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1
Huang, Shanshan. "Nanoparticulate nickel sulfide". Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54754/.
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Nickel sulfide possesses a variety of typical structures and stoichiometries that distinguish itself from iron sulfide and exhibits unique roles in the prebiotic reactions which are proposed to be involved in the origin of life. Nickel sulfide precipitate is hydrated and nanocrystalline, modelled as a 4 nm sphere with a 1 nm crystalline and anhydrous NiS (millerite) core, surrounded by a hydrated and defective mantle phase. It is a metastable but fairly robust structural configuration. It may be formulated as NiSxFbOx approximates to 1.5 and decreases on heating. The fresh nanoparticulate nickel sulfide precipitates undergo structural transformation from the initial millerite-like NiS to the more crystalline polydymite-like Ni3S4. This reaction is accompanied by the formation of a less crystalline Ni3S2 (heazlewoodite) phase. The reaction, happening in ambient conditions, occurs more readily for the solids precipitated from acidic environments (i.e., pH 3) and may be facilitated by the hydrogen and water bonding contained in this material. The performance of nickel sulfide and iron sulfide precipitates is investigated in the formaldehyde world under ambient and sulfidic environments which mimic the ambient ancient Earth environments to some extent. The catalytic capacity of the metal sulfides is not obvious in these experiments. An interesting finding is that, trithiane, the cyclic (SCH2)3, also suppresses the pyrite formation and thus promotes the greigite formation in the reaction between FeS and H2S. This provides another cause for the greigite formation in the Earth sedimentary systems and adds information to the origin-of-life theory in the iron sulfur world. Voltammetry experiments reveal that the nickel-cysteine complex lowers the overpotential for molecular H2 evolution in sea water to -1.53 V under ambient conditions. This catalytic property of the abiotic nickel-cysteine complex apparently mimics the Ni-S core in some hydrogenase enzymes functioning in physiological conditions. This bridges the abiotic and biotic worlds and supports the idea that life originated in the prebiotic ancient ocean.
2
Weatherwax, Trent. "Integrated mining and preconcentration systems for nickel sulfide ores". Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/238.
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As part of a strategic research initiative at UBC to design and evaluate integrated underground mining and mineral processing systems, work has been done to determine how to utilize the coarse rejects of pre-concentration in the underground environment. An amenability study for nine orebodies from four of Xstrata Nickel’s Ontario operations evaluated both processing and waste disposal methods. Metallurgically the orebodies showed amenability to dense media separation and conductivity sorting. The dense media results showed high mass rejections and high metal recoveries for all nine orebodies. Conductivity sorter results were not as consistent, but still showed good results. Dense media rejects were examined to determine the applicability of their use in rockfills and composite minefills. The geotechnical properties indicated that the rejects would provide a competent material for minefills. The mix designs were examined for both strength and rheological properties and showed that fills utilizing rejects were comparable to fills currently used by industry. Composite fills containing rejects had significantly lower void ratios, decreasing cement requirements for a given strength requirement. Conceptual designs for pre-concentration systems based on the metallurgical, reject characterization, and mix design were developed for each of the four mines in the study. The designs took into consideration the current mining plans.
3
Lane, Monica Leonie. "Nickel sulphide mineralization associated with Archean komatiites". Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1005594.
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The distribution of Archean Nickel sulphide deposits reflects tectonic controls operating during the evolution of the granitoid greenstone terrains. Important deposits of komatiitic-affinity are concentrated within, and adjacent to, younger (∼2.7 Ga), rift-related greenstone belts (e.g. Canada, Western Australia and Zimababwe). Two important classes of Archean Nickel sulphide deposits exist, formerly known as "Dunitic" and "Peridotitic", these are now referred to as Group I and Group II deposits, based on their characteristic structure and composition. Mineralization varies from massive and matrix to disseminated, and is nearly always concentrated at the base of the host unit. Primary ores have a relatively simple mineralogy, dominated by pyrrhotite-pentlandite-pyrite, and to a lesser degree millerite. Metamorphic grades tend to range from prehnite-pumpellyite facies through to lower and upper amphibolite facies. Genesis of Group I and II deposits is explained by the eruption of komatiites into rift-phase greenstone belts, as channelized flows, which assimilated variable amounts of footwall rocks during emplacement. Sulphide saturation was dependent on the mode of emplacement and, the amount of sulphidic sediments that became assimilated prior to crystallization. This possibly accounts for variations in ore tenor. The Six Mile Deposit (SMD) in Western Australia, is an adcumulate body of the Group IIB-type, exhibiting disseminated mineralization. The ore has been "upgraded" due to hydration and serpentinization. A profound weathering sequence exists, which was subsequently utilized during initial exploration. Exploration techniques has been focused on Western Australia, as it is here that the most innovative ideas have emerged.
4
Chang, Xiangning. "Short term sublethal studies in rats exposed to nickel subsulfide and nickel ore : effects on oxidative damage, antioxidant and detoxicating enzymes /". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ55491.pdf.
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5
Zhang, Liping. "Hydrodenitrogenation of organonitrogen compounds over nickel-molybdenum sulfide and Molybdenum nitride catalysts /". The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487942739805674.
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6
Ji, Yijie. "Metal Organic Frameworks Derived Nickel Sulfide/Graphene Composite for Lithium-Sulfur Batteries". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron152233332526446.
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7
Tong, Libin. "Sulfur dispersing agents for nickel sulfide leaching above the melting point of sulfur". Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/3427.
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The effects of sulfur dispersing agents (SDAs) in the oxygen pressure leaching of nickel concentrate at medium temperature were investigated. Liquid sulfur-aqueous solution interfacial tensions and liquid sulfur-sulfide mineral contact angles were measured at 140ºC, 690 kPa overpressure by nitrogen, and 1.0 mol/L NiSO₄. The effects of SDAs including lignosulfonate, Quebracho, o-phenylenediamine (OPD), and humic acid were evaluated by the calculation of the work of adhesion in the liquid sulfur-sulfide mineral-aqueous solution systems. It was found that the sulfide mineral surface is sulfophobic at pH from 4.1 to 4.5 due to the hydrolysis of nickel (II) ions to nickel hydroxide and the deposition of nickel hydroxide on the mineral surface. These findings apply to four different sulfide mineral systems, including pentlandite, nickeliferous pyrrhotite, pyrrhotite, and chalcopyrite. Lignosulfonate, Quebracho, and humic acid were found to significantly reduce the work of adhesion indicating they should be effective SDAs. OPD is ineffective in changing the work of adhesion of sulfur on the mineral sulfides indicating that it is not a good candidate for sulfur dispersion.
The adsorption behavior of SDAs, including lignosulfonate, Quebracho, OPD, and humic acid on elemental sulfur and on nickel sulfide concentrate was investigated. Lignosulfonate, Quebracho, and humic acid were characterized by their infrared spectra. The charge changes on elemental sulfur surface were characterized by the measurement of the electrokinetic sonic amplitude (ESA) in the absence or presence of SDAs. The adsorption of lignosulfonate on molten sulfur surface was calculated by the Gibbs Equation. The adsorption of lignosulfonate, Quebracho, and humic acid on the nickel concentrate was investigated at ambient temperature. The adsorption of lignosulfonate, Quebracho, and humic acid on the nickel concentrate was found to be monolayer adsorption, which was fitted to the Langmuir adsorption isotherm. Electrostatic interaction and ion-binding are the possible mechanisms for the adsorption of lignosulfonate and humic acid on the nickel concentrate. Quebracho is adsorbed on the nickel concentrate through hydroxyl and sulfonate groups. OPD cannot adsorb on the molten sulfur surface. OPD undergoes chemical change in aqueous solution in the presence of ferric at ambient temperature.
Oxygen pressure leaching experiments were performed at 140 or 150ºC under 690 kPa oxygen overpressure. The particle size of the nickel concentrate was found to be an important factor in leaching. During the leaching of nickel concentrate with P₈₀ of 48 µm, the SDAs were believed to be fully degraded before nickel was fully extracted. At most 66% nickel was extracted in the presence of 20 kg/t OPD. Fine grinding (P₈₀ of 10 µm) was sufficient for 99% nickel recovery at low pulp density while at high pulp density, the nickel extraction increased from 95% to 99% with addition of SDAs. Based on the leaching results on a nickel concentrate sample (-44 µm), OPD had the effect of increasing the nickel extraction to about 99%, followed by Quebracho (83%), lignosulfonate (72%), and humic acid (61%). It is suggested that the oxidation product of OPD is effective in solving the sulfur wetting problem in leaching. 97% nickel was recovered in the presence of 5 g/L chloride ion. Chloride ion has an effect to enhance the performance of lignosulfonate under leaching conditions.
8
Pillay, Keshree. "Mineralogical effects on the dense medium separation of low grade nickel sulfide ore". Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/13751.
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Dense medium separation (DMS) is a method often used to upgrade base metal sulfide (BMS) ores before their main processing stage, with varying results achieved for different ore types. The process makes use of the density differences between the BMS minerals and the lower density silicate/carbonate gangue minerals, using a separating medium of density between the two ore components. The separation is accelerated using a dense medium cyclone (DMC) to form two products: overflow (tailings) and underflow (concentrate). The purpose of DMS is to reject large quantities of gangue upfront, resulting in reduced time, energy and costs associated with processes such as milling and flotation. Preconcentration of ores using physical methods such as DMS is becoming an important consideration as lower grade ores are mined, to increase the feasibility of mining such ores. Two nickel sulfide deposits were chosen as case studies in order to understand differences in DMS efficiency for different ores. The first is the Main Mineralised Zone (MMZ) of the Nkomati Nickel deposit in Mpumalanga, South Africa, which is part of the Uitkomst Complex. The Phoenix deposit is also considered, and forms part of the Tati greenstone belt in eastern Botswana. Both deposits are magmatic Cu-Ni-PGE (platinum group element) deposits with similar sulfide mineralogy and pentlandite as the main nickel host. A process mineralogy approach was used to evaluate samples of both ores, describing the differences in the mineralogical properties within the overflow and underflow of each ore in order to understand the extent to which individual properties affect the separation.
9
Franchuk, Anatoliy. "HIGH TENOR NI-PGE SULFIDE MINERALIZATION OF THE SOUTH MANASAN ULTRAMAFIC INTRUSION, THOMPSON NICKEL BELT, MANITOBA". Thesis, Laurentian University of Sudbury, 2014. https://zone.biblio.laurentian.ca/dspace/handle/10219/2195.
