Reduction Of Nickel Research Articles

New Insights into Layered Graphene Materials as Substrates to Regulate Synthesis of Ni-P Nanomaterials for Electrocatalytic Oxidation of Methanol and Water.

The doping ring-core nickel phosphide/graphene nanomaterial is obtained by H2 reduction of the flower-like nickel phosphates/graphene oxide (NiPOGO) and sea urchin-like nickel phosphates/chemically converted graphene (NiPOG) substrates. The obtained structure of nickel phosphates depends on the influence of different kinds of oxygen-containing groups on the graphene substrate. The substrate can also affect the particle size and distribution of nickel phosphate nanoparticles. The substrate can adjust the particle size, distribution, and exposed growth direction of nickel phosphide. These materials with high activity are employed as electrochemical catalysts for methanol oxidation reactions, which is ∼7 times that of pure nickel phosphide, and there is a very small Tafel slope of 47 mV decade-1 in the water oxidation reaction. Our results highlight that the substrate structure is essential to catalytic materials for electrochemical oxidation of methanol and water.

On the Fabrication of a High-Quality Optical Surface of an Amorphous Nickel Coating on a Beryllium Substrate

The physical and mechanical properties of modern materials used for manufacturing optical-electronic space-based devices ensuring a high mirror roughness at a level of Ra = 1 nm are analyzed. The deposition of nickel obtained as a result of nickel reduction from aqueous solutions by the chemical method on a beryllium substrate to obtain an amorphous structure is studied. The coating is analyzed by X-ray methods. The phase and chemical composition of the coating is determined and its thickness is measured. The amorphous structure of the coating is confirmed. The coating has a high chemical resistance and hardness and provides conditions for effective optical polishing. Regulation of the chemical composition during the deposition process allows thermal matching of the coating with the substrate to be achieved.

PREPARATION OF NICKEL NANOWIRES AND EFFECTS OF SYNTHESIS CONDITIONS ON THEIR MORPHOLOGY

Nickel nanostructures prepared by various methods have received considerable attentions due to their numerous applications. In this study, one-dimensional nickel nanowires (NiNWs) were synthesized by the reduction of nickel (II) chloride in polyol medium. Poly (vinylpyrrolidone) (PVP) served as the surfactant and hydrazine hydrate was used as the reductant. The effects of different experimental parameters, i.e. concentration of Ni2+, volume of N2H4, concentration of PVP and reaction temperature on the formation and morphology of NiNWs were studied. The structure, composition and surface morphology of the materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the morphology as well as the diameter of NiNWs could be effectively controlled by adjusting parameters of the synthesis process.

Интенсификация бактериально-химического выщелачивания никеля, меди и кобальта из сульфидной руды с применением микроволнового излучения

Currently, Russia and other countries display a steady tendency to decrease the amount of high grade and free- milling ore reserves. In this regard, the attention is being paid to the technology of bacterial-chemical leaching (BCL), which, unlike traditional pyrometallurgical enrichment methods, is well applicable for processing low-grade mineral raw materials. However, this technology has a significant drawback, which is the inability of microorganisms to create sufficiently aggressive conditions for the effective destruction of mineral complexes, which negatively affects the duration of the processes. The article presents the results of an experiment, the purpose of which was to study the multiple short-term effects of microwave radiation on the efficiency of extraction of nickel, copper, and cobalt in the process of bacterial-chemical leaching of sulfide ore. A microwave oven with a power of 900 W and a radiation frequency of 2.45 GHz was used as a source of microwave radiation. Irradiation was carried out every day throughout the experiment. The exposure time was 5 and 10 s; the flux density was 0.7 W/cm2. It was found that for all the studied microwave irradiation modes, a significant increase in the efficiency of biomass accumulation and the oxidizing ability of the medium was observed in comparison with the control that was not exposed to microwave radiation. Irradiation for 5 s twice a day increased the reduction of nickel by 16 %, cobalt by 15 % and copper by 6 %. The results of the study allow us to assess the prospects for the application of new biotechnology methods in the industrial practice of ore processing with an improvement in qualityindicators.

