Dissertationen: „Thermochemical and kinetic studies“

1

Khan, Mohammad A. „Thermochemical kinetic studies of organic peroxides relevant to the combustion of hydrocarbons“. Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.290241.

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In the combustion of fuels and related organic compounds the initial step consists of a free radical forming process occurring either homogeneously or heterogeneously, such as RH + O_{2 → R + HO}_2 (1) The radical R, reacts with oxygen to produce an alkyl or other peroxy radical: R + O_2 ↔ RO₂ (2) One of the controversies involved in the mechanism for the oxidation of hydrocarbons is the route for the unimolecular decomposition of the hydroperoxy alkyl radical (R_-HOOH). This would be produced as a result of the isomerisation of the alkyl peroxy radical (RO₂). There are three possible unimolecular paths for R_-HOOH together with the addition of oxygen to form hydroperoxy alkyl peroxy radical. This study is concerned with the generation of an alkyl peroxy alkyl radical and its decomposition to both epoxide and olefin formation and at lower temperatures predominantly follows the thermochemically more favourable route. No direct information is available about the rate constants of the two decomposition routes of alkyl peroxyalkyl/hydroperoxy alkyl radicals. There are different ways to find out the rate constants for the decomposition of alkyl peroxy alkyl/hydroperoxy alkyl radical to olefin and oxirane. One such way was a study of the gas phase, hydrogen chloride catalysed decomposition of di-t-butyl peroxide. A surrogate hydroperoxy alkyl radical was generated via this study and the most favourable route for the decomposition of dtBP_-H is confirmed. Again, on thermochemical grounds, the formation of isobutene oxide predominates over the formation of isobutene. The modelling of this study assisted considerably in choosing the reaction steps for a probable mechanism and in the assessment of rate parameters for the individual steps. A bonafide hydroperoxy alkyl radical was generated via the study of the sensitized decomposition of t-butyl hydroperoxide in an uncoated, coated reaction vessel and also in the presence of oxygen. The Arrhenius parameters for the ratio of the rate of formation of isobutene to isobutene oxide was observed experimentally, and are in good agreement with the estimated values in the coated reaction vessel but in uncoated and in the presence of oxygen, this ratio is nearly doubled which suggests that isobutene is formed heterogeneously and surface played an important role. In order to observe the effect of surface: volume ratio on product formation, this system was studied in four different coated reaction vessels and it was concluded that the surface effect was negligible on a coated spherical reaction vessel. The bond dissociation energy DH^o(RO-OH) in alkyl hydroperoxides, is important because the value of the rate constant is critical to cool flames production. The pyrolysis of t-butyl hydroperoxide was carried out, in a bath of isobutane in order to isolate the tBuO-OH bond breaking step. Acetone formation constituted a direct measure of the rate of decomposition of t-butyl hydroperoxide. The O-O bond dissociation energy was found experimentally, which is in good agreement with other group workers values.

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2

Davies, Joanne Wendy. „Studies of gas-phase radical reactions“. Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329952.

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3

Stewart, Paul Hendry. „Theoretical and experimental studies of unimolecular reactions relevant to combustion and the atmosphere“. Thesis, University of Aberdeen, 1986. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU366734.

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The pyrolysis of methyl nitrite (1 torr) in the presence of nitrogen dioxide (1 torr) was studied at 458K over the pressure range 0-760 torr of carbon tetrafluoride. The only detectable products were methyl nitrate and formaldehyde. The decomposition can be described by the following simple mechanism: CH₃ONO + M → CH₃O + NO + M (1); CH₃O + NO₂ → CH₃ONO₂ (2); CH₃O + NO₂ → HCHO + HONO (3). Step (1) was found to be stongly pressure dependent with a P½ value of 760 torr. The rate constant for decomposition k₁ was found from RRKM modelling to be given by the following expression: log (k₁/s⁻¹) = 15.89 - 8879/T. The ratio k₃/k₂ was determined over the pressure range and was also found to be pressure dependent. This was attributed to the pressure dependence of step (2). Estimates were also made for the ratio of disproportionation to combination for the reaction between nitric oxide and the methoxy radical. This ratio was also found to be strongly pressure dependent. The pyrolysis of perfluoroazo-2-propane, PAP, (25 torr) was studied over the temperature range 450-514K. The products were nitrogen and perfluorohexane, PFH, which were produced in equal amounts. The production of nitrogen was found to be first order with respect to the azo compound. First order kinetics were observed even for extents of reaction exceeding 60%. No surface effects were observed. The reaction was pressure independent. i-C₃F₇N²i-C₃F₇ → i-C₃F₇N₂ + i-C₃F₇ (4). The rate constant for decomposition, k₄, was found to be given by the following expression: log(k₄) = 16.74 - 9856/T. The pyrolysis of formaldehyde (4-10 torr) was studied using a static system over the temperature range 705-773K and 150-760 torr of carbon dioxide. Methane (4-10 torr) was used as an inert marker. Preliminary experiments showed that methane did not decompose under these experimental conditions. The only measurable products were hydrogen and carbon monoxide. No pressure dependence was observed, even at the highest temperatures studied. The rate of formation of products was found to be 1.04 ± 0.05 with respect to formaldehyde. From this the reaction was taken to be first order. The addition of small concentrations of toluene was found to markedly reduce the rate of formation of products. There did not appear to be any surface effects, indicating that the reaction was homogeneous.

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4

Fiagome, Elizabeth Delanyo. „Thermochemical studies of some iodates“. Thesis, Teesside University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387140.

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5

Chatre, Lucas. „Étude et modélisation des phénomènes de transport et réactionnels dans un four à vis“. Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASB034.