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The South Manasan ultramafic intrusion (ca. 1880 Ma) located in the Early Proterozoic
Thompson Nickel Belt (TNB) contains Ni and platinum group element (PGE) mineralization
hosted by disseminated sulfide. Whole-rock Ni values range from 0.3 to 1.7 wt. % and total
precious metals (TPMs) range from 0 to 1.3 ppm Pt + Pd + Au and equate to tenor values (i.e.,
metal in 100% sulfide) of 11-39 wt. % Ni and 8-27 ppm TPMs. The South Manasan intrusion is
a steeply dipping sill-like body with a boudinaged outline having a strike length of
approximately 1200 m, average width of 125 m and a minimum depth extent of 1000 m. The
intrusion is composed of approximately 25% fresh dunite, 50% serpentine altered dunite and
25% tectonized and carbonate altered dunite. The most intense alteration is found near the
intrusion’s margin where it is in contact with metasedimentary rocks of the Pipe Formation, part
of the surrounding Ospwagan Group. In fresh dunite the sulfide assemblage characterized by an
intercumulate texture is dominated by pentlandite with accessory pyrite; the latter having a
symplectic-like texture. The pentlandite-pyrite assemblage in the serpentinized dunite, although
still characterized overall by an intercumlate-texture, has well developed platy intergrowths with
chlorite and serpentine. In the most intensely modified unit (the carbonate altered dunite) the
sulfide assemblage consists primarily of pyrrhotite and pentlandite.
Whole-rock geochemical data (n=360), modal mineralogy and mineral chemistry
obtained on representative drill core throughout the South Manasan intrusion have been used to
establish a type section in order to evaluate the relative roles of primary magmatic versus
secondary (i.e., serpentinization, carbonate alteration and deformation) processes. These data
indicate that the primary silicate-sulfide assemblage was systematically modified during : serpentinization, carbonate alteration and deformation of the South Manasan intrusion such that a
sequence of primary versus secondary events can be established. Intrusion of the original
komatiitic magma and formation of the South Manasan intrusion took place at a shallow level
into consolidated Ospwagan Group sediments with subsequent contamination of this melt with
crustal S. This triggered sulfide saturation and generation of an immiscible sulfide melt.
Calculated Ni and TPM tenor values constrain the R factor to between 500 and 2500. The early
crystallization of olivine inhibited the sulfide melt from settling to the bottom of the magma
column and as a consequence, the sulfides now have a primary interstitial magmatic texture. The
current sulfide association dominated by pentlandite>>pyrite>chalcopyrite has a mineral
paragenesis that is consistent with subsolidus re-equilibration of a primary pentlanditepyrrhotite-
chalcopyrite assemblage. The subsequent processes of serpentinization, deformation
and carbonate alteration resulted in modifying the primary sulfide assemblages and their textures
(i.e., to platy habits), but did not greatly alter the bulk composition, in particular metal contents,
except for addition of volatiles (H2O, CO2).
It is concluded therefore that the enrichment of the sulfide assemblage at South Manasan
in Ni and PGEs is a consequence of a primary magmatic process involving high R factor and that
the effects of later overprinting processes (alteration, deformation) are not responsible for the
presently observed high-tenor sulfide association.
10
Kilickaplan, Isil. "Effect of pulp rheology on flotation : the nickel sulfide ore with asbestos gangue system". Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12765.
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Pulp rheology is a sensitive indicator of the state of aggregation/dispersion of mineral particles. In this study, possible correlation between the rheological properties of flotation pulp and the flotation response was investigated through a series of rheological and batch flotation tests.
The nickel-sulfide ore from the Mt. Keith plant (Western Australia) was used for the tests. It is a low-grade nickel sulfide ore which is characterized by complex mineralogical composition with a large content of serpentine minerals.
The experimental program included agglomerate flotation tests and rheological tests with the use of a slurry produced by grinding the nickel-sulfide ore. In order to see the effect of solids content on flotation, a series of tests were performed at various pulp densities in the absence and presence of oil in both conditioning and flotation stages. The agglomerate flotation and rheological tests were repeated with dispersants in order to investigate the correlation between degree of agglomeration/dispersion and flotation response.
The agglomerate flotation tests conducted at various solids content in the flotation stage revealed that the fastest flotation rate was observed at the lowest solids content. The entrainment was found to increase with increasing solids content due to elevated pulp viscosity. The “boiling” was observed in the flotation cell in the tests at a high pulp density, the effect likely associated with a high pulp viscosity. High pulp viscosity is clearly increasing the size of bubbles in the flotation system. In line with this the high recoveries by entrainment are observed in the tests at high pulp density. Under such conditions the concentrate grade was low since a large proportion of the nickel recovery resulted from entrainment. In distilled water the use of a dispersant improved considerably flotation performance.
The presence of chrysotile in the system strongly affects the pulp viscosity. In the tests with pure chrysotile the pulp with a solids content of around 0.8% by volume is close to the critical packing fraction. However, in the tests with the nickel ore containing more than 80% of chrysotile the viscosity is still far from the critical packing even at 7.6 % solids content by volume. This shows a very beneficial dilution effect; the presence of other non fibrous minerals dramatically decreases the viscosity of the chrysotile suspensions. Without such minerals processing of this ore would have been entirely impossible.
11
Yukna, Jennifer. "Computational and experimental investigations of the structural properties, electronic properties, and applications of silver, gold, mercury selenide, silver sulfide, and nickel sulfide nanoparticles /". Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1482010021&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2007."Department of Chemistry and Biochemistry." Keywords: Electronic properties, Silver, Gold, Mercury selenide, Silver sulfide, Nickel sulfide, Nanoparticles. Includes bibliographical references (p. 170-180). Also available online.
12
Piercey, Stephen John. "An integrated study of magmatism, magmatic Ni-Cu sulphide mineralization and metallogeny in the Umiakoviarusek Lake Region, Labrador, Canada /". Internet access available to MUN users only, 1998. http://collections.mun.ca/u?/theses,32157.
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13
Cameron, Rory. "Bioleaching of low-grade nickel sulphide ore at elevated pH". Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19784.
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This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).
14
Khan, Feroze. "Effect of Hydrogen Sulfide in Landfill Gas on Anode Poisoning of Solid Oxide Fuel Cells". Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1338838003.
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15
Becker, Megan. "The mineralogy and crystallography of pyrrhotite from selected nickel and PGE ore deposits and its effect on flotation performance". Thesis, Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-09272009-100136/.
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16
Francis, Jérémy. "Vers un design orienté de nouveaux catalyseurs zéolithiques sélectifs pour l'hydrocraquage". Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10013.
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L’emploi de cristaux de zéolithe USY comme fonction acide et de phases sulfures de type NiMoS comme fonction hydro/deshydrogénante (H/DH) dispersée sur un liant de type alumine [NiMoS/(_-Al2O3 + USY)] permet l'obtention de catalyseurs bifonctionnels d’hydrocraquage très actifs mais dont la sélectivité en distillats moyens est relativement faible. Une des causes invoquées pour expliquer ces performances est la distance importante entre les sites H/DH et les sites acides qui entraine des réactions secondaires et la formation de produits légers. Dans ce travail, une phase H/DH additionnelle (nickel) a été insérée dans des zéolithes USY par différentes méthodes afin d’obtenir des catalyseurs contenant une phase sulfure localisée au plus proche des sites acides. L’utilisation de zéolithes imprégnées à sec et échangées avec du nickel dans des catalyseurs typiques d’hydrocraquage permet d’obtenir de meilleures activités et sélectivités en distillats moyens en hydroconversion du squalane (2,6,10,15,19,23- hexamethyltetracosane) que l’utilisation de zéolithe ne contenant pas de Ni. L’étude de la relation structure-réactivité des catalyseurs a permis de mettre en évidence que l’amélioration de la proximité entre fonction acide et fonction H/DH est bien à l’origine de l’amélioration des propriétés catalytiques. De plus, l’utilisation d’une zéolithe dans laquelle le nickel a été inséré à la synthèse conduit aussi à des résultats prometteurs. Ce travail ouvre ainsi une voie d’amélioration pour des catalyseurs d'hydrocraquage plus actifs et plus sélectifs en distillats moyens par insertion d’une phase H/DH additionnelleHydrocracking bifunctional catalysts can be obtained using USY zeolite crystals as an acid function and NiMoS metal sulfide phase as a hydro/dehydrogenating (H/DH) function dispersed on an alumina binder [NiMoS/(_-Al2O3 + USY)]. These catalysts are very active but have a moderate selectivity towards middle distillates. One of the suggested explanations is the large distance between the two different types of catalytic sites leading to secondary reactions and to the formation of light products. In this work, an additional H/DH phase (nickel) has been inserted in USY zeolites using various methods in order to obtain catalysts in which a sulfided phase is located in the vicinity of the acid sites. The use of impregnated or ion exchanged nickel containing zeolites in a typical hydrocracking catalyst leads to higher activities and middle distillates selectivities in the squalane (2,6,10,15,19,23-hexamethyltetracosane) hydroconversion reaction than the use of bare zeolites. According to the structure-reactivity relation of the catalysts, these enhancements are ascribed to an increased proximity between the H/DH function and the acid sites. Moreover, the use of a synthesized Ni-zeolite leads to promising results. The use of an additional H/DH phase as an optimization route for the production of more active and selective hydrocracking catalysts is then clearly supported by this work
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Oliveira, Diogo Padilha, i 92981837414. "Síntese hidrotermal do sulfeto de níquel/carbono para aplicação em supercapacitores". Universidade Federal do Amazonas, 2018. https://tede.ufam.edu.br/handle/tede/6586.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The materials research for high efficiency in energy storage has grown in recent years. Different phases of NiS for application in supercapacitors have been synthesized at different temperatures by hydrothermal method, which is a simple and low cost way. In this work different phases of NiS in powdered carbon were obtained, and their evaluation was made for use in supercapacitors. The material obtained showed better electrochemical properties in the condition synthesis 2 mmol of Na2 S · 9H2O, 1 mmol of Ni (NO3) 2 · 6H2O and 10% by weight of Vulcan carbon at 160 ° C, with a specific capacitance value of 685,66 F g-1. The NiS / Carbon was able to provide a good power density, 327.87 W kg-1, with an energy density of 15.24 Wh kg -1 and 26.10% of capacitance retention after 1000 cycles. The low values of energy density and capacitance retention can be justified by the material amorphous morphology, which has a direct influence on the interaction of the electrode with the electrolyte. Due to these results, the obtained NiS / Carbon is a material with potential use for the application in electrochemical capacitors.
A pesquisa por materiais com alta eficiência em armazenamento de energia tem crescido muito nos últimos anos. Diferentes fases de NiS para aplicação em supercapacitores têm sido sintetizadas em diferentes temperaturas através do método hidrotermal, que tem como principais vantagens ser simples e de baixo custo. Neste trabalho foram obtidas diferentes fases de NiS em carbono em pó, e foi feita sua avaliação para a utilização em supercapacitores. O material obtido apresentou melhores propriedades eletroquímicas na condição de síntese 2 mmol de Na2S·9H2O, 1 mmol de Ni(NO3)2·6H2O e 10% em peso de carbono Vulcan a 160 °C, alcançando valor de capacitância específica de 685,66 F g-1. O NiS/Carbono conseguiu fornecer uma boa densidade de potência, 327,87 W kg-1, com uma densidade de energia de 15,24 Wh kg-1, obtendo 26,10 % de retenção da capacitância em 1000 ciclos. Os baixos valores de densidade de energia e de retenção da capacitância podem ser justificados pela morfologia amorfa deste material, que tem influência direta na interação do eletrodo com o eletrólito. Devido a esses resultados, o NiS/Carbono obtido é um material com potencial uso para a aplicação em capacitores eletroquímicos.
