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Sun, Yifei. "Decomposition of polychlorinated biphenyls with activated carbon-supported iron." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/136149.
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ESPINO, OLIVER EUGENIO EVERETT. "STUDY OF SUPPORTED AND NOT SUPPORTED IRON NANO PARTICLES IN THE REACTION OF FISCHER TROPSCH." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=26936@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Catalisadores de ferro suportados em sílica alumina e em sílica mesoporosa, além de nano partículas de ferro não suportadas, foram estudados. A preparação dos catalisadores suportados ocorreu pelo método de impregnação do ponto úmido incipiente com soluções aquosas de cloreto de ferro, para obter 2 por cento ou 5 por cento de metal, sendo um desses preparado pelo método da ureia, onde uma quantidade apropriada de uma solução aquosa de FeCl3·6H2O (99 por cento -Merck) foi misturada com ureia. As amostras foram caracterizadas por medidas de fisissorção de N2, difração de Raios-X (DRX), redução com temperatura programada (RTP) e microscopia eletrônica de transmissão (TEM). A quantidade de metal foi determinada usando espectroscopia de absorção atômica (EAA). Os suportes de sílica alumina e de sílica mesoporosa foram caracterizados ainda por análise termogravimétrica (ATG/DTG). As propriedades texturais mostraram que após a introdução do metal nos suportes, a área específica, o volume de poros e o diâmetro de poro decresceram conforme o teor metálico foi aumentado. As análises de DRX com refinamento de Rietveld detectaram a formação das fases de FeO, Fe3O4, Fe0, para todas as amostras suportadas. Os perfis de redução (RTP) para as amostras de ferro suportadas mostraram, principalmente, duas regiões de redução, a primeira atribuída a redução de Fe2O3 para FeO e a segunda a redução de FeO para Fe0.
Iron catalysts supported on silica alumina and mesoporous material, beside non supported iron nanoparticles, were studied. The preparation of supported catalysts occurred by incipient wetness impregnation method with aqueous solutions of iron chloride to give 2 percent or 5 percent of metal. One iron catalyst supported on silica alumina was prepared by the method of urea, in which an appropriate amount of an aqueous solution of FeCl3·6H2O (99 percent - Merck) was mixed with urea for impregnation. The samples were characterized by measurements of N2 physisorption, X-ray diffraction (XRD), temperature programmed reduction with (TPR), transmission electron microscopy (TEM). The amount of metal embedded in each sample was determined using atomic absorption spectroscopy (AAS). The silica alumina and mesoporous silica supports were also characterized by thermogravimetric analysis (DTA/TGA). The textural properties showed that after introduction of the metal into the supports, the specific area, pore volume and pore diameter decreased as the metal content was increased. XRD analysis with Rietveld refinement showed the formation of phases the following phases FeO, Fe3O4, Fe0, for all supported samples. Reduction profiles (TPR) for the supported iron samples showed mainly two reduction regions, assigned for Fe2O3 to FeO and for FeO to Fe0, respectively.
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Zhang, Lei 1970. "Sol-gel matrix-mediated synthesis of superparamagnetic iron oxide clusters and supported iron porphyrin oxidation catalysts." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9968.
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Thomas, Christine Marie Stoltz Brian M. Peters Jonas C. "Novel reactivity at iron centers supported by poly(phosphino)borate ligands /." Diss., Pasadena, Calif. : Caltech, 2006. http://resolver.caltech.edu/CaltechETD:etd-05162006-201134.
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Duggan, Michael J. "The use of isotopic oxygen exchange to investigate carbon monoxide oxidation over supported gold catalysts." Thesis, Nottingham Trent University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271214.
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Blignaut, Annalie. "Influence of basicity in Fischer-Tropsch synthesis over supported iron-based catalysts." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/7477.
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Includes bibliographical references (leaves 115-124).The Fischer-Tropsch synthesis catalyzed by iron is a well-established process for the production of synthetic fuels, waxes and high-value chemicals, such as α-olefins. A draw-back of the currently used iron-based catalysts is their short lifetime, caused by sintering and particle break-up. These disadvantages might be overcome by utilizing a supported iron-based catalyst. However, supported iron Fischer-Tropsch synthesis, which has been tested up to now, show a high methane selectivity. This might be caused by a lack of alkali near the catalytic site, which can be alleviated by using a basic support. Classical basic supports such as CaO and MgO will react with CO2 (a major by-product in iron-catalyzed Fischer-Tropsch synthesis) yielding carbonates and can therefore not be used, since the formation of carbonates will result in a large particle expansion. An alternative would be to generate a silica-based basic support by attaching basic groups to the silica. In this study iron Fischer-Tropsch catalysts supported on silica were tested for conversion of synthesis gas to hydrocarbon products. Silica was modified with aminopropyltriethoxysilane (APTeS) by impregnation followed by calcination to provide basic surface groups onto the silica surface. The CHN analysis and IR-analysis indicate the presence of amine groups in the APTeS-modified silica. The pore radius distribution of silica is slightly shifted towards higher pore radii in comparison to APTeS-modified silica. It might thus be stated that aminopropyltriethoxysilane covers the pore walls and does not seem to result in pore blockage. Thermal gravimetric analysis indicates that the thermal stability of APTeS-modified silica is low. A major difference between silica and APTeS-modified silica was their zeta-potential. Whereas the surface of silica is mainly negatively charged in the pH-range of interest during impregnation, the surface of APTeS-modified silica is mainly positively charged. This is attributed to the presence of amine groups on the surface. Iron was brought onto the support by impregnation. The surface modification of silica with APTeS seems to be destroyed upon calcination of the impregnated catalysts. The iron phase in the calcined iron catalyst supported on silica catalysts is mainly hematite (Fe203), whereas the iron phase in the calcined iron catalyst supported on APTeS-modified silica catalysts is mainly iron oxide hydroxide FeOOH. The presence of basic amine groups may favour the formation of FeOOH crystallites during the impregnation/calcination on the APTeS-modified silica. The FeOOH-crystallites on the APTeS-modified silica support are typically smaller than the Fe203 crystallites on silica. The maximum catalytic activity is obtained at 0.01 mol K I mol Fe for the iron catalyst supported on silica and at 0.02 mol K I mol Fe for the APTeS-modified catalyst, indicating the optimum potassium loading. The difference in the optimum potassium loading might be linked to the smaller crystallite sizes obtained with the APTeS-modified catalyst. All the potassium promoted catalysts show a lower methane selectivity compared to the 0 K iron catalyst supported on silica and the 0 K iron catalyst supported on APTeS-modified silica. The 1-olefin and n-olefin content in the fraction of linear hydrocarbons increase with increasing potassium loading over all the iron catalyst supported on silica promoted with potassium except for the catalysts 0.005 K and 0.01 K. Increasing potassium content on the catalyst resulted in higher 1-olefin content in the fraction of linear olefins. The trend suggests that potassium promotion suppresses secondary double bond isomerisation of 1-0lefin into internal olefins. The high degree of branching obtained with the 0.005 K catalyst and the 0.01 K catalyst, is characteristic of weak alkali promotion. The iron catalysts supported on APTeS-modified silica indicate an increase in the degree of branching with increasing potassium content.
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Ngekpe, B. E. "Punching shear failure of reinforced concrete flat slabs supported on steel edge column." Thesis, Coventry University, 2016. http://curve.coventry.ac.uk/open/items/5f0f9112-1838-448f-a245-cacc0bc3a9f5/1.
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This study examines punching shear failure at edge supported flat slab. Due to the significant dearth of research on punching shear at edge steel column, this study focuses on the design and performance of a novel shearhead system proposed for edge connection. By considering multi-stage processes and parameters that influence punching shear failure, both numerical and experimental studies were adopted. Firstly linear finite element analysis was employed to study the relationship between the continuous structure and the representative specimen; in order to support decisions on boundary conditions that create the similitude. A nonlinear (NLFEA) model was proposed where various concrete material constitutive models were compared and contrasted. The Total Strain crack model was adopted on the ground that it accounts for the tensile strength of cracked concrete which was ignored in previous theoretical model that lead to poor prediction of punching shear. By considering the appropriate material constitutive model for concrete and steel, material parameters, appropriate modelling scheme capable of predicting punching shear was formulated. The adopted modelling scheme was validated using previous research work. Numerical results reveal that punching shear is influenced most significantly by concrete tensile strength, fracture energy. The shearhead assembly was design with using ACI318-05 and Newzealand codes recommendations with some modifications. These are only codes that provide design guidance on shearhead. Experimental and numerical results show that the shearhead contributes appreciably to punching shear capacity of the edge connection. Various design codes on punching shear were compared; Eurocode 2 provides a good prediction of punching shear at edge support; which correlate well with experimental result. Hence, it was adopted to propose an equation for punching shear for edge connection with shearheads. Most importantly, appropriate design guidance and analytical equation have been proposed for shearhead connection. The design guidance and equation would enable practising Engineers to design shearheads without going through the rigor of experimental or numerical investigation. This study has contributed appreciably to the applicability of steel column in flat slab construction.
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Leanord, Donald Robert. "A study of the oxidation of alkenes catalysed by polymer supported iron porphyrins." Thesis, University of York, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329654.
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Mock, Michael T. "Synthesis and reactivity of thioether-supported organoiron and low-valent iron complexes and cyanide-bridged binuclear complexes." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 282 p, 2008. http://proquest.umi.com/pqdweb?did=1481668291&sid=19&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Critchfield, Brian L. "Statistical Methods For Kinetic Modeling Of Fischer Tropsch Synthesis On A Supported Iron Catalyst." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1670.pdf.
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Croy, Jason Robert. "Supported mono and bimetallic platinum and iron nanoparticles electronic, structural, catalytic, and vibrational properties." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4652.