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Les convoyeurs à vis sont très largement utilisés dans l'industrie chimique. Du fait de leur capacité de mélange et de transport, ils sont mis en œuvre pour différentes applications (convoyage, séchage, pyrolyse, etc.). Cette technologie se voit ainsi utilisée dans le retraitement de matière nucléaire, notamment pour stabiliser des oxalates de plutonium en oxyde. De nombreuses études ont été menées à l'échelle du laboratoire afin d'établir précisément les mécanismes réactionnels par analyse thermogravimétrique (ATG) et les propriétés physico-chimiques des espèces mises en jeu. Il s'agit de réactions de décomposition thermique de chaînes carbonées couplées en phase hétérogène (réactions solide/gaz). Dans un four à vis, les phénomènes de transfert de chaleur, de matière et de quantité de mouvement peuvent significativement modifier la vitesse de réaction apparente et par conséquent l'avancement de la calcination. L'objectif de ce travail est d'améliorer un outil de simulation phénoménologique, permettant de transposer vers les plus grandes échelles les résultats des études menées en ATG sur de petites quantités de poudre supposées uniformes à chaque instant en composition et en température. Ce travail est réalisé en uranium, utilisé comme simulant du plutonium.L'outil de simulation est basé sur un modèle compartimenté, lié à l'hydrodynamique des poudres dans le réacteur. Ainsi, une majeure partie de la thèse se focalise sur l'écoulement à l'échelle globale et locale. Pour le mélange global, le point de débordement, caractérisant le changement de régime hydrodynamique, a été identifié. La Distribution des Temps de Séjour (DTS) a également été mesurée. Des modèles adimensionnels ont été élaborés pour prédire à la fois le point de débordement et la forme de la DTS. Pour le mélange local, deux études expérimentales ont été menées, en utilisant un système optique et des outils de traitement d'images. La première s'est intéressée au renouvellement de la surface du lit de poudre et la seconde au renouvellement des particules dans l'entrefer vis-tube. Ces études hydrodynamiques permettent de mieux comprendre et donc modéliser, respectivement les interactions gaz/solide et solide/paroi. Des modèles adimensionnels ont été développés pour prédire ces paramètres caractéristiques. Enfin, l'écoulement des poudres a pu être étudié en détail grâce à la modélisation de la rhéologie par mécanique des fluides numériques (CFD). En premier lieu, le modèle d'écoulement et ses paramètres ont été calibrés à partir de mesures expérimentales obtenues dans un tambour tournant ; appareil de géométrie plus simple et où la dynamique des poudres est similaire à celle observée dans un convoyeur à vis. Ce modèle a par la suite été confronté avec succès aux mesures expérimentales réalisées sur les maquettes à l'échelle pilote. Au final, le modèle a pu fournir des informations sur des données difficilement accessibles expérimentalement au sein d'un convoyeur à vis, comme l'épaisseur de la surface active ou les vitesses d'écoulement à l'intérieur de la poudre.Des études en ATG couplée à une analyse de calorimétrie différentielle à balayage (ATG/DSC) ont été menées afin d'obtenir des données cinétiques et thermochimiques robustes sur la calcination de l'oxalate d'uranium sous atmosphère oxydante et inerte, ainsi que sur la conversion de l'UO2 en U3O8. Enfin, les signaux ATG obtenus expérimentalement ont pu être modélisés, validant les paramètres cinétiques.L'outil de simulation du four à vis a été amélioré grâce à une meilleure représentation des phénomènes ayant lieu dans ce type de réacteur pendant la calcination de l'oxalate d'uranium. Ces améliorations permettent d'avoir accès aux différents profils de température et de concentration de toutes les espèces dans différentes zones prédéfinies. L'outil de simulation est capable de prédire des données expérimentales mesurées sur le four à vis pilote
Screw conveyors are widely used in the chemical industry. Thanks to their mixing and transport capacity, they are used for a variety of applications (conveying, drying, pyrolysis, etc.). This technology is also used in the reprocessing of nuclear materials, in particular to stabilise plutonium oxalates into oxides. Numerous studies have been carried out on a laboratory scale to establish precisely the reaction mechanisms using thermogravimetric analysis (TGA) and the physico-chemical properties of the species involved. The reactions involved are thermal decomposition of coupled carbon chains in a heterogeneous phase (solid/gas reactions). In a screw kiln reactor, heat, mass and momentum transfer phenomena can significantly modify the apparent reaction rate and consequently the progress of the calcination. The aim of this work is to improve a phenomenological simulation tool, enabling the transposition to larger scales the results of studies carried out in TGA on small quantities of powder assumed to be uniform in composition and temperature at all times. This work is carried out in uranium, used as a simulant for plutonium.The simulation tool is based on a compartment model, linked to the hydrodynamics of the powders in the reactor. Thus, a major part of the thesis focuses on the flow at the global and local scales. With regard to global mixing, the overflow point, which characterises the change in hydrodynamic regime, has been identified. The Residence Time Distribution (RTD) was also measured. Dimensionless models were developed to predict both the overflow point and the shape of the RTD. Concerning the local mixing, two experimental studies were carried out, using an optical system and image processing tools. The first one looked at the renewal of the surface of the powder bed, while the second one at the renewal of the particles within the screw-tube clearance. These hydrodynamic studies will allow a better understanding and a modeling of gas/solid and solid/wall interactions respectively. Dimensionless models have been developed to predict these characteristic parameters. Finally, the powder flow was studied in detail by modelling the rheology using Computational Fluid Dynamics (CFD). First, the flow model and its parameters were calibrated using experimental measurements obtained in a rotating drum, a device with a simpler geometry and where the powder dynamics are similar to those observed in a screw conveyor. This model was then successfully compared with the experimental measurements carried out on the pilot-scale models. In the end, the model was able to provide information on data that is difficult to access experimentally within a screw conveyor, such as the thickness of the active layer or the flow velocities within the powder.TGA coupled with differential scanning calorimetry (TGA/DSC) studies were carried out to obtain robust kinetic and thermochemical data on the calcination of uranium oxalate in an oxidising and inert atmosphere, as well as on the conversion of UO2 to U3O8. Finally, the TGA signals obtained experimentally were modeled to validate the kinetic parameters.The screw kiln reactor simulation tool has been improved with a better representation of the phenomena taking place during the calcination of uranium oxalate in such apparatus. These improvements give access to the different temperature and concentration profiles of all the species in different predefined zones. The simulation tool is capable of predicting experimental data measured on the pilot screw kiln reactor

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6

Aubry, Christiane. „Thermochemical and mass spectrometric studies of gas phase ions“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq26103.pdf.