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Zhang, Jian, Tao Wang, Darius Pohl, Bernd Rellinghaus, Renhao Dong, Shaohua Liu, Xiaodong Zhuang i Xinliang Feng. "Interface Engineering of MoS2/Ni3S2 Heterostructures for Highly Enhanced Electrochemical Overall Water Splitting Activity". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-235457.
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To achieve sustainable production of H2 fuel through water splitting, low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are required to replace Pt and IrO2 catalysts. Here, for the first time, we present the interface engineering of novel MoS2/Ni3S2 heterostructures, in which abundant interfaces are formed. For OER, such MoS2/Ni3S2 heterostructures show an extremely low overpotential of ~218 mV at 10 mA cm-2, which is superior to that of the state-of-the-art OER electrocatalysts. Using MoS2/Ni3S2 heterostructures as bifunctional electrocatalysts, an alkali electrolyser delivers a current density of 10 mA cm-2 at a very low cell voltage of ~1.56 V. In combination with density function theory (DFT) calculations, this study demonstrates that the constructed interfaces synergistically favor the chemisorption of hydrogen and oxygencontaining intermediates, thus accelerating the overall electrochemical water splitting.
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Seat, Zoran. "Geology, petrology, mineral and whole-rock chemistry, stable and radiogenic isotope systematics and Ni-Cu-PGE mineralisation of the Nebo-Babel intrusion, West Musgrave, Western Australia". University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0202.
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The Nebo-Babel Ni-Cu-platinum-group element (PGE) magmatic sulphide deposit, a world-class ore body, is hosted in low-MgO, tube-like (chonolithic) gabbronorite intrusion in the West Musgrave Block, Western Australia. The Nebo-Babel deposit is the first significant discovery of a nickel sulphide deposit associated with the ca. 1078 Ma Giles Complex, which is part of the Warakurna large igneous province (LIP), now making the Musgrave Block a prime target for nickel sulphide exploration. The Musgrave Block is a Mesoproterozoic, east-west trending, orogenic belt in central Australia consisting of amphibolite and granulite facies basement gneisses with predominantly igneous protoliths. The basement lithologies have been intruded by mafic-ultramafic and felsic rocks; multiply deformed and metamorphosed between 1600 Ma and 500 Ma. The Giles Complex, which is part of the Warakurna LIP, was emplaced at ca. 1078 Ma and consists of a suite of layered mafic-ultramafic intrusions, mafic and felsic dykes and temporally associated volcanic rocks and granites. The Giles Complex intrusions are interpreted to have crystallised at crustal depths between 15km and 30km and are generally undeformed and unmetamorphosed.
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Zindine, El Mostafa. "Etude de la résistance à la corrosion de quelques métaux et alliages susceptibles d'être utilisés en connectique sans traitement de surface préalable". Besançon, 1987. http://www.theses.fr/1987BESA2029.
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Etude du comportement mecanique et de la resistance a la corrosion de certains metaux et alliages susceptibles d'etre utilises pour la fabrication de connecteurs sans revetement protecteur. Des alliages a base de nickel, a base de cuivre et a base de cobalt ont ete testes dans des milieux d'essais industriels (h::(2)s et/ou h::(2)s+so::(2)). La nature des produits de corrosion formes ete analysee par reduction electrochimique, diffraction des rx, microsonde de castaing et spectrometrie xps. Les resultats ont ete compares avec ceux obtenus par polarisation des echantillons dans une solution aqueuse de na::(2)s. L'influence des etats thermomecaniques et l'effet des elements d'addition a ete examinee
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Carvalho, Luciana Batista de. "Autoxidação dos complexos de tetra, penta e hexaglicina de Ni(II), Co(II) e Cu(II) induzida por S(IV). Determinação de S(IV) e aldeídos por quimiluminescência". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-30032007-153520/.
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A autoxidação dos complexos de Ni(II) e Co(II) com tetra, penta e hexaglicina, em meio de tampão borato, é acelerada por espécies de enxofre (IV) (H2S0
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Chamberlain, Anthony C. "The effect of stoichiometry on the thermal behaviour of synthetic iron-nickel sulfides". Curtin University of Technology, Department of Applied Chemistry, 1996. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=11365.
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The effect of stoichiometry on the pyrolytic decomposition, oxidation and ignition behaviour of synthetic violarite and pentlandite has been established. These minerals, of general formula (Fe,Ni)(subscript)3S(subscript)4 and (Fe,Ni)(subscript)9S(subscript)8 respectively, may vary considerably in Fe:Ni ratio. Pentlandite can also show some variation in metal:sulfur ratio. A series of samples, ranging in stoichiometry from Fe(subscript)0.96Ni(subscript)1.97S(subscript)4 to Fe(subscript)0.20Ni(subscript)2.72S(subscript)4 and Fe(subscript)5.80Ni(subscript)3.15S(subscript)8 to Fe(subscript)3.40Ni(subscript)5.55S(subscript)8, were synthesised and characterised using wet chemical analysis, electron probe micro-analysis (EPMA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer, Emmett and Teller (BET) surface area analysis.The thermal behaviour of these sulfides was examined using simultaneous Thermogravimetry-Differential Thermal Analysis (TG-DTA) at different heating rates and in different atmospheres. Partially reacted samples were collected at various temperatures and analysed using XRD, EPMA, SEM, optical microscopy (OM), and Fourier transform infrared (FTIR) spectroscopy. The endmembers of the violarite and pentlandite series were examined in detail to determine the effect of stoichiometry on the reaction mechanism. In this study the reaction mechanism refers to the sequence of reactions occurring during pyrolytic decomposition or oxidation of the sulfide minerals. Samples were sieved into four particle size fractions, 125-90, 90-63, 63-45 and 45-20 gm, to determine the effect of particle size on the reaction mechanism.When violarite was heated in an inert atmosphere at 10 degrees celsius min(subscript)-1, it initially decomposed to a monosulfide solid solution (mss), (Fe,Ni)(subscript)1-xS, and vaesite, (Ni,Fe)S(subscript)2, indicated by a ++sharp endothermic peak in the DTA trace. The decomposition temperature was found to be linearly dependent on the iron:nickel ratio, decreasing from 495 degrees celsius to 450 degrees celsius as the iron:nickel ratio decreased from 0.49 to 0.07. This was followed by a broader endothermic peak coinciding with a rapid mass loss, which was associated with the decomposition of vaesite to mss with the loss of sulfur. Between 615-805 degrees celsius the mss was converted to a high temperature form of heazlewoodite, (Fe,Ni)(subscript)3+/-S(subscript)2 melted incongruently at 835 degrees celsius and 805 degrees celsius for Fe(subscript)0.96Ni(subscript)1.97S(subscript)4 and Fe(subscript)0.20Ni(subscript)2.72S(subscript)4 respectively, with further loss of sulfur vapour forming a central sulfide liquid of general formula (Fe,Ni)(subscript)1+xS.Under similar experimental conditions, pentlandite pyrolytically decomposed forming mss and heazlewoodite with no associated loss of sulfur. The decomposition temperature decreased as the iron:nickel ratio deviated from the ideal value of 1:1. A maximum decomposition temperature of 610 degrees celsius was found at an iron:nickel ratio of 1.00, decreasing to 580 degrees celsius at a ratio of 1.84 and 0.61. Sulfur was evolved slowly at temperatures in excess of 760 degrees celsius as mss was converted to heazlewoodite, indicated by a gradual mass loss. The heazlewoodite then melted incongruently in excess of 840 degrees celsius indicated by a sharp endothermic peak, resulting in a further loss of sulfur.The oxidation of violarite and pentlandite was investigated at a heating rate of 10 degrees celsius min(subscript)-1 in an air atmosphere. The oxidation of violarite was initiated by decomposition to mss resulting in a rapid mass loss associated with the evolution of sulfur vapour, and an exothermic peak due to the gas phase oxidation of ++
the sulfur. The iron sulfide component of the mss was then preferentially oxidised to iron(II) sulfate between 485-575 degrees celsius, upon which the sulfate decomposed and the remaining iron sulfide was preferentially oxidised to hematite. The mss core was then converted to (Fe,Ni)(subscript)3+/-xS(subscript)2 between 635-715 degrees celsius, resulting in the loss of further sulfur which was oxidised. The sulfide core, which consisted of predominantly Ni(subscript)3+/-xS(subscript)2 with a minor amount of iron still remaining in solid solution, incongruently melted at a constant temperature of 795 degrees celsius regardless of the initial stoichiometry of the violarite sample. This was followed by the rapid oxidation of the liquid sulfide resulting in a sharp exothermic peak in the DTA trace.For pentlandite, the TG-DTA curve exhibited an initial mass gain commencing at approximately 400 degrees celsius, which was attributed to the preferential oxidation of iron. Evidence from SEM indicated that iron migrated towards the oxygen interface, where it was oxidised to hematite. During this process the metal: sulfur ratio decreased and pentlandite was converted to mss. The iron sulfide component of the mss phase was then preferentially oxidised to hematite as indicated by a major exotherm, which occurred in the temperature range 575-665 degrees celsius, forming an oxide product layer around a nickel sulfide core. The oxidation of the remaining nickel sulfide followed the same reaction sequence to that of violarite.By increasing the heating rate to 40 degrees celsius min(subscript)-1, and carrying out the oxidation in pure oxygen, the tendency of the sulfides to ignite was established. Ignition was characterised by a highly exothermic reaction which coincided with a rapid mass loss over a short time period. Overheating of the samples above the programmed furnace ++
temperature was also observed. Violarite exhibited ignition behaviour while pentlandite did not.Both sulfides were subjected to shock heating conditions (heating rate = 1500 - 5000 degrees celsius min(subscript)-1, oxygen atmosphere) using isothermal thermogravimetry (TG). This method produces heating rates analogous to those which are experienced in the reaction shaft of an industrial flash smelter. The effect of stoichiometry on ignition temperature and extent of oxidation for the entire series of synthetic violarites and pentlandites was determined. Partially ignited and ignited products were collected from isothermal TG experiments and were examined by OM, SEM and EPMA to establish the ignition mechanism.Both violarite and pentlandite ignited using the isothermal TG technique. A clear relationship was found between the stoichiometry of violarite and pentlandite and the ignition temperature, with an increase in the iron:nickel ratio causing a decrease in the ignition temperature. The ignition temperature also decreased as the size of the particles decreased.The extent of oxidation increased as the iron:nickel ratio increased, and also increased as the particle size decreased.
