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Gu, Lei. "Subgrade Support Characterization for Whitetopping Applications." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1226952766.
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Law, Yeuk Ting. "Investigation of reaction networks and active sites in ethanol steam reforming reaction over Ni and Co-based catalysts." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-00869963.
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Bimetallic catalysts have been widely exploited to improve the performance of various catalytic reactions. Understanding the surface properties and in particular, bimetallic interaction and support effect of the catalytic components is an important step towards rational catalyst design. In this thesis, Ni-Co thin film on polar ZnO single crystal was studied as a model catalyst for ethanol steam reforming reaction. The aim is to provide fundamental understanding of how the surface characteristics of the catalyst influence the mechanism and the efficiency of the reaction. This study focused firstly on the study of the interaction between Ni and Co in oxidative environment using Xray photoelectron spectroscopy (PES). Oxidation of Co is favoured over nickel and the surface is enriched with cobalt oxide. Secondly, Ni-Co thin film supported on polar Zn and O terminated ZnOwas studied by synchrotron based PES. The as deposited layer interacts readily with ZnO and Co is partially oxidized upon deposition, even at room temperature. The interaction of ethanol with Ni- Co/ZnO-Zn was studied by thermal desorption spectroscopy (TDS). Ethanol decomposes in different pathways on Ni and Co, in which C-C bond scission and methane production are favoured on Ni/ZnO-Zn while dehydrogenation is favoured on Co/ZnO-Zn. Finally, Ni-Co powder was studied byin-situ ambient pressure PES under reaction conditions in order to clarify the correspondence between the active state of the catalyst and the reaction activity. The product selectivity on Co catalyst is distinctly different from Ni and Ni-Co. Also, the decomposition of methyl group and the high amount of CO produced over Co is likely to be the cause for its high level of carbon deposition.
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Milburn, Claire Louise Maud Jackson. "The directed ortho metalation reaction of aryl O-carbamates on solid support." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63340.pdf.
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Buchanan, April Mary. "Online student support, development and user reaction to a Web-based mathematics anxiety workshop." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0009/NQ59939.pdf.
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Kababji, Ala'a Hamed. "Effects of Diluent Addition and Metal Support Interactions in Heterogeneous Catalysis: SiC/VPO Catalysts for Maleic Anhydride Production and Co/Silica Supported Catalysts for FTS." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/2035.
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This work begins with an introduction to catalysis focusing on heterogeneous systems and surface science phenomena. A study on the partial oxidation reaction of n-butane to maleic anhydride (MA) is presented in the first part. MA supplies are barely adequate for market requirements due to continued strong demand. Only slight improvement in catalytic performance would be welcome in the industrial community. The vanadium phosphorus oxide (VPO) catalyst was used in this work. The reaction is highly exothermic and the need to properly support the catalyst, not only for good dispersion but adequate heat dissipation is of crucial importance. For this, alpha-SiC commercial powders were used in synthesizing the catalyst due to its high thermal conductivity. Up to 25% MA yields were obtained and the reaction temperature was lowered by up to 28% using SiC/VPO mixed catalysts.
The second part of this work is focused on the Fischer-Tropsch synthesis (FTS) process using cobalt silica supported catalysts. The main objective is the production of synthetic ultra high purity jet fuel (JP5). This is a very timely topic given the energy issues our world is facing. Almost all aspects of the FTS process have been extensively studied, however the effects of calcination temperature and silica support structure on the catalyst performance are lacking in literature. The catalysts were prepared using various silica supports. The catalysts had different drying and calcination temperatures. It was found that lower support surface area and calcination temperature catalysts exhibited higher activity due to lower support cobalt phase interaction. Co/silica catalysts calcined at 573K showed the highest CO conversion and the lowest CH4 selectivity. Catalysts prepared with 300m²/g support surface area exhibited 79.5% C5+ selectivity due to higher reducibility and less metal support interaction.
The properties and performance of various prepared catalysts in both VPO and Co/silica systems are characterized by FTIR, XRD, BET, GC and XPS techniques. Theoretical FTS deactivation by sintering calculations and SiC/VPO particle temperature gradient calculations are presented as well. Finally, conclusions and future work on improving the yield and selectivity and scaling up the bench top setups are also presented.
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Allen, Nicholas A. "Computational Software for Building Biochemical Reaction Network Models with Differential Equations." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/30059.
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The cell is a highly ordered and intricate machine within which a wide variety of chemical processes take place. The full scientific understanding of cellular physiology requires accurate mathematical models that depict the temporal dynamics of these chemical processes. Modelers build mathematical models of chemical processes primarily from systems of differential equations. Although developing new biological ideas is more of an art than a science, constructing a mathematical model from a biological idea is largely mechanical and automatable.
This dissertation describes the practices and processes that biological modelers use for modeling and simulation. Computational biologists struggle with existing tools for creating models of complex eukaryotic cells. This dissertation develops new processes for biological modeling that make model creation, verification, validation, and testing less of a struggle. This dissertation introduces computational software that automates parts of the biological modeling process, including model building, transformation, execution, analysis, and evaluation. User and methodological requirements heavily affect the suitability of software for biological modeling. This dissertation examines the modeling software in terms of these requirements.
Intelligent, automated model evaluation shows a tremendous potential to enable the rapid, repeatable, and cost-effective development of accurate models. This dissertation presents a case study that indicates that automated model evaluation can reduce the evaluation time for a budding yeast model from several hours to a few seconds, representing a more than 1000-fold improvement. Although constructing an automated model evaluation procedure requires considerable domain expertise and skill in modeling and simulation, applying an existing automated model evaluation procedure does not. With this automated model evaluation procedure, the computer can then search for and potentially discover models superior to those that the biological modelers developed previously.Ph. D.
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Allen, Nicholas Alexander. "Computational Software for Building Biochemical Reaction Network Models with Differential Equations." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/30059.
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The cell is a highly ordered and intricate machine within which a wide variety of chemical processes take place. The full scientific understanding of cellular physiology requires accurate mathematical models that depict the temporal dynamics of these chemical processes. Modelers build mathematical models of chemical processes primarily from systems of differential equations. Although developing new biological ideas is more of an art than a science, constructing a mathematical model from a biological idea is largely mechanical and automatable.
This dissertation describes the practices and processes that biological modelers use for modeling and simulation. Computational biologists struggle with existing tools for creating models of complex eukaryotic cells. This dissertation develops new processes for biological modeling that make model creation, verification, validation, and testing less of a struggle. This dissertation introduces computational software that automates parts of the biological modeling process, including model building, transformation, execution, analysis, and evaluation. User and methodological requirements heavily affect the suitability of software for biological modeling. This dissertation examines the modeling software in terms of these requirements.
Intelligent, automated model evaluation shows a tremendous potential to enable the rapid, repeatable, and cost-effective development of accurate models. This dissertation presents a case study that indicates that automated model evaluation can reduce the evaluation time for a budding yeast model from several hours to a few seconds, representing a more than 1000-fold improvement. Although constructing an automated model evaluation procedure requires considerable domain expertise and skill in modeling and simulation, applying an existing automated model evaluation procedure does not. With this automated model evaluation procedure, the computer can then search for and potentially discover models superior to those that the biological modelers developed previously.Ph. D.