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Catalysis technologies are among the most important in the modern world. They are instrumental in the realization of a variety of products and processes including chemicals, polymers, foods, pharmaceuticals, fuels, and fuel cells. As such, interest in the catalysts that drive these processes is ongoing, and basic research has led to significant advances in the field, including the production of more environmentally friendly catalysts that can be tuned at the molecular/atomic level. However, there are many factors which influence the performance of a catalyst and many unanswered questions still remain. The first part of this work is concerned with the factors that influence the catalytic properties (activity, selectivity, and stability) of supported Pt and Pt-M nanoparticles (NPs). These factors are a synergistic combination of size, composition, support, oxidation state, and reaction environment (i.e. adsorbates, temperature, pressure, etc.). To probe the catalytic properties of complex and dynamic NP systems we have used MeOH decomposition and oxidation reactions, each of which has significant environmental and economic potential. We have given some emphasis to the state of NP oxidation, and with the aid of X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD), have followed the formation and temperature-dependent evolution of oxide species on Pt NPs. Further, we have explored how these species behave under the conditions of our probe reactions using a packed-bed mass flow reactor coupled to a quadrupole mass spectrometer (QMS). To carry out our investigations we exploit a NP synthesis method which is rather novel to nanocatalysis, micelle encapsulation. Since most available experimental techniques give information on ensemble averages, control over size distributions in NP samples is critical if unambiguous results are to be obtained. Micelle encapsulation allows us this control with several unique, inherent advantages.; It is to this end that micelle encapsulation has allowed us to probe the detailed structure of small (~1 nm), supported, Pt NPs with extended X-ray absorption fine structure spectroscopy (EXAFS). Furthermore, we were able to explore experimentally, for the first time, the vibrational density of states (VDOS) of supported, isolated, monodispersed, mono and bimetallic NP systems via nuclear resonant inelastic X-ray scattering (NRIX). These synchrotron-based techniques (EXAFS, NRIXS) rely heavily on the monodispersity of the NP ensemble for reliable information.ID: 028916773; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 204-229).
Ph.D.
Doctorate
Department of Physics
Sciences
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Weber, David P. "Promoter Effects on Iron-Based, SBA-15 Supported Ultra-High Temperature Fischer- Tropsch Catalysts." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7243.
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Promoter effects on SBA-15 supported iron Fischer-Tropsch catalysts were investigated for their potential to improve high temperature catalyst performance. FTS catalysts promoted by manganese (0.15%-1.4%), copper (0.15%-1%), and potassium (0.5%-3%), with all percentages stated on the basis of mass percentage of final catalysts, were prepared and tested at 430°C and ambient pressure in a fixed bed reactor. Manganese showed the ability to promote the FT reaction, increasing both the CO conversion and the average chain length of hydrocarbon products. Compared to the unpromoted catalyst composed only of iron supported on SBA-15, 1.4%Mn (mass) promotion of 15% (mass) iron on SBA-15 improved CO conversion from 29% to 32%, increased alpha from 0.21 to 0.34, decreased carbon dioxide selectivity from 76% to 50%, increased C2-C4 selectivity from 9.6% to 30% and increased C5+ selectivity from 0.21% to 2.2%. Copper promotion gave increased conversion, but did not significantly affect alpha or carbon dioxide selectivity. Potassium promotion in the range of 0.5% to 3% by mass, on the other hand, had a negative effect on CO conversion at all concentrations tested.
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Ali, H. Saad Moh'd. "Selective catalytic oxidation of ammonia using copper and iron supported on ZSM-5 catalysts." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525661.
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Sabeña, Vila Gerard. "High-valent iron complexes supported with tetradentate and pentadentate ligands based on the triazacyclononane scaffold." Doctoral thesis, Universitat de Girona, 2017. http://hdl.handle.net/10803/406145.
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In this work we have prepared octahedral non - heme iron species in high oxidation states. Iron (IV) - oxo and iron (IV) - imido complexes based on triazacyclononane scaffold had been synthesised and all of them had been spectroscopicaly characterised. We studied the reactivity of the oxo complexes in the oxygen atom transfer to sulfur atoms and in the abstraction of hydrogen from alkylbenzene substrates; in the case of imido complexes the transfer of imido group to sulfur atoms was studied. Moreover we studied the photolysis of iron - azide octahedral complexes to obtain high - valent iron - nitrido species. Following this procedure we achieved the synthesis of an iron (V) - nitrene species with a very high purity. We also achieved the functionalisation of C(sp2) - H bonds of arenes through diazoacetates decomposition using non - heme iron and manganese catalysts for the first time. We proposed this reaction to occur through a postulated iron - carbene species, that we failed to isolate. Despite this fact we achieved remarkable results in this reactionsEn aquest treball s'han preparat espècies no - hemo octahèdriques de ferro en alts estats d'oxidació. S'han sintetitzat complexes de ferro (IV) - oxo i ferro (IV)- imido amb lligands pentadentats basats en el sistema triazaciclononà i tots ells s'han caracteritzat espectroscòpicament. S'ha estudiat la reactivitat dels oxo en la transferència d'àtom d'oxigen a sulfurs i abstracció d'hidrògen en alquilbenzens; en el cas dels complexes imido s'ha analitzat la transferència del grup imido a sulfurs. A més s'ha estudiat la fotòlisi de complexes octahèdrics no - hemo de ferro - azida per a l'obtenció d'espècies ferro - nitrè en alts estats d'oxidació. Amb aquesta metodologia s'ha aconseguit preparar una espècies ferro (V) - nitrè amb una puresa molt alta. També s'ha aconseguit la funcionalització d'enllaços C(sp2) - H d'arens mitjançant la descomposició de diazoacetats utilitzant per primera vegada catalitzadors no - hemo de ferro i manganès. Aquesta reacció s'ha suggerit que funciona a través d'espècies ferro - carbè que no s'ha pogut aïllar. Malgrat aquest fet s'han obtingut resultats molt remarcables en aquestes reaccions
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Stokes, Sheree Lynell 1971. "Synthesis and characterization of iron complexes supported by bulky amide ligands : reduction and oxidation chemistry." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9856.
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Chowdhury, Md Abu Raihan. "Removal of Select Chlorinated Hydrocarbons by Nanoscale Zero-valent Iron Supported on Powdered Activated Charcoal." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1496150130687849.
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Carballo, Manuel. "Strength of z-purlin supported standing seam roof systems under gravity loading." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/45952.
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The objective of the Standing Seam Roof Systems Research Project at the Virginia Polytechnic Institute and State University is to develop a design procedure for the strength of Z-purlin supported standing seam roof systems under gravity leading. Various approaches were taken to calculate the strength of systems with either torsional restraint, third point span restraint, or midspan restraint. Since few test results are available for single and three span continuous, two purlin line systems, the primary focus of this research is analytical. Even though the test setup used for these tests does not represent actual field conditions, the data obtained will be extremely useful in the development of analytical models to predict system strength. However, at least four multiple purlin line tests will be required to verify the accuracy of the design procedure. The analytical formulation will include the effects of sliding friction in the clips and "drape" restraint effects of the standing seam deck.
Master of Science
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Dolci, Mathias. "Design of magnetic iron oxide nanoparticle assemblies supported onto gold thin films for SPR biosensor applications." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAE001/document.
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La bio-détection de molécules reposant sur le phénomène de résonnance plasmon permet de détecter des espèces en utilisant les propriétés optiques de films métalliques. L’utilisation de ce type de capteurs nécessite néanmoins l’augmentation de leurs performances afin de détecter des concentrations faibles d’analyte dans des milieux complexes. L’assemblage de nanoparticules d’oxyde de fer sur des substrats d’or, en utilisant des groupements complémentaires spécifiques via la méthode de chimie « click », permet de contrôler leur distribution spatiale à la surface du substrat. Les propriétés magnétiques portées par les nanoparticules sont ainsi étudiées en fonction de leurs distances inter-particules ainsi que de leurs tailles. Par ailleurs, le plasmon de surface du substrat étant directement influencé par l’assemblage des nanoparticules, il sera possible de contrôler la sensibilité du capteur pour étudier la détection de différentes biomolécules impliquées dans des processus biologiques. La présence des nanoparticules augmente les propriétés optiques intrinsèques de la surface du substrat et la géométrie de l’assemblage permet d’augmenter la quantité de biomolécules détectéesBiomolecular detection based on the surface plasmon resonance phenomenon allow detecting species by using the optics properties of metallic thin films. This kind of biosensors require the increase of their performances in order to detect low concentration analyte in complex medium. The assembly of iron oxide nanoparticles on gold substrates by using specific complementary groups via the “click” chemistry technique allows controlling their spatial distribution on the substrate surface. The magnetic properties carried by the nanoparticles are studied as function of their inter-particle distances and their sizes. Moreover, the surface plasmon of the substrate is directly influenced by the nanoparticle assembly and the control of the sensor sensitivity will be possible in order to study the detection of different biomolecules implies in biological processes. The presence of nanoparticles increases the intrinsic optical properties at the substrate surface and the geometry of the assembly allow increasing the number of biomolecules detected
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Mmelesi, Olga Kelebogile. "Synthesis and characterization of pine cone carbon supported iron oxide catalyst for dye and phenol degradation." Thesis, Vaal University of Technology, 2017. http://hdl.handle.net/10352/418.