23
ARROUIJAL, FATIMA-ZOHRA. "Etude de la transformation biologique et des proprietes genotoxiques et immunotoxiques du sous-sulfure de nickel (alpha ni3s2)". Lille 2, 1991. http://www.theses.fr/1991LIL2T006.
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Zuo, Donghua. "Etude des propriétés de catalyseurs à base de sulfure de nickel et de tungstène". Lyon 1, 2003. http://www.theses.fr/2003LYO10039.
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Les spécifications environnementales concernant la teneur en soufre contenue dans les gazoles ne cessent de se durcir (500 ppm en 1996, 50 ppm en 2005). Ces nouvelles normes expliquent pourquoi l'hydrodésulfuration catalytique (HDS) est un procédé du raffinage en pleine évolution et pour lequel la recherche de nouveaux catalyseurs basées sur de nouvelles phases actives ou de nouveaux supports suscite de nombreux efforts de recherche. L'objectif de ce travail est l'étude de catalyseurs à base de sulfure de tungstène WS2 en portant particulièrement attention à l'effet du promoteur nickel et à l'influence du support sur les performances catalytiques. Une première partie concerne l'étude d'une série de catalyseurs NiWS/Al203, à teneur constante en tungstène mais de rapport r=Ni(Ni+W) variable, dans les réactions d'HDS du thiophène et du 4,6-diméthyldibenzothiophène. La caractérisation de ces systèmes catalytiques par DRX, XPS, TPR, MET et adsorption de CO suivi par spectroscopie infrarouge a permi de préciser le rôle du promoteur. Ainsi, pour des valeurs de (r) inférieures à 0,4 l'addition progressive de Ni au WS2 conduit à la formation graduelle de la phase mixte "NiWS" dont l'activité catalytique est très supérieure à celle de WS2 (effet de synergie catalytique) mais dont la stabilité est dépendante des conditions expérimentales. Cet effet promoteur est plus marqué dans l'étape d'élimination du processus d'HDS que dans les étapes d'hydrogénation et semble relié à une modification des propriétés acido-basiques de la phase sulfure. Dans une seconde partie la même phase active a alors été préparée sur des supports d'acidité variable (silices-alumines, alumine modifiée par une zéolithe échangée). Ces masses catalytiques ont été évaluées dans les réactions d'HDS précédentes et dans l'isomérisation de l'ortho-xylène. Si pour l'HDS du thiophène les activités et sélectivités sont comparables, dans l'HDS de molécules réfractaires les sélectivités mettent clairement en évidence un effet du support. L'acidité du support semble diminuer légèrement la formation de la phase mixte, mais favorise la désulfuration dite directe (conversion avec faible consommation d'H2). Une étude dé́taillée des conditions de préparation dévrait permettre d'xalter cette dernière propriété et laisse espérer une nouvelle génération de catalyseurs aux sélectivités contrôlées
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Yousfi, Oussama. "Transformations de phase des sulfures de nickel dans les verres trempés". Grenoble INPG, 2009. http://www.theses.fr/2009INPG0031.
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Le sulfure de nickel (NiS) peut former des inclusions dans les verres trempés conduisant à une fracture due à la transformation de phase avec changement de volume. Un traitement thermique, provoquant cette transformation de phase, est actuellement utilisé afin de réduire cet effet. Pour proposer des traitements plus efficaces, une étude allant des mécanismes de transformation jusqu’à la modélisation a été menée. Selon la composition et la température, deux mécanismes de transformation (avec ou sans partition) ont été mis en évidence par l’étude microstructurale et calorimétrique donne les lignes directrices de la modélisation. Une étude in situ en microscope optique a fourni les informations complémentaires indispensables (taux de germination, mobilité des interfaces) pour construire des modèles cinétiques. La modélisation décrit la transformation en condition isotherme pourra être adaptée aux conditions anisothermes proches du traitement industrielNickel sulfide (NiS) can form inclusions in tempered gass which lead to fracture due to a pahse transformation with volume change. A heat treatment, aiming to provoke this phase transformation, is currently used to reduce this effect. In order to propose more efficient treatments, a complete study going from identification of the transformation mechanisms to the modelling of the transformation was carried out. Depending on stoichiometry and temperature, two mechanisms for the transformation (partitioned or partitionless) have been evidenced by detailed microstructural and calorimetric studies which give the main lines for the modelling. An in situ following of the transformation by optical microscopy has provided information (like nucleation rate and interface migration velocity) necessary to build the kinetic models. This modelling which described the transformation under isothermal treatment can be further extended to anisothermal condition closer to the industrial one
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Ikogou, Maya Devi. "Etude des processus de biominéralisation des sulfures de fer et des mécanismes de piégeage du nickel : contexte des sédiments de mangrove de Nouvelle-Calédonie". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066705/document.
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Ces travaux de thèse avaient pour objectifs (i) d’étudier le comportement du fer et du nickel au cours de la biominéralisation de sulfures de fer par des bactéries sulfato-réductrices et (ii) de tenter une première estimation de l’influence de l’exploitation minière sur les communautés microbiennes des sédiments de mangrove de Nouvelle-Calédonie. Pour atteindre ces objectifs, des expériences d’incubation ont été conduites en anoxie avec une espèce unique de bactérie (thio)sulfato-réductrice (i.e. Desulfovibrio capillatus) et avec un consortium de bactéries sulfato-réductrices natives de sédiments de mangrove de Nouvelle-Calédonie. Ces expériences ont été réalisées avec différentes sources de Fe(III) (i.e. goethite, ferrihydrite et citrate-ferrique) et en présence de nickel structural ou en solution. Les résultats montrent que l’activité bactérienne sulfato-réductrice (qu’elle soit synergique ou issue d’une espèce unique) conduit, dans toutes les expériences, à la formation principale de mackinawite (FeS). Ce sulfure de fer précipite sous forme de cristallites nanométriques et dont la cristallinité augmente avec la durée d’incubation. Lorsque le nickel est présent en solution, la quasi-totalité de cet élément peut se substituer au fer (i.e. substitution 4% molaire) dans la structure de la mackinawite. Ainsi, la formation d’une faible proportion de mackinawite permet de fixer la quasi-totalité du nickel initialement en solution (e.g. ratio FeS:Ni de 1). Ce mécanisme semble stable sur le long terme (pas de relargage de nickel en solution) et il accélère la croissance cristalline de la mackinawite, ce qui engendre une stabilité accrue de ce minéral. Ces résultats soulignent le rôle efficace des bactéries sulfato-réductrices dans la formation des sulfures de fer de type mackinawite et dans le piégeage du nickel, suggérant une stabilisation de cet élément dans les sédiments de mangrove et la limitation de sa biodisponibilité. Ceci pourrait expliquer les résultats de l’étude comparative des consortiums bactériens autochtones qui ne permet pas de déceler d’impact de l’activité minière sur les communautés bactériennes sulfato-réductrices présentes en Nouvelle-CalédonieThe aims of the present work were (i) to study the behavior of iron and nickel in the biomineralization of iron sulfides by (thio)sulfate-reducing bacteria and (ii) to estimate the influence of open-cut mining activities on microbial communities development in mangrove sediments in New Caledonia. To achieve these objectives, incubation experiments were conducted under anoxic conditions with the (thio)sulfate-reducing bacteria (i.e. Desulfovibrio capillatus) and a consortium of sulfate-reducing bacteria native mangrove sediments of New Caledonia. These experiments were carried out with different Fe(III) precursors (i.e. goethite, ferrihydrite and ferric citrate) and in the presence of structural or soluble nickel. The results show that the sulfate-reducing bacterial activity leads, in all experiments, to the formation of mackinawite (FeS). This iron sulfide precipitates as nanosized crystallites that increase in size with incubation time. When nickel is present in solution, the total soluble amount can be substituted to iron (i.e. replacing 4 mol%) in the structure of mackinawite. Thus, the formation of a small proportion of mackinawite scavenged total soluble amount of nickel initially present in solution (e.g. FeS:Ni ratio of 1). This sequestration mechanism appears to be stable over time (no nickel was released in solution) and accelerates the crystal growth of mackinawite, leading to the stabilization of this mineral. These results highlight the effective role of sulfate-reducing bacteria in the biomineralization of iron sulfides such as mackinawite and in the sequestration of nickel, suggesting a stabilization of this element in mangrove sediments and limitation of its bioavailability. These results could explain the absence of negative impact of open-cut mining activities on the sulfate-reducing bacterial communities present in New Caledonia
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Barbaroux, Romain. "Développement d'un procédé hydrométallurgique de récupération du nickel". Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL087N/document.
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Cette recherche s’inscrit dans le contexte de la conception d’une filière originale comprenant la phytoextraction du nickel par la plante hyperaccumulatrice Alyssum murale, endémique des sols de serpentine d’Albanie et de sa valorisation de ce nickel, l’objectif étant d’arriver à un produit à haute valeur ajoutée. Les sols de serpentine peuvent être considérés comme une ressource secondaire. Ils contiennent des concentrations élevées en nickel mais à des teneurs insuffisantes pour être exploités par l’industrie minière. La plante Alyssum murale peut extraire et concentrer le nickel dans ses tissus. Le nickel présent dans la biomasse a pu être solubilisé quasiment totalement à l’acide sulfurique, en réacteur fermé puis à contre-courant en trois étapes. Cette lixiviation a produit une solution contenant du nickel lié à des molécules organiques ainsi que d’autres métaux et composés organiques. Les procédés de raffinage directs comme la précipitation sélective ou l’électroplaquage n’ont pas permis d’isoler le nickel. Deux voies ont été explorées : (i) l’extraction par un solvant organique sélectif du nickel (Cyanex 272) suivie d’une contre extraction par une solution aqueuse et électrodéposition et (ii) la cristallisation d’un sel double à partir du lixiviat préparé après incinération de la biomasse. La première voie a permis d’obtenir le nickel métal sous forme de cathode, la seconde a conduit au sel double sulfate de nickel et d’ammonium. Les produits ont été caractérisés par différentes techniques. Une étude technico-économique a montré le fort potentiel économique de la production de sel doubleThis research has been done in the context of the design of an original method aiming at obtaining high added value products of nickel, combining phytoextraction and valorization. Phytoextraction is conducted with the hyperaccumulating plant Alyssum murale, endemic species of serpentine soils in Albania. Serpentine soils can be considered as secondary resources: they contain high concentrations of nickel, which are not high enough for conventional mining techniques. The plant Alyssum murale can extract and concentrate nickel in its tissues. Nickel present in the biomass could be almost totally solubilized in batch reactor and with a 3 step countercurrent process. This leaching produced a solution containing nickel bound to organic molecules and other metals and organic compounds as well. Direct separation processes (e.g. selective precipitation and electrowinning) did not enable us to obtain nickel. Two methods have been investigated: (i) extraction by an organic nickel –selective solvent (Cyanex 272), extraction by an aqueous solution and electrowinning and (ii) crystallization of a double salt, nickel ammonium sulfate, from a leaching solution obtained from biomass ashes. Nickel products were characterized by different techniques. A technico-economical study showed the high commercial potential of the double salt production
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Lakhdar, Mahjoub. "Application de la reaction d'hydrodesazotation de la pyridine a la caracterisation de l'activite et de la selectivite de catalyseurs sulfures". Caen, 1987. http://www.theses.fr/1987CAEN2021.