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7

Huynh, Kathy Tang. „Gas-Phase Thermochemical Properties of Proline-Containing Dipeptides and Fluorinated Alcohols using the Extended Kinetic Method“. W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1539626981.

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8

Dasopoulos, P. „Thermochemical studies of siliceous zeolites for vapour phase adsorption processes“. Thesis, University of Surrey, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374206.

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9

Hall, I. W. „Kinetic studies of atmospheric reactions“. Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236263.

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10

Hindmarsh, Kathryn. „Kinetic studies of platinum complexes“. Thesis, University of Canterbury. Chemistry, 1998. http://hdl.handle.net/10092/8647.

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Since the chance discovery, in 1967, of the anti-tumour activity of cisplatin, cis-dichlorodiammineplatinum(II), research has focussed on studying the reactions of this and other related complexes in an effort to elucidate the nature of the biological activity. This thesis presents a study of the aqueous solution chemistry of some platinum(II) and platinum(IV) complexes in order to extend what is known about the simple chemistry of this biologically important class of compounds. The chloride ion anation of diaqua (cis-[Pt(OH₂)₂(N)₂]²⁺) complexes is investigated as is the bromide ion anation of the bromoaqua (cis-[PtBr(OH₂)(N)₂]⁺) and diaqua (cis-[Pt(OH₂)₂(N)₂]²⁺) species, all in 1.0 M HC1O₄. The kinetics are studied using UV/Vis spectroscopic methods - both conventional and stopped-flow. High-pressure stopped-flow is used for selected reactions to determine the effect of pressure on the anation process. The collective data are used to calculate activation parameters from which conclusions are drawn as to the mechanism of the reaction. The redox kinetics of the platinum(II)/platinum(IV) couple are investigated using a variety of redox agents. These data provide a basis on which to form mechanistic interpretations for both the oxidation and reduction processes. Extrapolations are made to the biological system for the reduction of anti-tumour active platinum(IV) drugs. Platinum(IV) complexes are known to be very inert. An investigation into the base hydrolysis of platinum(IV) complexes is presented and a mechanism proposed.

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11

Jones, J. „Kinetic studies on NADsup(+):ADPribosyltransferase“. Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372662.

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12

Wong-Pascua, David Han Yen. „Kinetic studies of carotenoid degradation“. Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12389/.

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Carotenoids are a diverse family of naturally occurring pigments that are produced by plants, photosynthetic bacteria and certain fungi. Their biological roles within these organisms include the quenching of reactive oxygen species, acting as accessory pigments in photosystems and the colouration of flowers and fruits. Although mammals do not produce carotenoids, they may be obtained through the diet. Numerous health benefits in humans have been found to be associated with carotenoid containing diets, such as the maintenance of cardiovascular health and protection against degenerative eye diseases. These discoveries have led to an interest in ways to increase the stability of carotenoids within foodstuffs. Contrary to the vast majority of studies involving carotenoids, the detergency industry is interested in finding solutions to decolourise carotenoid containing stains. Carotenoid stains are usually composed of oily hydrophobic soils that adhere strongly to fabrics and sequester away from water. Due to the difficulty in complete removal of carotenoid stain material from fabric and the strong colouration of carotenoids, the detergency industry has adopted the approach of making the stain less perceivable through bleaching rather than attempting to eliminate all stain material. Although processes involved in the oxidative degradation of carotenoids are well established and there are numerous investigations of carotenoid decomposition in foodstuffs, quantitative studies of factors influencing the bleaching of carotenoids under conditions relevant to an aqueous washing environment are scarce. We have performed a quantitative study of the effect of fatty acid, surfactant and pH on the bleaching of β-carotene in oil-in-water emulsions. Experiments were monitored using UV-Vis spectrophotometry and focussed on quantifying initial rates of oxidation of fatty acid (a process closely related to carotenoid oxidative degradation) and the bleaching of β-carotene. Linoleic acid was found to autoxidise faster at lower pH while the bleaching of β-carotene in the presence of linoleic acid was found to proceed more faster at neutral pH. Experiments were performed in the absence and presence of lipoxygenases (LOXs) from soybean. These enzymes promote the bleaching of carotenoids by accelerating the formation of hydroperoxide bleaching species from polyunsaturated fatty acids. LOXs are known to be relatively slow, however, a study in the literature has reported that a bleaching synergy exists between two isozymes, LOX1 and LOX3. The activities of LOX1 and LOX3 linoleic acid oxidation and β-carotene degradation were quantified and found to be pH and surfactant dependent. Combinations of these enzymes were used to quantified this synergy under a range of conditions. To complement bleaching experiments in microemulsion solutions, work was performed at P&G Newcastle to investigate factors influencing the bleaching of carotenoid stains on fabrics. Stain decolourisation was quantified by stain removal index (SRI) values obtained by DigiEye. The effect of concentration of linoleic acid and α-tocopherol (a powerful antioxidant) in stain material was found to show correlation with results obtained from solution bleaching experiments and confirmed that the majority of fatty acid dependent bleaching of carotenoids on fabric is reliant on a radical mechanism. A study of the effect of fabric type and treatment discovered that stain removal in the wash was more facile on hydrophilic fabric, however, bleaching of carotenoid stain material after the wash appeared to be faster on hydrophobic materials. In experiments monitoring the bleaching of carotenoid containing microemulsions in the presence of fabric, cotton and polycotton were found to strongly inhibit the bleaching process while polyester slowed the rate but not the extent of bleaching. A side project, involved the preliminary study of the hydrolysis of triethyloxonium tetrafluoroborate, a commercially available alkylating agent, usually restricted to use in dry organic solvents. Preliminary results showed a pH independent region from pH 2 to 10. A pH dependent region was discovered above pH 10, however, reactions proceeded too rapidly to quantify rate constants. Hydrolysis rate constants were also measured in 50% acetonitrile with rate constants almost identical to those in 100% water.