Preparation and characterization of electrodeposited Ni-Ru alloys: morphological and catalytic study

Nickel-ruthenium alloys with various compositions have been deposited by electrodeposition for the first time. Cyclic voltammetry and linear stripping voltammetry measurements show that codeposition of nickel with ruthenium is possible below the potential value of nickel reduction. High-quality alloys containing nickel and ruthenium can be plated at cathodic potentials ranging from − 0.5 to − 1.0 V vs SCE. Deposited coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The diffractograms obtained show that an increase of nickel concentration in alloy will lead to a change in the phase composition and formation of NiRu (100) and (101) phases which is observed to be 78 mas.% Ni. SEM studies confirm the surface homogeneity and presence of small, regular grains. AFM observation allows the estimation of the real surface area of obtained alloys which increase with more negative electrodeposition potentials. Ni-Ru alloys were found to be highly electroactive in the water splitting process, which can be connected with the presence of the NiRu phase and a well-developed electroactive area.Graphical Electrochemical deposition of Ni-Ru alloys with various composition and their catalytic activity in water splitting process

Термодинамическое моделирование восстановления металлов из расплавов B2O3-СaO-Ni(Zn,Pb,Cu)O монооксидом углерода

Thermodynamic modeling technique is used to describe the metal reduction from oxide melt by carbon monoxide. The B2O3-CaO-MeO (Me – Ni, Zn, Pb, Cu) system, was used with periodic output of the metal phase and gases from the working body. The approach originality is that the equilibrium is determined for each single portion of the gas injected into the working body, and the metal oxides content being reduced in each calculation cycle is taken from the previous data. This approach gives qualitative possibility to make simulated processes closer to real ones. The proposed method calculations allow determining, such parameters as the oxide melt and metal phase compositions, degree of elements reduction, oxide and metal phases mass ratio, equilibrium composition of the gas, reducing ability of gas utilization degree, and others, depending on the introduced gas quantities. Reducing process modeling of Nickel, Copper, Lead and Zinc from B2O3-CaO-MeO melts gives opportunity to determine the process for each metal. Copper reducing from CuO, goes with intermediate oxide (CuO → Cu2O → Cu) formation. Reduction of Nickel (NiO → Ni), Lead (PbO → Pbs + Pbg) and Zinc (ZnO → Zng) proceeds in one stage. The temperature dependence of the non-ferrous metals content in the oxide melt, its reduction degree and reducing agent quantity introduced are described by the second-order polynomial equations. The information obtained may be useful for thermo-extraction processes prognosis during the Nickel, Copper, Lead, and Zinc extraction from non-ferrous metallurgy slag in bubbling process of oxide melt by reducing gases.

Nickel (Ni) reduction in Sorowako post-mining soil through application of mycorrhiza Acaulospora sp. associated with Canavalia ensiformis L.

The nickel (Ni) content in a post-mining soil of Pomalaa mines reached 14,200 mg.kg-1 and became a limiting factor in the plant growth process. A Ni reduction in the soil by using phyto-accumulator such as Jack bean (Canavalia ensiformis L.) can be improved by combining it with arbuscular mycorrhizal (AM) fungi. The purpose of this study was to determine the effect of the mycorrhizal fungus Acaulospora sp. on the efficiency of Ni reduction by C. ensiformis. This experiment was carried out by using a randomized block design with three different treatments, include: 1) C. ensiformis without Acaulospora sp. inoculation (negative control), 2) C. ensiformis inoculated with indigenous Acaulospora sp. and 3) C. ensiformis inoculated with non-indigenous Acaulospora sp. The study was conducted in the nursery that belongs to PT. Vale Indonesia Tbk., Sorowako, South Sulawesi, Indonesia. The results showed that highest nickel accumulation was found in the root inoculated with indigenous Acaulospora sp. (9500 mg.kg-1), followed by stem (1400 mg.kg-1), leaf and pod (1300 mg.kg-1), seed (1200 mg.kg-1), and flower (1100 mg.kg-1). This study indicates that application of the indigenous Acaulospora sp. can improve C. ensiformis efficiency to reduce Ni content at Sorowako post-mining area.

