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Dissertations / Theses on the topic 'Hydrocarbons Chemical reactions'

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Published: 4 June 2021
Last updated: 1 February 2022

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1

Goto, Masashi. "Kinetics of atmospheric chemical reactions of fluorinated hydrocarbons." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/145179.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(地球環境学)
甲第11759号
地環博第1号
新制||地環||1(附属図書館)
23402
UT51-2005-D508
京都大学大学院地球環境学舎地球環境学専攻
(主査)教授 川崎 昌博, 教授 田村 類, 助教授 川崎 三津夫
学位規則第4条第1項該当
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2

Lai, Chiu-Kin Steven. "Thermal reactions of aromatic hydrocarbons and m-cresol over calcium oxide." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/15044.

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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1986.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaves 284-290.
by Chiu-Kin Steven Lai.
Sc.D.
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3

Lachance, Russell Philip. "Oxidation and hydrolysis reactions in supercritical water : chlorinated hydrocarbons and organosulfur compounds." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/33533.

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4

Nishino, Noriko. "Mechanistic studies of atmospheric chemical reactions of hydroxyl radicals with aromatic hydrocarbons, including 2-ring polycyclic aromatic hydrocarbons, and terminal alkenes." Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?index=94&did=1907248571&SrchMode=1&sid=1&Fmt=7&retrieveGroup=0&VType=PQD&VInst=PROD&RQT=309&VName=PQD&TS=1270251046&clientId=48051.

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5

Jamal, Adeel. "Ab Initio Quantum Chemical Studies on Neutral-Radical Reactions of Ethynyl (C2H) and Cyano (CN) with Unsaturated Hydrocarbons." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/736.

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An Ab Initio/RRKM study of the reaction mechanism and product branching ratios of neutral-radical ethynyl (C2H) and cyano (CN) radical species with unsaturated hydrocarbons is performed. The reactions studied apply to cold conditions such as planetary atmospheres including Titan, the Interstellar Medium (ISM), icy bodies and molecular clouds. The reactions of C2H and CN additions to gaseous unsaturated hydrocarbons are an active area of study. NASA’s Cassini/Huygens mission found a high concentration of C2H and CN from photolysis of ethyne (C2H2) and hydrogen cyanide (HCN), respectively, in the organic haze layers of the atmosphere of Titan. The reactions involved in the atmospheric chemistry of Titan lead to a vast array of larger, more complex intermediates and products and may also serve as a chemical model of Earth’s primordial atmospheric conditions. The C2H and CN additions are rapid and exothermic, and often occur barrierlessly to various carbon sites of unsaturated hydrocarbons. The reaction mechanism is proposed on the basis of the resulting potential energy surface (PES) that includes all the possible intermediates and transition states that can occur, and all the products that lie on the surface. The B3LYP/6-311g(d,p) level of theory is employed to determine optimized electronic structures, moments of inertia, vibrational frequencies, and zero-point energy. They are followed by single point higher-level CCSD(T)/cc-vtz calculations, including extrapolations to complete basis sets (CBS) of the reactants and products. A microcanonical RRKM study predicts single-collision (zero-pressure limit) rate constants of all reaction paths on the potential energy surface, which is then used to compute the branching ratios of the products that result. These theoretical calculations are conducted either jointly or in parallel to experimental work to elucidate the chemical composition of Titan’s atmosphere, the ISM, and cold celestial bodies.
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6

Broeker, Jeffrey Lee. "Theoretical and experimental studies on oxidation and interactions of mono- and dithioethers and their derivatives." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184506.

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The potential energy surface of naphtho (1,8-b,c) -1,5-dithiocin and its mono-, di-, tri-, and tetraoxides was analyzed by dynamic ¹H NMR spectroscopy, AM1 semiempirical calculations, and x-ray crystallography. The lowest energy conformers of these compounds in the solid state, the gas state, and in solution, as well as the energy barriers for the interconversion between their conformers are reported. The electronic structure of naphtho (1,8-b,c) -1,5-dithiocin was analyzed by the AM1 semiempirical method. An experimental method was developed to verify these calculations. Comparison of the relative intensities of the bands observed in the He I and He II photoelectron spectra of aromatic thioethers provides an effective means for assigning bands to ionizations from specific molecular orbitals. Such methodology confirmed the calculations which showed that naphtho (1,8-b,c) -1,5-dithiocin has a large sulfur-sulfur lone pair splitting of 1.6-2.0 eV. Dissolution of naphtho (1,8-b,c) -1,5-dithiocin-1-oxide in concentrated sulfuric acid produced the corresponding disulfide dication, which upon hydrolysis regenerated the sulfoxide. The mechanism of this reaction sequence was investigated using 2-monodeuterated naphtho (1,8-b,c) -1,5-dithiocin-1-oxide. This stereochemical probe showed that both the formation of the disulfide dication and its hydrolysis occurred with retention of stereochemistry at the sulfoxide sulfur. The molecular structure of naphtho (1,8-b,c) -1,5-dithiocin-1-oxide, determined by x-ray crystallographic methods, showed evidence of transannular interaction between the sulfur atoms. Vibronic analysis on naphtho (1,8-b,c) -1,5-dithiocin and naphtho (1,8-b,c) -1,5-dithiocin-1-oxide using the Hartree-Fock method with the STO-3G basis set showed no evidence of bond formation in naphtho (1,8-b,c) -1,5-dithiocin-1-oxide compared with naphtho (1,8-b,c) -1,5-dithiocin. Thus this transannular interaction in the sulfoxide must be due to electrostatic interaction and not incipent sulfurane formation. The mechanism of the photodecompositions of perester and aldehyde compounds with β substituted sulfur moieties was investigated. The photodecomposition of these compounds produced their corresponding alkenes without stereocontrol. These results suggest that the decompositions occur via a stepwise non-stereoselective mechanism. Flash photolysis of peresters β substituted with sulfonium salt groups was shown to produce thioether cation radicals, e.g., the 1,5-dithiocane cation radical. This demonstrated that the photodecomposition of β sulfonium salt peresters is potentially a powerful and novel method for making cation radicals.
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7

