Dissertationen zum Thema „Réactions élémentaires“
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Peuch, Vincent-Henri. „Modélisation et simulation d'étapes élémentaires impliquées dans des réactions catalytiques“. Lyon, École normale supérieure (sciences), 1996. http://www.theses.fr/1996ENSL0024.
Reignier, Denis. „Contributions théoriques à l'étude de quelques réactions élémentaires à trois atomes“. Bordeaux 1, 2001. http://www.theses.fr/2001BOR12314.
Zhang, Cuihong. „Étude expérimentale des réactions élémentaires d'importance atmosphérique : la réactivité des radicaux peroxyles“. Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR090.
Peroxy radicals are important intermediates in atmospheric chemical reactions and play an important role in atmospheric radical chain reactions. Kinetics and product information of radicals are key parameters in global atmospheric model simulation, and are of great significance for understanding scientific questions such as atmospheric oxidation capacity, photochemical pollution, and secondary organic aerosol formation. Ethane is one of the most abundant non-methane hydrocarbons in the atmosphere, its oxidation reaction generates the ethyl peroxy radical C2H5O2. However, in the literature there are still insufficient information and inconsistent measurement results in its self- and cross-reaction kinetics. Accurately measuring the rate constant and product branching ratio of C2H5O2 will help to understand the C2H5O2 chemistry in low NOx environments and its contribution to formation of OVOCs and secondary organic aerosol in the atmosphere.Absorption spectroscopy and photoionization mass spectrometry (PIMS) have been used to study the kinetics and products of C2H5O2. Based on dual-path cavity ringdown spectroscopy (CRDS), the self- and cross- reaction of C2H5O2 radicals have been studied, and the rate constant and branch ratio has been obtained. Based on PIMS, and synchrotron radiation photoelectron photoion coincidence spectroscopy (PEPICO), the products were detected
Madelaine, Guillaume. „Simplifications exactes et structurelles de réseaux de réactions biologiques“. Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10015/document.
System biology aims at understanding and analyzing biological systems using mathematical and computational models. The explosion of the number of experimental data leads to larger and larger models. In order to be able to easily analyze them and quickly simulate them, it is necessary to be able to simplify them. In this thesis, we propose simplification methods for biochemical reaction networks. These methods are sufficiently rich to be able to simplify an important number of networks from biological applications. They are contextual, allowing to consider a network as a sub-module of a larger model, and to simplify it without modifying the behavior of the global model. Finally, our simplifications are sound, meaning that they preserve the semantics of the networks. Firstly, we are interested in a non deterministic semantics, based on the capability to converge to some attractors of the network. Then we study some simplifications for the deterministic semantics, allowing for instance to remove intermediate species at steady-state. Finally, we are interested by the confluence of this simplification, as well as the relation between the elimination of intermediate species and the computation of the elementary modes of a network
Bonard, Amélie. „Etude cinétique de réactions élémentaires d'intérêt pour la combustion : application aux réactions du radical OH avec des éthers et des acétals“. Orléans, 2000. http://www.theses.fr/2000ORLE2029.
Dusanter, Sebastien. „Application des diodes laser infrarouges accordables à deux problématiques : la métrologie de polluants : la cinétique des réactions élémentaires“. Lille 1, 2002. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2002/50376-2002-247.pdf.
Javoy, Sandra. „Détermination de constantes de vitesse de réactions chimiques élémentaires importantes dans la combustion de l'hydrogène en régime d'écoulement supersonique“. Orléans, 2001. http://www.theses.fr/2001ORLE2037.
Paul, Jean-François. „Etapes élémentaires de réactions catalytiques sur les métaux du groupe 10 : étude quantique de la chimisorption et de la transformation de fragments organiques“. Lyon 1, 1996. http://www.theses.fr/1996LYO10037.
Morin, Mathieu. „Gazéification de la biomasse en double lit fluidisé circulant : étude des réactions élémentaires de gazéification et de combustion du char et de reformage des goudrons“. Thesis, Toulouse, INPT, 2017. http://www.theses.fr/2017INPT0089/document.