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13

Jouvelet, Benjamin. „Kinetic studies of supramolecular polymer“. Paris 6, 2013. http://www.theses.fr/2013PA066102.

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Appropriately designed bis-urea monomers dissolved in apolar solvent self-assembled through intermolecular hydrogen bonds into two distinct aggregates. Simple filaments with one monomer in the cross-section are formed at high temperature, although tubes with three bis-ureas in the cross section are formed at low temperature. These two aggregates self-assembled in a highly cooperative fashion and are in dynamic equilibrium with free monomers in solution. Kinetic studies were conducted on this system to determine different mechanistic purposes. By using chiral bis-urea monomers, supramolecular chirality was used to assess the exchange mechanism of material between the self-assembled tubes. The thermal transition between filaments and tubes is a reversible and very sharp process. A monomer with a precise moiety exhibits a strong hysteresis: the transition from tube-to-filament is fast, on the contrary the inverse transition is a very slow process. This particularly property was analysed towards differential scanning calorimetry and infrared spectroscopy. The chiral versions of this monomer induces a kinetic chiral self-sorting during the filament-to-tube transition. By mixing two competing chiral monomers, the resulting supramolecular chirality was a counter-intuitive combination of the homopolymers: a small amount of the "dominant" monomer is sufficient to "inverse" the orientation of the major (but "recessive") monomer in the mixed tubes
Dissous dans un solvant apolaire, des monomères de type bis-urées s'autoassemblent par liaisons hydrogènes en deux aggrégats distincts. De simples filaments présentant un unique monomère dans la section se forment à température élevée, à l'inverse des tubes avec trois bis-urées par section se forment à plus basse température. Ces deux structures supramoléculaires s'auto-assemblent de manière coopérative et sont en équilibre dynamique avec les monomères libres en solution. Des études cinétiques ont été menées sur ce système pour en déduire plusieurs mécanismes. En utilisant des monomères chiraux, la chiralité supramoléculaire induite a été exploitée pour accéder au mécanisme d'échange des monomères entre les tubes. La transition thermique entre les filaments et les tubes est un processus réversible et véloce. Un monomère présentant une architecture particulière induit un phénomène d'hystérésis important: la transition du tube vers le filament est rapide, à l'inverse la transition du filament vers le tube est un processus très lent. Cette propriété a été étudiée par analyse enthalpique différentielle et par spectroscopie infrarouge. La version chirale de ce monomère induit un phénomène d'auto-ségrégation métastable durant la transition du filament vers le tube. Il a été montré qu'en mélangeant deux monomères chiraux compétiteurs, la chiralité supramoléculaire résultante est une combinaison paradoxale de la chiralité des homopolymères: une faible quantité du monomère "dominant" est suffisante pour "inverser" l'orientation du monomère majoritaire (mais récessif) dans les tubes mélangés

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14

Ruzicka, Alexander Marion. „Petrologic-kinetic studies of meteorites“. Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/187466.

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This dissertation presents the results of six published and submitted papers covering various petrologic and kinetic studies of meteorites. The principal topic was the formation of mineralogically layered structures by diffusion-controlled reactions during metamorphism or metasomatism. Previous steady-state models for forming mineral layers by metasomatism were modified to make such models more versatile. These models were used in conjunction with chemical and petrographic data obtained with microprobe, scanning-electron-microscopy (SEM), and optical microscopy techniques to study (1) olivine coronas in mesosiderites and (2) layers associated with Ca-Al-rich inclusions (CAIs) in carbonaceous chondrites. CAI layers occur both near the margins of coarse-grained CAIs as "rims", and throughout the interiors of fine-grained CAIs, and the data strongly suggest that the processes for forming rims and fine-grained CAIs were essentially the same. A wide variety of otherwise puzzling textural, mineralogical, and phase composition data for olivine coronas and CAI layers can be explained if these layer structures formed by coupled reaction-diffusion processes. Olivine coronas formed by the reaction of olivine mineral clasts with surrounding mesosiderite-like matrix during high-temperature metamorphism in the near-surface region of the mesosiderite parent body. CAI layers appear to have formed in part by the reaction of melilite-rich CAIs with a surrounding environment that consisted mainly of Mg-Si-rich gas and forsteritic olivine in a probable nebular setting. There is evidence that steady-state growth models for the CAI layers are oversimplified, and that a steady-state condition was not fully attained. Unrelated petrologic studies were also performed for (1) a large, distinctive Si-rich clast in the Bovedy (L3) ordinary chondrite, and (2) a "new" L6 chondrite, Nullarbor 018, that was discovered in Australia. The Si-rich clast was studied with SEM, microprobe, and neutron activation analysis techniques in addition to a collaborative effort to determine its O-isotopic composition. These data suggest that the clast is a complex igneous differentiate that formed on a parent body that was initially similar to, but distinct from, ordinary chondrites.

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15

Hischier, Illias. „CO₂ splitting via a solar thermochemical cycle based on Zn/ZnO redox reactions: thermodynamic and kinetic analysis“. Zürich : ETH, Swiss Federal Institute of Technology Zurich, Institute of Energy Technology, 2008. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=360.

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16

Villano, Stephanie M. „Gas-phase negative ion chemistry: Photoelectron spectroscopy, reactivity, and thermochemical studies“. Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337158.

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17

Schmidt, Mark. „Thermochemical Treatment of TiO2 Nanoparticles for Photocatalytic Applications“. Scholar Commons, 2007. http://scholarcommons.usf.edu/etd/3428.