Mashino, Michio. "Photoinduced Chemical Reaction of Halogenated Hydrocarbons." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147629.

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8

Zarif, Najafi Nooshin M. H. "A study of mechanochemical reactions of spin traps in hydrocarbon polymers." Thesis, Aston University, 1990. http://publications.aston.ac.uk/9762/.

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The identification and quantification of spin adducts and their reduction products (>NOH, >NOR) formed from nitroso compounds and nitrones in EPR and PP during spin trapping techniques have been examined. The nitroxyl yield and polymer bound nitroxyl percentage formed from these spin traps were found to be strongly dependent on the nature of spin trap and radical generator, processing temperature, and irradiation time. The nitroxyl yield and % bound nitroxyl of the spin traps improved significantly in the presence of Trigonox 101 and 2-0H benzophenone. The effect of these spin traps used as normal additive and their spin adducts in the form of EPR-masterbatch on the photo and thermal-oxidation of PP have been studied. Aliphatic nitroso compounds were found to have much better photo-antioxidant activity than nitrones and aromatic nitroso compounds, and their antioxidant activity improved appreciably in the presence of, a free radical generator, Trigonox 101, before and after extraction. The effect of heat, light and oxidising agent (meta-dichloro per benzoic acid) on the nitroxyl yield of nitroso tertiary butane in solution as a model study has been investigated and a cyclic regenerative process involving both chain breaking acceptor and chain breaking donor process has been proposed.
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9

Fox, Clayton D. L. "Modeling Simplified Reaction Mechanisms using Continuous Thermodynamics for Hydrocarbon Fuels." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37554.

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Commercial fuels are mixtures with large numbers of components. Continuous thermodynamics is a technique for modelling fuel mixtures using a probability density function rather than dealing with each discreet component. The mean and standard deviation of the distribution are then used to model the chemical reactions of the mixture. This thesis develops the necessary theory to apply the technique of continuous thermodynamics to the oxidation reactions of hydrocarbon fuels. The theory is applied to three simplified models of hydrocarbon oxidation: a global one-step reaction, a two-step reaction with CO as the intermediate product, and the four-step reaction of Müller et al. (1992), which contains a high- and a low-temperature branch. These are all greatly simplified models of the complex reaction kinetics of hydrocarbons, and in this thesis they are applied specifically to n-paraffin hydrocarbons in the range from n-heptane to n-hexadecane. The model is tested numerically using a simple constant pressure homogeneous ignition problem using Cantera and compared to simplified and detailed mechanisms for n-heptane. The continuous thermodynamics models are able not only to predict ignition delay times and the development of temperature and species concentrations with time, but also changes in the mixture composition as reaction proceeds as represented by the mean and standard deviation of the distribution function. Continuous thermodynamics is therefore shown to be a useful tool for reactions of multicomponent mixtures, and an alternative to the "surrogate fuel" approach often used at present.
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10

Al, Kazzaz Marwan. "Pyrolyse du chlorure de méthyle induite par le chlore : une nouvelle voie de valorisation du méthane." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL024N.

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La conversion du méthane, principal constituant du gaz naturel, en produits valorisables et facilement transportables constitue un enjeu économique important, et un défi pour la recherche. Une étude théorique conduit à une nouvelle voie de conversion du méthane en chlorure de vinyle par chloro-pyrolyse du chlorure de méthyle. La réaction CH3Cl/Cl2 en phase gazeuse a été étudiée entre 500 et 1000°C. À basse température, on observe la réaction de chloration bien connue qui produit CH2Cl2. À haute température, on observe une nouvelle réaction: la chloro-pyrolyse qui produit principalement du chlorure de vinyle et de l'acétylène ; les autres produits sont CH2Cl2, C2H4, CH4 et C4H4. L'influence des paramètres, température, temps de passage, taux de chlore, taux de dilution, et l'addition d'oxygène, sur la réaction a été étudiée. Il ressort de cette étude que la température joue un rôle déterminant sur la répartition des produits de la réaction. Nos résultats sont interprétés au moyen d'un mécanisme radicalaire homogène qui permet de comprendre la réaction: à basse température la réaction est une réaction de chloration en chaines longues, alors qu'à haute température la réaction est en chaines courtes avec des réactions importantes de recombinaisons des radicaux. Ce travail peut conduire à une nouvelle voie de valorisation du gaz naturel par un procédé en deux étapes: une première étape de chloration du méthane classique, la deuxième étape convertit le chlorure de méthyle en chlorure de vinyle et acétylène par chloro-pyrolyse
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11

Seljeskog, Morten. "Shock Tube Experiments on Nitromethane and Promotion of Chemical Reactions by Non-Thermal Plasma." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-98.