The thermochemical conversion of biomass at high temperature (>700°C) in Fast Internally Circulating Fluidized Bed (FICFB) is a promising alternative route to fossil fuels (oil, coal) to produce syngas which can be used in several applications. The aim of the present work is to develop methodologies as well as theoretical and experimental tools for determining the intrinsic kinetic of biomass transformations (biomass pyrolysis, char gasification and combustion, cracking and reforming of tars). Firstly, a fluidized bed reactor has been designed and built at the Laboratory of Chemical Engineering (LGC). This reactor can operate for temperatures between 20 and 1000°C with a well-defined gas supply (N2, O2, H2, H2O and tars). A sampling and analysis gas system enables the continuous quantification of the non-condensable gases and tars molar fractions. A hydrodynamic and thermal study enabled the determination of the operating conditions for each experimental study. Secondly, the char gasification and combustion was performed in the fluidized bed reactor. The influence of the operating conditions (temperature and compounds partial pressure) led to the modelling of the different solid transformation kinetics. Besides, in the case of char combustion, a reaction scheme was proposed and the kinetic obtained in the fluidized bed was compared to that obtained in a thermogravimetric analyzer. Finally, a study on the tar reforming in a fluidized bed reactor highlighted the effect of the reactive atmosphere on the reaction scheme of toluene conversion over olivine and char
Martin, Ludovic. „Contribution théorique à l'étude de la réactivité élémentaire gaz/surface d'intérêt en rentrée atmosphérique“. Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13823/document.
During an atmospheric re-entry, the thermal shields of spacecrafts undergo an important heating, a significant fraction (~30%) of which is due to the chemical reactions at their surface. This thesis is a contribution to the understanding of this heterogeneous reactivity, catalycity, with the tools of theoretical chemistry. A method to build a global potential energy surface is developed and applied to the study of elementary processes dynamics (dissociative molecular adsorption, atomic absorption, Eley-Rideal recombination …) for the N,N2/W(100,110) and O,O2/Cu(100) chemical systems. These approaches are then coupled with a kinetic model quantifying catalycity
Ayina, Bouni. „Les concepts élémentaires de la chimie entre la chimie du chimiste et la chimie de l’élève : proposition de séquences d’enseignement inspirées d’une analyse sémio-épistémologique de l’histoire de la chimie“. Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10283.
Our contribution focuses on the process of conceptualization and modeling of matter and its transformations in chemistry. It consists of two parts. A first part consisting of an analysis of the semio-epistemological type of this process during the late 18th - early 19th centuries. We mobilize for this semiotic theory of C.S. Peirce as a framework for analysis. It allowed to relocate the experimental chemistry as being a set of signs that extends the theoretical at the same time that he founded. The iconic sign far from signs of a primitive thought appears as a true neo writing, a privileged heuristic instrument used by chemists to probe the matter for clues on a structure that can make account of his behavior, he allowed them, after much controversy, lead to a particulate structure, and build the concepts of atom, the molecule and its atomicity. A second part where the semio-epistemological analysis was our theoretical framework for a didactic transposition of this context. Our research question is to know if the sign iconic, as defined in the peircien sense, can be mobilized spontaneously by students from ages 13-15 to build reasoning in chemistry, and if he can help in accessing the infinitely small on the basis of this converted context? We then developed a corpus of 20 sequences of teaching engaging students in a process that requires the construction of evolutionary models. Our results to say that the iconic sign far from a pedagogical means of transmission facilitated, a teaching assistant is instead a heuristic instrument in the construction of knowledge by students, as it is at the chemist
Nhut, Jean-Mario. „Réaction d'oxydation sélective de l'hydrogène sulfuré (H2S) en soufre élémentaire“. Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13240.
Studies realised on the desulfurisation reaction at high temperature led us to selectively control the active phase location on the support, with the development of a new impregnation method (called bi-phasic impregnation). This method was based on the duality of the SiC surface (hydrophilic, hydrophobic), and allowed to depose the iron oxide particles (active phase) exclusively on pure SiC zones. These zones were proven to be hydrophobic and located on the outer surface of the pores of the material, and then allowed a better accessibility reactant against the active phase. As a function of time on stream the iron oxide based active phase was transformed into an iron oxysulfide phase (T = 230-240 °C). This phase was very active and selective and was extremely stable during the reaction (more than 1000 h of time on stream), whatever the nature of the reaction mixture, i. E. With or without impurities (H2, CO2, SO2, CO, NH3). The discovery of new materials like carbon nanostructures (nanofibers, nanotubes) allowed us to develop new catalysts, based on NiS2, able to selectively oxidize at 60 °C H2S into elemental sulfur with extremely high sulfur yield and high space velocity (WHSV = 0. 03 h-1). The results obtained showed the importance of these supports on the desulfurisation activity and their great capacity of solid sulfur storage. To explain these results on nanotubes, the hypothesis of a confinement effect induced by their tubular morphology was advanced while the high activity observed on the nanofibers composite was attributed to their high external surface due to their nanosize. Moreover, a particular mode of deposition was advanced to explain their activity and their high solid sulfur storage capacity during the reaction (existence of surface duality of the materials: hydrophilic/hydrophobic)
Cardoso-Leite, Pedro M. „Comparaison des réponses perceptives et motrices dans les tâches psychophysiques élémentaires“. Paris 5, 2008. http://www.theses.fr/2008PA05H040.