The effect of iron content on the reduction of nickel laterite by direct reduction method

Reduction and the compounds formed when the reduced laterite nickel has been investigated. Nickel laterite with average grain size below 0.149 mm mixed with 13% (weight percent) of coal as reductant then reduced in muffle furnace with temperature from 700 °C to 1000 °C. Type of laterite is used which has high iron (saprolite) and low iron content (limonite). Reaction time varied 30, 60 and 90 minutes. The reduction of nickel during reduction is determined by an analysis of metallization values. Metallization analysis used bromine methanol method, while the compound analysis was formed using x-ray Diffractometer. Based on the metallization test, it is known that the laterite nickel ore containing high iron will produce a higher nickel reduction than the laterite nickel ore containing low iron. This corresponds to the oxide phases formed. The higher iron contain on the ore tend to produce the fayalite mixture and slightly forsterite, while at low iron content will form a forsterite. Forsterite tends to inhibit reduction of nickel.

Technosols on mining wastes in the subarctic: Efficiency of remediation under Cu-Ni atmospheric pollution

The copper-nickel factory's emissions in the Murmansk region, Russia, led to the degradation of plant cover and topsoil with the subsequent formation of industrial barrens. In this study, the industrial barrens were remediated by means of Technosol engineering, when grasses were sown on the two different types of mining wastes (carbonatite and serpentinite-magnesite) covered by hydroponic vermiculite. The serpentinite-magnesite waste was significantly different from the carbonatite waste in the content of silicon (Si) and manganese (Mn), pH, and texture. Both wastes had an alkaline pH level and high content of calcium (Ca) and magnesium (Mg). The vegetation and Technosol properties at the remediated sites were analyzed in 2017 and compared to the initial state (2010 year) to assess the efficiency of the long-term remediation. The quality and sustainability of Technosols based on the serpentinite-magnesite wastes were substantially higher compared to the carbonatite-based Technosol. Biomass and a projective cover of the grass community depended on Si content in the original mining waste and were found to be higher in the serpentinite-magnesite Technosol. The content of organic carbon and its fractions, microbial biomass and basal respiration after seven years of Technosol evolution was comparable to natural values. These parameters were directly related to plant cover state and were inversely proportional to copper (Cu) content in Technosol. The Technosol development led to the reduction of nickel (Ni) and Cu migration in soil-plant ecosystems due to neutralization and adsorption properties of mining wastes and phytostabilization by underground parts of grass communities. The Technosol development in its early stage of pedogenesis indicates the efficiency of applied remediation technology to the degraded acidic soil under the conditions of industrial atmospheric pollution.

Effects of current density on mechanical properties of electroplated nickel with high speed sulfamate bath

In this work, defect-free and high mechanical strength nickel films are deposited at a high growth rate using a high concentration sulfamate bath for applications in fabrication of MEMS components. Effects of the applied current density on the morphology, average grain size, Vickers hardness, micro-mechanical property, and thickness distribution are studied. The average grain size is refined to a minimum value when the current density is increased from 10 to 20 mA/cm2. The finest grain size obtained is 349.8 nm. The grain refinement effect is a result of the promoted nucleation rate as the applied current density increased. When the current density is beyond 20 mA/cm2, overpotential of the nickel reduction reaction is lowered because of the promoted hydrogen evolution and causes coarsening of the average grain size. The film electroplated at 20 mA/cm2 shows a high growth rate at 0.296 μm/min, the highest Vickers hardness at 371 HV, and the yield stress evaluated by micro-compression test is 1.3 GPa. Relationship between the average grain size and the applied current density follows the Hall-Petch relationship well.

Metal Phase Formation in Bubbling Reduction of Nickel and Iron from Oxide Melt

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Partial Oxidation of Methane to Syngas Over Nickel-Based Catalysts: Influence of Support Type, Addition of Rhodium, and Preparation Method.

