热

为说明氢在多壁碳纳米管(MWCNTs)上所受吸附作用的强弱,文中基于氢和77 K氮的吸附数据,比较了由非局域密度泛函理论(NDFT)、等量吸附线和归一化等温线线性化确定的等量吸附热。结果表明,氢在MWCNTs上等量吸附热随温度变化且表现出在弱的能量不均匀表面吸附的特点,平均值约为3—4 kJ/mol;由77 K氮吸附等温线确定的孔大小分布(PSD)和比表面积影响NDFT计算初始吸附时的精度;在吸附量和吸附温度都较低时,等量吸附线标绘结果与归一化等温线线性化方程确定的等量吸附热之间的偏差较小,在200—290 K温度区间则与ND-FT计算结果更为接近。然而,当温度大于310 K时,3种方法计算结果间的偏差较大。     

氯碱厂副产氢气的分离提纯方法

从纯化机制入手,介绍了氯碱厂的副产氢气经分离提纯到99．9％及99．9999％以上的方法：低温吸附法、变压吸附法和膜分离法等。     

镁基储氢合金改性的研究进展

介绍了镁基合金的合成方法及主要的镁基合金的性能改善方法,并全面介绍了元素取代镁基合金对镁基合金性能进行改善的最新研究进展。