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Williamson, Andrew Ian. "Cognitive emotional analysis of support workers' reaction to challenging behaviour in adults with learning disabilities." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/4295.
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Previous research has explored the applicability of Weiner’s (1986) attributional model of helping behaviour to support workers of people with learning disabilities regarding challenging behaviour using optimism as a measure of the expectancy of success. No research has investigated the applicability of Weiner’s (1993) attributional model of helping behaviour to this group which gives a role to attributions of responsibility. Other research has found that self efficacy affects emotional response to challenging behaviour. The aim of the current research was to examine the relative applicability of these two theories to support workers regarding challenging behaviour using self efficacy as a measure of the expectancy of success. Method A total of 88 support workers completed measures addressing causal attributional dimensions, emotional reactions, attribution of responsibility, self efficacy and willingness to help in response to each of three vignettes regarding the challenging behaviours of aggression, self injury and destruction of property. Data was analysed using Spearman’s r correlations. Results None of the hypothesised significant correlations were found between measures of causal attributional dimensions and measures of responsibility or self efficacy. Attributing responsibility for the development of a challenging behaviour to the person engaging in it was significantly positively correlated with negative emotion. Self efficacy was significantly negatively correlated with negative emotion and significantly positively correlated with willingness to help. Emotional reaction was not significantly correlated with willingness to help. Conclusions The results provided little support for Weiner’s (1993) attributional theory of helping behaviour but provided more support for the expectancy of success aspect of Weiner’s (1986) theory and indicated that self efficacy is a useful measure of the expectancy of success. No firm conclusion could be drawn as to whether the failure to find significant correlations between causal attributions and other aspects of the theories was a genuine finding or due to the modified use of the Challenging Behaviour Attributions scale. It is concluded that a measure specifically designed for measuring causal attributional dimensions in this area is required. It is also concluded that low self efficacy may contribute to the development and maintenance of challenging behaviour via its impact on support workers’ intent to help. Efforts should therefore be made to raise support workers’ self efficacy by altering the perceived cause of challenging behaviour and highlighting to support workers the role of their level of effort, adherence to support plans and the role of any temporary external factors in the development and maintenance of challenging behaviour.
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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.
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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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Haglind, Daniel. "Coping with success and failure – Among Swedish and Portuguese track and field athletes and coaches." Thesis, Halmstad University, Halmstad University, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-122.
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The aim of this study was to examine how athletes and coaches, in Sweden and Portugal, perceive and experience success and failure in relation to sport. Moreover, study if there were cultural differences in coping. The main objectives of the study consisted of examining differences based on culture and coaches vs. athletes in the following research questions; how athletes and coaches define, react and cope with success and failure, how they perceive consequences and how coaches help athletes to cope with success and failure. Fifteen (n=15) individual semi structured interviews was carried out with ten (n=10) Swedish and five (n=5) Portuguese sportsmen. An interview guide based on the objectives of the study was developed. 1226 raw data units were identified and categorised using categorization, tagging and regrouping of relevant concepts. The results are discussed according to several stress-coping theories. Moreover, the result showed some differences based on both culture and on coaches vs. athletes. Furthermore success was mainly defined as reaching goals and failure as performance related mistakes. Reactions on both success and failure were mainly emotional. Negative consequences of both success and failure were most common and problem- focused coping were adopted to cope with those situations. The coaches supported the athletes by adopting emotion- and problem-focused coping.
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CAIX-HAUMESSER, SANDRINE. "Approche synthetique d'un aminocycloheptane trihydroxyle. Application de l'etape cle : reaction de cycloaddition dipolaire-1,3 sur support solide, nouvelle synthese de systemes tropaniques supportes sur resine." Paris 6, 2000. http://www.theses.fr/2000PA066087.
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Notre projet de recherche s'integre dans un projet plus vaste fonde sur la chimie combinatoire, dont le but est de trouver de nouvelles molecules biologiquement actives pour le domaine pharmaceutique. Notre objectif a terme est la synthese d'une librairie de composes presentant une structure aminocycloheptane polyfonctionnalisee. La strategie de synthese envisagee repose sur l'ouverture apres fonctionnalisation d'un systeme tropanique. L'interet d'un systeme bicyclique rigide reside dans la possibilite d'introduire stereoselectivement les differents groupes fonctionnels. Le tropane de depart est obtenu par reaction de cycloaddition dipolaire-1,3 entre la 3-hydroxypyridine et la phenylvinylsulfone (reaction de a. R. Katritzky). Dans un premier temps, la validite de cette strategie de synthese generale des aminocycloheptanes polyfonctionnalises est etudiee par la synthese en solution d'un aminocycloheptane trihydroxyle. A partir de l'enone resultant de la reaction de cycloaddition dipolaire-1,3, les trois fonctions hydroxyles sont introduites par reduction dans les conditions de luche puis osmylation catalytique de l'alcool allylique. Diverses strategies d'ouverture du pont azote sont explorees. Le cycloheptane desire est finalement obtenu par une reaction d'elimination grace a l'utilisation du bromure de methylmagnesium. Le but a terme etant de faire de la synthese combinatoire sur support solide, la reaction de cycloaddition dipolaire-1,3, etape cle, est testee en phase solide. La resine de wang conduit a une betaine supportee, ce qui permet l'introduction d'une grande diversite fonctionnelle par la simple variation de la nature du dipolarophile. L'enone est ensuite clivee, dans des conditions relativement douces, par divers chlorures d'acyle, ce qui introduit une deuxieme diversite tres interessante. Notre voie de synthese constitue une nouvelle approche de la synthese de systemes tropaniques hautement fonctionnalises supportes sur resine.
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Hantzer, Sylvain. "Nouveaux materiaux pour la reaction d'hydrodesulfuration (hds)." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13120.
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Nouveau modele de phase active obtenu par interpretation des resultats de rmn du **(59)co et de microscopie electronique haute resolution pour des catalyseurs d'hydrotraitement a base de sulfure de molybdene et de cobalt. Application a d'autres systemes : nire, core, rhre et rhmo. Etude de l'empoisonnement par la porphyrine de catalyseur nimo/al::(2)o::(3)
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Davies, Janet. "Changing your trainers? : is reaction evaluation used by Primary National Strategy consultants to support development of their training skills?" Thesis, Open University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437804.
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Twinley, Rebecca. "The perceived impacts of woman-to-woman rape and sexual assault, and the subsequent experience of disclosure, reaction, and support on victim/survivors' subjective experience of occupation." Thesis, University of Plymouth, 2016. http://hdl.handle.net/10026.1/6551.