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This dissertation was undertaken to study two different subjects both related to molecular decomposition by applying a shock tube and non-thermal plasma to decompose selected hydrocarbons. The first approach to molecular decomposition concerned thermal decomposition and oxidation of highly diluted nitromethane (NM) in a shock tube. Reflected shock tube experiments on NM decomposition, using mixtures of 0.2 to 1.5 vol% NM in nitrogen or argon were performed over the temperature range 850-1550 K and pressure range 190-900 kPa, with 46 experiments diluted in nitrogen and 44 diluted in argon. By residual error analysis of the measured decomposition profiles it was found that NM decomposition (CH3NO2 + M -> CH3 + NO2 + M, where M = N2 /Ar) corresponds well to a law of first order. Arrhenius expressions corresponding to NM diluted either in N2 or in Ar were found as kN2 = 1017.011×exp(-182.6 kJ/mole / R×T 3/mole×s> and kAr = 1017.574×exp(-207 kJ/mole / R×T )/mole×s>, respectively. A new reaction mechanism was then proposed, based on new experimental data for NM decomposition both in Ar and N2 and on three previously developed mechanisms. The new mechanism predicts well the decomposition of NM diluted in both N2 and Ar within the pressure and temperature range covered by the experiments.

In parallel to, and following the decomposition experiments, oxidative experiments on the ignition delay times of NM/O2/Ar mixtures were investigated over high temperature and low to high pressure ranges. These experiments were carried out with eight different mixtures of gaseous NM and oxygen diluted in argon, with pressures ranging between 44.3-600 kPa, and temperatures ranging between 842-1378 K.

The oxidation experiments were divided into different categories according to the type of decomposition signals achieved. For signals with and without emission, the apparent quasi-constant activation energy was found from the correlations, to be 64.574 kJ/mol and 113.544 kJ/mol, respectively. The correlations for the ignition delay for time signals with and without emission were deduced as τemission = 0.3669×10-2×[NM]-1.02[O2]-1.08×[Ar]1.42×exp(7767/T) and τno emission = 0.3005×10-2×[NM]-0.28[O2]0.12×[Ar]-0.59×exp(13657/T), respectively.

The second approach to molecular decomposition concerned the application of non-thermal plasma to initiate reactions and decompose/oxidize selected hydrocarbons, methane and propane, in air. Experiments with a gliding arc discharge device were performed at the university of Orléans on the decomposition/reforming of low-to stoichiometric concentration air/CH4 mixtures. The presented results show that complete reduction of methane could be obtained if the residence time in the reactor was sufficiently long. The products of the methane decomposition were mainly CO2, CO and H2O. The CH4 conversion rate showed to increase with increasing residence time, temperature of the operating gas, and initial concentration of methane. To achieve complete decomposition of CH4 in 1 m3 of a 2 vol% mixture, the energy cost was about 1.5 kWh. However, the formation of both CO and NOx in the present gliding discharge system was found to be significant. The produced amount of both CO (0.4-1 vol%) and NOx (2000-3500 ppm) were in such high quantities that they would constitute an important pollution threat if this process as of today was to be used in large scale CH4 decomposition. Further experimental investigations were performed on self-built laboratory scale, single- and double dielectric-barrier discharge devices as a means of removing CH4 and C3H8 from simulated reactive inlet mixtures. The different discharge reactors were all powered by an arrangement of commercially available Tesla coil units capable of high-voltage high-frequency output. The results from each of the different experiments are limited and sometimes only qualitative, but show a tendency that the both CH4 and C3H8 are reduced in a matter of a 3-6 min. retention time. The most plausible mechanism for explaining the current achievements is the decomposition by direct electron impact.

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12

Morrell, Claire. "FTIR emission studies of chemical processes." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326026.

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13

Hughes, Robert T. "NOx FORMATION IN LIGHT-HYDROCARBON, PREMIXED FLAMES." UKnowledge, 2018. https://uknowledge.uky.edu/me_etds/118.

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This study explores the reactions and related species of NOx pollutants in methane flames in order to understand their production and consumption during the combustion process. To do this, several analytical simulations were run to explore the behavior of nitrogen species in the pre-flame, post- flame, and reaction layer regions. The results were then analyzed in order to identify all "steady-state" species in the flame as well as the determine all the unnecessary reactions and species that are not required to meet a defined accuracy. The reductions were then applied and proven to be viable.
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14

Kasumba, John. "Organic Chemical Characterization Of Primary And Secondary Biodiesel Exhaust Particulate Matter." ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/358.

