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排序方式: 共有2107条查询结果,搜索用时 15 毫秒
1.
讨论了直流法在线测量钯氢化物电极电阻时的电化学效应,计算了电解液的共导、测量电流与电解电流引起的浓差电池效应以及电极作为集流体引起的电阻贡献。结果表明:当电极具有高的长度与半径比值、粗糙的表面、高的溶液电导以及大的电解电流时容易引起显著的附加电阻。 相似文献
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保证氢冷机组氢气安全运行是电厂安全管理的一项重要工作。将钯触媒应用于氢冷发电机组,降低氢气含氧量,对安全起到了保障作用本文讨论钯触媒的使用特性及使用后氢气纯度的标准、计量等问题。 相似文献
5.
Jennifer K. Edwards Adrian Thomas Benjamin E. Solsona Philip Landon Albert F. Carley Graham J. Hutchings 《Catalysis Today》2007,122(3-4):397-402
The direct synthesis of hydrogen peroxide from H2 and O2 using a range of supported Au–Pd alloy catalysts is compared for different supports using conditions previously identified as being optimal for hydrogen peroxide synthesis, i.e. low temperature (2 °C) using a water–methanol solvent mixture and short reaction time. Five supports are compared and contrasted, namely Al2O3, -Fe2O3, TiO2, SiO2 and carbon. For all catalysts the addition of Pd to the Au only catalyst increases the rate of hydrogen peroxide synthesis as well as the concentration of hydrogen peroxide formed. Of the materials evaluated, the carbon-supported Au–Pd alloy catalysts give the highest reactivity. The results show that the support can have an important influence on the synthesis of hydrogen peroxide from the direct reaction. The effect of the methanol–water solvent is studied in detail for the 2.5 wt% Au–2.5 wt% Pd/TiO2 catalyst and the ratio of methanol to water is found to have a major effect on the rate of hydrogen peroxide synthesis. The optimum mixture for this solvent system is 80 vol.% methanol with 20 vol.% water. However, the use of water alone is still effective albeit at a decreased rate. The effect of catalyst mass was therefore also investigated for the water and water–methanol solvents and the observed effect on the hydrogen peroxide productivity using water as a solvent is not considered to be due to mass transfer limitations. These results are of importance with respect to the industrial application of these Au–Pd catalysts. 相似文献
6.
Maciej Winiewski Artur Jakubiak Jan Szymanowski 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):209-214
Decyl isonicotiniate and decyl nicotiniate permit a rapid extraction of palladium(II) from its hydrochloride solutions. Decyl picoliniate is not a suitable extractant. 4-Octylphenylamine can act as a phase transfer catalyst when its concentration in the organic phase is at least 2·5 × 10?4 M . It seems that the interfacial adsorption of pyridine carboxylates and of 4-octylphenylamine is not the decisive phenomenon in palladium(II) extraction. The negligible protonation of the pyridine-type extractants and the phase transfer catalysis explains well the quick extraction of palladium(II) with the commercial and highly hydrophobic extractant ACORGA CLX-50. 相似文献
7.
The kinetics of disproportionation of methylamine to dimethylamine and ammonia in the presence of hydrogen have been investigated over a silica-supported palladium catalyst. At a fixed partial pressure of methylamine, the reaction rate generally increases with decreasing hydrogen partial pressure, approaching a limiting or maximum value at sufficiently low pressures of hydrogen. The existence of a maximum is supported by the observation that the presence of some hydrogen appears to be necessary for the reaction to proceed at a conveniently measurable rate. At a fixed hydrogen partial pressure, the reaction rate increases with increasing methylamine partial pressure. When the methylamine partial pressure is sufficiently low or the hydrogen partial pressure is sufficiently high, the reaction order with respect to methylamine can be somewhat higher than one. At such conditions, a mechanism involving a bimolecular reaction between two partially dehydrogenated methylamine molecules on the surface appears to make a significant contribution to the overall catalytic reaction. 相似文献
8.
T. R. Guilinger M. J. Kelly J. R. Scully T. M. Christensen D. Ingersoll J. A. Knapp R. I. Ewing W. H. Casey S. S. Tsao 《Journal of Fusion Energy》1990,9(3):299-304
We describe several electrochemical methods used to investigate the possibility of cold fusion phenomena in palladium and titanium tritide cathodes. We performed long-term (up to 77 days) electrolysis experiments with electrochemical cells of the University of Utah type at current densities as high as 1 A/cm2, while monitoring neutron and tritium levels. With some cells, we pulsed the current to determine if neutron bursts would result. In another cell, we used titanium tritide as the cathode to determine if D-T reactions yielding neutrons would occur. In no instance were levels of neutrons or tritium significantly above background except in the titanium tritide cell where isotopic exchange, occcurring between the electrode and the electrolyte, resulted in significant tritium levels. We also combined x-ray photoelectron spectroscopy (XPS) and electrochemical hydrogen permeation experiments to determine the effectiveness of various Pd surface treatment procedures on the resultant electrochemical hydrogen absorption efficiency. Electroanalytical and thermal desorption/gas analysis techniques indicated the maximum loading of H in Pd was to a ratio of HPd=0.8. 相似文献
9.
形态对钯-氢体系热力学性质的影响 总被引:4,自引:0,他引:4
唐涛 《稀有金属材料与工程》2005,34(5):826-829
基于实验测定海绵Pd颗粒在278K-323K范围内吸放H2,D2的P-C-T曲线.结合文献给出的其它形态的Pd吸放氢结果进行系统比较分析.探讨了形态对钯-氢体系热力学性质的宏观影响和微观本质。在室温附近,氢的饱和固溶度与坪压随Pd的粒度减小而增加;Pd的形态或粒度对氢的饱和固溶度和吸氧坪压的影响程度刚随温度升高而减小,而且坪压之间的差别在温度较高时不再明显甚至消失。吸氘坪压差别大,解吸坪压差别小。Pd—H体系中α→β的相变热焓、热熵(绝计值)随粒度减小而减小,单晶Pd相应热力学函数最小。海绵Pd颗粒中的压力迟滞效应最明显.材料本底缺陷密度决定不同形态Pd-H体系的压力迟滞效应的大小。 相似文献
10.
A chitosan (CTN)/silica‐supported nanosized palladium catalyst was obtained from a silica‐supported chitosan palladium complex through a complex transition method. An adsorption model was employed to simplify the structure of the di‐supporter. It was indicated that when the polymer coil adsorbed on the silica surface with even a monolayer the catalytic activity would reach an optimum value, and different situations of the, nanosized palladium particles would cause a different catalysis. The molar ratio of the chitosan structure unit to the palladium would affect the metal's size, which therefore influenced its catalytic activity. The experimental results corresponded with the inferences. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 989–994, 2002 相似文献