There is great economic incentive in developing efficient catalysts to produce hydrogen or syngas by catalytic partial oxidation of methane (CPOM) since this is a much less energy-intensive reaction than the highly endothermic methane steam reforming reaction, which is the prominent reaction in industry. Herein, we report the catalytic behavior of nickel-based catalysts supported on different oxide substrates (Al2O3, CeO2, La2O3, MgO, and ZrO2) synthesized via wet impregnation and solid-state reaction. Furthermore, the impact of Rh doping was investigated. The catalysts have been characterized by X-ray diffraction, N2 adsorptiondesorption at −196°C, temperature-programmed reduction, X-ray photoelectron spectroscopy, O2-pulse chemisorption, transmission electron microscopy, and Raman spectroscopy. Supported Ni catalysts were found to be active for CPOM but can suffer from fast deactivation caused by the formation of carbon deposits as well as via the sintering of Ni nanoparticles (NPs). It has been found that the presence of Rh favors nickel reduction, which leads to an increase in the methane conversion and yield. For both synthesis methods, the catalysts supported on alumina and ceria show the best performance. This could be explained by the higher surface area of the Ni NPs on the alumina surface and presence of oxygen vacancies in the CeO2 lattice, which favor the proportion of oxygen adsorbed on defect sites. The catalysts supported on MgO suffer quick deactivation due to formation of a NiO/MgO solid solution, which is not reducible under the reaction conditions. The low level of carbon formation over the catalysts supported on La2O3 is ascribed to the very high dispersion of the nickel NPs and to the formation of lanthanum oxycarbonate, through which carbon deposits are gasified. The catalytic behavior for catalysts with ZrO2 as support depends on the synthesis method; however, in both cases, the catalysts undergo deactivation by carbon deposits.

Phase composition and thermal properties of the Sakharinskoe deposit oxidized nickel ore

X-ray diffraction, optical microscopy and X-ray microanalysis were used to determine the composition and distribution of elements in the main mineral constituents of oxidized nickel ore at the Sakhalin deposit (goethite, hematite, serpentine, talc and chlorite). The main fraction of nickel is concentrated in iron oxides, where its content reaches 2,4 %, while in magnesium silicates it does not exceed 0,4 %. The sequence and temperature intervals of transformations were established when heating ore in inert and reducing media by means of thermal analysis methods combined with mass-spectrometric analysis of gases and subsequent X-ray phase analysis of products. The temperature regimes of ore roasting for the reduction of nickel and iron from their minerals were justified. The temperature regimes of sample heating are assumed to be close to the conditions implemented in industrial units (electric furnaces) where the rate of charge heating varies within 5—15 degrees/min, up to the melting point (1450 °С) of ferronickel and slag. It is proposed to use information on material composition, thermal properties and metal forms in ore to select regimes and technologies for their pyro-or hydrometallurgical processing. Nickel and iron recovery from oxides in CO environment occurs above 800 °С, while serpentines remain stable up to 1200 °С. The use of coke as a reducing agent allows reducing iron and nickel from serpentines at temperatures above 1250 °С. The obtained data were used to substantiate the operating conditions of roaster and electric furnaces during ferronickel smelting from oxidized ores. When roasting, resulting ferronickel particles will contain 2—4 % Ni. Completing recovery processes in the electric furnace will ensure metal recovery from magnesium silicates, which will slightly increase the nickel content in ferro-nickel.

Modeling and simulation for the control of post-combustion in the conditions of the nickel reduction process

Complex physical and chemical processes occur in reduction furnaces characterized by multiple inputs and multiple outputs strong interactions nonlinearities and dynamic characteristics that vary with time Attempts to control the oven using classical control strategies have not been successful Taking into account that the operation is carried out by operators based on their experience skill and on the historical behaviour of the process variables experimental identification is carried out in the afterburning area with the scoop of knowing the dynamics of the process for its better study and understanding The identification gives us the possibility of obtaining a mathematical model as close as possible to the plant which can be used to propose a strategy of temperature control in households and of the furnace A survey is made of the main theoretical aspects related to the processes of nickel reduction and identification as well as the input signal to excite the system The experiments that were carried out are described and the mathematical models obtained are validated using as tool of calculation the quot Toolbox quot of identification of the MATLAB program finally an economic and environmental analysis of an adequate control in the post combustion is presented

Syngas chemical looping combustion using a highly performing fluidizable oxygen carrier

