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Influences of synthesis methods and modifier addition on the properties of Ni-based catalysts supported on reticulated ceramic foams

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International Journal of Minerals,Metallurgy and Materials 2014年第8期21卷 806-812页

作者： vesna Nikolic Zeljko Kamberovic Zoran Antic Marija Korac Miroslav Sokic vesna maksimovic Innovation Center of the Faculty of Technology and Metallurgy University of Belgrade Karnegijeva 4 11120 Belgrade Serbia Faculty of Technology and Metallurgy University of Belgrade Karnegijeva 4 11120 Belgrade Serbia Innovation Center of the Faculty of Chemistry University of Belgrade Studentski trg 12-16 11000 Belgrade Serbia Institute for Technology of Nuclear and other Raw Materials Bulevar Frans d'Eperea 86 11000 Belgrade Serbia Institute for Nuclear Sciences ‘Vinca’ Mike Petrovica Alasa 12-14 11001 Belgrade Serbia

A method of synthesizing Ni-based catalysts supported on α-Al2O3-based foams was developed. The foams were impregnated with aqueous solutions of metal chlorides under an air atmosphere using an aerosol route. Separate procedures involved calcination to form oxides and drying to obtain chlorides on the foam surface. The synthesized samples were subsequently reduced with hydrogen. With respect to the Ni/Al2O3 catalysts, the chloride reduction route enabled the formation ofa Ni coating without agglomerates or cracks. Further research included catalyst modification by the addition of Pd, Cu, and Fe. The influences of the additives on the degree of reduction and on the low-temperature reduction effectiveness （533 and 633 K） were examined and compared for the catalysts obtained from oxides and chlorides. Greater degrees of reduction were achieved with chlorides, whereas Pd was the most effective modifier among those investigated. The reduction process was nearly complete at 533 K in the sample that contained 0.1wt% Pd. A lower reduction temperature was utilized, and the calcination step was avoided, which may enhance the economical and technological aspects of the developed catalyst production method.

关键词： catalysts nickel ceramic foams modification aerosol process catalytic properties

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Comparative morphological and crystallographic analysis of copper powders obtained under different electrolysis conditions

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Transactions of Nonferrous Metals Society of China 2019年第6期29卷 1275-1284页

作者： Nebojsa D. NIKOLIC Ljiljana AVRAMOVIC Evica R. IVANOVIC vesna M. maksimovic Zvezdana BASCAREVIC Nenad IGNJATOVIC ICTM-Department of Electrochemistry University of Belgrade Njego.eva 12 Belgrade Serbia Mining and Metallurgy Institute Zeleni Bulevar 35 Bor Serbia Faculty of Agriculture University of Belgrade Nemanjina 6 Belgrade-Zemun Serbia Vinca Institute of Nuclear Sciences University of Belgrade Belgrade Serbia Institute for Multidisciplinary Research University of Belgrade Kneza Viseslava 1a Belgrade Serbia Institute of Technical Sciences of the Serbian Academy of Science and Arts Knez Mihailova 35/IV Belgrade Serbia

Production of copper powders by the potentiostatic electrolysis under different hydrogen evolution conditions was investigated. Copper powders were characterized by the scanning electron microscope(SEM),X-ray diffraction(XRD),particle size distribution(PSD), and by the determination of the specific surface area(SSA) of the formed powders. Depending on quantity of hydrogen generated during electrolysis, the two types of particles were formed: dendrites and cauliflower-like particles. The dendrites were formed without, while cauliflower-like particles with the quantity of evolved hydrogen enough to achieve strong effect on hydrodynamic conditions in the near-electrode layer. Although macro structure of the particles was very different, they showed similar micro structure. Namely, both types of the particles consisted of smalal agglomerates of approximately spherical Cu grains at the micro level. The existence of the spherical morphology was just responsible for random orientation of Cu crystallites in both types of particles. The SSA of cauliflower-like particles was more than two times larger than that of the dendrites, while their size was considerably smaller than that of the dendritic particles. In this way, the useful benefit of Cu powder formation in the conditions of vigorous hydrogen evolution is shown.