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M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of TechnologyFenton oxidation is classified into two processes, homogeneous and heterogeneous. Homogeneous Fenton oxidation process, have been shown to be efficient in the degradation of organic pollutants. However, it was shown to have limitations which can be addressed by the heterogeneous Fenton oxidation. Despite the high efficiency of the heterogeneous Fenton oxidation process in the degradation of recalcitrant organic pollutants, the currents synthesis trends of the heterogeneous Fenton catalyst have been proven to be time and energy constraining, since it involves the multi-step were the activated carbon have to be prepared first then co-precipitate the iron oxide on the activated carbon. However, as much as the heterogeneous Fenton catalyst has been proven to have high catalytic activity towards degradation of organic pollutants, these catalysts have some limitations, such limitations include metal ions being leached from the catalyst support into the treated water causing catalyst deactivation and a secondary pollution to the treated water. In this thesis, these catalysts have been applied in the degradation of recalcitrant organic pollutants such as methylene blue and phenols. This study focuses on the single step synthesis of iron oxide nanoparticles supported on activated carbon, were carbonaceous material is impregnated with iron salt then pyrolysed via microwave heating. Microwave power and the amount of iron salt were optimized. The prepared activated carbon-iron oxide composites were applied to the degradation of 2-nitrophenol (2-NP) and methylene blue (MB). Methylene blue was used as a model compound due to the fact that it is easier to monitor the degradation process with UV-Vis as compared to 2-nitrophenol . 2-nitrophenol the additional step for the adjustment of pH is required since nitrophenols are colorless in color at lower pH. The characterization showed that the microwave power and the amount of the iron precursor have an influence on the porosity and surface functional groups of the activated carbon. Further it was vi observed that microwave power and iron precursor influnces the amount of iron oxide formed on the surface of the support. It was also observed that the activated carbon-iron oxide composite have the catalytic effects on the Fenton oxidation process of MB and 2-NP. The parameters such as H2O2, pH, catalyst dose, initial concentration, temperature affect the degradation of both MB and 2-NP. Kinetics studies showed that Fenton is a surface driven reaction since the results fitted the pseudo first order model. The thermodynamics parameters also showed that the reaction is endothermic, spontaneous and is randomized. This implies that the reaction of the degradation of MB and 2-NP is feasible and the catalysts prepared have high catalytic activity. MB and 2-NP were degraded to smaller organic molecules (carboxylic acids). The stability of the catalyst observed to decrease as the number of cycles increased, this is due to the leaching of iron ions from the support material. Hence it was concluded that the activated carbon-iron oxide composite was successfully synthesized and had the high catalytic activity for the degradation of MB and 2-NP.
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Najjarpour, Jabbary Farzin. "COMPARISON OF NICKEL AND IRON-BASED OXYGEN CARRIERS SUPPORTED ON ALUMINA IN SYNGAS-FUELED CHEMICAL LOOPING COMBUSTION." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1501.
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Chemical looping is considered as a novel technology capable of resolving both energy and environmental problems in combustion process. The possibility of using oxides of nickel (Ni) and iron (Fe) as oxygen carriers was investigated. Solid oxygen carriers were prepared by deposition of metal oxides on γ-Alumina (Al2O3) particles by incipient wet impregnation method. The reactivity of metal oxides was examined in a thermogravimetric analyzer (TGA), where they were exposed to syngas (34% CO, 66% H2) and steam for reduction, and to air (79% N2, 21% O2) for oxidation at temperature ranging from 700°C to 900°C. Fe and Ni particles showed high reactivity at high temperatures with reduction rate of 95%/min and 85%/min, respectively. Oxidation rate for both metal oxides were 100%/min. Furthermore, nickel oxide showed promising potential to be used under cyclic conditions since it showed high strength under multiple cycles while Fe particles show sign of agglomeration which affect their reactivity during multiple cycles.
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Keyvanloo, Kamyar. "Preparation of Active, Stable Supported Iron Catalysts and Deactivation by Carbon of Cobalt Catalysts for Fischer-Tropsch Synthesis." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5705.
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The first half of this dissertation reports the development of supported Fe FT catalysts including the effects of various, carefully chosen preparation methods on the performance of alumina-supported iron/copper/potassium (FeCuK/Al2O3); it was determined that non-aqueous slurry impregnation and co-impregnation yielded catalysts with activities as high as any reported in the literature. Furthermore, the effects of support properties including pore size, hydroxyl group concentration, and support stabilizer were investigated for FeCuK/Al2O3 catalysts containing 20 or 40% Fe. For the first time, we report the performance of a supported Fe FT catalyst that is not only more active and stable than any supported Fe catalyst previously reported, but also has activity equivalent to that of the most active, unsupported catalysts. More importantly, the catalyst is extremely stable as evidenced by the fact that after 700 h on stream, its activity and productivity are still increasing. These catalyst properties result from the use of a novel γ-alumina support material doped with silica and pretreated at 1100°C. This unique support has a high pore volume, large pore diameter, and unusually high thermal stability. The ability to pretreat this support at 1100°C enables preparation of a material having a low number of acid sites and weak metal oxide-support interactions, all desirable properties for an FT catalyst. The second half of this dissertation investigates the effects of operating conditions including the partial pressures of CO and H2 and temperature on the deactivation by carbon of 25 wt% Co/ 0.25 wt% Pt/Al2O3 catalyst. It also reports the kinetics of the main FT reaction on this catalyst. As temperature increases, the H2 and CO orders for the main reaction (in the absence of deactivation) become more positive and more negative, respectively. A new mechanism was proposed to account for the inhibition effect of CO at high reaction temperatures, which includes H-assisted dissociation of CO to C* and OH*. Further, twelve samples of the CoPt/Al2O3 catalyst were tested over a period of 800 hours and XCO < 24%, each at a different set of CO and H2 partial pressures and temperature (220-250°C). At reaction temperature of 230°C, increasing PCO or PH2 increases the deactivation rate; possibly due to formation of polymeric carbons. The H2 and CO partial pressure orders for the deactivation rate at 230°C were found to be 1.12 and 1.43, respectively using a generalized-power-law-expression (GPLE) with limiting activity of 0.7 and 1st order deactivation. For a H2/CO of 2 (PH2 = 10 bar and PCO = 5 bar) the deactivation rate increases as process temperature increases from 220 to 250°C with an activation energy of 81 kJ/mol. However, at higher CO partial pressure (PCO = 10 bar) the deactivation rate for the Co catalyst of this study decreases with increasing temperature; this can possibly be attributed to the formation of more active cobalt sites at higher temperatures due to surface reconstruction.
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Seby, Sreya Mariya. "Effect of Promoter (Mn) on the Performance of SBA-15 Supported Iron Catalysts for High Temperature Fischer-Tropsch Synthesis." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7932.
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Development of an effective High Temperature Fischer-Tropsch Synthesis (HTFTS) catalyst is of interest in process intensification that combines methane reforming with long chain hydrocarbon production. Literature indicates iron catalysts supported on mesoporous silica performed relatively well in high temperature applications. In this work, we investigated the effect of manganese promoter on iron catalysts for FTS at 430 °C as it was known from previous studies that manganese promotion could enhance the CO conversion with higher hydrocarbon yields. Also, the effect of temperature on FTS activity was evaluated by testing the base and promoted Fe/SBA-15 catalysts for temperature ranging from 370 to 430 °C.
Incipient wetness impregnation method was used to prepare the catalysts. The catalysts used in this work were un-promoted iron (15 wt%) and Mn promoted (1.4, 2.8, 4.2, 5.6, 11.2 wt%) iron (15 wt%) catalysts supported on SBA-15. The catalysts were characterized using XRD, TPR, N2 Physisorption, and SEM. These catalysts were first activated in synthesis gas (H2: CO = 2:1) at 430 °C and then tested for their catalytic performance at the same temperature and atmospheric pressure. Prior work with SBA-15 supported iron catalysts showed that manganese promotion could improve the CO conversion when compared to copper and potassium.
The main goal of this work was to study the effect of varying the manganese content on SBA-15 supported iron catalysts to determine the optimum loading of Mn along with the effect of temperature. It was found that CO conversion increases from 27% to74% with increasing the amount of manganese. The yield of CO2 increased substantially with higher Mn loadings. When different Mn promoted iron catalysts were compared, the catalysts with 2.8 wt% Mn loading showed the best performance in terms of the CO conversion and yield of C2+ hydrocarbons. Catalyst with 2.8 wt% of manganese loading yielded a CO conversion of 54%, with a methane yield of 17%, 32% (carbon) yield of C2- C4 and 9%(carbon) yields of C5+ hydrocarbon products, respectively.
The effect of operating temperature on the catalytic performance of both the base catalyst 15Fe/SBA-15 and the promoted 2.8Mn/15Fe/SBA-15 catalyst was also examined. The unpromoted iron catalyst showed an improved catalytic activity at 400 °C with the total CO conversion of 38% and a higher yields of C5+ hydrocarbons. A significant decrease was also observed in the yields of CH4 and CO2. The methane and carbon dioxide yield increased from 11% and 8% to 25% and 40%, respectively, as the temperature increased from 400 to 450 °C. The catalyst with 2.8 wt% of manganese promotion gave better CO conversion and hydrocarbon product yields at 430 °C. Lower temperature showed negative effect on hydrocarbon product yield for manganese promoted catalysts.
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Oschatz, M., Deelen T. W. van, J. L. Weber, W. S. Lamme, G. Wang, B. Goderis, O. Verkinderen, A. I. Dugulan, and Jong K. P. de. "Effects of calcination and activation conditions on ordered mesoporous carbon supported iron catalysts for production of lower olefins from synthesis gas." Royal Society of Chemistry, 2016. https://tud.qucosa.de/id/qucosa%3A30312.
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Lower C2–C4 olefins are important commodity chemicals usually produced by steam cracking of naphtha or fluid catalytic cracking of vacuum gas oil. The Fischer–Tropsch synthesis of lower olefins (FTO) with iron-based catalysts uses synthesis gas as an alternative feedstock. Nanostructured carbon materials are widely applied as supports for the iron nanoparticles due to their weak interaction with the metal species, facilitating the formation of catalytically active iron carbide. Numerous synthetic approaches towards carbon-supported FTO catalysts with various structures and properties have been published in recent years but structure-performance relationships remain poorly understood. We apply ordered mesoporous carbon (CMK-3) as a support material with well-defined pore structure to investigate the relationships between calcination/activation conditions and catalytic properties. After loading of iron and sodium/sulfur as the promoters, the structures and properties of the FTO catalysts are varied by using different calcination (300–1000 °C) and activation (350 or 450 °C) temperatures followed by FTO testing at 1 bar, 350 °C, H2/CO = 1. Carbothermal reduction of iron oxides by the support material occurs at calcination temperatures of 800 or 1000 °C, leading to a higher ratio of catalytically active iron(carbide) species but the catalytic activity remains low due to particle growth and blocking of the catalytically active sites with dense graphite layers. For the samples calcined at 300 and 500 °C, the formation of non-blocked iron carbide can be enhanced by activation at higher temperatures, leading to higher catalytic activity. Olefin selectivities of ∼60%C in the formed hydrocarbons with methane of ∼10%C are achieved for all catalysts under FTO conditions at low CO conversion. The influence of the calcination temperature is further investigated under industrially relevant FTO conditions. Promoted CMK-3-supported catalysts obtained at low calcination temperatures of 300–500 °C show stable operation for 140 h of time on stream at 10 bar, 340 °C, H2/CO = 2.