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Biodiesel use and production has significantly increased in the United States and in other parts of the world in the past decade. This change is driven by energy security and global climate legislation mandating reductions in the use of petroleum-based diesel. Recent air quality research has shown that emission of some pollutants such as CO, particulate matter (PM), SO2, hydrocarbons, and carcinogenic polycyclic aromatic hydrocarbons (PAHs) is greatly reduced with biodiesel. However, studies have also shown that some unregulated emissions, such as gas-phase carbonyls, are increased with biodiesel combustion. Very limited research has been done to investigate the particle-phase carbonyl and quinone emissions from biodiesel combustion. Also, very limited studies have investigated the ozone oxidation of biodiesel exhaust PM. Fatty acid methyl esters (FAMEs) are found in high abundance in biodiesel exhaust PM. The presence of these FAMEs in biodiesel exhaust PM can potentially alter the kinetics of the reactions between ozone and particle-phase PAHs. In this study, an Armfield CM-12 automotive light-duty diesel engine operated on a transient drive cycle was used to generate PM from various waste vegetable oil (WVO) and soybean biodiesel blends (containing 0%, (B00), 10% (B10), 20% (B20), 50% (B50), and 100% (B100) biodiesel by volume). The primary PM emissions were sampled using Teflon-coated fiberfilm filters. Laboratory PAHs, FAMEs, and B20 exhaust PM were exposed to ~0.4 ppm ozone for time periods ranging from 0-24 hours in order to study the effect of FAMEs and biodiesel exhaust PM on the ozonolysis of PAHs. Organic chemical analysis of samples was performed using gas chromatography/mass spectrometry (GC/MS). PAHs, carbonyls, FAMEs, and n-alkanes were quantified in the exhaust PM of petrodiesel, WVO and soybean fuel blends. The emission rates of the total PAHs in B10, B20, B50, and B100 exhaust PM decreased by 0.006-0.071 ng/µg (5-51%) compared to B00, while the emission rates for the FAMEs increased with increasing biodiesel content in the fuel. The emission rates of the total n-alkanes in B10, B20, B50, and B100 exhaust PM decreased by 0.5-21.3 ng/µg (4-86%) compared to B00 exhaust PM. The total emission rates of the aliphatic aldehydes in biodiesel exhaust PM (B10, B20, B50, and B100) increased by 0.019-2.485 ng/µg (36-4800%) compared to petrodiesel. The emission rates of the total aromatic aldehydes, total aromatic ketones, and total quinones all generally decreased with increasing biodiesel content in the fuel. With the exception of benzo[a]pyrene, the pseudo-first order ozone reaction rate constants of all the PAHs decreased by 1.2-8 times in the presence of the FAMEs. Phenanthrene, fluoranthene, and pyrene were the only PAHs detected in the B20 exhaust PM, and their ozone reaction rate constants were about 4 times lower than those obtained when the PAHs alone were exposed to ozone. The findings of this study indicate that there are both positive and negative effects to emissions associated with biodiesel use in light-duty diesel engines operating on transient drive cycle.
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15

Barthomeuf, Marie-Odile. "Etude par simulation de la chimie en phase gazeuse d'une couche limite atmospherique : influence des hydrocarbures legers et des hydrocarbures naturels sur la formation d'oxydants." Toulouse 3, 1988. http://www.theses.fr/1988TOU30098.

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La chimie en phase gazeuse des basses couches de l'atmosphere est regie par le cycle reactionnel des oxydes d'azote et des hydrocarbures. Les oxydes d'azote ont une origine anthropogenique liee aux combustions et aux activites industrielles et une origine naturelle liee a l'activite bacterienne des sols. De meme, pour les hydrocarbures, on note une composante anthropogenique et une composante naturelle due a des emissions a partir de la vegetation. Le travail presente a consiste a developper un modele lagrangien de chimie de l'atmosphere etudiant le comportement des gaz traces dans une atmosphere peu polluee, en presence d'hydrocarbures legers et naturels. Ce modele etudie l'evolution du profil vertical des composants dans une masse d'air se deplacant dans le sens de l'advection au-dessus d'une source homogene de grande surface, dans le cas d'une situation anticyclonique. Il traite a la fois l'aspect dynamique, parametrise par un profil de coefficients de diffusion, kz, variable en fonction du temps, et l'aspect chimique du probleme, qui considere les reactions en phase gazeuse homogene et comporte les chaines reactionnelles des oxydes d'azote et des hydrocarbures legers et naturels. L'introduction d'hydrocarbures legers dans le schema reactionnel conduit a une formation d'ozone d'autant plus importante que les teneurs en oxydes d'azote sont fortes. Pour de faibles sources de nox, l'introduction d'hydrocarbures biogeniques se traduit par un puits d'ozone, tandis que pour de fortes sources de nox, on note un accroissement des concentrations dans la masse d'air. L'introduction d'hydrocarbures legers et biogeniques se traduit egalement par une diminution des teneurs en hno::(3) et une augmentation des teneurs en produits pernitrates dans la masse d'air. Il ressort de cette etude que la cinetique chimique influe essentiellement sur l'evolution des concentrations des differents produits tandis que la dynamique, transfert vertical et depot au sol joue sur l'evolution de leur profil vertical
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16

Lannuzel, Frédéric. "Influence des aromatiques sur la stabilité thermique des pétroles dans les gisements." Phd thesis, Institut National Polytechnique de Lorraine - INPL, 2007. http://tel.archives-ouvertes.fr/tel-00473215.