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Zhang, Xin. "Procédé hydrométallurgique pour la valorisation du nickel contenu dans les plantes hyperaccumulatrices". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0172/document.
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Certaines plantes, dites hyperaccumulatrices, ont la capacité de se développer sur des sols riches en métaux et d’accumuler ces métaux à des concentrations élevées. L’incinération de la biomasse produit des cendres qui contiennent de 10 à 25% en masse de Ni. Ce travail s’inscrit dans la continuité d’une recherche menée par l’équipe depuis plusieurs années, qui a donné lieu notamment à un brevet sur la production du sel double sulfate de nickel et d’ammonium hexahydraté (ANSH) à partir de la biomasse d’Alyssum murale. Le manuscrit comprend d’abord une synthèse bibliographique sur la phytomine, allant des hyperaccumulateurs aux procédés de valorisation, essentiellement centrée sur le nickel. Ensuite, ont été comparées quinze plantes hyperaccumulatrices (des genres Alyssum, Leptoplax et Bornmuellera) provenant d’Albanie ou de Grèce, en vue de leur application pour la phytomine. Les teneurs en nickel ont été mesurées dans les différents organes des plantes et dans les cendres obtenues par combustion. Les trois genres ont de l’intérêt pour l’application, les plantes contiennent 1 à 3% en masse de nickel et les cendres 15 à 20 %. Le procédé hydrométallurgique de production d’ANSH a été étudié étape par étape en vue d’optimiser chaque étape pour produire un sel très pur tout en économisant matière et énergie et minimisant la production d’effluents et de déchets. Ce travail a conduit à l’amélioration du procédé de départ. Enfin, de nouvelles pistes ont été proposées pour conduire à de nouveaux procédés et produits du nickel. Les résultats obtenus et la dynamique actuelle autour de la phytomine montrent l’intérêt de cette approche et annoncent son développement imminentSome plants, known as hyperaccumulators, are able to develop on metal containing soils and to accumulate these metals at high concentrations in shoots. Biomass incineration leads to ash containing 10 to 25 wt % nickels, greater than in some mineral ores. This work follows a research that has been carried out by the team for several years, which has resulted in a patent on the hydrometallurgical production of the double salt ammonium and nickel hexahydrate (ANSH) from the biomass of Alyssum murale. It aims at improving the synthesis method of this salt in order to upscale it at the pilot scale and explore new methods leading to new products. The manuscript begins with a bibliographic review on phytomining from hyperaccumulators to metal recycling processes, essentially focused on nickel. Then ca 15 hyperaccumulator plants (genus Alyssum, Leptoplax and Bornmuellera) collected in Greece or Albania have been compared, in the objective of phytomining. Nickel concentrations were measured in the plant organs and in the ashes after combustion. The three types of plants are of great interest for the technology, they contain 1 to 3 wt % of nickel and the ashes 15 to 20%. The hydrometallurgical process of ANSH production was investigated step by step to optimize each step to produce a salt of high purity, to decrease materials and energy consumption and to minimize effluent and waste production. The process was thus improved. Eventually, new ideas have been tested for new processes and nickel products. The obtained results and the current dynamics prove the interest of phytomining and announce its imminent development
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Jiang, Nan. "First-Row Transition Metal Sulfides and Phosphides as Competent Electrocatalysts for Water Splitting". DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6480.
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Conversion of renewable energy resources (such as solar and wind) through water splitting to hydrogen and oxygen has attracted increasing attention. The sole product of hydrogen combustion is water, rendering a carbon-neutral energy cycle. Water splitting consists of two redox half reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Both of these two transformations involve multi- electron/proton movement and thus are kinetically sluggish. In order to accelerate the reaction rates for practical application, efficient catalysts are needed. State-of-the-art catalysts for water splitting are usually composed of noble metals, such as platinum, ruthenium, and iridium, whose scarcity and high cost limit their wide employment. Consequently, it is of critical importance to develop competent and non-precious catalysts via low-cost preparation.
Owing to the thermodynamic convenience and potential application in proton exchange membrane and alkaline electrolyzers, traditionally, most HER catalysts were developed under strongly acidic conditions while OER catalysts under strongly alkaline conditions. In order to accomplish overall water splitting, the coupling of HER and OER catalysts in the same electrolyte is mandatory. This thesis will summarize our recent efforts towards developing 1st-row transition metal-based sulfides and phosphides for electrocatalytic water splitting under ambient conditions.
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Hantzer, Sylvain. "Nouveaux materiaux pour la reaction d'hydrodesulfuration (hds)". Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13120.
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Nouveau modele de phase active obtenu par interpretation des resultats de rmn du **(59)co et de microscopie electronique haute resolution pour des catalyseurs d'hydrotraitement a base de sulfure de molybdene et de cobalt. Application a d'autres systemes : nire, core, rhre et rhmo. Etude de l'empoisonnement par la porphyrine de catalyseur nimo/al::(2)o::(3)
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Nhut, Jean-Mario. "Réaction d'oxydation sélective de l'hydrogène sulfuré (H2S) en soufre élémentaire". Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13240.
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Les travaux réalisés sur la réaction de désulfuration à haute température ont permis de contrôler sélectivement la localisation de la phase active par rapport au support, grâce à la mise au point d'une nouvelle méthode d'imprégnation (appelée imprégnation bi-phasique). Cette méthode est basée sur les propriétés de dualité de surface du SiC (hydrophile, hydrophobe), et permet de déposer les particules d'oxyde de fer (phase active) exclusivement sur les zones purement SiC de nature hydrophobe, qui s'avèrent être localisées à l'extérieur des pores du matériau et permettent une meilleure accessibilité de la phase active. Au cours de la réaction (T = 230-240°C), la phase active à base d'oxyde de fer se transforme sous flux réactionnel en une phase oxysulfure de fer. Cette phase très active et sélective s'avère d'une extrême stabilité tout au long de la réaction (test >1000 h) et quel que soit la nature du mélange réactionnel, i. E. En présence ou non d'impuretés (H2, CO2, SO2, CO, NH3). La découverte de nouveaux matériaux comme les nanostructures de carbone (nanofibres, nanotubes) nous ont permis de développer de nouveaux catalyseurs, à base de NiS2, capables d'oxyder sélectivement à 60 °C l'H2S en soufre élémentaire avec des rendements en soufre extrêmement élevés, et ce avec des vitesses spatiales relativement élevées (WHSV = 0,03 h-1). Les résultats obtenus ont montré l'importance de ces supports sur l'activité désulfurante et leur grande capacité à stocker le soufre solide. Sur les nanotubes, l'hypothèse d'un effet de confinement induit par leur morphologie tubulaire, est avancée tandis que sur les composites nanofibrés, la forte activité observée est attribuée à l'importante surface externe due à leur taille nanoscopique. Un mode de dépôt particulier du soufre solide est avancé pour expliquer l'activité des catalyseurs et leur grande capacité à stocker le soufre solide pendant la réaction (existence d'une dualité de surface hydrophile/ hydrophobe)Studies realised on the desulfurisation reaction at high temperature led us to selectively control the active phase location on the support, with the development of a new impregnation method (called bi-phasic impregnation). This method was based on the duality of the SiC surface (hydrophilic, hydrophobic), and allowed to depose the iron oxide particles (active phase) exclusively on pure SiC zones. These zones were proven to be hydrophobic and located on the outer surface of the pores of the material, and then allowed a better accessibility reactant against the active phase. As a function of time on stream the iron oxide based active phase was transformed into an iron oxysulfide phase (T = 230-240 °C). This phase was very active and selective and was extremely stable during the reaction (more than 1000 h of time on stream), whatever the nature of the reaction mixture, i. E. With or without impurities (H2, CO2, SO2, CO, NH3). The discovery of new materials like carbon nanostructures (nanofibers, nanotubes) allowed us to develop new catalysts, based on NiS2, able to selectively oxidize at 60 °C H2S into elemental sulfur with extremely high sulfur yield and high space velocity (WHSV = 0. 03 h-1). The results obtained showed the importance of these supports on the desulfurisation activity and their great capacity of solid sulfur storage. To explain these results on nanotubes, the hypothesis of a confinement effect induced by their tubular morphology was advanced while the high activity observed on the nanofibers composite was attributed to their high external surface due to their nanosize. Moreover, a particular mode of deposition was advanced to explain their activity and their high solid sulfur storage capacity during the reaction (existence of surface duality of the materials: hydrophilic/hydrophobic)
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Mijoin, Jérôme. "Transformation de dérivés carbonylés sur catalyseurs à base de sulfure de molybdène ; contribution à la compréhension de l'effet des promoteurs et application à la synthèse de thiols". Poitiers, 1999. http://www.theses.fr/1999POIT2351.
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La transformation de derives carbonyles sur catalyseurs a base de sulfure de molybdene promu ou non par le cobalt ou le nickel a ete realisee en phase gazeuse a 220\c et a pression atmospherique en presence d'un melange h 2s/h 2. La molecule modele utilisee, la cyclopentanone, se transforme selectivement en cyclopentanethiol avec de bons rendements. Le schema reactionnel determine a revele la presence d'un intermediaire thiocetonique, et la formation parallele de produits de condensation ainsi que d'olefines provenant principalement de la deshydrosulfuration du thiol. L'application de cette reaction a des composes tres encombres autour de la fonction carbonyle a montre que la thioreduction etait tres fortement inhibee par la presence de groupements methyles en position alpha. Cela peut etre attribue a l'encombrement sterique ou a un effet inducteur donneur. La transformation de composes carbonyles aromatiques en thiols est tres difficile, car les olefines resultant de la deshydrosulfuration des thiols sont fortement stabilisees par resonance avec le cycle aromatique. La derniere partie de ce travail a permis de correler les activites en hydrodesulfuration du dibenzothiophene et en thioreduction de la cyclopentanone de deux series de catalyseurs a base de sulfure de molybdene promus par differents taux de cobalt ou de nickel. Un effet promoteur important est observe dans les deux cas. L'interpretation proposee est qu'en diminuant la force des liaisons molybdene-soufre, le promoteur augmente la densite electronique sur les atomes de soufre. Cela a pour consequence d'augmenter la basicite et le caractere nucleophile des anions s 2 - ou sh - qui peuvent etre impliques dans les deux reactions.
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Schoeman, Liezl. "Evaluation of polarisation parameters as predictor of morphology of nickel electrodeposits produced from sulfate electrolyte". Thesis, University of Pretoria, 2018. http://hdl.handle.net/2263/66022.