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The traditional and universal assumption that rape and sexual assault are gendered in nature - perpetrated by men upon women in order to control, oppress, or subordinate them - has implications for victim/survivors of every other form of unwanted sexual contact and non-contact. The historical focus upon male-to-female rape has overlooked the fact that – regardless of gender – children and adults are sexually victimised by people of all ages and genders. In my thesis, I explore the experiences of a group of victim/survivors who national and international research, and anti-sexual-victimisation efforts, have essentially ignored: women who have been sexually victimised by another woman, or women. From my reading, my thesis constitutes the first documented primary research endeavour to create a methodology that combines an auto/biographical approach with an occupational science perspective. This supports my belief that I cannot divorce myself from any aspect of my research, whilst ensuring my perspective remained occupation-focused. I used a web-based survey to generate data regarding the experience and awareness of woman-to-woman rape and sexual assault amongst those members of the general public who responded. One-hundred and fifty-nine surveys were used for analysis. Twenty countries were recorded to describe the respondents’ nationalities, with the large majority from the United Kingdom (UK). Respondents who are victim/survivors of female-perpetrated rape and sexual assault totalled n=59 (37.3%). These are people who identified as a woman and were over 16 years old (the UK age of sexual consent) at the time of their victimisation. No respondents indicated they do not believe woman-to-woman rape and sexual assault is possible. Used as a sampling tool, survey respondents interested in sharing their story in more depth provided a contact email address. I interviewed 10 respondents face-to-face, in various UK locations. An eleventh respondent shared her story through correspondence with me. As intended, hearing and reading these stories enabled me to conduct a deep exploration of the respondents’ victimisations, and their subsequent experience of disclosure, reaction, and support. Four key themes emerged: Identity; Emotion; Survival; and Occupation. Specifically, the victim/survivors expressed the emotional and deleterious impacts which influenced their subjective experience of occupation. Hence, the daily activities, tasks, and things they need or want to do (occupation), that contribute to who they are, their sense of self, their relationship to others (identity), and their experience of health and wellbeing, was affected. Considered in the social and cultural context within which it occurs, my thesis contributes new and unique evidence regarding woman-to-woman rape and sexual assault; this has significance for relevant disciplines and service providers, including criminal justice, health, and sexual victimisation support services. Woman-to-woman rape and sexual assault is a complex form of sexual offending which has an equally complex impact upon victim/survivors; for my respondents, this has remained largely unaddressed and, for many, unresolved. I contend it is unacceptable to perceive rape and sexual assault as only committed by men against women; these are not solely gendered perpetrations and should not, therefore, be exclusively understood and addressed as gendered crimes.
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Hudgins, Kenna D. "The Effect of Music Therapy on the Grief Process and Group Cohesion of Grief Support Groups." Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1181099998.
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Daire, Fabrice. "Etude d'electrodes modifiees par fixation de composes de coordination sur un support conducteur du type polypyrrole : application en electrosynthese organique." Paris 6, 1988. http://www.theses.fr/1988PA066176.
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Proprietes electrochimiques des complexes co-l, cu-l, ni-l (ou l=methyl-4, bipyridine-2,2', derive du pyrrole) dans l'acetonitrile. Polymerisation electrolytique de ces complexes sur des electrodes d'or, platine et carbone. Proprietes electrochimiques du polymere co-bipyridyl-polypyrrole; utilisation dans la reduction catalytique des derives allyliques
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Fodor, Anna. "Heterogeneous metal-catalysed C-C coupling reactions : research and development." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2256/document.
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Des nouveaux catalyseurs bimétalliques à base de palladium et de cuivre ont été développés. Deux voies de préparation ont été testées : l'imprégnation successive (TSI) et la co-imprégnation (CI) en utilisant la zéolithe 4Å (4A) et l'oxyde mixte MgAlxOy comme support. Les catalyseurs ont été caractérisés à l'état frais et testés dans la réaction de couplage Suzuki–Miyaura afin de comparer leurs activités, sélectivités et stabilités. L'étude de stabilité nous a montré que le catalyseur Cu-Pd-4A-TSI restait actif pendant six cycles alors que l'activité du catalyseur Cu-Pd-4A-CI diminuait. Sur le support MgAlxOy, le catalyseur CI était stable pendant six cycles contrairement au catalyseur TSI. Nous avons montré que le point clé pour l'obtention d'une bonne activité et stabilité est la présence de la phase active correspondant à l'alliage Cu/Pd 1/1 identifiée grâce à la caractérisation des catalyseurs et ce quelle que soit la méthode de préparation des catalyseurs. Une différence cruciale existe entre les catalyseurs supportés sur MgAlxOy et 4A : le catalyseur Cu–Pd supporté sur MgAlxOy permet de réduire le temps de réaction de moitié pour une même conversion par rapport à Cu-Pd-4A-TSI. De plus, l'utilisation d'un support plus basique permet, dans une certaine mesure, la diminution de la quantité de la base ajoutée durant la réaction. La réaction Petasis-borono Mannich a été aussi effectuée avec succès sur ces catalyseursNew bimetallic palladium/copper catalysts were developed by successive impregnation (TSI) and co-impregnation (CI) on 4Å molecular sieve (4A) and MgAlO mixed oxides supports. The fresh catalysts were characterised and tested in the Suzuki–Miyaura reaction to test their activity, selectivity and stability. It was observed that while the Cu-Pd-4A-TSI catalyst kept its activity during six cycles that of the Cu-Pd-4A-CI dropped. On MgAlO support the catalyst prepared with CI proved to be stable even for six runs contrary to TSI. The active phase of the reaction – namely the Cu–Pd alloy with atomic ratio 1:1 - was determined with the help of catalyst characterisation of the recovered catalysts. This observation confirms that whatever the way of preparation or the support is, the key-point is the presence of Pd-Cu 1:1 particles to enhance the catalytic performances. A crucial difference between the MgAlO and 4A supported catalyst was found in the reaction time necessary for the Suzuki–Miyaura reaction. With the Cu-Pd-MgAl-CI catalyst the reaction time could be reduced to thirty minutes contrary to one hour with Cu-Pd-4A-TSI. Moreover it was concluded that with a more basic support the reduction of the quantity of the base was possible however it brought slightly decreasing yield. The Petasis-borono Mannich reaction was also performed in the presence of each mono-and bimetallic catalysts
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Reocreux, Romain. "Biomass derivatives in heterogeneous catalysis : adsorption, reactivity and support from first principles." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN019/document.