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Cette étude vise à mieux comprendre les réactions mpliquées dans le craquage thermique des huiles en basins sédimentaires. Des pyrolyses d'octane, de toluène et de mélanges octane/toluène ont été effectuées entre 330°C et 450°C et des pressions allant de 1 bar à 700 bar. Le mécanisme radicalaire développé permet de rendre compte de l'influence de la température et de la pression sur la distribution des produits ainsi que sur la conversion jusqu'aux conditions de gisement (200°C, 150-1000 bar). Les pyrolyses du toluène pur et du mélange octane/toluène ont permis de modéliser le rôle inhibiteur des alkylaromatiques sur le craquage des hydrocarbures. Cette étude démontre l'importance des co-réactions et donc de la composition des huiles sur la stabilité thermique des pétroles en gisements.
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17

Bizot, Patrice. "Vers un système expert de conception de mécanismes réactionnels complexes en phase gazeuse : application à la pyrolyse et à l'oxydation de composés organiques." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL102N.

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Ce mémoire traite de la mise au point d'un logiciel de conception assistée par ordinateur de génération de mécanismes réactionnels complexes en phase gazeuse. Il est appliqué à des réactions thermiques de pyrolyse et d'oxydation de composés organiques, plus particulièrement d'alcanes et de molécules chlorées. Le logiciel est constitué: - d'une partie procédurale qui comprend un compilateur de notation linéaire, des procédures de canonicité des constituants et des fonctions de génération de processus élémentaires, - d'une partie système expert qui gère et coordonne l'ensemble en demandant à l'utilisateur les options de génération qu'il souhaite appliquer. Les mécanismes primaires générés peuvent être exhaustifs et/ou simplifiés à l'aide de règles qualitatives ou semi-quantitatives énoncées à priori et à posteriori
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18

Dauscher, Anne. "Etudes des reactions de rearrangement de squelette des hexanes sur des catalyseurs a base de platine en presence ou non d'interactions metal-support." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13032.

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19

Nobel, Dominique. "Coordinats fonctionnels en chimie des metaux de transition : synthese et reactivite, application a la telomerisation catalytique du butadiene et du dioxyde de carbone." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13109.

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20

Tellier, Frédérique. "Synthese et reactivite de dienes, enynes et styrenes fluores." Paris 6, 1986. http://www.theses.fr/1986PA066521.

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21

Ourari, Ali. "Étude de deux réactions d'électrocatalyse : hydrogénation électrocatalytique sur des films de polymères contenant des microparticules de métaux nobles et activation de l'oxygène par des complexes Mn(III) - bases de Schiff." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10171.

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Ce travail est relatif a l'etude de deux reactions d'electrocatalyse. La premiere partie concerne la mise au point de cathodes moleculaires, realisees par l'inclusion de microparticules de metaux nobles dans des films de polypyrrole fonctionnalise et a leur application en hydrogenation electrocatalytique. L'etude de l'hydrogenation de deux substrats test, le limonene et la carvone, a montre qu'il est possible d'orienter la selectivite de ces electrodes modifiees selon la nature du metal incorpore (pt, pd ou rh). Le resultat le plus significatif est que l'incorporation dans le meme film de polymere de deux metaux d'activite catalytique differente (pt + pd ou rh + pd) conduit a des cathodes dont l'efficacite et la selectivite sont largement superieures a celle des cathodes basees sur un seul metal. La deuxieme partie de ce travail est consacree a l'etude de l'activation electrochimique de l'oxygene par des complexes mn (iii) - bases de schiff. Il apparait que le complexe mn (ii) - salen substitue en 5,5 par des atomes de chlore est le catalyseur le plus stable et le plus efficace pour la reaction test d'epoxydation du cyclooctene. D'autre part, la rigidification du complexe par l'utilisation d'un pont 1,2-cyclohexylidene ou 1,2-phenylene reliant les deux motifs salicylaldehyde du ligand, a la place du groupe ethylidene ligand salen, entraine une forte diminution de l'activite catalytique des complexes correspondants. Ce systeme electrocatalytique a egalement ete applique a l'oxydation de la tetraline et de la triphenylphosphine
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22

Anderson, Rebecca S. "Carbon kinetic isotope effects in the gas-phase reactions of nonmethane hydrocarbons with hydroxyl radicals and chlorine atoms /." 2005. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR11544.

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Thesis (Ph.D.)--York University, 2005. Graduate Programme in Chemistry.
Typescript. Includes bibliographical references (leaves 178-194). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR11544
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23

Gomez, Elaine. "Tandem Reactions of Carbon Dioxide Reduction and Hydrocarbon Transformation." Thesis, 2019. https://doi.org/10.7916/d8-pvb5-rr62.