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Titanium Dioxide (TiO 2) has been considered an ideal photocatalyst due to factors such as its photocatalytic properties, chemical stability, impact on the environment and cost. However, its application has been primarily limited to ultraviolet (UV) environments due to its high band gap (3.2 eV). This high band gap limits the harvesting of photons to approximately 4% of sunlight radiation. Research today is focused on lowering this gap by doping or coupling TiO 2 with other semiconductors, transition metals and non-metal anions, thereby expanding its effectiveness well into the visible range. This thesis explores the effects of thermal and thermochemical ammonia treatment of nano-particulated TiO 2. The objective is to synthesize a photocatalytic activity in the visible range while at the same time retaining its photocatalytic properties in the UV range. Specifically, this study utilizes pure commercial nano-particulated TiO 2 powder (Degussa P-25), and uses this untreated TiO2 as a baseline to investigate the effects of thermal and thermochemical treatments. Nitrogen-doping is carried out by gas phase impregnation using anhydrous ammonia as the nitrogen source and a tube furnace reactor. The effects of temperature, time duration and gas flow rate on the effectiveness of thermally and thermochemically treated TiO 2 are examined. Thermally treated TiO 2 was calcinated in a dry inert nitrogen (N2) atmosphere and the effects of temperature and treatment duration are investigated. The band gap of the thermally treated and thermochemically ammonia treated TiO 2 have been measured and calculated using an optical spectrometer. The photocatalytic properties of all materials have been investigated by the degradation of methyl orange (MO) in an aqueous solution using both visible simulated solar spectrum (VSSS) and simulated solar spectrum (SSS) halogen light sources. Methyl orange degradation has been measured and calculated using an optical spectrometer. The phase structure and particle size of the materials is determined using x-ray diffraction (XRD). The BET surface area of the samples has been obtained using an Autosorb. Surface or microstructure characterization has also been obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

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18

Hughes, Morris. „Kinetic studies of electrical storage cells“. Thesis, Loughborough University, 1985. https://dspace.lboro.ac.uk/2134/27952.

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The thesis describes an investigation of the kinetics of certain electrochemical energy storage systems. The work mainly involves A.C. impedance measurements made over a wide frequency range on some primary and secondary cells. In a number of cases this was sufficient to establish the electrochemistry and evaluate the magnitudes of the circuit elements of the analogue for the cell. In some other cases (secondary cells) the electrode behaviours of anode and cathode had to be established in order to produce the composite cell behaviours.

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19

Alkherraz, Abdulfattah M. „Kinetic studies of phosphoryl transfer reactions“. Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531190.

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20

Morris, Philippa Ann. „Kinetic and product studies involving thionitrites“. Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6675/.

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The kinetics of nitrosation of cysteine, cysteine methyl ester, N-acetylcysteine, penicillamine, N-acetylpenicillamine, glutathione and thioglycolic acid was undertaken. These thiols exhibited identical rate laws which are interpreted as nitrosation at sulphur by H(_2)NO(_2)(^+)/NO(^+). The rate constants determined show the high reactivity of thiols towards the nitrosating agent. The nucleophile catalyzed reactions were also investigated and the order of reactivity NOCl > NOBr > NOSCN was observed. Normally in these nucleophile catalyzed reactions there is a first order dependence on [thiol]. However, for N-acetylcysteine and thioglycolic' acid at high [thiol] the rate of formation of NOX tends to become the rate determining stage. The difference in rate constants between cysteine and penicillamine and their N-acetyl derivatives is explained in terms of internal stabilization. The decomposition of S-nitrosocysteine (S-NOCys) at pH 5.5, 7 and 9.8 in the presence and absence of C1(^-), Br(^-) and SCN(^-), and also alanine and sodium bicarbonate at pH 7, and S-nitrosoglutathione (GS-NO) at pH 7 in the presence and absence of alanine, C1(^-), and sodium bicarbonate was studied. The decomposition profiles were complex, but showed that S-NOCys was least stable at pH 7, and that GS-NO was more stable than S-NOCys. The addition of the aforementioned species did not significantly affect the rate of decomposition of the thionitrites. Finally the potential of S-NOCys, GS-NO and S-nitroso-N-acetyl- penicillamine as nitrosating agents towards amines was investigated at pH 7 and pH 8. These thionitrites nitrosated morpholine to give approximately the same yield of N-nitrosomorpholine (ca -17%) at pH 7, and less at pH 8 for S-NOCys and GS-NO. The addition of sodium acetate, sodium chloride, sodium bicarbonate, alanine and glucose, compounds liable to be present in vivo, did not significantly affect the yield of N-nitrosomorpholine. The transnitrosation reaction was complete before total decomposition of the thionitrite and a direct reaction between the thionitrite and morpholine is proposed.

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21

Colthurst, Matthew John. „Kinetic studies of carbonyl group transfer“. Thesis, University of Kent, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240168.

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22

Martin, Paul Anthony. „Transient kinetic studies of propane hydrogenolysis“. Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239493.

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23

Kwak, Yungwan. „Kinetic studies on living radical polymerizations“. 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144032.

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24

Pisano, Mary Grace. „Determining the Efficacy of the Extended Kinetic Method for Determination of Thermochemical Properties of Small, High-Entropy, Organic Molecules“. W&M ScholarWorks, 2015. https://scholarworks.wm.edu/etd/1539626795.

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25

Steiner, Petr. „Kinetic and Deactivation Studies of Hydrodesulfurization Catalysts“. Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-94.

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Hydrodesulfurization is an important part of the hydrotreating process. More stringent regulations on the quality of fuels bring new requirements to the catalytic processes. The removal of sulfur has become a key issue in the oil refining and this work aims to address several aspects of the process.

