Littérature scientifique sur le sujet « Chlore – Composés atmosphériques »
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Thèses sur le sujet "Chlore – Composés atmosphériques":
Troussier, Fabien. « Évolution spatio-temporelle des teneurs en composés organiques volatils en atmosphère urbaine et périurbaine et contribution de leurs sources ». Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-Troussier.pdf.
Srour, Zainab. « Unravelling the chlorine chemistry using simulations from the molecular scale to the global scale ». Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR038.
The discovery of the ozone hole over the Antarctic in the 1970s established the significance of gas-phase halogenated species in the atmosphere. These species play a crucial role in tropospheric and stratospheric chemistry, influencing ozone budget, atmospheric concentrations of key species (such as OH, NOx, and volatile organic compounds), and halogen interactions. Numerous studies have explored halogen chemistry using global models, however, most of the focus has been on bromine and iodine due to their higher reactivity compared to chlorine. This preference arises from the greater chemical stability of HCl compared to other halogen acids (HX, where X = Br, I).This thesis aims to unravel the chlorine chemistry in the troposphere starting from the molecular up to the global scales. This is done through the employment of different numerical tools: (i) quantum chemistry tools to predict the reactivity and thermokinetic parameters of the reaction between OH radicals and CH2ClOOH, which are challenging to obtain experimentally, (ii) the kinetic model “ASTEC” to determine the reactivity of gaseous chlorinated compounds on a short time scale; and (iii) the chemistry transport model “MOCAGE” to evaluate the impact of chlorine on the global atmospheric budget.The results show that the reaction between CH2ClOOH and OH radicals is of atmospheric interest with an overall rate constant 6.55 × 10-11 cm3 molecule-1 s-1 at 298 K computed at the M06-2X/6-311++G(3df,3p) level of theory. The kinetic modelling showed that the daytime reactivity of chlorinated compounds is more important than the night-time reactivity governed by photolysis and reactivity with OH radicals. Moreover, the global modelling by MOCAGE showed that the chlorine atmospheric budget is not only affected by chemical transformation, but also, it is altered by the physical processes including transport and deposition
El, Dib Gisèle. « Dégradation atmosphérique des composés organiques volatils carbonyles (amides, aldéhydes aromatiques) par le radical nitrate et l’atome de chlore et réactivité atmosphérique du radical benzylperoxyle ». Reims, 2006. http://theses.univ-reims.fr/exl-doc/GED00000952.pdf.
The purpose of this thesis is to determine the atmospheric fate of a number of VOCs widely used in different applications or directly produced into the troposphere by degradation of other VOCs. We have studied the degradation of benzylperoxy radical, a series of amides (N-dimethyl formamide, N-dimethyl acetamide, N-methylpyrrolidinone, N-dimethyl proprionamide) and a series of aromatic adehydes (2,4-dimethyl benzaldehyde, 2,5-dimethyl benzaldehyde, 2,6-dimethyl benzaldehyde, 3,4-dimethyl benzaldehyde and 3,5-dimethyl benzaldehyde). This work has been realised using several experimental techniques. We have determined the UV spectrum of benzylperoxy radical and the rate constants of the self reaction and the cross reaction with HO2 as a function of temperature (298-353 K) by using the laser photolysis technique with time resolved absorption UV-visible spectroscopy. The reaction rate constants of amides with NO3 radical have been determined as a function of temperature (277-353 K), by using the laser photolysis technique. This work provides the first kinetic study for the reaction of amides with NO3 as function of temperature. The absorption cross sections of aldehydes have been measured by UV-Visible spectrometry. The rate constants of the reaction of aldehydes with Cl atom have been determined at room temperature by using smog chambers. The analyses have been realized by Gas phase chromatography. This work represents the first reported kinetic study of the reaction of Cl atoms with these aldehydes. The whole results are discussed in order to assess the atmospheric implications of the compounds investigated (lifetimes and environmental impact)
Lendar, Maria. « Dégradation atmosphérique d’une série d’alcools, d’esters et de l’hexafluoroisobutène ». Thesis, Orléans, 2012. http://www.theses.fr/2012ORLE2042/document.
In this thesis we report the atmospheric fate of three saturated alcohols: CH3(CH2)4OH, CH3CH2CH2CH(OH)CH3 and (C2H5)2CHOH, three esters: CH3CH2CH2C(O)OC2H5, CH3CH2COOC2H5 and CH3CH2COOCH2CH2CH3 and an unsaturated HFC with OH radicals and Cl atoms. The rate coefficients of OH reactions with these compounds have been measured over the temperature range 253 – 373 K, using the Pulsed Laser Photolysis – Laser Induced Fluorescence technique (PLP-LIF). Moreover the rate coefficients of OH and Cl reactions with alcohols, esters and hexafluoroisobutene (HFIB) have been determined at room temperature, using smog chambers. For the reaction of OH radicals with HFIB and Cl atoms with esters and HFIB, the rate coefficients obtained in this study present the first determination. The results have been compared with the literature and the reactivity of the compounds has been discussed. Finally, the atmospheric lifetimes of these compounds have been determined and the OH oxidation products have been identified, which allows us to estimate the atmospheric impact of these compounds
Aslan, Lina. « Dégradation atmosphérique de composés organiques multifonctionnels : les hydroxycétones et les aldéhydes insaturés ». Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10120/document.