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High atmospheric concentrations of CO2 contribute to adverse effects that impact human health and the climate. The need to reduce CO2 is evident, and climate stabilization will require a combination of mitigation, utilization, and even negative emission technologies. Thus, one key approach will be to transform abundant CO2 into a useful feedstock for processes that not only produce value-added products but also match the scale necessary to impact anthropogenic emissions. The tandem CO2 reduction and light alkane transformation reactions over specialized bifunctional catalysts have the potential to produce olefins or synthesis gas by efficiently utilizing the C2-C4 components in shale gas while reducing a greenhouse gas. The reactions of CO2 with light alkanes may occur through two distinct pathways, oxidative dehydrogenation (CO2 + CnH2n+2 → CnH2n + CO + H2O, CO2-ODH) and dry reforming (nCO2 + CnH2n+2 → 2nCO + (n+1)H2, DR). The two reactions can occur simultaneously at temperatures ≥823 K with considerable conversions. Until recently, there has been little understanding regarding the identification of bimetallic catalytic systems that either selectively cleave the C-H bonds to produce olefins or effectively break all the C-C and C-H bonds to produce dry reforming products. In this work, we discuss a combined approach of flow reactor experiments, in situ characterization, and density functional theory (DFT) calculations to help create a design platform for catalysts that are inherently active and selective for the reactions of CO2 and light alkanes. Particularly, it was of interest to use propane as CO2 reduction feedstock due to its increasing abundance and highly marketable respective olefin. Through the combined approach, non-precious Fe3Ni1 and precious Ni3Pt1 supported on CeO2 were identified as promising catalysts for the CO2-ODH and DR of propane, respectively. In situ X-ray absorption spectroscopy measurements revealed the oxidation states of metals under reaction conditions and DFT calculations were utilized to identify the most favorable reaction pathways over the two types of catalysts. While both the CO2-ODH and DR reactions of alkanes produce valuable molecules, the separation of gas phase products is challenging. Therefore, it was highly desirable to develop a tandem reaction scheme in which the reaction of CO2 and alkanes can produce liquid products. Another potential chemistry with increased similarity to the operating conditions of CO2-ODH, is the tandem reactions of CO2-assisted oxidative dehydrogenation and aromatization of light alkanes (CO2-ODA). In this process, alkanes are transformed directly into aromatics without the need for expensive naphtha while increasing the consumption of CO2 per mol of value-added product and facilitating downstream separation because of the production of liquid aromatics. One critical change upon the introduction of CO2 to the dehydrogenation/aromatization pathway is the formation of water. The presence of water under reaction conditions has been shown to be problematic for zeolites as it causes changes in the framework. Phosphorous modification at an optimal loading improved the hydrothermal stability of Ga/ZSM-5, reduced coke formation on the catalyst surface, and allowed for the formation of more liquid aromatics through the CO2-ODAE reaction pathway compared to the direct dehydrogenation and aromatization reaction. With the aid of DFT calculations, the mechanisms for the production of aromatics from ethane were identified, providing insight on the effect of Ga modification on ethylene formation over ZSM-5 as well as the role of CO2 on the aromatization of ethylene. Future efforts should be geared toward enhancing aromatics yield through the design of hydrothermal stable zeolite-based materials with bimetallic active centers that are capable of activating CO2.
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24

Irani, Karishma. "Characterization of Competitive Oxidation Reactions Over a Model Pt-Pd/Al2O3 Diesel Oxidation Catalyst." Thesis, 2009. http://hdl.handle.net/10012/4419.

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There has been a growing interest in using lean-burn engines due to their higher fuel economy and associated lower CO2 emissions. However, there are challenges in reducing NOX in an O2-rich (lean-burn) exhaust, and in low temperature soot oxidation. NOX storage/reduction (NSR) and selective catalytic reduction (SCR) are commercial NOX reduction technologies, and both are more efficient with levels of NO2 that are higher than those that are in engine exhaust (engine-out NO2 levels are ~10% of the total NOX). Therefore diesel oxidation catalysts are installed upstream of these technologies to provide NO2 through NO oxidation. The motivation behind this research project was two-fold. The first was to gain a better understanding of the effect of hydrocarbons on NO oxidation over a monolithic diesel oxidation catalyst. The second was to spatially resolve competitive oxidation reactions as a function of temperature and position within the same diesel oxidation catalyst (as that used in the first part). A technique known as spatially resolved capillary-inlet mass spectrometry (SpaciMS) was used to measure the gas concentrations at various positions within the catalyst. Diesel engine exhaust contains a mixture of compounds including NO, CO and various hydrocarbons, which react simultaneously over a catalyst, and each can influence the oxidation rates of the others. While studying the effect of hydrocarbons on NO oxidation in this project, propylene was found to have an apparent inhibition effect on NO oxidation, which increased with increasing propylene concentration. This apparent inhibition is a result of the NO2, as a product of NO oxidation, reacting with the propylene as an oxidant. Experiments with NO2 demonstrate a significant temperature decrease in the onset of NO2 reduction when propylene was present, which decreased further with increasing amounts of propylene, verifying NO2 as an oxidant. Similar results were observed with m-xylene and dodecane addition as well. The results also demonstrate that NO2 was consumed preferentially relative to O2 during hydrocarbon oxidation. With low inlet levels of O2, it was evident that the addition of NO2 had an apparent inhibition effect on propylene oxidation after the onset of NO2 reduction. This subsequent inhibition was due to the NO formed, demonstrating that C3H6 results in reduced NO2 outlet levels while NO inhibits C3H6 oxidation. The development of new models as well as validation of existing models requires the ability to spatially resolve oxidation reactions within a monolith. Spatially-resolved data will also give catalyst manufacturers insight into the location of active fronts, thereby directing the design of more efficient catalysts. In this research project, spatially resolving the oxidation reactions demonstrated that H2 and CO are oxidized prior to C3H6 and C12H26 and clearly show back-to-front ignition of the reductant species. An enhancement in NO oxidation was observed at the same time as dodecane oxidation light off, likely related to dodecane partial oxidation products.
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25

(6594134), Jeremy M. Manheim. "MASS SPECTROMETRY IONIZATION STUDIES AND METHOD DEVELOPMENT FOR THE ANALYSIS OF COMPLEX MIXTURES OF SATURATED HYDROCARBONS AND CRUDE OIL." Thesis, 2020.