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Oschatz, M., Deelen T. W. van, J. L. Weber, W. S. Lamme, G. Wang, B. Goderis, O. Verkinderen, A. I. Dugulan, and Jong K. P. de. "Effects of calcination and activation conditions on ordered mesoporous carbon supported iron catalysts for production of lower olefins from synthesis gas." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-224310.
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Lower C2–C4 olefins are important commodity chemicals usually produced by steam cracking of naphtha or fluid catalytic cracking of vacuum gas oil. The Fischer–Tropsch synthesis of lower olefins (FTO) with iron-based catalysts uses synthesis gas as an alternative feedstock. Nanostructured carbon materials are widely applied as supports for the iron nanoparticles due to their weak interaction with the metal species, facilitating the formation of catalytically active iron carbide. Numerous synthetic approaches towards carbon-supported FTO catalysts with various structures and properties have been published in recent years but structure-performance relationships remain poorly understood. We apply ordered mesoporous carbon (CMK-3) as a support material with well-defined pore structure to investigate the relationships between calcination/activation conditions and catalytic properties. After loading of iron and sodium/sulfur as the promoters, the structures and properties of the FTO catalysts are varied by using different calcination (300–1000 °C) and activation (350 or 450 °C) temperatures followed by FTO testing at 1 bar, 350 °C, H2/CO = 1. Carbothermal reduction of iron oxides by the support material occurs at calcination temperatures of 800 or 1000 °C, leading to a higher ratio of catalytically active iron(carbide) species but the catalytic activity remains low due to particle growth and blocking of the catalytically active sites with dense graphite layers. For the samples calcined at 300 and 500 °C, the formation of non-blocked iron carbide can be enhanced by activation at higher temperatures, leading to higher catalytic activity. Olefin selectivities of ∼60%C in the formed hydrocarbons with methane of ∼10%C are achieved for all catalysts under FTO conditions at low CO conversion. The influence of the calcination temperature is further investigated under industrially relevant FTO conditions. Promoted CMK-3-supported catalysts obtained at low calcination temperatures of 300–500 °C show stable operation for 140 h of time on stream at 10 bar, 340 °C, H2/CO = 2.
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Busch, Jan Philip [Verfasser], and Sascha Eric [Akademischer Betreuer] Oswald. "Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) for groundwater remediation / Jan Philip Busch ; Betreuer: Sascha Eric Oswald." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218601876/34.
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Busch, Jan [Verfasser], and Sascha Eric [Akademischer Betreuer] Oswald. "Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) for groundwater remediation / Jan Philip Busch ; Betreuer: Sascha Eric Oswald." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218601876/34.
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Busch, Jan [Verfasser], and Sascha [Akademischer Betreuer] Oswald. "Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) for groundwater remediation / Jan Philip Busch ; Betreuer: Sascha Eric Oswald." Potsdam : Universität Potsdam, 2015. http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-76873.
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Cruz, Marcia Gabriely Alves da. "SÃntese e anÃlise de catalisadores de ferro suportados em carbono ativado para sÃntese de Fischer-Tropsch." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11666.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorEste trabalho teve como objetivo sintetizar catalisadores metÃlicos de ferro suportados em carbono ativado a base de polÃmeros para sÃntese de Fischer-Tropsch. A preparaÃÃo dos catalisadores foi realizada pelo mÃtodo de impregnaÃÃo a umidade incipiente, utilizando soluÃÃo aquosa de nitrato de ferro nonahidratado para obtenÃÃo de amostras com, aproximadamente, 55% de ferro. Duas amostras foram preparadas (FeCP1 e FeCP2) e caracterizadas por fluorescÃncia de raios-X por energia dispersiva (EDXRF), difraÃÃo de raios-X (DRX), medidas de fisissorÃÃo de nitrogÃnio, espectroscopia fotoeletrÃnica de raio-X (XPS), microscopia eletrÃnica de varredura (SEM-EDS) e reduÃÃo à temperatura programada (TPR). As amostras foram submetidas tambÃm a testes catalÃticos, utilizando-se diferentes condiÃÃes de temperatura (513, 528 e 543 K), pressÃo (20, 25 e 30 atm) e razÃo molar H2:CO de 1 e 0,5. Os dados de EDXRF evidenciaram considerÃvel diferenÃa no teor de metal impregnado entre os dois catalisadores; o FeCP2 apresentou teor prÃximo ao esperado enquanto o catalisador FeCP1 ficou aquÃm do desejado. Os difratogramas obtidos por DRX mostraram um maior grau de cristalinidade da amostra FeCP2, enquanto FeCP1 e os dois suportes (CP1 e CP2) apresentaram-se como semi-cristalinos. Para o catalisador FeCP2, apresentaram-se duas fases ativas presentes, α-Fe2O3 e γ-Fe2O3; jà no FeCP1, hà apenas α-Fe2O3. A anÃlise das caracterÃsticas texturais revelou que, apÃs a introduÃÃo metÃlica no suporte, houve decrÃscimo nos valores de Ãrea especÃfica, volume de poros e diÃmetro de poros, sendo mais perceptÃvel para o catalisador FeCP2. As curvas de XPS expuseram os grupos funcionais oxigenados presentes na superfÃcie dos suportes, bem como a presenÃa do Fe+3 como fase ativa predominante em ambos os catalisadores. O espectro de ambos os catalisadores apresentou tambÃm um pico satÃlite que sugere a presenÃa de um outro estado de valÃncia do ferro semelhante ao que se tem no carbeto de ferro. As imagens obtidas por SEM exibiram forma e superfÃcie irregulares, sendo as partÃculas presentes no FeCP2 maiores que a do FeCP1 devido a sua cristalinidade. Os dados de EDS demonstraram que, aproximadamente, metade do percentual de ferro presente no catalisador encontra-se na superfÃcie. Pode-se inferir tambÃm por essa anÃlise, utilizando-se seu espectro, a presenÃa de carbeto de ferro na superfÃcie do catalisador. As curvas de TPR evidenciaram uma maior estabilidade do catalisador FeCP2 mediante o FeCP1, por este ter apresentado trÃs etapas de reduÃÃo do Ãxido de ferro e nÃo duas, como apresentada para aquele Ãltimo. O teste catalÃtico expÃs a melhor eficiÃncia do catalisador FeCP2 para a produÃÃo de hidrocarbonetos na faixa de C5-C9, para as mesmas condiÃÃes de temperatura, pressÃo e razÃo molar. Entretanto, a diminuiÃÃo da razÃo molar desfavoreceu a obtenÃÃo de hidrocarbonetos pesados.
The aim of this work was to synthesize iron catalysts supported on polymer-based activated carbons, for the Fischer-Tropsch synthesis. The preparation of the catalysts was performed by incipient wetness impregnation method using an aqueous solution of iron nitrate nonahydrate to obtain samples with approximately 55 % of iron. Two samples were prepared (FeCP1 and FECP2) and characterized by energy dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD), nitrogen adsorption measurements, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM-EDS) and temperature-programmed reduction (TPR). The samples were also submitted to catalytic tests using different conditions of temperature (513, 528 and 543 K), pressure (20, 25 and 30 atm), and H2:CO molar ratio of 1 and 0.5. EDXRF data showed considerable difference in content of impregnated metal for both catalysts. FeCP2 exhibited an iron load close to the value expected while FeCP1 presented an iron load significantly lower than expected. XRD patterns showed a higher degree of crystallinity of the sample FeCP2, whereas FeCP1 and both supports used (CP1 and CP2) were found to be semi-crystalline. FeCP2 catalyst presented two active phases, α-Fe2O3 and γ-Fe2O3, while FeCP1 showed only one phase, α-Fe2O3. The analysis of the textural characteristics revealed a decrease in the values of the specific area, pore volume and pore diameter after the introduction of the metal into the support, which was more noticeable with the FeCP2 catalyst. XPS patterns indicated oxygen functional groups on the support surface and the presence of Fe+3 as the predominant active phase on both catalysts. The spectrum of both catalysts also showed a satellite peak which shows the presence of another valence state similar to the iron carbide. Images obtained by SEM revealed irregular shape and surface, being the particles present in FeCP2 greater than those on FeCP1 due to the crystallinity of the former. EDS data showed that approximately half of the iron percentage present in the catalyst bulk is on the surface. The presence of iron carbide on the catalyst surface can be inferred by using this spectrum analysis too. TPR graphics demonstrated a higher stability of the FeCP2, due to the three-step reduction of iron oxide instead of two as shown for the FeCP1. According to the results of the catalytic tests FeCP2 exhibited a better efficiency for the production of hydrocarbons in the C5-C9 range, for the same conditions of temperature, pressure and molar ratio. However, the decrease in the molar ratio disfavors the production of heavy hydrocarbons.
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Monteiro, Ana Paula de Melo. "Influência do método de preparação nas propriedades do óxido de ferro suportado." Programa de Pós-Graduação em Química da UFBA, 2005. http://www.repositorio.ufba.br/ri/handle/ri/9950.