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L’abandon progressif des ressources fossiles s’accompagne de l’exploitation croissante de la biomasse. Cette transition nécessite de développer de nouveaux procédés notamment en catalyse hétérogène. Les chimistes se heurtent alors à deux défis majeurs : (i) désoxygéner la biomasse (cellulose/lignine) pour revenir à la chimie maîtrisée des grands intermédiaires (ii) rendre les catalyseurs résistants à l’eau, omniprésente en biomasse. En collaboration avec des expérimentateurs de l’Université d’Ottawa, nous nous sommes d’abord intéressés à la désoxygénation d’aromatiques de type lignine. Les calculs ab initio (DFT) nous ont permis de dresser les caractéristiques d’adsorption de ces composés sur Pt(111) en termes de descripteurs moléculaires simples. Nous avons ensuite étudié le mécanisme de décomposition de l’anisole et du 2-phénoxyéthanol, molécules modèles. Nos études ont montré l’importance de l’hydrogène et des fragments carbonés sur la réaction de désoxygéna6on de ces composés. En parallèle nous nous sommes intéressés à la stabilité, dans l’eau, d’un des supports catalytiques majeurs : l’alumine-γ. Ce sujet clé pose des défis considérables en modélisation, puisqu’il nécessite d’utiliser des méthodes de dynamiques moléculaires ab initio. Celles-ci nous ont permis de caractériser la structuration de l’eau au contact de l’alumine et l’importance de la solvatation sur les aluminols de surface. À l’aide de méthodes d’événements rares (dynamique contrainte, métadynamique) nous avons enfin abordé la réactivité d’alcools et de l’eau avec l’alumine hydratée. Ces simulations ont permis d’identifier les premières étapes d’hydratation et de mieux comprendre comment les limiterMoving away from fossil ressources is currently being accompanied by the increasing exploitation of biomass.This shift requires the development of new processes, in particular in heterogeneous catalysis. Chemists are nowfacing two major challenges: (i) deoxygenate biomass (cellulose/lignin) to produce platform intermediates with aeel-known chemistry (ii) make catalysts resistant to water, ubiquitous within the context of biomass.Within a collaboration with experimentalists at the University of Ottawa, we have first studied the deoxygenationof lignin-like aromatics. From an ab initio (DFT) inspection, we have characterized and described the adsorptionof such aromatic oxygenates on Pt(111) with simple molecular descriptors. We have then investigated thedecomposition mechanism of anisole and 2-phenoxyethanol. For these two model compounds, we have showedthe significance of hydrogen and carbonaceous species to have the deoxygenation reaction proceed properly.Meanwhile, we have examined the stability, in water, of γ-alumina, a major support in heterogeneous catalysis.The necessity to perform ab initio molecular dynamics simulations makes the modeling of such a systemparticularly challenging computationally. The simulations have nevertheless enabled us to characterize thestructuration of liquid water in contact with alumina and the significance of solvation on surface aluminol groups.Using rare-event methods (constrained dynamics, metadynamics) we have eventually been able to probe thereactivity of alcohols and water with hydrated alumina. We have then identified the first steps of hydration andgained insights on how to limit them
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Pochet, Sylvie. "Synthèse d'oligodésoxynucléotides comportant des sites ambigus ou apuriniques et de sondes ancrées à un support solide." Paris 6, 1986. http://www.theses.fr/1986PA066065.
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Synthèse et étude par spectroscopies RMN, IR et DC d'oligodésoxyribonucléotides contenant un résidu sans base: coexistence des conformations b et z sur un même duplex. Elaboration d'une base universelle dans la série des nucléosides pyrimidiques. Synthèse d'oligodésoxynucléotides ancrés à un support solide; applications.
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Cassidy, Timothy John. "Pulsed reaction studies of simple reactions on alumina supported rhodium." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241471.
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LAMOUROUX, DOMINIQUE. "Construction et criblage par expression d'une banque d'adn complementaire de leishmania infantum : isolement de sequences codant pour des peptides support de la reaction immune de l'hote." Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX20902.
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Lakhdar, Mahjoub. "Application de la reaction d'hydrodesazotation de la pyridine a la caracterisation de l'activite et de la selectivite de catalyseurs sulfures." Caen, 1987. http://www.theses.fr/1987CAEN2021.
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Töyrä, Emilia. "Anestesisjuksköterskors upplevelser efter en kritisk händelse i samband med anestesi." Thesis, Luleå tekniska universitet, Omvårdnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74353.
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Anestesisjuksköterskan möter i sitt arbete på kritiska händelser vilket för anestesisjuksköterskan kan leda till fysiska och psykiska yttringar vilka i sig kan leda till att de inte kan prestera normalt vilket påverkar patientvården. Forskning inom detta är framförallt internationell och mot bakgrund av detta behövs även forskning inom detta område även i Sverige. Syfte med studien var att undersöka anestesisjuksköterskors upplevelser efter en kritisk händelse i samband med anestesi. Studien är av kvalitativ design. Datainsamlingen genomfördes med hjälp av sex semistrukturerade intervjuer. Vid analys av data användes kvalitativ innehållsanalys vilket resulterade i tre kategorier; Känslomässig reaktion som anestesisjuksköterska; Behov av stöd; Anestesisjuksköterskans arbete förändrades. En slutsats kan utifrån studien dras att anestesisjuksköterskan i sitt arbete möter på händelser som framkallar känslomässig rektion och att anestesisjuksköterskan har ett behov av stöd. Händelsen påverkar anestesisjuksköterskans arbete och stödet är av vikt både för anestesisjuksköterskans hälsa och för fortsatt omvårdnadsarbete.
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Soutif, Jean-Claude. "Etude de l'addition des acides carboxyliques sur les structures oxiranne : application aux polymeres epoxydes." Le Mans, 1987. http://www.theses.fr/1987LEMA1010.
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La modification chimique au deuxieme degre de polymeres epoxydes a ete etudiee pour developper une methode de fixation de principes actifs (medicaments, colorants, complexants) comportant des fonctions acides, sur des supports macromoleculaires. Le catalyseur est un sel de tetramethylammonium de l'acide a fixer. Epoxydation de polyisoprene et polybutadiene
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Sommer, William J. "Supported catalysts, from polymers to gold nanoparticles supports." Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-07062007-225935/.
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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008.Christoph J. Fahrni, Committee Member ; Mostapha A. El-Sayed, Committee Member ; Christopher W. Jones, Committee Member ; Marcus Weck, Committee Chair ; E. Kent Barefield, Committee Member.
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Lin, Liming. "Craquages d'alcanes sur catalyseurs zeolithiques : influence du nickel et du vanadium." Poitiers, 1987. http://www.theses.fr/1987POIT2316.
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Bach, Delpeuch Antoine. "Etude du mécanisme de la réaction d'oxydation de l'éthanol sur électrocatalyseurs à base de Pt, Rh, SnO2 sur support carboné en milieu acide." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI089/document.
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L'étude du mécanisme de la réaction d'oxydation de l'éthanol (EOR) a été réalisée sur des électrocatalyseurs bi- et tri-métalliques à base de Pt, Rh et SnO2 sur support carboné à l'aide de méthodes électrochimiques couplées (DEMS, in situ FTIR). Deux importantes problématiques de l'EOR ont été abordées: la déshydrogénation de la molécule d'éthanol et la cassure de sa liaison C-C.L'investigation de certains paramètres expérimentaux, comme l'épaisseur de la couche d'électrocatalyseur, a permis de démontrer q'une couche active épaisse conduit à une meilleure électrooxydation plus complète de l'éthanol en CO2, mais également que l'empoisonnement de l'électrocatalyseur par de très forts adsorbats advient dans l'épaisseur de couche active.Les performances de chaque électrocatalyseur ont été comparées entre elles et ont mis en évidence une meilleure sélectivité de l'EOR sur Pt-Rh-SnO2/C, ainsi que l'engendrement de courants plus élevés à bas potentiel à température ambiante. La tendance est amplifiée à température plus élevée (T = 60 °C)The study of the ethanol oxidation reaction (EOR) mechanism was performed on carbon supported bi- and tri-metallic Pt-, Rh-, SnO2-based electrocatalysts via electrochemical coupled techniques (DEMS, in situ FTIR). Two of the most important issues related to the EOR have been broached: the dehydrogenation of the ethanol molecule and its C-C bond breaking.The investigation of some experimental parameters, such as the thickness of the electrocatalyst layer, enabled demonstrating the better complete ethanol electrooxidation into CO2 for large electrocatalysts layers, combined to the enhanced poisoning effect inside the catalyst layer by very strong adsorbates.The performances of each electrocatalyst were compared and evidenced an improved selectivity of the EOR on Pt-Rh-SnO2/C, as well as the generation of higher currents at low potential at room temperature. The tendency was amplified at elevated temperatures (T = 60 °C)
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Brown, Ronald. "A study of hydrocarbon reactions over supported metal catalysts : support and metal dependence." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/13013.