A central issue in cognitive sciences is the quest for understanding how physical stimulations give rise to conscious experience and motor behaviour. The layman's view, according to which perception informs and generates action, is refuted by experimental evidence from neuropsychology, neurophysiology, functional anatomy and behavioural studies which led to the conclusion that perception and action are controlled by independent systems. This conclusion has however been contested on methodological and empirical grounds. The first part of this thesis introduces this debate whereas the second part presents my experimental contribution to thos topic. I investigated the relationship between perceptual and motor responses using tasks that were both heterogeneous and sufficiently simple to be compare. The perceptual-motor relationship has been studied with supra and near threshold stimuli. Supra threshold stimuli were used to investigate stimulus intensity effects on the moments of perceptual and motor detections, as inferred respectively from temporal order judgements or anticipatory response times reaction times. Supra threshold stimuli were also used to compare spatial integration of stimuli presented across the natural blind spot as measured via brightness judgments (perceptual task) or simple reaction times (motor task). Finally I studied the effects of near threshold stimuli in double-task paradigms where observers had on each trial to report the stimulus presence (yes/no detection task) and provided a motor response (saccade or key press). The results from these studies show that perceptual and motor responses are different - as the requirements of perceptual and motor tasks are - but they are not independent. The view that emerges from these and other studies from the literature is that peception and action are not fundamentally distinct systems, but represent manifestations of a same process where perceptual and motor decisions depend on distinct decision criteria which depend on task-specific constraints and context
Laquièvre, Aurélie. „Mécanismes élémentaires de plasticité des systèmes polymères amorphes : influence de la modification de la structure macromoléculaire par la chimie « Click »“. Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10124/document.
The main objectives of this work were the elaborate new reversible crosslinked materials and to get a better understanding of their physical and mechanical properties. Two strategies have been investigated to prepare such materials. The first one consisted in applying to well-defined furan functionalized side-chain copolymers the Diels-Alder (DA) / retroDiels-Alder reactions. The second approach was based on the high reactivity of azlactone units embedding in well-defined copolymer chains toward primary amines. The controlled radical polymerization has been exploited in order to provide an effective way for the control synthesis of the well-defined side-chain functionalized copolymers. Then, various crosslinked materials have been prepared using the DA reaction and characterized to determine their glass transition temperature and their swelling ratio. The study of their thermal and viscoelastic properties highlighted the deep impact of the crosslinking. Then, their reversible and mechanical behaviors were investigated and we observed a correlation between the plastic deformation mechanisms and the induced structural evolution. Concerning the azlactone based copolymer, we have shown that this new polymeric platform could be efficiently modified by various primary amines, affording new materials with interesting properties (fluorescence, electroactive,…). The ring-opening reactions of azlactone functionalized copolymers were fully characterized proving the quantitative character of this reaction. Endly, crosslinked materials have been also elaborated by treating the azlactone copolymer with a diamino component
Nguyen, Van Nuoi Patrick. „Optimisation du catalyseur supporté sur β-SiC pour la réaction d'oxydation directe de l'H2S en soufre élémentaire, du laboratoire à l'industrie“. Université Louis Pasteur (Strasbourg) (1971-2008), 2006. https://publication-theses.unistra.fr/public/theses_doctorat/2006/NGUYEN_VAN_NUOI_Patrick_2006.pdf.
Rozé, Emmanuel. „Processus élémentaires associés à la réaction d'oxydation de CO à basses températures sur des catalyseurs à base de Palladium et d'Or supportés sur Al2O3 et SiO2“. Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00807672.
Subercaze, Alexandre. „Utilisation combinée des rayons X et gamma émis lors de l'interaction avec la matière d'ions légers aux énergies intermédiaires : des mécanismes primaires de réaction aux applications“. Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0053/document.