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Crude oil is a mixture of hydrocarbons so complex that it is predicted to comprise as many compounds as there are genes in the human genome. Developing methods to not only recover crude oil from the ground but also to convert crude oil into desirable products is challenging due to its complex nature. Thus, the petroleum industry relies heavily on analytical techniques to characterize the oil in reservoirs prior to enhanced oil recovery efforts and to evaluate the chemical compositions of their crude oil based products. Mass spectrometry (MS) is the only analytical technique that has the potential to provide elemental composition as well as structural information for the individual compounds that comprise petroleum samples. The continuous development of ionization techniques and mass analyzers, and other instrumentation advances, have primed mass spectrometry as the go-to analytical technique for providing solutions to problems faced by the petroleum industry. The research discussed in this dissertation can be divided into three parts: developing novel mass spectrometry-based methods to characterize mixtures of saturated hydrocarbons in petroleum products (Chapters 3 and 5), exploring the cause of fragmentation of saturated hydrocarbons upon atmospheric pressure chemical ionization to improve the analysis of samples containing these compounds (Chapter 4), and developing a better understanding of the chemical composition of crude oil that tightly binds to reservoir surfaces to improve chemically enhanced oil recovery (Chapter 6).

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26

KHALED, Fethi. "Reactivity of Hydrocarbon Fuels: Reaction Kinetics and Ignition Delay Times." Diss., 2018. http://hdl.handle.net/10754/630072.

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This PhD thesis is an analysis of the chemical kinetics and oxidation behavior of fuel components via experiments and correlations. First, a number of experimental studies of the reactivity of OH radicals with unsaturated hydrocarbons are performed at temperatures ranging from 294 to 1400 K by OH absorption and laser induced fluorescence techniques in two different reactors: shock tube and flow reactor. It is found that OH has a tendency to add to the unsaturated CC bond, forming a relatively stable adduct. The thermal stability of these adducts is vital for a better understanding of the kinetics of olefins, poly-olefins, alkynes and other unsaturated components in real and surrogate fuel blends. In this work, the reaction rate coefficient of the reaction of hydroxyl radical with many olefins (butenes, pentenes, hexenes), di-olefins (butadienes, and pentadienes) and allyl radical are measured. A strong competition between H-abstraction and OH-addition pathways is seen particularly in the intermediate temperature window of ~ 400 to 900 K. All of these measured elementary reactions give new insights into the chemical kinetics of fuels and allow modelers to improve the predictive capability of their models. Second, measurements of the ignition delay times of propene, isobutene, 2-methylhexane and 2-methylbutanol in air are performed using a high-pressure shock tube. Details about multi-stage ignition and ignition delay dependence on various thermodynamic properties is investigated for these four hydrocarbons. We followed this with a correlation study of ignition delay times of fuel blends and real fuel streams. The main requirement of these correlations is that these should be predictive enough to compete with the predictive capabilities of detailed chemical kinetic models but at a much reduced computational cost. The obtained correlation scheme does not only predict ignition timing during CFD simulations but also other combustion properties such as low-temperature heat release timing and resulting temperature and pressure increases due to cool flame. A discussion on the weak dependence of high-temperature ignition delay times on the composition of real fuels is also presented, where universal Arrhenius type expressions of ignition delay times of gasoline, diesel and jet fuels are given.
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27

Oh, Harry Hyunsuk. "C3H6/NOx Interactions Over a Diesel Oxidation Catalyst: Hydrocarbon Oxidation Reaction Pathways." Thesis, 2012. http://hdl.handle.net/10012/6894.