Kinetic studies of the hydrodesulfurization reaction over conventional (molybdenum-based) and new (Pt/Y-zeolite) catalysts are reported. The hydrodesulfurization of both the real oil (light gas oil from Statoil Mongstad refinery) and model compounds (thiophene and dibenzothiophene) over a NiMo/γ-Al₂O₃ catalyst were studied. In a high-pressure study of the light gas oil, substituted alkyl-DBTs were found to be the most difficult to desulfurize and the order of reactivity was found to be DBT > 4-MDBT > 4,6-DMDBT. Steric hindrance together with electronic effects were identified as possible reasons for this behavior. The difference in reactivities of the individual compounds was found to decrease with the increasing reaction temperature. A gas chromatograph equipped with the atomic emission detector (GC-AED) was used for the analysis of the individual components of the oil.

The initial deactivation and the steady-state kinetics were studied during the HDS of thiophene at atmospheric pressure. Unpromoted Mo/γ-Al₂O₃, CoMo/γ-Al₂O₃, NiMo/γ-Al₂O₃, and phosphorus modified NiMo/γ-Al₂O₃ were used for the deactivation study, while NiMo/γ-Al₂O₃,CoMo/γ-Al₂O₃, and Pt/Y-zeolite (with three different pretreatments) were used for the steadystate study. Several experiments related to the deactivation of Mo/γ-Al₂O₃ and NiMo/γ-Al₂O₃catalysts prepared with the chelating agent (NTA) were also performed and NTA was found to have no significant effect on the activity of the catalysts.

In the deactivation study, a fast initial decrease in the activity was observed on all the catalysts. However, nickel promoted catalysts were found to be more resistant to deactivation than unpromoted ones. The presence of phosphorus slightly increased the activity of the catalyst towards the thiophene HDS, but had no effect on the deactivation behavior. Several methods to regenerate the catalyst were investigated. During the resulfiding experiments, a difference between Mo/γ-Al₂O₃ and NiMo/γ-Al₂O₃ was observed. Deactivation of the Mo catalyst was more severe with increasing temperature, while for the NiMo catalyst the opposite behavior was observed. Carbon deposition on catalysts followed the similar trend: More carbon was observed on the Mo catalyst at higher temperatures, while the opposite is true for NiMo. The restoration of the activity of NiMo was complete, while the reactivation of the Mo catalyst was only partial. The results from the reactivation experiments with pure H₂ and inert gas (helium) suggest that several mechanisms of the restoration of activity exist: Resulfiding of the desulfided active sites, hydrogenation and removal of the deposited carbonaceous species, and the desorption of the reactants and products from the active sites of the catalyst. Based on the observed results, the higher hydrogenation activity of nickel is assumed to be the reason for the behavior. Hydrogenation causes the faster removal of the deposited carbonaceous species and this leads to the conclusion that the desulfiding of the active sites and the adsorption of the reaction species is significantly less pronounced on the NiMo/γ-Al₂O₃catalyst.

Characterization studies show differences between standard and NTA-based catalysts. The higher amount of carbon on the NTA catalysts is attributed to the presence of the carboncontaining precursor - NTA. The changes in the surface area and the pore volume were observed only during the sulfiding process. In the case of standard catalysts the surface area and the pore volume decreased, while for the NTA-based catalysts the opposite is true. No change in the surface area and the pore volume with the increasing time on stream indicates that the deactivation is not due to structural changes of the catalyst. The amount of sulfur was found to be constant during the time on stream for all the catalysts.

In the steady-state study of the HDS of thiophene, CoMo and NiMo catalysts were found to be equally active. The activity of the Pt/Y-zeolite catalyst was found to be comparable to conventional catalysts when based on the amount of active material, but a fast deactivation was observed. The product selectivities during the HDS of thiophene were found to be the same for all standard catalysts, but slightly different for the Pt/Y-zeolite catalyst. This was attributed to a higher hydrogenation activity of the Pt/Y-zeolite catalyst.

The inhibition effect of other sulfur compounds and aromatics on the high-pressure hydrodesulfurization of dibenzothiophene (DBT), the so-called “matrix effect” was studied. Thiophene and DMDS have the same inhibiting effect on the total conversion of DBT, but differences exist in the effect on the selectivities of the products at low concentrations. The results indicate that the inhibiting effect of H₂S on the direct desulfurization route is stronger than the effect of thiophene on the hydrogenation pathway. In the study of aromatics, both toluene and naphthalene affect the total conversion of DBT. Naphthalene was found to be a much stronger inhibitor and inhibits mainly the direct desulfurization pathway, while the hydrogenation route is more affected by the presence of toluene.

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26

Cornell, Stephen John. „Studies of freezing in kinetic Ising models“. Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257825.

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27

Moroney, S. E. „Kinetic studies on the biosynthesis of penicillin“. Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354849.

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28

Beltran-Alvarez, Pedro. „Kinetic studies on the actinorhodin polyketide synthase“. Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492551.

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The actinorhodin (act) minimal polyketide synthase (PKS) from Streptomyces coelicolor consists of three proteins: an acyl carrier protein (ACP), and two P-ketoacyl ACP synthase components known as KSa and KSp. The act minimal PKS catalyzes at least 18 separate reactions, which can be divided into loading, initiation, extension, and cyclization and release phases.

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29

Crookes, Michael Jonathan. „Kinetic studies of nitrosations by alkyl nitrites“. Thesis, Durham University, 1988. http://etheses.dur.ac.uk/6586/.

