Anodic behaviour of oxidised Ni–Fe alloys in cryolite–alumina melts

Nickel-iron alloys have been identified as promising inert anode candidates for the Hall–Héroult process. In this study, binary Ni–Fe alloys of various compositions were subjected to short-term galvanostatic electrolysis in a cryolite–alumina bath at 960 °C. Prior to electrolysis, the anodes were oxidised at 800 °C for 48 h, forming a protective scale. Fe₂O₃, Ni_xFe_3−xO₄ and Ni_xFe_{1 − x}O were identified as the major scale components using a combination of X-ray diffraction (XRD) analysis and energy dispersive X-ray spectroscopy (EDX). Anodes having Ni content of 50–65 wt% performed adequately during short-term electrolysis, operating at a steady potential of 3–3.5 V vs. AlF₃/Al. Overall, it was found that the pre-formed oxide scale was effective in reducing anode wear and fluoridation. In the absence of a pre-formed scale, anodes were shown to undergo appreciable internal corrosion and/or passivation due to metal fluoride formation. Analysis of the anodes following electrolysis was performed using XRD and electron microprobe analysis (EPMA).     

高容量泡沫式镍电极的研制

本文介绍了一种高容量泡沫式镍电极,确定了电极的工艺参数,考察了由其作为正极的圆柱密封氢镍电池的性能。     

碱性二次电池中新型镍电极

本文论述了四种镍电极电池的电化学原理、优缺点及其新进展,介绍了三类新型镍电极的制备方法及结构特点并综合分析了活性物质的充填方法及添加剂(Co、Cd、Zn和Li等)的作用机理。     

Comparison of Soybean and Cottonseed Oils upon Hydrogenation with Nickel,Palladium and Platinum Catalysts

There is current interest in reducing the trans fatty acids (TFA) in hydrogenated vegetable oils because consumption of foods high in TFA has been linked to increased serum cholesterol content. In the interest of understanding the TFA levels, hydrogenation was carried out in this work on soybean oil and cottonseed oil at two pressures (2 and 5 bar) and 100 °C using commercially available Ni, Pd, and Pt catalysts. The TFA levels and the fatty acid profiles were analyzed by gas chromatography. The iodine value of interest is ~70 for all-purpose shortening and 95–110 for pourable oil applications. In all cases, higher hydrogen pressures produced lower levels of TFA. In the range of 70–95 iodine values for the hydrogenated products, the Pt catalyst gave the least TFA, followed closely by Ni, and then Pd, for both oils. For all three catalysts at 2- and 5-bar pressures and 70–95 iodine values, cottonseed oil contained noticeably less TFA than soybean oil; this is probably because cottonseed oil contains a lower total amount of olefin-containing fatty acids relative to soybean oil. Approximate kinetic modeling was also done on the hydrogenation data that provided additional confirmation of data consistency.     

Controllable preparation of Ni nanoparticles for catalysis of coiled carbon fibers growth

The mass preparation of high-purity coiled carbon fibers (CCFs) remains challenging due to the high complexity and low controllability of reaction. In this work, a controllable growth of Ni particles was fulfilled by liquid phase reduction of nickel sulfate with hydrazine hydrate. The impacts of the reaction temperature, NaOH concentration, and reaction time on the particle size and purity were investigated. The as-deposited Ni particles were characterized by scanning electron microscopy and X-ray diffraction. In addition, these Ni particles were also applied in preparing high-purity CCFs both on graphite and ceramic substrates. The diameter of the as-grown carbon microcoil was about 500 nm, and the related growth mechanism was discussed.     

Preparation of promoted nickel catalysts supported on mesoporous nanocrystalline gamma alumina for carbon dioxide methanation reaction

Nickel-based catalysts supported on mesoporous nanocrystalline gamma Al₂O₃ promoted with various promoters (CeO₂, MnO₂, ZrO₂, La₂O₃) were prepared and employed in the carbon dioxide methanation reaction. It was found that the addition of promoters to the catalyst varied the specific surface area from 139.4 to 147.4 m²/g and CeO₂ and MnO₂ improved the reducibility of catalyst. The catalytic results showed that the catalyst with 2 wt% of cerium promoter possessed high activity and stability in CO₂ methanation reaction and showed a high CO₂ conversion of 80.3% at 350 °C.     

新型镍体系催化丁二烯聚合动力学

本文研究了Ｎｉ（ｎａｐｈ）２Ａｌ（ｉＢｕ）３－ＢＦ３·ＯＥｔ２＋ＲＯＨ新型镍系催化体系催化丁二烯的聚合动力学，考察了该体系的动力学曲线、速度方程、聚合度，测定了催化剂利用率、活性中心浓度等动力学参数。聚合速率对单体浓度呈一级关系，表观活化能为４０．４ｋＪ／ｍｏｌ，催化剂利用率约为１０％。     

Separation of Copper and Nickel from Ammoniacal/Ammonium Carbonate Solutions Using ACORGA PT5050

ABSTRACT

ACORGA PT5050 diluted with iberfluid (kerosene-type diluent, mostly aliphatic) was used to coextract copper and nickel from ammoniacal carbonate solutions. The influence of kinetics, temperature, equilibrium pH, and extractant concentration on the extraction of both metals has been studied. It was observed that nickel extraction is very sensitive to aqueous pH and that the extraction falls beyond an equilibrium pH of 9. For a typical solution containing near 3 g/L each of copper and nickel and 60 g/L ammonium carbonate, conditions were established for the coextraction and selective stripping of nickel and copper.     

Catalytic dry-reforming on Ni-zeolite supported catalyst

In the present work, the catalytic behaviour in the dry reforming of methane on Ni-based Silicalite-1 type catalyst was studied. The Silicalite-1 support has been synthesized in order to check the role of the silanol groups on the overall catalyst performance: methane and carbon dioxide conversion, hydrogen/carbon monoxide ratio and coke deposition. The population of defect groups on the Silicalite-1 surface was modified by aging of the gel, thermal treatment, ionic exchange and silylation procedure. Among these treatments, the silylation of the support surface leads to the formation of smaller and more reducible Ni-oxide species that not only improve the CH₄ and CO₂ conversion but also reduce the deactivation of the catalyst due to coke deposition and the obtained H₂/CO value is 1.04.     

镍系胶光氧老化过程研究

介绍了液体核磁共振波谱法(NMR)、傅里叶变换红外光谱法(FT-IR)、扫描电镜(SEM)和热失重分析(TGA)4种现代分析方法在橡胶光氧老化分析中的应用。NMR法能分析橡胶链中单元链节的组成、FTIR法能表征镍系胶在光氧老化过程中分子结构的动态变化结果,SEM能研究样品的聚集状态及低温下的结晶行为,TG研究样品的热稳定性等。