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Industrial electrowinning of nickel requires specific control and optimisation of the electrolyte composition, the presence of impurities, the addition of additives (to achieve particular deposit properties) and the operating parameters (such as pH and temperature) in order to produce electroplated nickel of high quality and desirable morphological characteristics. Without understanding and strict control of the electrocrystallisation process, nickel can delaminate due to internal strain, frequent pitting of the deposit can occur, current efficiency can decrease significantly or dendritic growth can cause short circuits. Prediction of the effect of the electrolyte composition and operating parameters on the structure and morphology of the plated metal in the early stages of electrodeposition could be paramount to controlling and/or eliminating such problems during the later stages of electrowinning. Such prediction remains an enormous challenge.
The use of polarisation measurements to investigate the electrocrystallisation process and predict the outcome of the resulting deposit quality and morphology was used with variable success in early investigations. Some of the main problems with techniques such as cyclic voltammetry and the later-developed continuous monitoring techniques are inaccuracy and unreliability of the results. The aim of the present work was to develop a galvanodynamic polarisation technique to investigate the electrocrystallisation process of nickel metal from sulfate electrolyte in order to examine the effect of electrolyte composition, operating parameters and the presence of impurities or additives. This could then be used to optimise these factors and thereby predict the outcome of the quality and morphological characteristics of the produced nickel deposit. The idea was that a relatively easy and concise method needed to be developed that could be implemented industrially to monitor and detect problems in the early stages of electrowinning in order to take control and rapid corrective action if needed.
A two-step galvanodynamic method was developed to measure plating and nucleation potentials accurately and repeatably. It was shown that the relationship between the two potentials could be used as an indication of the effect of electrolyte composition and operating parameters on the composition and morphological characteristics of the produced nickel electrodeposits. This method, together with studies on the buffering capabilities of electrolyte solutions, can be used to investigate the influence of additives and impurities industrially introduced during the process in the electrolytes. Typical variations in commercial electrolytes and nickel electrodeposits were evaluated using this developed technique and results compared with those obtained from synthetic electrolyte. The insights gained from this work can be useful to predict and manipulate the electrodeposition process in order to optimise electrocrystallisation and the production of high quality nickel deposits.Thesis (PhD)--University of Pretoria, 2018.
Materials Science and Metallurgical Engineering
PhD
Unrestricted
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Evans-Lamswood, Dawn. "Physical and geometric controls on the distribution of magmatic and sulphide-bearing phases within the Voisey's Bay nickel-copper-cobalt deposit, Voisey's Bay, Labrador /". Internet access available to MUN users only, 1999. http://collections.mun.ca/u?/theses,26958.
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Thesis (M.Sc.), Memorial University of Newfoundland, 2000.Restricted until January 2002. The CD-ROM "includes a series of .AVI files... the .AVI files are digital video captures of the 3-dimensional models used to produce the 2 dimension figures contained in this document." Bibliography: leaves 254-265. Also available online.
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Brémaud, Mickaël. "Etude du mode d'action des catalyseurs à base de sulfure de molybdène par échange isotopique (H-D) et par hydrogénation d'oléfines". Poitiers, 2003. http://www.theses.fr/2003POIT2350.
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Romero, Perez Yilda. "Hydrodésoxygenation de composés phénoliques modèles représentatifs d'une bio-huile issue de matières lignocellulosiques sur catalyseurs sulfures promus (NiMo/Al2O3 et CoMo/Al2O3) et non-promu (Mo/Al2O3)". Poitiers, 2010. http://theses.edel.univ-poitiers.fr/theses/2010/Romero-Perez-Yilda/2010-Romero-Perez-Yilda-These.pdf.
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La valorisation de la biomasse lignocellulosique comme source alternative pour la production de carburants de type gazole impose le développement de procédés spécifiques pour les traitements des bio-huiles issues de sa transformation. Pour atteindre les nouvelles directives européennes sur l'utilisation de ces nouveaux types de biocarburants, il est nécessaire d'éliminer l'oxygène de ces bio-huiles par un procédé d'hydrodésoxygénation. Les performances de trois catalyseurs sulfures ((Co,Ni)Mo/Al2O3) sur la transformation de composés phénoliques modèles (phénol, 2-éthylphénol et 4-éthylphénol) ont été étudiées dans des conditions proches de celles utilisées dans les procédés d'hydrotraitement industriels (340°C sous 7 MPa de pression totale). Trois voies de transformation du 2-éthylphénol ont été mises en évidence : une voie qui implique les propriétés hydro-désoxygénantes du catalyseur, conduisant majoritairement à la formation d'éthylcyclohexane (voie HYD), une voie de désoxygénation directe et conduisant exclusivement à l'éthylbenzène (voie DOD), et une troisième voie qui fait intervenir à la fois les propriétés acides et désoxygénantes du catalyseur (voie ACI). Un effet promoteur dû à la présence de cobalt ou de nickel a été observé : le nickel ne favorise que la voie HYD, alors que le cobalt permet une augmentation des deux voies, la voie DOD étant généralement plus promue que la voie HYD. Il a été mis en évidence que, même si H2S a un effet négatif important sur la voie DOD, il doit être introduit dans la charge réactionnelle afin d'assurer la stabilité de ces catalyseursBio-oils obtained by the transformation of lignocellulosic biomass material could be an alternative source for fuels production. However, the development of specific processes for the treatment of these bio-oils is required in order to reach the new EU directives related to the use of these types of fuels. The removal of oxygen can be carried out by a specific hydrodeoxygenation process. The performance of three sulfided catalysts ((Co,Ni)Mo/Al2O3) on the transformation of phenolic compounds (phenol, 2-ethylphenol and 4-ethylphenol) was studied under conditions close to industrial hydrotreating processes (340°C under 7 MPa of total pressure). Three pathways for 2-ethylphenol transformation were identified: the first one involves the hydro-deoxygenation properties of the catalyst (HYD pathway), leading mainly to ethylcyclohexane; the second one, a direct deoxygenation pathway (DDO pathway), leads to ethylbenzene as the only product; and the last pathway involves both the acidic and deoxygenation properties of the catalysts (ACI pathway). A promoting effect due to the presence of cobalt or nickel was observed: nickel only favors the HYD pathway, while cobalt allows an increase in both pathways, the DDO pathway being more promoted than the HYD pathway. It was observed that H2S has a significant negative effect on the DDO pathway. However, it must be introduced into the feed to ensure the stability of these catalysts
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Ben, Tayeb-Meziane Karima. "Voies de préparation innovantes pour les catalyseurs d’hydrocraquage nickel-tungstène supportés : intérêt de l’utilisation de précurseurs hétéropolyanioniques". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10155/document.
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Le développement de la phase hydro-déshydrogénante pour la préparation de catalyseurs d’hydrocraquage innovants et plus performants est nécessaire pour l’évolution du marché des carburants orienté vers une production maximale en produits légers (gazole, kérosène) moins polluants. Les catalyseurs actuellement utilisés sont du type NiW/SiAl (solution de métatungstate d’ammonium et de nitrate de nickel déposée sur une silice-alumine). Ce travail propose une nouvelle méthode de synthèse de ces solides. Nous avons préparé des catalyseurs d’hydrocraquage à partir de sels d’hétéropolyanions à structure de Keggin et Keggin lacunaire associant le tungstène, le nickel et le phosphore ou le silicium, le nickel étant introduit en contre-ion de l’unité de Keggin. Par ailleurs, une préparation originale d’hétéropolyanion monosubstitué, où le nickel est présent en contre-ion et également au sein même de l’unité de Keggin à la place d’un atome de tungstène, est présentée. Les caractérisations physico-chimiques réalisées à chaque étape de la préparation du catalyseur permettent de décrire la genèse des précurseurs oxydes. Ces solides sont activés par sulfuration. Les catalyseurs sont testés en hydrogénation du toluène et les activités sont comparées à celles obtenues avec des catalyseurs préparés selon les procédures industrielles. Le catalyseur innovant à base d’hétéropolycomposé Ni4SiW11O39 a une activité en hydrogénation supérieure de 30 % à celle du catalyseur classique. Une meilleure décoration des feuillets de WS2 (l’espèce active du catalyseur) par le nickel lors de l’étape de sulfuration explique l’amélioration de l’activité catalytiqueThe development of the hydro-dehydrogenation phase for the preparation of innovative and more efficient hydrocracking catalysts is necessary for the evolution of the fuel market oriented toward a maximum production in light products cleaner (diesel, kerosene). The catalysts currently used are NiW/SiAl (solution of ammonium metatungstate and nickel nitrate deposited on a silica-alumina). This work deals with a new method of preparation of the oxidic precursor of the hydrocracking catalysts. They have been prepared using salts of Keggin type heteropolyanions containing tungsten, nickel and phosphorus or silicon as starting material. Moreover, a novel preparation of monosubstituted heteropolyanion, in which nickel replace one tungsten atom in the Keggin unit, is presented. Physicochemical studies performed at various steps of the catalysts synthesis allow to describe the genesis of oxidic precursors. These solids were sulphided and their activities in toluene hydrogenation were measured and compared with those obtained with catalyst prepared by conventional methods. The innovating Ni4SiW11O39 HPC based catalyst, is 30 % more active in hydrogenation than the conventional catalyst. A better decoration of WS2 slabs (the active species of the catalyst) by nickel during the sulfidation step explains the improvement of catalytic activity
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Sanches, Carlos Vinícius [UNESP]. "Disponibilidade de Ni em um latossolo vermelho distrófico em função da aplicação de gesso agrícola e caracterização fisiológica e bioquímica do algodoeiro". Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151924.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O algodoeiro apresenta uma sensibilidade elevada nos sistemas de cultivo. A acidez do solo aliada a alta concentração alumínio e a baixa disponibilidade de cálcio em profundidade podem limitar a produtividade sendo possível verificar distúrbios nutricionais. Nesse contexto, o níquel, nutriente essencial, componente da metaloenzima urease tem sua importância comprovada no metabolismo do nitrogênio e vem sendo estudado como alternativa para melhorar a qualidade do sistema de cultivo por meio da eficiência do uso do nitrogênio disponível. Outra vertente de estudos diz respeito a capacidade do níquel de agir como metal pesado sendo prejudicial para as culturas, dessa maneira faz-se necessário entender a dinâmica desse nutriente dentro dos sistemas de cultivo. Tendo em vista o exposto, o objetivo deste trabalho foi verificar os efeitos da aplicação de diferentes doses de níquel e gesso, e a interação entre os dois sobre o crescimento, produtividade e estado nutricional de plantas de algodoeiro em condições de campo. O experimento foi desenvolvido em dois anos, os tratamentos utilizados foram 0,0; 1,0; 2,0; 6,0; 12 e 16 kg ha-1 de Ni e 0, 200, 400 e 800 kg ha-1 de gesso, aplicados via solo. Utilizou-se o delineamento em blocos ao acaso em um fatorial 6x4 com 3 repetições. Para mensurar o efeito dos tratamentos, os parâmetros de crescimento (altura, diâmetro e número de ramos), estado nutricional (P, K, Ca, Mg, S, Cu, Fe, Mn, Zn e Ni), e produtividade (número de estruturas reprodutivas, produtividade de algodão em caroço, rendimento de fibra e massa de 20 capulhos), foram submetidos a análise de variância e regressão polinomial por meio do software de análise estatística Sisvar 5.1. Há variações na produtividade em função das condições climáticas, em déficit hídrico severo foi possível concluir que o aumento na dose de gesso pode reduzir a produtividade do algodoeiro linearmente, a aplicação de doses de níquel e gesso, nas condições apresentadas nesse experimento, não exercem influência no crescimento e desenvolvimento do algodoeiro. O fornecimento de gesso até 800 kg/ha interfere na absorção de Ni, verifica-se um antagonismo entre cálcio e níquel. O fornecimento de níquel via solo não interfere na absorção de nutrientes com exceção do cálcio. O cálcio exerce antagonismo em relação ao manganês. As doses de níquel não promoveram efeitos positivos ou negativos no crescimento e desenvolvimento do algodoeiro.