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O estireno é uma das substâncias químicas básicas mais importantes para produção de valiosos artigos como poliestireno, acrilonitrila-butadieno-estireno e estireno-butadieno-estireno. É produzido comercialmente pela desidrogenação do etilbenzeno com excesso de vapor d’água a temperaturas altas de 600-700ºC. Este processo é termodinamicamente limitado e consome energia. O uso de um oxidante, tal como oxigênio, permite superar as limitações termodinâmicas e por conseguinte operar a temperaturas mais baixas com reação exotérmica. Porém, há uma perda significantiva de seletividade a estireno, assim se buscou outro oxidante por muito tempo. O uso de gás carbônico surge como um potencial oxidante, além da conveniência do uso do gás causador do efeito estufa. Na busca de um catalisador alternativo para esta reação, neste trabalho estudou-se o efeito do método de preparação nas propriedades de óxido de ferro. As amostras foram preparadas incorporando óxido de ferro em lantânia, nióbia, titânia, magnésia e zircônia através de dois métodos: a impregnação de nitrato férrico e a deposição de nanoparticulas de óxido de ferro previamente preparadas. Os sólidos foram calcinados a 600ºC por 4 h e caracterizados por análise química, termogravimetria, análise térmica diferencial, difração de raios X, área de superfície específica e medidas de porosidade e redução a temperatura-programada. Os catalisadores foram avaliados na desidrogenação do etilbenzeno na presença de dióxido de carbono, usando um microreator que opera a 1 atm e a 600ºC e uma relação molar gás carbônico/etilbenzeno de 10. Depois dos testes, as amostras foram caracterizadas por difração de raios X e área de superfície específica. Observou-se que a concentração do óxido de ferro incorporado depende do tipo do suporte e do método de preparação. A hematita foi observada nos catalisadores novos. Durante a desidrogenação do etilbenzeno, os suportes não se alteraram, mas a hematita se transformou em magnetita. Os suportes e os catalisadores são sólidos macroporosos com pequena contribuição de mesoporos. A área específica mudou devido à adição de óxido de ferro e foi influenciada pelo método de preparação. A incorporação das nanoparticulas conduziu a um aumento da área superficial específica, indiferentemente do tipo do suporte, fato que foi atribuído ao tamanho pequeno das partículas. As áreas específicas não se alteraram durante a reação. Os sólidos mostraram diferentes resistência contra redução que se deve ao suporte e ao método de incorporação do óxido de ferro. A impregnação de nitrato férrico produziu sólidos menos redutíveis. Os suportes foram cataliticamente ativos na desidrogenação do etilbenzeno na presença de gás carbônico e também eram seletivos a estireno. A adição de compostos de ferro melhorou estas propriedades e a deposição de nanoparticulas melhoraram ainda mais. O óxido ferro suportado em magnésia, preparado pela deposição de nanoparticulas, foi o mais ativo (2,8 x 10-3 mol.g-1.h-1) e catalisador seletivo a estireno (96%) na desidrogenação do etilbenzeno na presença de gás carbônico. A atividade e a seletividade foram mais altos do que um catalisador comercial à base de óxido de ferro, cromo e potássio (a=1,2 x 10-3 mol. g-1. h-1 e S=90%) , sendo o catalisador promissor na reação.
Salvador
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Chew, Ly May [Verfasser], Martin [Gutachter] Muhler, and Wolfgang [Gutachter] Grünert. "Catalytic hydrogenation of CO_2 and CO to short-chain hydrocarbons over iron nanoparticles supported on functionalized carbon nanotubes / Ly May Chew ; Gutachter: Martin Muhler, Wolfgang Grünert ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2015. http://d-nb.info/1204257035/34.
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Xu, Chunbao. "Continuous and batch hydrothermal synthesis of metal oxide nanoparticles and metal oxide-activated carbon nanocomposites." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-07302006-231517/.
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Thesis (Ph. D.)--Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2007.Teja, Amyn, Committee Chair ; Kohl, Paul, Committee Member ; Liu, Meilin, Committee Member ; Nair,Sankar, Committee Member ; Rousseau, Ronald, Committee Member.
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Duma, Viorel. "Heterogen katalysierte Gasphasen-Epoxidation von Propen an FeOx/SiO2-Katalysatoren." Doctoral thesis, Universitätsbibliothek Chemnitz, 2001. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200100686.
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Im Rahmen der vorliegenden Arbeit wurde eine neuartige Methode und die entsprechenden Katalysatoren für die heterogen katalysierte Gasphasen-Epoxidation von Propen entwickelt und optimiert. Das Propen wurde an FeOx/SiO2-Katalysatoren mit N2O als Oxidationsmittel epoxidiert. Die Katalysatoren wurden mittels XRD, TEM, XPS, Physi- und Chemisorption, TPR/TPO, TPD und IR untersucht und charakterisiert. Der Einfluß der Reaktionsbedingungen auf die Oxidationsergebnisse wurde bestimmt und Untersuchungen zum Reaktionsablauf durchgeführt. Es wurden Selektivitäten zu Propenoxid von 40-70%, bei Propenumsätzen von 3-12%, erreicht. Die maximalen erzielten PO-Ausbeuten betrugen über 5%, und sind damit den berichteten Ergebnisse aus der Literatur überlegen.
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FINCK, FRANCOISE. "Etude d'un nouveau systeme de depollution des gaz d'echappement automobile : modelisation par les techniques de surface." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13068.
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Etude portant sur un catalyseur pour epuration des gaz, compose de la phase catalytiquement active (surtout le palladium), du support d'impregnation (wash-coat d'alumine gamma) et du support mecanique (alliage fe-cr-al). Determination d'un mecanisme complet de formation de la couche de passivation d'alliages trimetalliques fe-cr-al
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Zhang, Liping. "Immobilisation de catalyseurs moléculaires de polymérisation d’oléfines sur nanomatériaux." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0013/document.
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Le présent travail de thèse décrit le développement de systèmes actifs de polymérisation d’oléfines basés sur des métaux de fin de transition (nickel et fer) supportés sur des nanomatériaux. Le chapitre I décrit l’état de l’art des systèmes catalytiques supportés ou non pour la polymérisation d’oléfines. Dans le chapitre II, nous décrivons la polymérisation de l’éthylène en utilisant des catalyseurs de nickel contenant un groupement –NH2 pour leur immobilisation covalente sur nanotubes de carbone ; montrant l’influence positive de l’immobilisation : les catalyseurs ainsi supportés sont en effet à la fois plus actifs et conduisant à des polymères de plus haut poids moléculaire. Dans le chapitre III, des complexes de fer contenant un groupement pyrène sont décrits et immobilisés sur nanotubes de carbone par interaction non covalente π-π. Dans ce cas, à la fois les systèmes homogènes et leurs analogues supportés catalysent la réaction de polymérisation de l’éthylène avec des activités particulièrement élevées. Il a également pu être mis en évidence l’importante influence du support carboné sur les performances du système catalytique ainsi que sur la structure des polymères obtenus. Différents types de complexes de nickel contenant un ligand imino-pyridine et différents groupes polyaromatiques ont été synthétisés et leur utilisation en polymérisation de l’éthylène est décrite dans le chapitre IV. L’influence de l’addition de faibles quantités de matériaux nanocarbonés (nanotubes de carbone ou graphène) au milieu réactionnel a ainsi été étudiée. Le graphène s’est dans ce cas révélé particulièrement bénéfique sur les performances du catalyseur. Enfin, le chapitre V décrit la polymérisation de l’isoprène à l’aide de catalyseurs de fer contenant des groupements polyaromatiques permettant leur immobilisation à la surface de nanoparticules de fer. Ces systèmes ont ensuite pu être confinés dans des nanotubes de carbone. Les systèmes catalytiques décrits sont particulièrement actifs produisant des polyisoprènes à température de transition vitreuse élevée et avec une haute sélectivité trans-1,4-polyisoprèneThis present thesis deals with the development of active olefin polymerization catalysts based on late transition metal (nickel and iron) imino-pyridine complexes supported on nanomaterial. Chapter I gives a comprehensive literature review of unsupported and supported ethylene polymerization catalyst. In Chapter II we report the ethylene polymerization studies using nickel complexes containing an –NH2 group for covalent immobilization on multi-walled carbon nanotubes (MWCNTs) of the corresponding precatalysts. Comparison of the homogeneous catalysts with their supported counterparts evidenced higher catalytic activity and higher molecular weights for the polymers produced. In Chapter III, iron complexes containing a pyrene group have been synthesized and immobilized on MWCNTs through non-covalent π-π interactions between pyrene group and surface of MWCNTs. Activated by MMAO, both the iron complexes and immobilized catalysts show high activities for ethylene polymerization. It was possible to evidence that MWCNTs have a great influence on the catalytic activity and on the structure of the resulting polyethylenes. Imino-pyridine nickel complexes containing various kinds of aromatic groups have been synthesized in Chapter IV and polymerization conditions in the presence and in the absence of nanocarbon materials, such as MWCNTs or few layer graphene (FLG), are discussed. For those nickel catalysts bearing 1-aryliminoethylpyridine ligands, the presence of MWCNTs in the catalytic mixture allows the formation of waxes of lower molecular weight and polydispersity, whereas the presence of FLG proved to be beneficial for the catalytic activity. In Chapter V, isoprene polymerization catalyzed by iron complexes containing polyaromatic groups and non-covalently supported on nanoparticles and confined into the inner cavity of MWCNTs (Cat@NPs and Cat@NPs@MWCNTs) are investigated. Iron complexes show excellent activity for the isoprene polymerization and produced high glass temperature polyisoprene with a high trans-1,4-polyisoprene selectivity. Polymer nanocomposites are produced by supported catalysts and, transmission electron microscopy (TEM) evidenced efficient coating of the resulting polyisoprene around the oxygen sensitive iron nanoparticles
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Zubeck, Michael W. "Nonlinear analysis of intermediate support regions of continuous span steel griders /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9974706.
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Smith, Stephen Findley. "Structural stability, support and excavation aspects of mine openings in stratified iron ore deposits." Thesis, University of Nottingham, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283587.
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Sala, Alessandro [Verfasser]. "Characterization of iron oxide thin films as a support for catalytically active nanoparticles / Alessandro Sala." Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1070218928/34.
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Bala, Leon Jerzy. "Why is information technology failing to support business needs?' : the 'Sishen Iron Ore Mine' story." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/49739.