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Chauvin, Camille. "Caracterisation d'oxydes de zinc et de catalyseurs de synthese du methanol cu-znal::(2)o::(4) : etude par spectroscopie infrarouge des sites d'adsorption et des mecanismes reactionnels." Caen, 1987. http://www.theses.fr/1987CAEN2017.
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Dunand-Sauthier, Marie-Noe͏̈lle. "Propriétés électrochimiques et photochimiques de complexes mono(2,2'-bipyridine) carbonyle de ruthénium (II) : applications à la réduction électrocatalytique du CO2 et à la photoimagerie." Grenoble 1, 1993. http://www.theses.fr/1993GRE10105.
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Ce memoire est consacre a l'etude des proprietes electrochimiques, photochimiques et aux applications dans le domaine de la photoimagerie et de la reduction electrocatalytique du dioxyde de carbone d'une serie de complexes monobipyridine carbonyle de ruthenium en phase homogene ou immobilises a la surface d'une electrode sous forme de films polymeriques. Nous avons tout d'abord demontre que le complexe considere dans la litterature comme etant cisru(bpy)(co)#2cl#2 (bpy=2,2-bipyridine) est en realite constitue d'un melange de ru(bpy)(co)#2cl#2 et de ru(bpy)(co)cl#3, ce dernier a pu etre isole sous sa forme reduite par une methode electrochimique originale. L'etude electrochimique detaillee de ces complexes a ete realisee et il a ete montre que l'electroreduction de certains de ces complexes permet de preparer un nouveau type d'electrodes modifiees par des polymeres inorganiques (appeles film bleu: fb). Ce travail s'est poursuivi par la mise en evidence de phenomenes de substitution de ligands par des molecules de solvant lorsque ces complexes sont irradies par la lumiere visible. Lorsque ces complexes sont immobilises a la surface d'une electrode par l'intermediaire de films polypyrroliques fonctionnalises, leurs proprietes photochimiques sont conservees et ces phenomenes ont permis l'utilisation de ces films en photoimagerie. Enfin, ces films (fb et polypyrroliques) se sont averes etre d'excellentes cathodes moleculaires pour la reduction electrocatalytique du co#2, avec la formation quasi quantitative de co meme dans des electrolytes purement aqueux
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Peyrovi, Mohammad-Hassan. "Etude de la destruction du coke et de ses précurseurs en presence d'hydrogène sur catalyseurs à base de platine." Poitiers, 1987. http://www.theses.fr/1987POIT2038.
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L'etude de la reaction et de la cinetique de decomposition du coke est realisee sur des catalyseurs bifonctionnels. L'influence de l'aire metallique ou d'addition de rhenium ou d'iridium sur la reaction de cokage est determinee. La formation, uniquement de methane, montre que l'elimination des precurseurs de coke est le resultat de l'hydrogenolyse
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Tchangai, Tchaa. "Caracterisation electrique des films de polyamide-imide et de leurs interfaces avec un substrat semiconducteur." Toulouse 3, 1988. http://www.theses.fr/1988TOU30101.
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Preparation de couches minces par pelliculage sur substrat de verre metallique ou semiconducteur. L'adherence se fait par des liaisons chimiques; les films resistent a la gravure par plasma fluore. Mecanisme de la conduction electrique
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Brinkley, Kendra W. "The Synthesis of Solid Supported Palladium Nanoparticles: Effective Catalysts for Batch and Continuous Cross Coupling Reactions." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3959.
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Catalysis is one of the pillars of the chemical industry. While the use of catalyst is typically recognized in the automobile industry, their impact is more widespread as; catalysts are used in the synthesis of 80% of the US commercial chemicals. Despite the improved selectivity provided by catalyst, process inefficiencies still threaten the sustainability of a number of synthesis methods, especially in the pharmaceutical industry. Recyclable solid supported catalysts offer a unique opportunity to address these inefficiencies. Such systems coupled with continuous synthesis techniques, have the potential to significantly reduce the waste to desired product ratio (E-factor) of the production techniques. This research focuses developing sustainable processes to synthesize organic molecules by using continuous synthesis methods. In doing so, solid supported metal catalyst systems were identified, developed, and implemented to assist in the formation of carbon-carbon bonds. Newly developed systems, which utilized metal nanoparticles, showed reactivity and recyclability, comparable to commercially available catalyst.
Nanoparticles are emerging as useful materials in a wide variety of applications including catalysis. These applications include pharmaceutical processes by which complex and useful organic molecules can be prepared. As such, an effective and scalable synthesis method is required for the preparation of nanoparticle catalysts with significant control of the particle size, uniform dispersion, and even distribution of nanoparticles when deposited on the surface of a solid support. This project describes the production of palladium nanoparticles on a variety of solid supports and the evaluation of these nanoparticles for cross coupling reactions.
This report highlights novel synthesis techniques used in the formation of palladium nanoparticles using traditional batch reactions. The procedures developed for the batch formation of palladium nanoparticles on different solid supports, such as graphene and carbon nanotubes, are initially described. The major drawbacks of these methods are discussed, including limited scalability, variation of nanoparticle characteristics from batch to batch, and technical challenges associated with efficient heating of samples.
Furthermore, the necessary conditions and critical parameters to convert the batch synthesis of solid supported palladium nanoparticles to a continuous flow process are presented. This strategy not only alleviates the challenges associated with the robust preparation of the material and the limitations of scalability, but also showcases a new continuous reactor capable of efficient and direct heating of the reaction mixture under microwave irradiation. This strategy was further used in the synthesis of zinc oxide nanoparticles. Particles synthesized using this strategy as well as traditional synthesis methods, were evaluated in the context industrially relevant applications.
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Ackerman, M. C. (Marthinus Casper). "Kernel support for embedded reactive systems." Thesis, Stellenbosch : Stellenbosch University, 1993. http://hdl.handle.net/10019.1/58022.
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Thesis (MSc)--Stellenbosch University , 1993.ENGLISH ABSTRACT: Reactive systems are event driven state machines which usually do not terminate, but remain in perpetual interaction with their environment. Such systems usually interact 'With devices which introduce a high degree of concurrency and some real time constraints to the system. Because of the concurrent nature of reactive systems they are commonly implemented as communicating concurrent processes on one or more processors. Jeffay introduces a design paradigm which requires consumer processes to consume messages faster than they are produced by producer processes. If this is guaranteed, the real time constraints of such .. system are always met, and the correctness of the process interaction is guaranteed in terms of the message passing semantics. I developed the ESE kernel, which supports Jeffay systems by providing lightweight processes which communicate over asynchronous channels. Processes are scheduled non-preemptively according to the earliest deadline first policy when they have messages pending on their input channels. The Jeffay design method and the ESE kernel have been found to be highly suitable to implement embedded reactive systems. The general requirements of embedded reactive systems, and kernel support required by such systems, are discussed.