• A high performing 20 wt%Ni-1 wt%Co-5 wt%La/γ-Al 2 O 3 oxygen carrier is reported. • The preparation method secures a stable fluidizable OC with enhanced reactivity. • This OC carrier is suitable for biomass gasification derived syngas combustion. • This OC yields up to 92% CO 2 yields in the 550-650 º C range. • This OC is free from NiAl 2 O 4 formation in the targeted temperature operating range. Biomass steam gasification produces a blend of H 2 , CO, CH 4 and CO 2 , designated as syngas. Syngas can be further combusted using fluidizable oxygen carriers (OC). This operation which is known as Chemical Looping Combustion (CLC), is valuable for syngas combustion as it involves nickel oxidation and nickel reduction, which are both exothermic reactions. To improve syngas CLC and establish its application, a new Ni-based oxygen carrier was studied using a Co and La modified γ-Al 2 O 3 support. This type of OC considerably limits the NiAl 2 O 4 formation. A Highly Performing Oxygen Carrier (HPOC) was engineered using a special preparation methodology to exclude NiAl 2 O 4 species formation. The evaluation of this HPOC was developed using the fluidized CREC Riser Simulator reactor at mild CLC 550–650 °C temperatures. Reaction conditions employed ranged from 2 to 40 s and used a 0.5–1 fuel to oxygen stoichiometric supply ratio (ψ). It is shown that under these conditions, the HPOC demonstrates a stable performance, yielding 75–92% CO 2 , displaying a 1.84–2.75 wt% (gO 2 /gOC) oxygen transport capacity with 40–60% solid phase oxygen conversion.

Reduction crystallization of nickel with hydrazine in the presence of an additive ethylene maleic anhydride

The removal of contaminants from process effluent streams is very important, as the demand for water continue to increase. The contaminants in the effluent also pose an environmental pollution challenge and result in affecting human health. The objective of this study was to investigate the reduction of nickel in the presence of hydrazine (reducing agent) and ethylene maleic anhydride (EMA) as an additive. Reduction crystallisation was conducted at 0.5 g/L of Ni metal solution, 1 M hydrazine in the presence of EMA and at temperature of 60oC and pH of 10.7-11. Various concentrations of EMA were investigated and varied from 2 mg/L to 10 mg/L. The effluent before and after the reduction crystallization process was analyzed to study the removal efficiency. The seeding material was also analyzed to measure the elemental composition, so as to understand the reduction mechanism and the particle size distribution of the nickel seed. Electron Microscopy. The results obtained showed that hydrazine in the presence of an additive can reduce nickel to its elemental state. When the concentration of EMA was increased the percentage removal of Ni2+ in Ni- solution also increased from ~0-115%. The highest Ni % removal was obtained when 5, 7 and 10mg/L of EMA was used with percentage removal above 80-115%. The XRF results also confirmed that as EMA concentration was increased, the relative proportion of nickel increased from 98.9% to 99.7% with the highest concentration of EMA (C=10mg/l). The presence of EMA contributed to the transformation the morphology of the nickel powder.

Thermodynamic analysis of chemical processes in Ni/Cr/Si structure for carbon nanotubes growing by CVD

This paper presents results of the thermodynamic analysis of chemical processes in the Ni/Cr/Si structure during the formation of catalytic centers and the growth of carbon nanotubes on them. It is shown that before starting CVD process Ni/Cr/Si structure is oxidized in atmosphere, and the Cr underlayer oxidation occurs due to an exchange reaction between Cr and NiO, with the formation of chromium oxide. Argon is supplied during the heating displaces residual atmospheric gases, and ammonia due to decomposition under the action of temperature allows to bind the free oxygen in the water vapor. The activation step may be accompanied by a reduction reaction of the oxide of catalyst material up to full reduction of nickel. It was revealed that under nickel CC formed the complex composition underlayer Cr/CrxOy/CrSi2, which is a diffusion barrier, which prevents the interaction of nickel with a silicon substrate. It is shown that in the growth stage decomposition of acetylene occurs on nickel CC with the release of free carbon, however in the underlayer may be formed a solid solution of Cr2O3 and Cr3C2.