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The reactions of tertiary butyl nitrite and isopropyl nitrite in aqueous acid solution have been studied. In the case of Isopropyl nitrite the rates of reaction with hydrazoic acid, sulphamic acid, thioglycolic acid and N-methylaniline are markedly reduced by the addition of propan-2-ol. This has been explained in terms of a rapid hydrolysis of the alkyl nitrite to yield an equilibrium concentration of nitrous acid which then effects nitrosation. Analysis of the results gives values for the equilibrium constant for isopropyl nitrite hydrolysis and for the rate constants for nitrous acid nitrosation of the substrate, which are in good agreement with the literature values obtained by direct measurement. For tertiary butyl nitrite the extent of hydrolysis is so large and rapid that the kinetics are identical to those obtained using nitrous acid. The reactions of isopropyl nitrite in isopropanol and tertiary butyl nitrite in tertiary butanol with thiourea and thioglycolic acid have been studied. In both cases the reactions are acid catalysed and the results are consistent with a direct reaction between the protonated alkyl nitrite and the substrate. The reactions with thioglycolic acid were subject to catalysis by chloride and bromide salts and thiourea. The results for chloride and bromide salt are best explained in terms of formation of hydrochloric or hydrobromic acid which can then act as a general acid catalyst. For thiourea the catalysis is due to the formation of an equilibrium concentration of s-nitrosothiourea. In acetonitrile the reactions of tertiary butyl nitrite, isopropyl nitrite, isoamyl nitrite and nitrous acid with alcohols and thioglycolic acid were found to be kinetically zero order with respect to the substrate concentration. The results have been interpreted in terms of rate limiting formation of the nitrosonium ion. With less reactive substrates, aniline, N-methylaniline, p-toluidine, acetylacetone, 1,1,1,trifluoroacetylacetone and 1,1,1, 5,5, 5, hexafluoroacetylacetone, the reactions are kinetically first order with respect to the substrate concentration and have been interpreted in terms of rate limiting reaction of the nitrosonium ion with the free (at low acidity) or protonated (at high acidity) form of the amine. For the ketones reaction occurs, in a rate limiting step with either the enols or enolate ions.

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30

Moore, Dominic Thomas. „Kinetic studies of catalysed oxidations by H2O2“. Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300393.

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31

Borman, Christopher David. „Kinetic studies on galactose oxidase and laccase“. Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391288.

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32

Gharibi, Hussein. „Electrochemical and kinetic studies in surfactant solutions“. Thesis, University of Salford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258365.

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33

Mandani, Faisal Mohammad. „Kinetic and deactivation studies during catalytic dehydrogenation“. Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305913.

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34

Nashat, Khalid Hashim. „Kinetic studies of the hepatic reticuloendothelial system“. Thesis, University of Sheffield, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280637.

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35

Knowles, Terence Spencer. „Crystallographic and kinetic studies on ruthenium catalysts“. Thesis, University of Surrey, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388993.

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36

Miles, Caroline S. „Kinetic and spectroscopic studies of flavocytochrome b2“. Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/12657.

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Flavocytochrome b₂ (b₂) from baker's yeast catalyses the two electron oxidation of L(&43 )lactate to pyruvate and subsequent reduction of cytochrome c. The enzyme is a tetramer of identical subunits, each of which consists of two functionally distinct domains; a flavodehydrogenase domain containing flavin mononucleotide (FMN) and a cytochrome domain containing protoheme IX. The work in this thesis describes the investigation of the roles of specific amino acid residues, carried out through the kinetic and spectroscopic characterisation of site-directed mutant forms of b₂. Tyr143 is an active site residue which lies between the flavodehydrogenase and cytochrome domains of b₂. Its role in the catalytic cycle was examined by replacement of this residue with phenylalanine. The most significant effect of this mutation was a change in the rate-limiting step of catalysis. In the wild-type enzyme, this is abstraction of the lactate C2-H. In the mutant enzyme, interdomain electron transfer between the flavin and heme prosthetic groups is now the slowest step. The rate of heme reduction by lactate, determined using the stopped-flow method, is decreased by > 20-fold from 445 ± 50 s^-1 in the wild type enzyme to 21 ± 2 s^-1 in the mutant enzyme. Decreases in kinetic isotope effects seen with [2-²H]lactate for the mutant enzyme compared to the wild-type, both for flavin and for heme reduction, also provide support for a change in the nature of the rate-limiting step. Other kinetic parameters are all consistent with the mutation having a dramatic effect on inter domain electron transfer. It therefore appears that Tyr143 plays a key role in facilitating electron transfer between the flavin and heme groups. Further studies on the role of Tyr143 were carried out by replacing this residue with glutamine. Kinetic results show that the enzyme is a poor lactate dehydrogenase. Furthermore, the lactate K_M has increased by > 100-fold from 0.5mM in the wild-type enzyme to -65mM in the mutant enzyme. These and other kinetic results suggest that lactate to flavin electron transfer is the slowest step in catalysis, due to conformational effects at the active site. This is consistent with circular dichroism studies which show that a significant flavin/aromatic residue interaction has been lost. Two other interdomain residues, Phe325 and Tyr97, were investigated by substitution with alanine and tyrosine respectively. Although kinetic results indicate that Tyr97 is not of great functional significance, it is shown that Phe325 contributes towards domain/domain integrity and recognition.

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37

Williamson, Mark Allen. „Thermodynamic and kinetic studies of sulfur geochemistry“. Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/38485.

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38

Jang, Mei-Huei. „Mechanistic and kinetic studies of Trimethylamine Dehydrogenase /“. The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488191124572066.

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39

Abdel, Aziz May. „Kinetic and Thermodynamic Studies of Thrombin Inhibitors“. VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/2956.