AFRIKAANSE OPSOMMING: Reaktiewe stelsels is toeatandsoutomate wat aangedryf word deur gebeure in hul omgewins. So 'n stelsel termineer gewoonlik nie, maar bly in 'n voortdurende wisselwerking met toestelle in sy omgewing. Toestelle in die omgewing van 'n reaktiewe stelsel veroorsaak in die algemeen 'n hoë mate van gelyklopendheid in die stelsel, en plaas gewoonlik sekere intydse beperkings op die stelsel. Gelyklopende stelsels word gewoonlik as stelsel. van kommunikerende prosesse geïmplementeer op een of meer prosessors. Jeffay beskryf 'n ontwerpsmetodologie waarvolgens die ontvanger van boodskappe hulle vinniger moet verwerk as wat die sender hulle kan stuur. Indien hierdie gedrag tussen alle pare kommunikerende prosesse gewaarborg kan word, sal die stelsel altyd sy intydse beperkings gehoorsaam, en word die korrektheid van interaksies tussen prosesse deur die semantiek van die boodskapwisseling gewaarborg. Die "ESE" bedryfstelselkern wat ek ontwikkel het, ondersteun stelsels wat ontwerp en geïmplementeer word volgens Jeffay se metode. Prosesse kommunikeer oor asinkrone kanale, en die ontvanger van die boodskap met die vroegste keertyd word altyd eerste geskeduleer. Jeffay se ontwerpsmetode en die "ESE" kern blyk in die praktyk baie geskik te wees vir reaktiewe stelsels wat as substelsels van groter stelsels uitvoer. Die vereistes van reaktiewe substelsels, en die kemondersteuning wat daarvoor nodig is, word bespreek.
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Cadieu, Marie-Claude. "Reactions de contact des octanes sur des catalyseurs a base de platine et de palladium." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13023.
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Etude des differences de comportements catalytiques entre des catalyseurs supportes pt et pd a partir d'un nouveau type d'hydrocarbure test: les octanes. Mecanisme de cyclisation et d'isomerisation des aliphatiques et d'hydrogenolyse des cyclopentanes
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Haidar, Fatima. "Nanostructures 2D et supports d’oxydes métalliques pour des cathodes de piles à combustible à faible teneur en platine." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS121.
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Les piles à combustible à membrane échangeuse de protons sont des dispositifs de conversion de l’énergie propre et efficace. Les gammes de puissance accessibles permettent leur utilisation dans le domaine de transport et des applications stationnaires. Il existe deux verrous technologiques à lever pour le déploiement de la cathode:i) Diminution de la quantité de platine dans le catalyseur.ii) l'amélioration de la stabilité du support de catalyseur à haut potentiel. Dans ce travail, nous présentons deux stratégies qui permettent de faire face à ces problématiques et améliorer les performances et la durabilité des cathodes: développer de nouveaux électrocatalyseurs à très faible quantité de platine et des supports à base de matériaux résistants à la corrosion.Afin de réduire la quantité de platine dans le catalyseur, nous avons développé des nanostructures fines de platine, qui permettent une exploitation électrocatalytique maximale et une quantité minimale de métal noble. Pour atteindre cet objectif, nous avons utilisé une méthode électrochimique basée sur le dépôt sous potentiel et le déplacement galvanique. Les nanostructures fines déposées sur le substrat modèle ont été caractérisées électrochimiquement ainsi que par des techniques microscopiques et d'analyse élémentaire.Pour réaliser un support résistant à la corrosion, notre approche a consisté en le remplacement du carbone noir conventionnel par un matériau conducteur d’oxyde d'étain dopé. Les matériaux à base de SnO2 ont démontré leur efficacité comme support électrochimique stable mais également efficace pour la réaction de réduction de l'oxygène. Dans cette étude, l’oxyde d’étain dopé au tantale a été préparé par électrofilage suivi d'une étape de calcination, permettent ainsi d’obtenir des fibres de morphologie tubulaires. Ces fibres ont été utilisées comme support de nanoparticules de platine préparées par la méthode de polyol assistée par micro-ondes, puis caractérisées pour leurs propriétés physico-chimiques et électrocatalytiques. En particulier, la stabilité aux cyclage en potentiel a été évaluée par analyse électrochimique ex situ. La possibilité d’associer l'électrocatalyseur à surface étendue avec les supports résistants à la corrosion pour obtenir des cathodes actives et durables est en coursProton exchange membrane fuel cells are clean and efficient energy converters. Their accessible power ranges allow their use in the field of transport or stationary applications. Two main challenges concern the cathode deployment:i) The reduction of the amount of low abundant platinum group metal in the catalyst.ii) The enhancement of stability of the catalyst support at high voltage.In this work we present two strategies to address these challenges and improve performance and durability of the cathodes: developing novel ultra-low loaded platinum electrocatalysts and corrosion resistant support materials.To reduce noble metal amount in the catalyst, we developed platinum thin films, which allow maximal electrocatalytic exploitation thus minimal loading. For that, we have used electrochemical methods based on under-potential deposition and galvanic displacement. The thin structures deposited on model substrates were characterized by electrochemical, elemental analysis and microscopy techniques.To prepare corrosion resistant supports, our strategy was the replacement of conventional carbon black with a doped conducting tin oxide. SnO2-based materials have been demonstrated as electrochemical stable supports also promoting platinum activity for the oxygen reduction reaction. In this work, tantalum-doped tin oxide was prepared by electrospinning followed by calcination, leading to a fiber-in-tube morphology. This support was catalyzed with platinum nanoparticles prepared by a microwave-assisted polyol method, and characterized for their physico-chemical and electrocatalytic properties. In particular, stability to voltage cycling was evaluated by ex situ electrochemical analysis.The possibility to associate the extended surface electrocatalyst with the corrosion resistant supports to obtain active and durable cathodes is in progress
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Martinez, Hugo. "Influence des proprietes acido-basiques du couple support-reactif lors du cokage des catalyseurs metalliques supportes." Poitiers, 1988. http://www.theses.fr/1988POIT2320.
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Comparaison des depots de colce obtenus a partir de l'anthracene et du phenanthrene sur des catalyseurs d'acidites variables. Augmentation de la quantite de colce en presence du platine. L'effet de l'addition de chlore a l'alumine depend de la temperature
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Ferhat-Hamida, Zohra. "Caractérisation des catalyseurs cuivre-zinc par thermodésorption d'hydrogène et thermoréaction." Poitiers, 1987. http://www.theses.fr/1987POIT2011.
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Molina, Stéphane. "Homologation du méthane par chimisorption sur surfaces métalliques et hydrogénation ultérieure." Nancy 1, 1994. http://www.theses.fr/1994NAN10428.