The cotton plant has a high sensitivity in the cropping systems. The soil acidity allied to high aluminum concentration and low calcium availability in depth may limit the productivity and develop nutritional disorders. In this context, nickel, essential element, component of metalloenzyme urease, has its importance proven in the nitrogen metabolism. It has been studied as an alternative to improve the cropping system quality through an efficient use of the available nitrogen. Another strand of studies mentions about the nickel capacity to act as a heavy metal and being harmful to the crops, thereby making it necessary to understand this nutrient dynamic within the cropping systems. Based on the foregoing, the objective of this study was to verify the effects of the application of different nickel and gypsum doses, and the interaction between them on the growth, crop yield and nutritional status of cotton plants under field conditions. The experiment was conducted in two years, the treatments used were 0,0; 1,0; 2,0; 6,0; 12 and 16 kg ha-1 of Ni and 0, 200, 400 and 800 kg ha-1 of gypsum, applied via soil. A randomized complete block design was used in a 6x4 factorial scheme with 3 repetitions. In order to measure the treatment effects, the parameters of growth (high, diameter and number of branches), nutritional status (P, K, Ca, Mg, S, Cu, Fe, Mn, Zn and Ni), and crop yield (number of reproductive structures, seed cotton yield, fiber cotton yield and mass of 20 cotton bolls), were submitted to an analysis of variance and polynomial regression through a software of statistical analysis Sisvar 5.1. There are variations in the crop yield in function of the climate conditions; in severe water deficit, it was possible to conclude that the increase in gypsum doses can reduce cotton crop yield linearly. The application of doses of nickel and gypsum, under the conditions presented, do not influence the growth and development of the cotton plants. The supply of gypsum up to 800 kg ha-1 interfere in the absorption of Ni, verifying an antagonism between calcium and nickel. The supply of nickel via soil do not interfere in the nutrients absorption with exception of calcium, which exerts antagonism over manganese. The doses of nickel did not promote positive or negatives effects in the growth and development of the cotton plants.
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Zakaria, Siti Nurul Azian binti. "Insight into the surface structure of iron (-nickel) sulfides in aqueous environments for CO2 reduction applications using in-situ spectroelectrochemistry". Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10039695/.
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Iron sulfides and iron nickel sulfides, specifically greigite, (Fe3S4), and violarite, (FeNi2S4), have been shown to reduce CO2 on application of low electrode potentials (up to −1.3 V vs AgCl|Ag). However, at such low potentials, metal sulfides are predicted to undergo reductive decomposition and competing reactions such as water reduction may also take place. The aim of the work in this thesis was to determine the stability of the iron (-nickel) sulfides under conditions where CO2 reduction has been demonstrated to take place. In-situ Attenuated Total Reflectance Fourier Transformed Infrared Spectroscopy (ATRFTIR) and X-ray Absorption Spectroscopy (XAS) techniques were used to monitor and characterise the structural transformations of iron and iron-nickel sulfides in aqueous solutions on application of an external potential. Additional iron (- nickel) sulfides investigated in this work include pyrrhotite (Fe7S8) and pentlandite ((Fe,Ni)9S8). Pourbaix diagrams were used to preliminarily assign the redox features in the cyclic voltammograms of these iron and iron-nickel sulfides. These assignments were then correlated with the spectroscopic data to verify the assignments. Iron hydroxide / oxyhydroxide was detected on applying negative potentials on both the iron and iron-nickel sulfides, which was not predicted by the Pourbaix diagrams at constant solution pH. The formation of the iron hydroxide / oxyhydroxide was proposed to be instigated by water reduction occurring at low electrode potentials, causing an increase in the local pH. The XAS spectra showed the transformation to iron hydroxide / oxyhydroxide was surface confined as a high percentage of sulfide character remained within the nanoparticles. The significant shift in the local pH near the electrode, due to water reduction, contributed to the stability of the iron hydroxide / oxyhydroxide formed at pH 4 and 7. On introduction of CO2, the formation of iron hydroxide / oxyhydroxide was halted. This was attributed to the adsorption of CO2 and its dissolved species HCO3 −, based on the spectroscopic evidence collected. Current suppression was observed in the voltammograms of the iron sulfides, while current enhancement was observed in the voltammograms of the iron-nickel sulfides. These differences were linked to the different nature and transformations of the electrode surface of the iron and iron-nickel sulfides on application of potential with electrolyte media. On variation of the Fe:S and Fe:Ni stoichiometries of the iron and iron-nickel sulfides, the voltammetric responses remained similar with small differences in the anodic currents attributed to different amounts of sulfates and elemental sulfur produced. The work described in this thesis provides a new insight into the stability and potential thermodynamic transformations of iron (-nickel) sulfides, on application of an applied electrode potential, in aqueous environments essential for future CO2 reduction applications.
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Bernardon, Guillaume. "Hydrodésoxygénation de molécules modèles sur catalyseur sulfures de nickel et de molybdène déposés sur alumine". Poitiers, 1996. http://www.theses.fr/1996POIT2331.
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L'objectif general de ce travail etait d'examiner la possibilite d'introduire les huiles de pyrolyse de la biomasse dans les charges des unites d'hydrotraitement. Il fallait donc savoir s'il etait possible de convertir des molecules oxygenees dans les conditions de l'hydrotraitement sur le meme type de catalyseur et en presence de molecules caracteristiques des charges a hydrotraiter, notamment les molecules azotees. Cette etude a donc porte sur la transformation de molecules oxygenees modeles, et plus particulierement le benzofuranne, dans des conditions proches de la realite industrielle (reacteur dynamique, 350c, pression d'hydrogene: 50 bar, catalyseur nimo/al#2o#3). La transformation du benzofuranne se produit par l'intermediaire du 2-ethyl phenol qui s'hydrogene ensuite pour conduire au 2-ethyl cyclohexanol. Ce dernier se deshydrate tres rapidement en ethylcyclohexene, lui meme s'hydrogenant tres vite en ethylcyclohexane. Une reaction parallele d'hydrogenolyse, minoritaire, permet d'obtenir l'ethylbenzene directement a partir du 2-ethyl phenol. Le benzofuranne exerce un effet inhibiteur important sur la transformation de son intermediaire: le 2-ethyl phenol, ce qui explique la faible hydrodesoxygenation obtenue meme a conversion elevee du benzofuranne alors que l'hydrodesoxygenation du 2-ethyl phenol dans les memes conditions de reaction est importante. La comparaison des differentes reactions d'hydrotraitement a montre que l'hydrodesulfuration etait la plus facile des reactions d'hydrotraitement tandis que l'hydrodesazotation etait la plus difficile. Le schema reactionnel de l'hydrodesulfuration est different de celui de l'hydrodesoxygenation puisque le benzothiophene conduit directement a l'ethylbenzene sans passer par le 2-ethylcyclohexanethiol. Le produit final de l'hydrodesazotation est l'ethylcyclohexane comme dans le cas de l'hydrodesoxygenation. Enfin, il existe un effet inhibiteur tres important mais totalement reversible de la n-butyl amine sur la decomposition du benzofuranne, du a une competition a l'adsorption sur les sites actifs
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Roebuck, James William. "Reagents for selective extraction of nickel(II), cobalt(II) and copper(II) from highly acidic sulfate feeds containing iron". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/17976.
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This thesis focuses on development of new regents which are suitable for recovering nickel, cobalt and copper from laterite leach solutions, specifically focusing on reagent requirements for novel base metal flowsheets developed by Anglo American. The work aims to design reagents which can extract nickel(II), cobalt(II) and copper(II) from a highly acidic aqueous sulfate solutions whilst showing selectivity over iron(II) and iron(III). Chapter 1 reviews current extractive metallurgy processes for separating and concentrating metals in laterite ores and describes new flowsheets proposed by Anglo American. Chapter 2 considers whether single reagent molecules with sets of tridentate donor atoms can generate sufficiently stable nickel(II) complexes to allow selective extraction of nickel from an aqueous sulfate solution. The salicylaldimines, 3-X-4-alkyl-6-(quinolin-8-imino)phenol, 3-X-4-alkyl-6-(2- methoxyphenylimino)phenol and 3-X-4-alkyl-6-(2-thiomethoxyphenylimino)phenol (alkyl = tert-butyl or tert-octyl; X = H, Br or NO2), were selected for study. The synthesis and characterisation of these proligands and their nickel(II) complexes are reported. XRD structures of Br-substituted salicylaldimines and their nickel(II) complexes are compared and discussed. The 4-tert-octylsalicylaldimines were used to extract nickel(II) from an aqueous sulfate solution with a pH > 2.8 and 3- nitro-4-tert-octyl-6-(quinolin-8-imino)phenol was found to be the strongest extractant in the series with a pH0.5 of 3.5. Computational studies of an analogous series of salicylaldimine proligands in the gas phase calculated the formation energies of their nickel(II) complexes and the predicted trend follows the experimentally determined solvent extraction results. Chapter 3 investigates modifications to phenolic pyrazoles, which are known copper(II) extractants. A series of 6-X-4-methyl-2-(5-alkyl-1H-pyrazol-3-yl)-phenols (X = H, OMe, Br and NO2) was synthesised and characterised. Varying the 6-X-substituent of the phenolic pyrazole altered the strength of copper extraction and 6-nitro-4-methyl-2-(5-(1,3,5-tri-methyl-pentyl)-1H-pyrazol-3-yl)-phenol was found to be the strongest extractant in the series. Analysis of XRD structures of related phenolic pyrazoles and their copper(II) complexes showed evidence of inter- and intra-molecular hydrogen bonding. Computational DFT studies in the gas phase were carried out to calculate the formation energies of analogous phenolic pyrazole copper complexes. The predicted order of these energies followed the same trend shown by experimental solvent extraction studies. The double deprotonation of 4-tert-butyl-(pyrazol-3-yl)-phenol at high pH forms a polynuclear complex in the organic phase with a copper(II) to ligand ratio of 1:1, thereby increasing the mass transport efficiency of copper by the reagent. The synthesis and characterisation of the [Cu16(4-tert-butyl-(pyrazol-3-yl)- phenolate)16(EtOH)4(H2O)2] wheel complex was carried out to demonstrate how such polynuclear copper(II) complexes could be formed under solvent extraction conditions. Chapter 4 explores the solvent extraction of nickel(II) and cobalt(II) by novel combinations of neutral nitrogen-donor heterocyclic ligands with organic acids, such as dinonylnaphthelenesulfonic acid (DNNSAH). The synthesis and characterisation of 2,6-bis(5-alkyl-1H-pyrazol-3-yl)-pyridine, 2-(5- alkyl-1H-pyrazol-3-yl)-pyridine and 5,5'-alkyl-3,3'-bi-1H-pyrazole (alkyl = tert-butyl or nonyl) and their nickel(II) complexes were reported. Also reported are synthesis and 6-N-alkyl-2-(2-pyridinyl)- benzothiazole (alkyl = n-butyl or n-decyl) and 2-(1-Isopropyl-benzimidazol-2-yl)-pyridine. The extraction of nickel(II) from highly acidic mixed metal aqueous sulfate solutions by some of these ligands was studied. These synergistic mixtures demonstrated remarkable strength and selectivity for nickel(II), and cobalt(II) over iron(II). XRD structures of nickel(II) complexes of 2,6-bis(5-tert-butyl- 1H-pyrazol-3-yl)-pyridine, 2-(5-tert-butyl-1H-pyrazol-3-yl)-pyridine and 5,5'-tert-butyl-3,3'-bi-1Hpyrazole with sulfonates or perchlorates as ion-pairs have intermolecular hydrogen bonding interactions between the inner-sphere ligands and the counterions.