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Thesis (MBA)--Stellenbosch University, 2002.ENGLISH ABSTRACT: Sishen Iron Ore Mine produced 24,5 million tons of iron ore during 2000/2001 of which 20 million tons was exported to clients overseas and the rest locally supplied. This production is a mere 2,5% of the world iron ore production. Sishen Iron Ore Mine is planning to produce 26,5 million tons during 2001/2002. The target is to produce more than 30 million tons in the near future. Information technology can only make a positive impact on reaching these goals, when the information technology strategy is aligned with that of the business and the information technology is managed well. This study will indicate red lights in that, if Sishen Iron Ore Mine continues to manage information technology as it has done in the past, the possibility exists that Sishen Iron Ore Mine will not reach the goals agreed upon. This study has, after a thorough investigation, shown where the shortcomings are and how to go about addressing these shortcomings. This study, furthermore, makes certain recommendations towards ensuring that information technology makes a positive impact in assisting Sishen Iron Ore Mine to reach the goals agreed upon. This study has shortly come to the conclusion that there is currently restricted alignment between the information technology strategy and the business strategy, and that the management of information technology does not follow best practice. Research was done and the results gathered pointed to specific shortcomings that needed to be addressed. These shortcomings could be summarised as follows: • Information technology strategy, with specific reference to the questions - Does information technology add value to the business? - Does information technology address business needs? - Why is development costs for information technology solutions so high? • Management of information technology, with regard to - Personnel - Information technology solution priorities - New information technologies - Information technology project management and planning - Management and user awareness and education - Management and user involvement After a thorough investigation of the applicable literature, it is recommended that Sishen Iron Ore mine take certain steps to align the information technology strategy with that of the business, and furthermore, that information technology will be satisfactorily managed. Short conclusions of the recommendations are as follows. • Information technology strategy - To develop a measurement mechanism that will determine the value added by information technology. - To develop thorough user specifications that will address business needs. - To further investigate initiatives to lower development costs for information technology solutions. • Management of information technology - The extension of the current information management organisation to address business needs. - To develop a priority matrix that will prioritise information technology solutions. - To construct forums to ensure that all parties are involved when investigating new information technologies. - To implement a thorough project management and planning environment for information technology projects. - To develop an awareness and education program of information technology for users and managers. - To develop a mechanism that will ensure that users and managers are involved during and after implementing information technology solutions.
AFRIKAANSE OPSOMMING: Die Sishen Ysterertsmyn het gedurende 2000/2001 24,5 miljoen ton ystererts geproduseer waarvan ongeveer 20 miljoen ton uitgevoer is na oorsese kliënte en die res plaaslik geabsorbeer is. Hierdie produksie is maar 'n skamele 2,5% van die wêreld se totale ysterertsproduksie. Die Sishen Ysterertsmyn beplan dan ook om gedurende 2001/2002 26,5 miljoen ton te produseer en binne die nabye toekoms meer as 30 miljoen ton. Inligtingstegnologie kan 'n positiewe bydrae maak tot nastrewing van hierdie doelwitte, indien die strategie daarvan gesinchroniseer is met die Sishen Ysterertsmyn se strategie asook die manier waarop inligtingstegnologie bestuur word. Hierdie studie het ten doeI om met rooi gevaarligte te identifiseer indien die Sishen Ysterertsmyn voortgaan met die bestaande bestuurswyse van inligtingstegnologie wat daartoe kan lei dat die Sishen Ysterertsmyn nie die ooreengekomde doelwitte gaan bereik nie. Hierdie studie het na 'n deeglike ondersoek uitgewys waar die leemtes lê en hoe 'n mens te werk moet gaan om die leemtes aan te spreek. Hierdie studie maak verder aanbevelings om te verseker dat inligtingstegnologie 'n positiewe bydrae kan maak om te verseker dat die Sishen Ysterertsmyn wel die ooreengekomde doelwitte bereik. Hierdie studie het kortliks tot die slotsom gekom dat daar tans beperkte sinchronisering is tussen die strategie vir inligtingstegnologie en die Sishen Ysterertsmyn se strategie en dat die bestuur van inligtingstegnologie nie beste praktyke nastreef nie. Navorsing omtrent die aangeleenthede is gedoen en het uitgewys dat daar spesifieke leemtes is wat aangespreek moet word. Hierdie leemtes behels die volgende: • Strategie vir inligtingstegnologie, met spesifieke verwysing na -of inligtingstegnologie waarde toevoeg tot die Sishen Ysterertsmyn; - of inligtingstegnologie voldoen aan die Sishen Ysterertsmyn se behoeftes; - of die ontwikkelingskoste vir die oplossing van inligtingstegnologie leemtes nie te hoog is nie. • Bestuur van inligtingstegnologie, met verwysing na - personeel; - prioriteite vir oplossing van inligtingstegnologie leemtes; - nuwe inligtingstegnologie; - projekbestuur en beplanning van inligtingstegnologie; - bewusmaking en opvoeding vir bestuur en gebruikers; - bestuur en gebruikers se betrokkenheid. Na 'n deeglike ondersoek met verwysings na verwante literatuur word daar aanbeveel dat die Sishen Ysterertsmyn die nodige stappe moet neem om sinchronisering te verseker tussen die strategie vir inligtingstegnologie en die Sishen Ysterertsmyn se strategie en dat die nodige goeie bestuur van inligtingstegnologie plaasvind. Vervolgens 'n kort samevatting van die aanbevelings met betrekking tot die volgende aspekte • Strategie vir inligtingstegnologie die daarstel van metingsmeganismes om waardetoevoeging van inligtingstegnologie te bepaal; - die opstel van deeglike gebruikerspesifikasies vir die bevrediging van die Sishen Ysterertsmyn se behoeftes; - die ondersoek na inisiatiewe om die ontwikkelingskoste vir die oplossing van inligtingstegnologie gebreke te verlaag. • Bestuur van inligtingstegnologie - die uitbreiding van die bestaande Bestuursinligtingsorganisasie om die Sishen Ysterertsmyn se behoeftes te bevredig; - die daarstelling van prioriteitsmatrikse om oplossing van inligtingstegnologie gebreke te prioritiseer; die daarstelling van forums sodat alle partye betrokke is by die ondersoek na nuwe inligtingstegnologie; - die daarstelling van deeglike projekbestuur en projekbeplanning vir inligtingstegnologie projekte; opvoedingsprogram oor inligtingstegnologie vir bestuur en gebruikers; - die daarstelling van 'n meganisme wat sal verseker dat bestuur en gebruikers meer betrokke raak en bly by die implementering van inligtingstegnologie.
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Motala, Muhammad. "[Ca₂₄Al₂₈O₆₄]⁴⁺(e⁻)₄ electride as a novel support system for iron-based Fischer-Tropsch synthesis." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29334.
Full textAbstract:
Iron-based Fischer-Tropsch (FT) technology is well established in the industrial production of hydrocarbon resources. The use of a stable inorganic electride as a support system, with potential promoter effects which could replace commonly used alkali metals, may have the potential to open a new facet within the research and development of iron-based FT technology. The hydrothermally produced [Ca₂₄Al₂₈O₆₄]⁴⁺(e⁻)₄ electride material as carrier for Ru nanoparticles for the synthesis of ammonia from its elements has been reported in literature as support system and substitute to conventional alkali promotion. This is due to highly localized electrons present in the crystallographic cages of the material that may serve as a Lewis base and facilitate bond breaking of feedstock molecules adsorbed to the catalytic active sites. The hydrothermal preparation of this electride previously resulted in a surface area of up to 50m²·g⁻¹ and a two-fold rate increase in ammonia production. The low work function of [Ca₂₄Al₂₈O₆₄]⁴⁺(e⁻)₄ is comparable to that of potassium, therefore the iron loading onto the electride is postulated to mimic the promoting effects of potassium(oxide) in the FT synthesis. Following the hydrothermal synthesis of the electride produced at varying evacuation temperatures (800 °C and 1000 °C), supported iron catalysts were prepared using a stoichiometric amount of Fe(acac)₃ precursor to decompose as iron oxide onto the novel support. Iron supported on the unreduced mayenite precursor, [Ca₂₄Al₂₈O₆₄]⁴⁺(O²⁻)₂, and unpromoted precipitated iron diluted in γ-alumina were used as control/baseline catalysts. The testing of these catalysts was conducted at 240 °C and 15 bar with a 2:1 H₂/CO ratio. The electride and mayenite catalysts performed similarly with regards to hydrocarbon selectivities with the precipitated iron bulk catalyst. However, significantly larger CO₂ selectivity and olefin/paraffin ratios were observed for the supported catalysts showing little difference between the electride and its unreduced counterpart.
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Morillo, Martín Diego. "Superparamagnetic iron oxide nanoparticles as arsenic adsorbent. Development of Nanofiber SPION Supports and Arsenic Speciation Using Synchrotron and Hyphenated Techniques." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/129335.
Full textAbstract:
Los estudios que se han realizado en la presente tesis doctoral se basan en el desarrollo de
una metodología de síntesis y caracterización de sistemas nanoestructurados como recurso
innovador para la recuperación de arsénico en efluentes contaminados y la depuración de
dichos efluentes. Estos materiales tienen como elemento común, el uso de las
Superparamagnetic Iron Oxide Nanoparticles (SPION), con las que se han realizado
diferentes estudios de adsorción para evaluar los parámetros de adsorción óptimos (tiempo
de contacto, efecto del pH y de la concentración). Dichos estudios han permitido determinar
la máxima capacidad de adsorción del SPION a la hora de extraer el elemento contaminante
y observar como se ve afectada dicha capacidad de adsorción, en función de la especie
existente del elemento contaminante. La elección de SPION se fundamenta en el empleo de
la fuerte interacción Fe-As demostrada en muchos compuestos naturales, así como por su
capacidad magnética. A partir de éste estudio, se han desarrollado diferentes sistemas
adsorbentes en modo no soportados, basados en la funcionalización del SPION
(NanoComposites) o bien empleando sistemas soportados, ya sean con esponja de celulosa
(Forager® Sponge) impregnada de SPION o los más novedosos, sistemas basados en
nanofibras (de acetato de celulosa y poliacrilonitrilo). En este último caso, dichos sistemas
son sintetizados vía electrospinning y cargados con SPION con el objetivo de incrementar la
superficie específica de adsorción y facilitar su posible aplicación en muestras reales.