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La chimisorption dissociative du méthane a été étudiée entre la température ambiante et 275c sur des catalyseurs de rhodium et de nickel supportes. L'hydrogénation ulterieure de la couche adsorbée libère des alcanes pouvant compter jusqu'à 9 atomes de carbone. Ces résultats permettent d'étendre au rhodium et au nickel la méthode cyclique d'oligomérisation du méthane précédemment développée pour le platine et le ruthénium et consistant en expositions successives au méthane et à l'hydrogène. Lorsque cette procédure en deux étapes est ditherme, il apparait pour les deux métaux une sélectivité remarquable en faveur du cyclohexane. Des expériences de déplacement des espèces adsorbées par le monoxyde de carbone montrent que, dans l'un et l'autre cas, le précurseur du cyclohexane est le benzène adsorbé. L'adjonction de cuivre au nickel permet de ralentir l'hydrogénolyse dans la seconde étape et l'utilisation de catalyseurs bimétalliques ouvre de nouvelles perspectives à la procédure cyclique d'homologation du méthane, plus particulièrement si l'on vise la production d'hydrocarbures de rang supérieur aux butanes
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Kui, Tony. "Liquides ioniques dérivés de l'histidine comme organocatalyseurs chiraux pour la réaction d'aldolisation croisée." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30087.
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Un des aspects les plus attractifs de l'organocatalyse énantiosélective est la relative simplicité et disponibilité des espèces catalytiques. Les catalyseurs dérivés d'acides aminés ou de peptides occupent une place centrale liée à leur efficacité dans de nombreuses réactions. De plus, ces catalyseurs sont généralement faciles d'accès et s'avèrent particulièrement intéressants du fait de leur modularité. Quelques limitations demeurent néanmoins, telles que des taux catalytiques souvent élevés et un recyclage souvent difficile. L'utilisation d'un support soluble permettrait de pallier ces difficultés en facilitant le recyclage du catalyseur tout en conservant son énantiosélectivité. Nous nous sommes donc intéressés à l'élaboration de nouveaux di- et tripeptides incorporant un acide aminé porteur d'un groupe imidazolium dérivé de l'histidine, précédemment mis au point au laboratoire, et à leur exploitation en catalyse énantiosélective. La partie ionique jouera le rôle de support soluble, et sera immobilisée dans un solvant ionique afin de faciliter le recyclage du catalyseur. La première partie de ma thèse a consisté en l'élaboration de petits peptides supportés sur le support ionique dérivés de l'histidine. La formation de dérivés di- ou tripeptides supportés a été réalisé sur la position N-terminale de la plateforme histidinium en employant une méthode de couplage peptidique classique. Nous avons ainsi synthétisé deux dipeptides, comportant en position N-terminale soit la proline, largement employé en organocatalyse, soit l'alanine permettant d'avoir un site catalytique comportant une amine primaire et un tripeptide comportant également en position N-terminale, la proline liée avec un acide aminé non chiral, la glycine, comme espaceur. La deuxième partie de cette étude est consacrée à l'évaluation des espèces catalytiques synthétisées dans une réaction modèle : la réaction d'aldolisation croisée énantiosélective. Les deux dipeptides, comportant en position C-terminale un acide carboxylique libre, se sont avérées particulièrement intéressants. L'étude de la réactivité de ces deux dipeptides a été réalisée dans des solvants organiques usuels et dans des liquides ioniques où ces catalyseurs se sont révélés plus efficaces que dans les solvants organiques. Les meilleurs résultats ont été obtenus avec le dérivé dipeptide contenant la proline. La mise au point du recyclage du catalyseur supporté a été réalisée grâce à l'utilisation d'un solvant non miscible avec le milieu réactionnel permettant l'extraction facile du produit de la réaction et le recyclage de l'ensemble solvant ionique / catalyseur supportéOne of the most attractive aspect of the enantioselective organocatalysis is the simplicity and availability of catalytic species. Catalysts derived from amino acids or peptides take up a central place due to their efficiency in several reactions. Moreover, these catalysts are in general easy to obtain and their modularity make them particularly interesting. Nevertheless, there are some limitations like quite high catalytic rate and difficult recycling. The use of a soluble support would allow to overcome these complications by helping the recycling of the catalyst along while retaining its enantioselectivity. Therefore, we are interested in the synthesis of new di- and tripeptides, containing an amino acid which carries a histidine derived imidazolium group, previously developed by our laboratory and in their utilization in enantioselective catalysis. The ionic part will act as soluble support and will be immobilized in an ionic solvent to simplify the recycling of the catalyst. The first part of my thesis consists of the synthesis of small peptides on an ionic support derived from histidine. The formation of supported di- or tripeptides derivatives has been realized on the N- terminal position of the histidinium platform by using a classic peptidic coupling method. Thereby, we have synthesized two dipeptides bearing in the N-terminal position either the proline, largely used in organocatalysis, either the alanine to have a catalytic site which carries a primary amine, and a tripeptide which is consisted in the N-terminal position of proline bound to a achiral amino acid, glycine as a linker. The second part of this study is focused on the evaluation of the synthesized catalytic species with a model reaction: the enantioselective cross-aldol reaction. The two dipeptides bearing in the C- terminal position a free carboxylic acid turned out to be particularly interesting. The study of the reactivity of these two dipeptides has been realized in common organic solvents and in ionic liquids where these catalysts proved to be more efficient than in the organic solvents. The best results have been obtained with the dipeptide derivative containing proline. The development of the recycling of the supported catalyst has been carried out thanks to the use of a solvent non-miscible with the reaction medium allowing an easy extraction of the product of the reaction and the recycling of the whole of ionic solvent and supported catalyst
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Anadani, Mohamed. "Decision support systems for nuclear reactor control." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341828.
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Eiriksson, Eysteinn. "Distribution grid capacity for reactive power support." Thesis, KTH, Elkraftteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-221829.
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The modern power system is changing at a rate faster than would have been expected20 years ago. More and more conventional power plants will be shut down in favour ofdistribution generation (DG). This is happening now with the trend of introducing renewableenergy sources (RES) to the power system.The grids were designed to transfer power from generating units connected to the highvoltage grids towards the end consumers connected to the low voltage grids. With changedpower mix, power flows in the system will change resulting in possible grid problems. Oneof the main problems is keeping the voltage within operational limits of the system. Whenthe generation exceeds the consumption in a distribution network, the power will flow fromthe low voltage network towards the high voltage network (reverse power flow) which willcause the voltage to rise in the low voltage network. Reactive power support from DG canbe a valuable resource to mitigate the problem. Reactive power is necessary to operatethe power system. The main source of reactive power is synchronous generators. If thissource is shut down, the reactive power must come from another source.This thesis investigates if DG could be used to support reactive power to the highvoltage transmission network to control the voltage. For this purpose, a distributionsystem located close toWorms, Germany will be studied. This distribution system consistsof two MV feeders with high penetration of DG, mostly photovoltaic (PV) but also windturbines (WT). Consumption and generation measurement data was provided by the localdistribution system operator (DSO). A few reactive power control methods are introducedand tested on this system. From the results, it is concluded that it is possible to providereactive power support from distribution networks and a voltage dependent reactive powercontrol can be used to this purpose.Det moderna kraftsystemet förandras snabbara än vad som hade förväntats för 20 årsedan. Fler och fler konventionella kraftverk kommer att stängas till fördel för distributionsgenering.Detta händer nu med trenden att introducera förnybara energikällor tillkraftsystemet.Nätverket utformades för att överföra kraft från generatorer som är anslutna till högspänningsnätetmot konsumenter anslutna till lågspänningsnätet. Med ändrad kraftblandningkommer strömflödena i systemet att förändras vilket resulterar i eventuella nätproblem.Ett av huvudproblemen är att hålla spänningen inom operativa gränser för systemet.När generationen överstiger förbrukningen i ett distributionsnät, kommer strömmen attströmma från lågspänningsnätet till högspänningsnätet vilket kommer att leda till attspänningen stiger i lågspänningsnätet. Reaktivt kraftstöd från distributionsgenering kanvara en värdefull resurs för att mildra problemet. Reaktiv effekt är nödvändig för att drivaelsystemet. Huvudkällan för reaktiv kraft är synkrona generatorer. Om den här källanstängs av måste den reaktiva effekten komma från en annan källa.Denna avhandling undersöker om distributionsgenering skulle kunna användas för attstödja reaktiv kraft till högspänningsöverföringsnätet för att styra spänningen. För dettaändamål studeras ett distributionssystem som ligger nära Worms, Tyskland. Detta distributionssystembestår av två MV-matare med med mycket distributionsgenerering, främstsolceller men även vindturbiner. Förbruknings- och generationsmätningsdata tillhandahöllsav den lokala distributionssystemoperatören. Några reaktiva effektstyrningsmetoderintroduceras och testas på detta system. Av resultaten dras slutsatsen att detär möjligt att tillhandahålla reaktivt kraftstöd från distributionsnät och en spänningsberoendereaktiv effektstyrning kan användas för detta ändamål.