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C3H6 oxidation over a Pt/Al2O3 catalyst with or without NOx present was investigated. In particular, its reaction mechanism was studied using diffuse reflectance infrared spectroscopy (DRIFTS), a reactor system designed for monolith-supported catalysts and a micro-reactor system designed for powder catalysts referred to as CATLAB. These experiments reveal that C3H6 oxidation is inhibited by the presence of NO, NO oxidation is inhibited by the presence of CeH6, and that adsorbed NOx can react with gas phase C3H6. DRIFTS and CATLAB results confirm the reaction between C3H6 and nitrates, which are formed during NOx adsorption, with linear nitrites observed as reaction products. Therefore, a reaction route is proposed for C3H6 oxidation in the presence of NOx, namely, nitrates acting as oxidants. Using NO2 instead of NO, or using a high NOx/C3H6 ratio, which is beneficial for nitrate formation, favors this reaction pathway. Data also showed that Pt is required for this reaction, which suggests the nitrates in proximity to the Pt particles are affected/relevant. Reaction kinetics studies of C3H6 oxidation over Pt/Al2O3 and Pt/SiO2 catalysts were performed in CATLAB using a temperature-programmed oxidation method with different oxidants: O2, NO2 and nitrates. The reaction kinetics of these possible reactions were compared in order to determine which reaction is more important. NOx adsorption does not occur on the SiO2 surface so the reaction between C3H6 and NO2 could be isolated and the effect of nitrates could be observed as well when compared to the results from Pt/Al2O3. The Pt dispersions were determined using H2 chemisorption and were 1.3 and 1.6% for Pt/Al2O3 and Pt/SiO2, respectively. C3H6 oxidation starts at a lower temperature with O2 than with NO2 but the activation energy was lower with NO2. This gives indication that hydrocarbons must be activated first for NO2 to be favored in hydrocarbon oxidation. When the experiment was done with C3H6 and nitrates, the reaction did not occur until NOx started to desorb from the catalyst at higher temperatures, when nitrates become unstable and decompose. Therefore, O2 was added to the system and the reaction began at even lower temperature than with just C3H6 and O2. This proved that hydrocarbons need to be activated in order for surface nitrates to affect C3H6 oxidation and this reaction also resulted in a lower activation energy than with just C3H6 and O2. Nitrate consumption was also observed as less NOx desorbed from the catalyst at the later stage of the temperature ramp compared to the amount desorbed when the catalyst was not exposed to C3H6.
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28

(11190201), Jacob R. Milton. "ION-MOLECULE REACTIONS STUDIED BY USING DENSITY FUNCTIONAL THEORY CALCULATIONS AND MASS SPECTROMETRY FOR SATURATED HYDROCARBON ANALYSIS AND THE STUDY OF ORTHO- AND PARA-PYRIDYNES." Thesis, 2021.

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The work described herein is related to gas-phase ion-molecule reactions studied by using mass spectrometry. Chapter 2 describes density functional theory, a method used in chapters 4 and 5 to propose reaction mechanisms for reactions previously observed by others by using mass spectrometry. Chapter 3 describes a study that demonstrates that the fragmentation of saturated hydrocarbons occurs due to proton-transfer reactions that occur between these species and protonated molecules generated from molecules present in air such as nitrogen and water. Saturated hydrocarbons are studied in a wide variety of fields, and better methods to analyze complex mixtures of these compounds would facilitate their analysis. Chapter 4 discusses mechanisms of reactions for previously studied ion-molecule reactions of pyridynes studied by others by using mass spectrometry. Reactions of pyridynes are important to study arynes have been previously used in organic synthesis, and pyridine moieties are particularly common in biological compounds. Chapter 5 discusses density functional theory calculations used to determine why some organic polyradical undergo hydride abstractions from cyclohexane while others do not. The study discusses reactions taking place between both singlet and triplets states of the 2,5-didehydropyridinium cation and cyclohexane as a model, which are compared to reactions of the 2-pyridyl cation and 2-dehydropyridinium cation with cyclohexane. These studies may help improve our understanding of the reactivity-controlling factors of organic polyradicals, which may help improve toxic drug candidates like cytostatic enediynes.
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29

Karimi, Abdullah. "Numerical study of hot jet ignition of hydrocarbon-air mixtures in a constant-volume combustor." Thesis, 2014. http://hdl.handle.net/1805/6249.

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Indiana University-Purdue University Indianapolis (IUPUI)
Ignition of a combustible mixture by a transient jet of hot reactive gas is important for safety of mines, pre-chamber ignition in IC engines, detonation initiation, and in novel constant-volume combustors. The present work is a numerical study of the hot-jet ignition process in a long constant-volume combustor (CVC) that represents a wave-rotor channel. The mixing of hot jet with cold mixture in the main chamber is first studied using non-reacting simulations. The stationary and traversing hot jets of combustion products from a pre-chamber is injected through a converging nozzle into the main CVC chamber containing a premixed fuel-air mixture. Combustion in a two-dimensional analogue of the CVC chamber is modeled using global reaction mechanisms, skeletal mechanisms, and detailed reaction mechanisms for four hydrocarbon fuels: methane, propane, ethylene, and hydrogen. The jet and ignition behavior are compared with high-speed video images from a prior experiment. Hybrid turbulent-kinetic schemes using some skeletal reaction mechanisms and detailed mechanisms are good predictors of the experimental data. Shock-flame interaction is seen to significantly increase the overall reaction rate due to baroclinic vorticity generation, flame area increase, stirring of non-uniform density regions, the resulting mixing, and shock compression. The less easily ignitable methane mixture is found to show higher ignition delay time compared to slower initial reaction and greater dependence on shock interaction than propane and ethylene. The confined jet is observed to behave initially as a wall jet and later as a wall-impinging jet. The jet evolution, vortex structure and mixing behavior are significantly different for traversing jets, stationary centered jets, and near-wall jets. Production of unstable intermediate species like C2H4 and CH3 appears to depend significantly on the initial jet location while relatively stable species like OH are less sensitive. Inclusion of minor radical species in the hot-jet is observed to reduce the ignition delay by 0.2 ms for methane mixture in the main chamber. Reaction pathways analysis shows that ignition delay and combustion progress process are entirely different for hybrid turbulent-kinetic scheme and kinetics-only scheme.
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