Nickel incorporation in perovskite-type metal oxides – Implications on reducibility

Nickel is often applied in heterogeneous catalysis for its high catalytic activity towards a large variety of reactions at affordable price. Nickel reduction from perovskite-type mixed oxides is increasingly exploited to generate active and stable Ni catalysts. To investigate implications of the host perovskite structure on Ni reducibility, Ni was incorporated on the B-site of three perovskite-type mixed metal oxides of different lattice symmetries (LaFeO3 – orthorhombic, LaCoO3 – rhombohedral and La0.3Sr0.55TiO3 – cubic). Structural parameters of the phase pure undoped and Ni-doped perovskites were determined using synchrotron X-ray diffraction (XRD) and Ni K-edge X-ray absorption spectroscopy (XAS). Rietveld refinement and extended X-ray absorption fine structure (EXAFS) data fitting were used to verify that at this substitution level Ni enters the B-site and adopts its coordination environment. Expansion of the unit cell was found in LaCoO3 and La0.3Sr0.55TiO3, whereas contraction was observed in the case of LaFeO3. X-ray absorption spectra showed that Ni-containing unit cells exhibit the same symmetry as the host perovskite-type mixed oxides. The mean oxidation state of Ni was found to be equal in all three cases irrespective of the host lattice (+2.5). Lattice symmetry had significant effect on lowering the Ni reduction temperature determined by hydrogen temperature programmed reduction and a correlation between reduction temperature and crystal tolerance factor was found.

Methanol Electrooxidation on PtM/C (M = Ni, Co) and Pt/(SnO2/C) Catalysts

We investigate the activity of bimetallic PtM/C (M = Ni, Co) catalysts with different microstructures and platinum catalysts supported on a nanostructured composite carrier (SnO2/C) in the electrooxidation reaction of methanol. For bimetallic catalysts, the effect of heat treatment on their structural and functional characteristics is also studied. Among bimetallic catalysts in the as-obtained state, the Pt@Ni/C catalyst prepared by the subsequent reduction of nickel and platinum from solutions of their compounds exhibited the highest activity in the methanol electrooxidation, significantly exceeding that for the commercial Pt/C product. Heat treatment at 350°C increased the activity of the PtCo/C catalyst containing nanoparticles of a solid solution but adversely affected the tolerance of all the studied bimetallic catalysts to the intermediate products of methanol oxidation. All the studied Pt/(SnO2/C) materials demonstrated a higher mass activity in the electrooxidation reaction of methanol compared to commercial Pt/C and bimetallic systems, while the catalyst with a weight fraction of platinum of 12% and a molar ratio of Pt: SnO2 of 1: 1.1 showed the highest mass activity.

Electrolytic production of Cu-Ni alloys in CaCl2-Cu2S-NiS molten salt

Abstract An alternative metal/alloy production method, known as direct electrochemical reduction (DER), was introduced for the fabrication of CuNi alloys from mixed sulfides (Cu2S, NiS) under both galvanostatic and potentiostatic conditions. The influences of the process parameters (e.g., cell voltage and current) on the compositions of the reduced compounds were investigated to yield industrially desirable alloys, namely, CuNi10, CuNi20, and CuNi30. The electrochemical behaviors of Cu2S and NiS in CaCl2 melt were examined at a temperature of 1200 °C via cyclic voltammetry (CV). Based on the CV results, the cathodic reduction of Cu2S occurred in one step and cathodic reductions of NiS occurred in two steps, i.e., Cu2S⇒Cu for copper reduction and NiS⇒Ni3S2 ⇒Ni for nickel reduction. Galvanostatic studies revealed that it was possible to fabricate high-purity CuNi10 alloys containing a maximum sulfur content of 320×10−6 via electrolysis at 10 A for 15 min. Scanning electron microscopy along with energy-dispersive X-ray spectrometry and optical emission spectroscopy (OES) examinations showed that it was possible to fabricate CuNi alloys of preferred compositions and with low levels of impurities, i.e., less than 60×10−6 sulfur, via DER at 2.5 V for 15 min.