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Piper, Lynn J. "Stressors, Social Support, and Stress Reactions: A Meta-Analysis." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5349/.
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This study examined, via a meta-analysis, the relations among stressors, social support, and stress reactions. Unexpectedly, small to medium negative, but robust effect sizes were found for the stressors-social support relation. As expected the stressor-stress reaction relation was positive, and the social support-stress reaction relation was negative. Both relations had small to medium effect sizes that ranged from weak to very robust. The direct effect of social support on the stressor-stress reaction was generally supported, whereas the suppressor and mediating models were not supported. Furthermore, the findings were inconclusive for the moderator effect of social support. Non-interpersonal traumas appear different in the stressor-social support and social support-stress reaction relations compared to other trauma types. These findings have important clinical implications.
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Davies, Cait Marie. "Supported ionic liquids as catalytic reaction media." Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427038.
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Aldosari, Obaid. "Hydrogenation reaction using supported palladium nano-particles." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/67364/.
Full textAbstract:
Hydrogenation is one of the major processes used in commercial and academic applications in the manufacture of chemical intermediates; high tonnage products of high value, and useful chemicals, such as agrochemicals and pharmaceuticals. Free solvent hydrogenation of cyclohexanol using Au, Au:Pd and Pd/CsxH0.5PW12O40 catalysts have been performed in the liquid phase. Reaction conditions, for example supports with/without Cs-salt loading, metal loading and/or ratio were varied to achieve ideal conditions. The Palladium supported on Cs2.5H0.5PW12O40 is a successful catalyst for such hydrogenation, and Cs2.5H0.5PW12O40 has been shown to be the best of the supports investigated for the preparation of catalysts using the impregnation method. Pd, Au and Au:Pd catalysts supported on TiO2 have been used for the hydrogenation of furfuryl alcohol and furfural with H2 at room temperature. The influence of the pressure, catalyst mass, support, Au:Pd variation, Pd loading and solvent have been investigated. In addition, Ru and Ru:Pd was studied with furfural, and also the effect of Ru:Pd ratios. The selective hydrogenation of both Furfuryl alcohol and Furfural into 2-methylfuran was investigated at room temperature using Palladium supported catalysts. This study has shown that Pd/TiO2 catalysts can be very effective for the synthesis of 2-methylfuran at room temperature and low pressure hydrogen (1-3 bar). The effect of various reaction conditions (pressure, catalyst amount, and solvent) has been studied. Controlling the catalyst composition can control the selectivity to molecules with multiple functioning groups, and reaction conditions can promote or hinder the various reaction pathways, thus increasing selectivity to the desired hydrogenation yields.
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Batista, Alvarez Maria Fernanda. "Hydroisomérisation et hydrocraquage de n-alcanes sur catalyseurs platine-zeolithe ushy et platine h-offretite." Poitiers, 1987. http://www.theses.fr/1987POIT2271.
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Zyade, Souâd. "Contribution a l'etude des mecanismes de reactions des hydrocarbures sur catalyseurs mono et bimetalliques (pt et pt::(x)co::(1-x)) : correlation avec des taux en residus hydrocarbones et les structures metalliques de surface." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13034.
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Boopalachandran, Praveenkumar. "Catalytic studies of supported Pd-Au catalysts." Texas A&M University, 2006. http://hdl.handle.net/1969.1/3826.
Full textAbstract:
Although Pd-Au high-surface area catalysts are used in industry to improve
activity and selectivity, a thorough understanding of the nature of these enhancements is
lacking. A molecular-level understanding of catalytic reactions under actual reaction
conditions is the ultimate goal. This thesis is mainly focused on the application of Pd-Au
supported catalysts for vinyl acetate synthesis and CO oxidation reactions using highsurface
area catalysts. We have attempted to improve the conventional Pd-Au based
catalyst by synthesizing novel acetate-based and polymer-based catalysts. The
corresponding catalytic reactivity and selectivity were measured and compared to
conventional Pd-Au based catalyst systems. Subsequent characterization was performed
using characterization techniques, such as, X-ray diffraction (XRD) and transmission
electron microscopy (TEM).
From our bimetallic catalytic studies, it was evident that the addition of Au to Pd
leads to increased reactivity and selectivity. This surface modification is an important
factor in the altered reaction kinetics for vinyl acetate (VA) synthesis and CO oxidation
reactions. Promoted and unpromoted Pd-Au/SiO2/K+ catalyst were used for VA synthesis
and the effect of pre-adsorbed O2, acetic acid and the role of oxygen were explored. The VA reaction rate of novel acetate-based Pd-Au/SiO2 catalyst was 3.5 times
higher than conventional Pd-Au catalysts. Also, 100% selectivity was obtained for
acetate-based Pd-Au/SiO2 at 130 oC and the VA formation rate was comparable to that of
conventional Pd-Au catalysts. Therefore, the acetate-based Pd-Au/SiO2 catalyst seems
very promising and can be explored further. Also, Pd(1):Au(4)/SiO2 catalysts
demonstrate 100% CO conversion at much lower temperatures (90 oC) compared with
other Pd-Au based catalysts. Furthermore, we were successful in obtaining sufficient CO
oxidation activity with increased metal loading (5 wt%) and these catalysts did not
deactivate under above-ambient reaction temperature conditions, which make 1:4 Pd-
Au/SiO2 catalyst a good candidate for further exploration in CO oxidation reactions.
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Ghazi, Mohamed. "Conversion du gaz de synthèse en produits oxygénés en présence de catalyseurs nickel-molybdène supportés." Poitiers, 1988. http://www.theses.fr/1988POIT2006.
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Tateyama, Miho. "Development of polymer-supported synthetic procedure for Heyns rearrangement products." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ55092.pdf.
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