This work was carried out with the objective of providing relevant information on the atmospheric fate of two families of multifunctional oxygenated volatile organic compounds (OVOCs), hydroxyketones and unsaturated aldehydes, to complement atmospheric models for air quality forecasts and for the drafting of regulations. The reactivity of the selected compounds was carried out in a flexible atmospheric simulation chamber equipped with various analytical techniques. The present work provides the first kinetic and mechanistic study of 4-hydroxy-4-methyl-2-pentanone (4H4M2P) photolysis and the first determination of the relative rate coefficient for the reaction of Cl atoms with 4H4M2P. The photolysis frequencies of 4-hydroxy-3-hexanone (4H3H) and 5-hydroxy-2-pentanone (5H2P) were also determined. These measurements enable estimating the atmospheric lifetimes of the three compounds by photolysis which ranged from 7 to 28 days. The main photolysis products of 4H4M2P were acetone (121±4)% and formaldehyde (20±1)%. These results allowed us to propose a mechanistic scheme for photolysis including a Norrish II intramolecular rearrangement process. In a second part, the preliminary study of photolysis kinetics of two unsaturated aldehydes, trans-2-hexenal (T2H) and trans-2-pentenal (T2P) was carried out. The estimated rate constant for photolysis of T2H ((1.2±0.6)´10-3 h-1) indicates that the photodissociation of T2H is negligible in the atmosphere. All the data obtained show that the photolytic reactivity of OVOCs is strongly linked to their structure
Riffault, Véronique. « Réactions de radicaux halogénés (chlorés, bromés) d'intérêt atmosphérique ». Phd thesis, Université d'Orléans, 2002. http://tel.archives-ouvertes.fr/tel-00275704.
Pour les réactions entre les radicaux halogénés et hydro-oxygénés, les résultats obtenus montrent que les réactions étudiées constituent des sources supplémentaires de l'espèce réservoir HX (X = Br, Cl) dans la stratosphère globale. Toutefois, les valeurs des constantes de vitesse obtenues semblent insuffisantes pour expliquer totalement l'écart entre observations et modélisations des concentrations de HX dans la stratosphère, et donc le partage des composés halogénés entre espèces actives et réservoirs.
Concernant le DMSO, ce travail confirme que les réactions avec les radicaux chlorés et bromés ne contribuent pas de manière significative à son oxydation, celle-ci étant amorcée principalement en phase gazeuse par le radical OH.
Guillemot, Marianne. « Elimination de composés organiques volatils (COV) chlorés sur zéolithes par couplage adsorption-oxydation catalytique ». Poitiers, 2006. http://www.theses.fr/2006POIT2286.
This study is focused on tetrachloroethylene (PCE) adsorption over faujasite type zeolites, in static and dynamic conditions, in dry and humid environment. In addition, catalytic oxidation of PCE over zeolite FAU based catalyst exchanged or not with platinum was studied. Lastly, PCE removal was carried out over dual functional adsorbent/catalyst system. The elimination of methylethylketone (MEK) was also performed by single adsorption and oxidation, and using adsorbent/catalyst media
Hormain, Laureline. « Etude théorique de l’interaction avec la surface de la glace de molécules halogénées d’intérêt atmosphérique ». Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10057/document.
The interaction between atmospheric ice particles and halogenated molecules generated much interest in the recent years. Indeed, theses species can produce destructive radicals for the ozone layer and these reactions are enhanced at the ice surface. The first part of this thesis presents the development of a potential energy surface describing the Cl2-ice interaction, on the basis of ab initio data describing the ground and the first excited states for the Cl2-H2O dimer. The second part is dedicated to the adsorption of Cl2 and CH3Cl on a hexagonal ice surface at stratospheric temperatures. The dynamics of Cl2 at the ice surface was study at 190 K and 235 K by implementing the developped potential energy surface in a classical molecular dynamics program. According to these simulations, the Cl2 molecule adsorbs forming an angle of 80° with respect to the normal of the ice surface. The results suggest the interaction between the molecule and the surface is rather weak, the pollutant molecule diffusing freely at the surface.Since, a classical force field was available to describe the CH3Cl interaction with the ice surface, the adsorption of methyl chloride on ice was investigated using the GROMACS package. The main result is that at 235 K the molecule is adsorbed with the chlorine-carbon axis parallel to the ice surface, the methyl group pointing toward the ice and the chloride toward the gas phase. Similarly to Cl2, CH3Cl forms weak bonds with the surface and consequently, does not remain trapped in a given adsorption site
Xueref-Remy, Irène. « Etude de l'incorporation d'HCl et d'HBr dans la glace par spectroscopies IR et EXAFS : applications atmosphériques ». Grenoble 1, 1999. https://tel.archives-ouvertes.fr/tel-00764801.