Particle Induced X-ray Emission (PIXE) and Particle Induced Gamma-ray Emission (PIGE) are multi-elemental and non-destructives techniques. They are based on the detection of characteristic X-ray and gamma emission induced by the interaction of accelerated charged particles with matter. Elements with an atomic number Z> 11 can be quantified reaching a limit of detection in the order of μg/g (ppm). X-rays from light elements are strongly attenuate by matter. Therefore, PIXE shows little sensitivity for lights elements. Those elements are analyzed simultaneously using PIGE. One of the benefits of PIXE/PIGE is its ability to perform analysis with different requirement (elemental concentration mapping, in-depth analysis, valuable objects). Homogeneous and non-homogenous samples can be studied thanks to PIXE/PIGE. High energy PIXE (HEPIXE) has been developed at the ARRONAX cyclotron using particles beams up to 70 MeV. Thus analysis of thick samples is achievable using HEPIXE. Using high energy beams can also reduce the risk of damaging the sample. First of all, the high energy PIXE/PIGE platform develop at ARRONAX is described. Then the results given by high energy PIGE analysis and the experimental procedure for gamma emission cross section measurements are discussed. Finally, the methods developed and the results obtained during the analysis of inhomogeneous samples (multi-layer and granular samples) are presented and discussed
Tahri, Aomar. „Contribution à l'étude de la méthanation des oxydes de carbone catalysée par du nickel dispersé sur silice : Étude en régime permanent de la cinétique réactionnelle et application de méthodes transitoires à l'identification de processus élémentaires“. Nancy 1, 1987. http://www.theses.fr/1987NAN10148.
Petuya-Poublan, Rémi. „Contribution à la description théorique de la dynamique des processus élémentaires hétérogènes : collisions de l'azote moléculaire et de l'hydrogène atomique avec des surfaces de tungstène“. Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0134/document.
Heterogeneous elementary processes at the gas-solid interface are ofgreat interest in many domains such as heterogeneous catalysis, atmospheric and interstellar media chemistry, spacecraft atmospheric re-entry and plasma-wall interactions description. This thesis focus on the dynamics of nitrogen, N2, non reactive scattering on a tungsten W(100) surface and hydrogen, H2, recombination processes on tungsten surfaces W(100) and W(110). The quasiclassical dynamics of these processes is simulated using potential energy surfaces based on density functional theory calculations. In particular, a multi-adsorbate potential is developed to include surface coverage in the dynamics simulation in order to scrutinize the interplay between both direct abstraction, the so-called Eley-Rideal recombination,and the Hot-Atom recombination process after hyperthermal diffusion on the surface
Morin, Mathieu Pierre. „Gazéification de la biomasse en double lit fluidisé circulant : étude des réactions élémentaires de gazéification et de combustion du char et de reformage des goudrons“. Phd thesis, 2017. http://oatao.univ-toulouse.fr/19462/1/MORIN_1.pdf.
Rozé, Emmanuel. „Processus élémentaires associés à la réaction d’oxydation de CO à basses températures sur des catalyseurs à base de Palladium et d’Or supportés sur Al2O3 et SiO2“. Thesis, 2010. http://www.theses.fr/2010LYO10290/document.
The aim of this thesis is to use an experimental microkinetic approach to characterize elementary steps involved in the oxidation of CO by O2 over Pd and Au catalysts supported on Al2O3 and SiO2 and to identify those controlling the rate of the reaction. On 1.4% Pd/Al2O3, the evolution of the production of CO2 (RCO2(t)) by oxidation of the adsorbed CO species (2 linear L and 2 bridged B) was followed during successive formationoxidation cycles. An induction period is observed leading to a CO2 peak characterized by tm and RCO2m. The study of the impacts of different experimental parameters on tm and RCO2m such as the duration of a desorption before oxidation, the partial pressure of O2, the temperature and thepretreatment of the catalyst allows us to characterize the different surface elementary steps of thereaction. A kinetic model is proposed which is based on the oxidation of the B CO species by a weaklyadsorbed O species formed on Pd sites liberated by the desorption and the oxidation of the L COspecies. This model allows us to interpret the differences in the catalytic activity of the catalyst for theCO/O2 reaction according to the pretreatment procedure after reduction with H2 at 713 K: cooling thesolid in hydrogen permits obtaining a CO conversion of ��100% in excess O2 whereas a desorption at713 K provides CO conversions < 4%. These differences are ascribed to the reconstruction of thesurface of the Pd particles during the hydrogen desorption at 713 K. On Au/Al2O3 and Au/SiO2, the study concerns the first step of CO oxidation: the adsorption of CO. For a set of experimental conditions (Temperature and partial pressures), the adsorption of CO at 300 K leads to a progressive reconstruction of the Au particles modifying significantly the propertiesof the adsorbed species. The kinetic of this reconstruction is studied