Todos los sistemas desarrollados disponen de un valor añadido, ya que las propiedades
magnéticas del SPION permiten recuperar las nanopartículas que pueden quedar expuestas
en las disoluciones contaminadas de una manera rápida y efectiva, evitando así, una
contaminación con nanopartículas del efluente tratado.
El trabajo realizado, ha permitido optimizar tanto la síntesis de SPION, vía co-precipitación,
como el desarrollo y caracterización de los sistemas adsorbentes. Adicionalmente, tras
determinar la máxima capacidad de adsorción para cada uno de los sistemas, se ha
estudiado la selectividad de dichos sistemas por las especies de arsénico en presencia de
iones metálicos (Cu2+, Ni2+ o Zn2+) y/o de los aniones más comunes en aguas (cloruro, nitrato,
sulfato y fosfato).
En lo referente a los estudios de especiación, se han aplicado técnicas de especiación directa
(técnicas de radiación sincrotrón) e indirecta (acoplamiento HPLC-ICP-MS) para determinar
la selectividad de los materiales frente a las diferentes especies inorgánicas de arsénico
(arsenito o arsenato), obteniéndose resultados satisfactorios que denotan una elevada
selectividad por As(V).
Por otra parte, se han evaluado las características y propiedades de los diferentes sistemas
adsorbentes. Dicha actividad ha comportado el empleo de diversas técnicas analíticas, desde
la microscopia (SEM y TEM) que permiten conocer el tamaño, distribución y morfología de
las nanopartículas y nanofibras, hasta técnicas que proporcionan información sobre las
características estructurales y propiedades físico-químicas de los materiales.
Así pues, los estudios llevados a cabo para la realización de esta tesis doctoral proporcionan
un significativo avance en el desarrollo de una serie de potenciales sistemas adsorbentes, los
cuales pueden ser aplicados para la eliminación de contaminantes altamente tóxicos como el
arsénico en muestras reales. Dicha aplicación, se caracteriza por unos valores de eficiencia,
eficacia y selectividad comparables, cuando no superiores a materiales existentes en el
mercado. Un ejemplo de la transferencia tecnológica derivada de esta tesis doctoral, es la
patente solicitada “Filtro de tratamiento de líquidos con nanopartículas de magnetita y
procedimientos correspondientes”. Ref: P201330144 y con fecha de prioridad del 6 de
Febrero de 2013.The studies that have been carried out in the present PhD thesis Project are based in the development of a synthesis methodology and characterization of nanostructured systems as an innovative facility for the recovery of arsenic from contaminated effluents and the purification of these effluents. These adsorbent materials have a base element, Superparamagnetic Iron Oxide Nanoparticles (SPION). With this nanoparticles have carried out arsenic adsorption experiments to evaluate the optimum adsorption parameters (contact time, pH effect and concentration effect). These studies have made it possible to determine the maximum adsorption capacity of SPION when the contaminant element is extracted, observe how is affected this adsorption capacity depending of the contaminant element existing specie. It is expected to use the high affinity and string interaction between Fe-As as it is proved in several natural compounds. Then, taking into account the previous work with SPION, different adsorbent systems have been developed, non-supported nanostructured systems by SPION surface functionalization (NanoComposites) or supported nanostructured systems as SPION loaded over a cellulose sponge (Forager® Sponge) and the most innovative, SPION loaded electrospun nanofibrous systems (with polymers such as cellulose acetate and polyacrylonitrile). In this last case, these systems have been synthesized by electrospinning techniques with the main aim of increase the specific surface area and to make easier the real sample applications. These nanostructured systems have an added value because of the SPION magnetic properties let recover the nanoparticles that are exposed in the contaminates solutions in a quick and effective way, avoiding then, an unwanted contamination with nanoparticles of the treated effluent. The developed work have made possible the SPION Synthesis by co-precipitation method was optimized and the development and characterization of the nanostructured adsorbent systems were performed successfully. Thus, apart from the maximum adsorption capacity determination for each system, arsenic selectivity of this systems was performed in presence of metal ions (Cu2+, Ni2+ o Zn2+) and/or in presence of most common interfering anions in water (chloride, nitrate, sulphate and phosphate). Regarding the speciation studies, direct (Synchrotron radiation techniques) and indirect (Hyphenated HPLC-ICP-MS) speciation techniques were put in practice to determine the selectivity of each system for the different inorganic arsenic species, arsenite or arsenate, obtaining successfully results of the arsenate selectivity for all systems. Furthermore, the characteristics and the properties of the adsorbent systems have been evaluated. Several techniques have been used, from microscopic techniques (SEM y TEM) that let measure and understand the size, distribution and morphology of nanoparticles and nanofibers, to other techniques as X-ray diffraction (XRD) or magnetization measures (SQUID) that provide information about structural characteristics and physico-chemical properties. All in all, this work provides knowledge, demonstrated advances and different nanostructured adsorbent systems that can be potentially applied to remove highly toxic contaminants such as arsenic. An example of the appropriate technologic transference derived from the PhD. Thesis is the Spanish Patent “Filtro de tratamiento de líquidos con nanopartículas de magnetita y procedimientos correspondientes”. Ref: P201330144 with priority date on Febrery 6th, 2013.
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Andreas, Instebø Jamne. "Can Sectarianism Explain Soft Power Support in ProxyConflicts?" Thesis, Uppsala universitet, Institutionen för freds- och konfliktforskning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446104.
Full textAbstract:
Proxy conflict seems to be on the rise as the contemporary form of armed conflict, particularly manifesting itself in the Middle East and North Africa. While proxy conflicts enjoy increased attention in academia, little research has focused on the type of support a sponsor provides to its proxy. This thesis contributes to the literature by asking under what circumstances does sponsor provide soft power support to proxies in proxy conflict? I employ a qualitative most-similar case design of Iran’ssupport to the Supreme Council for Islamic Revolution (SCIRI) and its military wing the Badr organization in Iraq, as well as United Arab Emirates’ (UAE) support to General Haftar and the Libyan National Army (LNA) in Libya. The theoretical argument posits that mobilized sectarian bonds between sponsor and proxy facilitate a trust that induces the sponsor to provide soft power support in addition to the baseline support of hard power. The empirical findings give mixed support for the argument, as both sponsors provided soft power support, albeit at somewhat various degrees. Notably, Iran mobilized deeper and broader amongst the organizational structure of the proxy and its followers, while UAE arguably only engaged with Haftar as a strong leader but less so with NLA as an organization and its followers. Therefore, there seems to a difference in how the two sponsors penetrated their mobilization of proxies.
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Chafik, Abdelghani. "Influence de terres rares (La, Ce) sur les propriétés de systèmes catalytiques Métal-Carbone (Métal : Fe, Co, Ni) dans la conversion d'oxydes de carbone." Poitiers, 1988. http://www.theses.fr/1988POIT2309.
Full text
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Boudouvas, Denis. "Effet du potassium sur un catalyseur composite Fe-Co-C en synthèse d'hydrocarbures." Grenoble INPG, 1989. http://www.theses.fr/1989INPG0092.
Full textAbstract:
Etude de la promotion par le potassium du catalyseur composite fe-co-c, c'est-a-dire de l'amelioration de son activite catalytique et de sa selectivite en alcenes. L'addition de potassium est realisee soit par impregnation par une solution aqueuse de k#2co#3, soit par la formation intermediaire d'un compose d'insertion avec le carbone de formule kc#3#2. L'evolution de la selectivite des catalyseurs promus et non promus par le potassium est etudiee a des conversions en monoxyde de carbone analogues a celles d'un procede industriel. Des tests catalytiques a faible conversion et des mesures de chimisorption de gaz reagissants sont effectues
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Hemberg, Annica. "How do sanctions affect government support in an autocratic setting? : A case study of Iran." Thesis, Uppsala universitet, Statsvetenskapliga institutionen, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-411410.
Full textAbstract:
Sanctions are presumed to work on the logic of a cost/benefit analysis, where the actors make concessions in response to induced pressure from the public who demands policy change because of hardened living conditions. The literature regarding sanctions effect on policy change are numerous, but less research has been made on what effects follow in domestic politics when sanctions are lifted. The theory of economic voting explains how voters reward or punish their leaders depending on the economic performance of the country. Most studies have focused on democratic developed countries, but this research will extend the theories to an autocratic setting. This essay fills a gap in the literature by a applying case study approach to a field of work that is largely dominated by quantitative research designs. Through a case of structured focused comparison of two periods where sanctions are implemented and then lifted, this essay is able to show that for the case of Iran, the coercive measures had an impact on support for the government. The public rewarded the incumbent for good performance when the sanctions were lifted, which confirms earlier findings that voter behavior in autocratic countries are similar to those in democracies. The economy is here shown to be of importance for regime approval, but more research is needed on what affects support for governments in non-consolidated democracies.
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Panaritis, Christopher. "Metal-Support Interaction and Electrochemical Promotion of Nano-Structured Catalysts for the Reverse Water Gas Shift Reaction." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41963.
Full textAbstract:
The continued release of fossil-fuel derived carbon dioxide (CO₂) emissions into our atmosphere led humanity into a climate and ecological crisis. Converting CO₂ into valuable chemicals and fuels will replace and diminish the need for fossil fuel-derived products. Through the use of a catalyst, CO₂ can be transformed into a commodity chemical by the reverse water gas shift (RWGS) reaction, where CO₂ reacts with renewable hydrogen (H₂) to form carbon monoxide (CO). CO then acts as the source molecule in the Fischer-Tropsch (FT) synthesis to form a range of hydrocarbons to manufacture chemicals and fuels. While the FT synthesis is a mature process, the conversion of CO₂ into CO has yet to be made commercially available due to the constraints associated with high reaction temperature and catalytic stability.