关键词： electrolysis copper particles specific surface area(SSA) particle size distribution(PSD)

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Correlation between crystal structure and morphology of potentiostatically electrodeposited silver dendritic nanostructures

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Transactions of Nonferrous Metals Society of China 2018年第9期28卷 1903-1912页

作者： Ljiljana AVRAMOVIC Evica R.IVANOVIC vesna M.maksimovic Miroslav M.PAVLOVIC Marina VUKOVIC Jasmina S.STEVANOVIC Nebojsa D.NIKOLIC Mining and Metallurgy Institute Zeleni bulevar 35BorSerbia Faculty of Agriculture University of BelgradeNemanjina 6Belgrade-ZemunSerbia Vinca Institute of Nuclear Sciences University of BelgradeBelgradeSerbia Institute of Chemistry Technology and MetallurgyDepartment of ElectrochemistryUniversity of BelgradeNjegoseva 12BelgradeSerbia Institute for Multidisciplinary Research University of BelgradeKneza Viseslava 1aBelgradeSerbia

Silver dendritic nanonstructures obtained by the potentiostatic electrolysis from different electrolytes at different overpotentials were characterized by the scanning electron microscopy(SEM)technique and X-ray diffraction analysis of the produced *** needle-like and fern-like dendrites were formed from the nitrate electrolyte at overpotentials inside and outside plateaus of the limiting diffusion current density,*** three-dimensional pine-like dendrites constructed from approximately spherical grains were formed from the ammonium electrolyte at overpotentials both inside and outside plateaus of the limiting diffusion current *** morphology of silver dendrites was correlated with their crystal structure at the semi quantiative *** change of crystal orientation from the strong(111)preferred orientation for the needle-like dendrites to almost randomly orientied spherical grains in the pine-like dendrites obtained at the overpotential outside the plateau of the limiting diffusion current density was *** trend in change of crystal orientation and morphology of Ag nanostructures was accompanied by considerable increase of the specific surface area(SSA)of the produced *** average crystallite sizes were in the range of 38-50 nm,proving nanostructural character of the formed Ag particles.

关键词： electrodeposition silver dendrites SEM XRD

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Influence of Ni^(2+)/Co^(2+)ratio in electrolyte on morphology,structure and magnetic properties of electrolytically produced Ni-Co alloy powders

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Transactions of Nonferrous Metals Society of China 2020年第4期30卷 1046-1057页

作者： vesna M.maksimovic Vladan B.KUSIGERSKI Milovan M.STOILJKOVIC Jelena R.MALETASKIC NebojSa D.NIKOLIC Institute of Nuclear Sciences “Vinca”University of BelgradeP.O.Box 522Belgrade 11001Serbia Laboratory for Advanced Nuclear Energy Institute of Innovative ResearchTokyo Institute of Technology2-12-1 OokayamaMeguro-kuTokyo 152-8550Japan ICTM-Department of Electrochemistry University of BelgradeNjegoseva 12P.O.Box 473Belgrade 11001Serbia

Nickel-cobalt(Ni-Co) alloy powders were produced galvanostatically by using sulphate electrolytes with various ratios of Ni2+/Co2+(mole ratios). The morphology, phase structure, chemical composition and magnetic properties were examined by scanning electron microscope(SEM), X-ray diffractometer(XRD), atomic emission spectrometer(AES), and SQUID-based magnetometer, respectively. Morphology of the particles changed from cauliflower-like and dendritic to coral-like and spongy-like ones with increasing Ni2+/Co2+ ratio from 0.25 to 4.0. XRD analysis of the Ni-Co powders revealed that the decrease of Ni2+/Co2+ ratios(the increase of Co content) caused a change of structure from face centered cubic(FCC) obtained for the ratios of 4.0, 1.5 and 0.67 to a mixture of FCC and hexagonal closed-packed(HCP) phases for the ratio of 0.25. The increasing content of nickel led to change of mechanism of electrolysis from irregular(up to 40 wt.% Ni in the electrolytes) to close to equilibrium(between 40 and 60 wt.% Ni in the electrolytes) and anomalous co-deposition(over 60 wt.% Ni in the electrolytes) type. All of the obtained Ni-Co alloy samples behaved as soft magnetic materials while their magnetic parameters showed immediate composition dependence since both coercivity and saturation magnetization almost linearly increased with increase of the Co content.

关键词： Ni-Co alloy powders electrolysis hydrogen morphology magnetic properties

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