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Shirali, Pirouz. "Etude in vitro de la toxicite du sous-sulfure de nickel (ni3s2) sur cellules pulmonaires : consequences sur la fluidite membranaire et la peroxydation lipidique". Lille 2, 1992. http://www.theses.fr/1992LIL2P252.
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Mennour, Ammar. "Caracterisation par spectroscopie infrarouge d'alumines modifiees et de catalyseurs w(mo) - ni(co) sulfures supportes sur alumine". Caen, 1987. http://www.theses.fr/1987CAEN2019.
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Sanches, Carlos Vinícius. "Disponibilidade de Ni em um latossolo vermelho distrófico em função da aplicação de gesso agrícola e caracterização fisiológica e bioquímica do algodoeiro /". Ilha Solteira, 2017. http://hdl.handle.net/11449/151924.
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Orientador: Enes Furlani JuniorResumo: O algodoeiro apresenta uma sensibilidade elevada nos sistemas de cultivo. A acidez do solo aliada a alta concentração alumínio e a baixa disponibilidade de cálcio em profundidade podem limitar a produtividade sendo possível verificar distúrbios nutricionais. Nesse contexto, o níquel, nutriente essencial, componente da metaloenzima urease tem sua importância comprovada no metabolismo do nitrogênio e vem sendo estudado como alternativa para melhorar a qualidade do sistema de cultivo por meio da eficiência do uso do nitrogênio disponível. Outra vertente de estudos diz respeito a capacidade do níquel de agir como metal pesado sendo prejudicial para as culturas, dessa maneira faz-se necessário entender a dinâmica desse nutriente dentro dos sistemas de cultivo. Tendo em vista o exposto, o objetivo deste trabalho foi verificar os efeitos da aplicação de diferentes doses de níquel e gesso, e a interação entre os dois sobre o crescimento, produtividade e estado nutricional de plantas de algodoeiro em condições de campo. O experimento foi desenvolvido em dois anos, os tratamentos utilizados foram 0,0; 1,0; 2,0; 6,0; 12 e 16 kg ha-1 de Ni e 0, 200, 400 e 800 kg ha-1 de gesso, aplicados via solo. Utilizou-se o delineamento em blocos ao acaso em um fatorial 6x4 com 3 repetições. Para mensurar o efeito dos tratamentos, os parâmetros de crescimento (altura, diâmetro e número de ramos), estado nutricional (P, K, Ca, Mg, S, Cu, Fe, Mn, Zn e Ni), e produtividade (número de estruturas reproduti... (Resumo completo, clicar acesso eletrônico abaixo)
Mestre
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Zahir, Najate. "Activités en hydrodésazotation et caractérisations de catalyseurs sulfures à base de molybdène et de nickel". Lyon 1, 1987. http://www.theses.fr/1987LYO11738.
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Ohnenstetter, Daniel. "Minéralisations associées aux complexes mafiques-ultramafiques en domaine océanique et continental". Nancy 1, 1990. http://docnum.univ-lorraine.fr/public/SCD_T_1990_0539_OHNENSTETTER.pdf.
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Ce mémoire de thèse comporte deux parties: l'une sur les ophiolites et l'autre sur les minéralisations de divers complexes basiques-ultrabasiques, dont les ophiolites, les komatiites et les sills archéens et protérozoïques. Les travaux sur les ophiolites ont abouti à deux résultats majeurs : 1) la reconstitution du puzzle ophiolitique corse ; 2) la diversité des ophiolites avec une classification en deux grands types, dont le magmatisme de l'un s'apparente à celui des rides médio-océaniques, tandis que le magmatisme de l'autre ressemble à celui des arcs immatures. Des études sur la minéralisation des corps basiques-ultrabasiques, il ressort que la nature des magmas parentaux est importante pour juger de leur potentialité métallogénique (Cr, Ni, éléments du groupe du platine EGP). Le caractère saturé à sursaturé des magmas basiques a été noté dans les ophiolites porteuses de gisements de chrome, dans les lopolites stratifiés enrichis en Cr, EGP. Des magmas de type boninitiques seraient à l'origine de certains de ces complexes. En conclusion de la thèse est présentée une classification des complexes basiques-ultrabasiques basées sur l'ordre de cristallisation des minéraux qui permet de discuter de l'origine des gisements des EGP par rapport à celle des autres minéralisations (chromite, concentration sulfurées).
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Ouafi, Driss. "Caracterisation par spectroscopie infrarouge des catalyseurs d'hydrotraitement ni-w supportes, a l'etat oxyde ou sulfure". Caen, 1986. http://www.theses.fr/1986CAEN2021.
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Refait, Philippe. "La rouille verte 1 chlorée : rôle dans les mécanismes de corrosion du fer en milieu aqueux chlores et chloro-sulfates, dans l'oxydation d'hydroxydes mixtes fer-nickel : sa structure cristallographique". Nancy 1, 1991. http://www.theses.fr/1991NAN10091.
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Nous avons étudié les processus d'oxydation des hydroxydes ferreux dans différents milieux aqueux chlores et chloro-sulfates en couplant une étude des équilibres électrochimiques à des analyses par diffraction x et spectrométrie Mössbauer. Nous nous sommes essentiellement intéressés aux mécanismes articulés autour de l'hydroxychlorure ferreux-ferrique dénommé rouille verte 1 (rv1). Nos travaux ont permis de déterminer les caractéristiques de rv1, formule chimique, potentiel chimique et structure cristallographique. Nous avons ainsi pu expliciter le rôle actif que jouent les ions chlorure dans l'oxydation de l'hydroxyde ferreux. Les processus d'oxydation des hydroxydes ferreux en milieux chloro-sulfates sont tributaires du rapport a=so4/cl. Lorsque A est grand, les mécanismes sont semblables aux mécanismes caractéristiques du milieu uniquement sulfaté. Lorsque A est faible, apparaissent des mécanismes spécifiques du milieu chloro-sulfaté. La transformation du fer(II) en fer(III) s'effectue alors en trois étapes, un composé ferreux-ferrique chloré, puis un compose ferreux-ferrique sulfaté, étant d'abord obtenus. Parallèlement nous avons étudié les processus d'oxydation d'hydroxydes mixtes ferreux-nickeleux et montré qu'ils s'apparentaient aux processus d'oxydation de l'hydroxyde ferreux. En milieu chloré, ces hydroxydes produisent en s'oxydant des hydroxychlorures nickeleux-ferriques stables isomorphes de rv1. Enfin, nous avons construit les diagrammes de Pourbaix spécifiques des milieux aqueux chlorés et chloro-sulfatés
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Leyral, Géraldine. "Synthèse et structuration de sulfure de molybdène promu nickel en présence de liquide ionique ou de polymère hydrosoluble amphiphile : application en catalyse hétérogène". Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20266.
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Avec l’épuisement progressif des ressources pétrolières, la production de biocarburant est actuellement en plein développement. Utiliser la biomasse en tant que source d’énergie permettrait également de limiter la concentration en dioxyde de carbone dans l’atmosphère et ainsi l’effet de serre. Cependant son processus de transformation implique une étape d’hydrodésoxygénation qui nécessite d’avoir recours à des catalyseurs de type sulfure de molybdène dopé par du cobalt ou du nickel. Ces catalyseurs sont également indispensables au cours du traitement du pétrole lors du procédé d’hydrodésulfuration qui est primordial pour limiter la pollution de l’air par les gaz de combustion des carburants. Cette thèse propose une méthode de synthèse et de structuration de catalyseurs massiques NiMoS facile à mettre en œuvre et rapide. Deux solvants ont été utilisés : l’eau et le formamide. L’ajout d’un polymère hydrosoluble amphiphile, le PEO113-b-PLLA32, dans l’eau et de liquides ioniques (BMIMNTf2 et BMIMBF4) dans le formamide ont permis la structuration des matériaux et l’obtention de surfaces spécifiques atteignant 55 m2g-1. Ceci représente une surface importante pour ce type de composé, en particulier dans le cadre d’une synthèse par chimie douce. Les premiers tests catalytiques réalisés vis-à-vis de la réaction d’hydrodésoxygénation de l’acide décanoïque montrent une activité catalytique très prometteuse pour ces matériauxWith the progressive decrease of oil resources, the production of biomass fuel is a fast growing field. This could limit the concentration of carbon dioxide in the atmosphere and thus the global warming. The production of this kind of fuel requires the use of catalysts such as nickel or cobalt promoted molybdenum sulfide. These materials are also crucial during the refining of oil, an essential step to limit atmospheric pollution during the classic fuel combustion. New methods to synthesize and structure NiMoS catalysts have been developed in this work. Two solvants have been studied: formamide and water. The addition of an amphiphilic water-soluble polymer (PEO113-b-PLLA32) in water and of ionic liquids (BMIMNTf2 and BMIMBF4) in formamide led to the structuring of the materials with specific surface areas up to 55 m2g-1. This is a high value for this kind of material, especially since the synthesis is carried out under soft conditions. The first catalytic tests dealt with decanoïc acid hydrodesoxygenation and highlighted a promising activity for these materials