Noble metal ruthenium (Ru) has been widely used for the RWGS reaction due to its high catalytic activity, however, several constraints hinder its practical use, associated with its high cost and its susceptibility to deactivation. The doping or bimetallic use of non-noble metals iron (Fe) and cobalt (Co) is an attractive option to lower material cost and tailor the selectivity of the CO₂ conversion towards the RWGS reaction without compromising catalytic activity. Furthermore, employing nanostructured catalysts as nanoparticles is a viable solution to further lower the amount of metal used and utilize the highly active surface area of the catalyst. Dispersing nanoparticles on ionically conductive supports/solid electrolytes which contain species like O²⁻, H⁺, Na⁺, and K⁺, provide an approach to further enhance the reaction. This phenomenon is referred to as metal-support interaction (MSI), allowing for the ions to back spillover from the support and onto the catalyst surface. An in-situ approach referred to as Non-Faradaic Modification of catalytic activity (NEMCA), also known as electrochemical promotion of catalysis (EPOC) is used to in-situ control the movement of ionic species from the solid electrolyte to and away from the catalyst. Both the MSI and EPOC phenomena have been shown to be functionally equivalent, meaning the ionic species act to alter the work function of the catalyst by forming an effective neutral double layer on the surface, which in turn alters the binding energy of the reactant and intermediate species to promote the reaction.
The main objective of this work is to develop a catalyst that is highly active and selective to the RWGS reaction at low temperatures (< 400 °C) by employing the MSI and EPOC phenomena to enhance the catalytic conversion. The electrochemical enhancement effect will lower energy requirements and allow the RWGS reaction to take place at moderate temperatures. Catalysts composed of Ru, Fe and Co were synthesized through the polyol synthesis technique and deposited on mixed-ionically conductive and ionically conductive supports to evaluate their performance towards the RWGS reaction and the MSI effect. The nano-structured catalysts are deposited as free-standing nanoparticles on solid electrolytes to in-situ promote the catalytic rate through the EPOC phenomenon. Furthermore, Density Functional Theory (DFT) calculations were performed to correlate theory with experiment and elucidate the role polarization has on the binding energy of reactant and intermediate species.
The high dispersion of RuFe nanoparticles on ion-containing supports like samarium-doped ceria (SDC) and yttria-stabilized zirconia (YSZ) led to an increase in the RWGS activity due to the MSI effect. A direct correlation between experimental and DFT modeling was established signifying that polarization affected the binding energy of the CO molecule on the surface of Ru regardless of the type of ionic species in the solid electrolyte. The electrochemical enhancement towards the RWGS reaction has been achieved with iron-oxide (FeOₓ) nanowires on YSZ. The in-situ application of O²⁻ ions from YSZ maintained the most active state of Fe₃O₄ and FeO towards the RWGS reaction and allowed for persistent-promoted state that lasted long after potential application. Finally, the deposition of FeOₓ nanowires on Co₃O₄ resulted in the highest CO₂ conversion towards the RWGS reaction due to the metal-oxide interaction between both metals, signifying a self-sustained electro-promoted state.
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Danjou, Pierre-Édouard. "Élaboration de nouveaux fluoroionophores et de supports chélatants en vue de l'amélioration de la caractérisation du fer dans les particules atmosphériques." Thesis, Littoral, 2012. http://www.theses.fr/2012DUNK0446/document.
Full textAbstract:
L'objet de ce travail est de fournir de nouveaux outils moléculaires pour la caractérisation physico-chimique des particules atmosphériques afin d'établir des liens entre leurs propriétés et leur toxicité pulmonaire. Nous nous sommes plus particulièrement intéressés à la détection, la quantification et le traçage du fer, élément majeur dans les particules industrielles du bassin dunkerquois. Pour ce faire, nous avons mis au point dans un premier temps, la synthèse rapide de nouvelles sondes fluorescentes par micro-ondes et ultrasons. L'étude des propriétés spectroscopiesde ces nouvelles sondes a été menée et a permis de mettre en avant un composé sélectif des ions ferriques en solution aqueuse non temponnée en présence d'autres ions métalliques. Dans un second temps, nous avons réalisé des supports solides contenant des entités chélatantes supramoléculaires ou bio-inspirées afin de séparer les traces de fer ferrique de matrices aqueuses complexesThe aim of this work is to provide new molecular tools for the physico-chemical characterization of atmospheric particles in order to establish a link between their properties and their pulmonary toxicity. We particularly investigate the detection and quantification of iron, a major element in industrial particle of Dunkirk city, France. So, in a first hand, we have developed the efficient synthesis of new fluorescents chemosensors by ultrasounds and microwave irradiation. Then the study of these compounds was undertaken and has revealed a highly selective sensor of ferric iron in non-buffered aqueous solution in presence of other metallic cation. In the other hand, we have synthesized new solid supports which beard supramolecular chelatant or bio-inspired entities in order to separate iron traces from complex aqueous matrix
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Mellergård, Emelia, and Liza Trulsson. "Well-being and distress related to social support and emotions in infertile women : A cross-cultural comparison between Sweden and Iran." Thesis, Örebro universitet, Institutionen för juridik, psykologi och socialt arbete, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-29353.
Full textAbstract:
The present survey study investigated cultural differences in social support, well-being, distress, positive and negative emotions in relation to infertility, by analyzing mean difference, correlation, regression and moderation on these variables. 117 women with primary infertility were recruited from fertility clinics in Sweden and Iran. Cultural differences were found regarding well-being and distress, indicating that infertility may pose a greater stigma in Iran than in Sweden. Even so, both samples reported high distress levels which confirmed infertility as a psychological stressor. Social support buffered against distress in the Swedish sample. Well-being was to a greater extent estimated by emotions in the Swedish sample, and by social support in the Iranian sample. Results were discussed in relation to aspects of individualism and collectivism.
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Jollet, Véronique. "Complexes de fer bio inspirés pour la catalyse d'oxydation : systèmes homogènes et supportés." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00915279.
Full textAbstract:
Certaines métalloenzymes catalysent l'oxydation de petites molécules organiques, dans des conditions douces (par activation du dioxygène à température et pression ambiante). Ce travail a pour but d'améliorer l'utilisation et l'efficacité catalytique des complexes de fer mimant cette activité.D'abord, par fonctionnalisation du ligand, un des complexes les plus efficaces pour catalyser l'oxydation de substrats aromatiques par H2O2, a pu être greffé dans des mésopores de silice. Ce matériau est utilisé comme support de catalyseur, en raison de sa grande surface spécifique et de sa chimie de surface versatile. Par ailleurs, la méthode de synthèse permet de structurer la taille des cavités formées, à l'aide d'un surfactant utilisé comme modèle. Le contrôle du nombre de sites catalytiques sur la surface est rendu possible par la procédure qui exploite le concept du pochoir moléculaire. Le confinement du catalyseur dans les pores pourrait être mis à profit pour former des produits à haute valeur ajoutée. En parallèle, ce complexe a aussi été greffé sur des billes de silices, un matériau moins élaboré pouvant être utilisé pour la dégradation de polluants. L'élaboration de ce type de catalyseurs supportés a nécessité de nombreuses caractérisations : analyses élémentaires, spectroscopies RMN, IR, XPS, UV-vis, RPE, isotherme d'adsorption d'azote, ATG, DRX sur poudre. Différentes méthodes de greffage ont été ainsi développées, et leur efficacité a été comparée. L'activité en catalyse d'oxydation de ces différents systèmes a aussi été évaluée.Concernant le développement des catalyseurs homogènes, le renforcement des positions des pyridines du ligand a permis l'obtention de nouveaux complexes de fer, possédant une meilleure stabilité pour réaliser des réactions catalytiques en milieu homogène et des propriétés structurales, spectroscopiques, chimiques et catalytiques analogues aux complexes de la même famille.Enfin, un autre complexe de fer a été mis en jeu dans un procédé électrochimique utilisant le dioxygène en présence de protons pour catalyser l'hydroxylation de substrats aromatiques.
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Rostami, Arian. "Marital satisfaction in relation to social support, coping, and quality of life in medical staff in Tehran, Iran." Doctoral thesis, Umeå universitet, Institutionen för socialt arbete, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-79478.
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Marital satisfaction is one of the main characteristics of a healthy family, and is known as an important predictor of overall quality of life. Stress is unavoidable in everyday life and it can affect marital relationships. Furthermore, employed married individuals encounter more stressors than do unmarried ones, especially when their jobs are demanding and stressful, such as working as medical professionals in hospitals. Applying effective coping strategies and receiving social support, especially from emotionally close persons, are protective factors which can help individuals deal with stress and buffer the negative effects of life stress on marital and life satisfaction. In the present cross-sectional investigation, marital satisfaction was studied in relation to socio-demographic variables, social support, ways of coping, and quality of life in medical staff in Tehran. Data were collected from 653 medical staff who worked in 12 hospitals affiliated with Tehran Medical University using socio-demographic questions, the ENRICH marital satisfaction questionnaire, the SF-36 questionnaire, the Social Support questionnaire, and the Ways of Coping questionnaire. The results indicated that marital satisfaction, quality of life and spousal support were significantly higher in men than women. Spousal support was significantly associated with marital satisfaction especially in women. Multiple regression analyses indicated that marital satisfaction, social support, and job satisfaction combined with socio-demographic variables explain between 12% and 28% of the variance in quality of life domains. Analysing the data with special focus on females revealed a significant negative relationship between subscales of marital satisfaction and using “seeking social support”, “confrontive coping”, “escape avoidance”, “distancing”, and “self-controlling” as ways of coping. Hierarchical regression analyses showed that job satisfaction, social support, and ways of coping explained between 24% and 38% of the variance in seven of the nine subscales of marital satisfaction. Therefore, focusing on the study findings could be helpful in promoting marital satisfaction and quality of life in married medical staff.
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Zhang, Ke [Verfasser], Hans-Joachim [Akademischer Betreuer] Freund, Hans-Joachim [Gutachter] Freund, and Mario [Gutachter] Dähne. "Scanning tunneling microscopy study of strong metal-support interaction in iron oxide based model catalysts / Ke Zhang ; Gutachter: Hans-Joachim Freund, Mario Dähne ; Betreuer: Hans-Joachim Freund." Berlin : Technische Universität Berlin, 2018. http://d-nb.info/1164076469/34.
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