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Sulfated low molecular weight lignins (LMWLs), CDSO3 and FDSO3, designed recently as macromolecular mimetics of heparin, were found to exhibit potent anticoagulant activity. Small molecules based on the same scaffold, SBD and SBT, showed promising thrombin inhibition. We were able to address the mechanism of the inhibition using Michaelis-Menten kinetics. All the molecules were found to be allosterically impairing thrombin activity using either noncompetitive or uncompetitive mechanism. Absence of competition with hirugen, an exosite 1 ligand, and competition with polymeric heparin points to exosite 2 as the site of interaction for these inhibitors. Yet mixed competition results with other exosite 2 ligands indicated that the molecules utilize different sub-sites within exosite 2 for interaction. Site-directed mutagenesis was used to pin point the key residues important for inhibition. All of all positively charged exosite 2 residues were mutated one at a time to alanine to abolish its charge. The data showed that Arg93 and Arg175 are the major residues involved in CDSO3 binding. FDSO3 showed a progressively greater defect in inhibition with double point mutations, the triple mutant Arg93,97,101Ala displayed a 50 fold drop in inhibition. A single mutant, Arg173Ala, displayed 22-fold reduction in IC50 of SBD, while Arg233Ala was the only mutation that impaired SBT inhibition. This proves the fact that inspite of the structural similarity between the two polymers and the two small molecules, thtey do not share the same binding space in exosite 2. To understand the types of interactions involved in thrombin interaction with the polymers, we resorted to salt-dependence studies. This showed that CDSO3 had fewer ionic contacts with thrombin, with most of its binding energy derived from non-ionic interactions. FDSO3 on the other hand had a balanced contribution of ionic and non-ionic forces. Thermodynamic studies showed that both polymers have a positive ΔCp of binding, which proves the involvement of electrostatic forces and signals the burial of the polar residues on thrombin exosite 2. These molecules offer a rare chance to study thrombin allostery. Little is known about the interplay between exosite 2, active site and sodium binding site. The allosteric nature of inhibition indicated that, for the first time, a link is proven to exist between exosite 2 and the active site that could be used to inhibit the enzyme. The presence of sodium was found to enhance the binding of FDSO3 at exosite 2, which establish the energetic coupling between exosite 2 and sodium binding site. The results identify novel binding sub-sites within exosite 2 that are energetically coupled to thrombin’s catalytic function and linked to the sodium binding site. The design of high affinity small molecules based on LMWLs scaffold presents major opportunities for developing clinically relevant, allosteric modulators of thrombin.

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40

López, Olvera Enrique Argenis. „Kinetic studies of carrier conjugated protease inhibitors“. Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-397114.

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Conjugates of soybean trypsin inhibitor (SBTI) and potato serine protease inhibitor (PSPI) immobilized on metal oxide particles of ~100nm diameter were prepared. Inhibition of trypsin hydrolysis of BAPA by these conjugates was measured and enzyme kinetics constants kcat, KM, kcat/KM and ki were determined. Metal oxide particles presented an inhibitory effect similar to that of a competitive inhibitor, noticed through the increase value of the K M constant. Furthermore, PSPI conjugates had the highest inhibition of trypsin, illustrated by the significantly higher value of KM relative to the value for particles only.

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41

Wang, Lijun. „Experimental and modelling studies of the thermophysical and thermochemical properties of some slag systems“. Doctoral thesis, Stockholm : Skolan för teknikvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11232.

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42

Woltz, Christian. „Kinetic studies on alkane hydroisomerization over bifunctional catalysts“. [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978158458.

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43

Gilvey, Lauren Brenna Galvagni. „Kinetic Studies of Dehaloperoxidase-Hemoglobin From Amphitrite Ornata“. NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-08302006-104458/.

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The focus of this research was to determine how three different factors affect the kinetics of the reaction between Dehaloperoxidase ? Hemoglobin (DHP-Hb), a halogenated phenol substrate, and a peroxide co-substrate. The factors examined were the order of addition of the substrate and co-substrate, the pH of the solutions, and the difference between using hydrogen peroxide (H2O2) and m-Chloroperbenzoic acid (MCPBA) as the co-substrates. The order of addition studies were carried out on a stop-flow apparatus. The results presented here demonstrate that the substrate must bind to DHP-Hb prior to the addition of the peroxide co-substrate. The effect of pH was examined using stop-flow and photodiode array spectrometry. These studies show how the pKa of the substrate affects the mechanism of the reaction. The kinetic results actually depend on the pKa of the substrate used. Stop-flow studies and UV-Vis assays were used to compare H2O2 and MCPBA as co-substrates. These studies demonstrate that the use of MCPBA as the co-substrate yields a faster rate of product formation. The use of H2O2 as the co-substrate results in a larger amount of product formation at all pHs studied, with the exception of pH 6.0.

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44

Shang, Shubo. „Kinetic studies of hydrocarbon reactions over ruthenium catalysis“. Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315931.

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45

Buxton, J. P. „Kinetic and dynamical studies of thermal decomposition reactions“. Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371510.

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46

Fogg, Andrew Michael. „Structural, kinetic and synthetic studies of intercalation compounds“. Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297906.

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47

Jiang, W. „TPD and steady-state kinetic studies of catalysts“. Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.605605.

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The first part is the use of a variety of temperature programmed desorption techniques, analytical studies and numerical simulation to see whether it is possible to identify differences in the nature and number of hydroxyl groups associated with Cabosil and sol-gel silicas. The motivations of this work are to examine the strength of this technique to provide quantitative information about the heterogeneous surface and to explore the effects of different kinetic parameters on TPD spectra through both analytical and Monte Carlo methods. The second part of this thesis focuses on using a Monte Carlo Lattice Dynamic code simulating temperature-programmed desorption to obtain a molecular level understanding of the desorption of hydrocarbon and aromatic species from the zeolite silicalite. Excellent agreement between experimental and simulated results is obtained and the results have been interpreted in terms of the rate of site-desorption events of the adsorbed species inside silicalite framework. Finally the modelling and discussion provide further insight into the adsorption mechanism of n-heptane in silicalite. The final part of this work is to set up a microreactor system to study ethene hydrogenation reaction over eight different Pt/alumina catalysts, which differ in terms of the alumina support and metal profile, and to see to what extent differences in reactivity correlate with any physical and chemical characterisation data. Temperature programmed desorption has been used to characterise the catalysts (Pure alumina, IMI-Pt-17 and IMI-Pt-18). The reactor data are also compared with the results of a Monte Carlo simulation of the ethene hydrogenation reaction. A comparison of the TPD data of ethene and hydrogen on pure support and Pt/Al₂O₃ with a microreactor study suggests that the presence of the transition is associated with alumina support. Therefore a new reaction mechanism including hydrogen spillover on the support is proposed to explain the kinetic transition in ethene reaction orders for ethene hydrogenation over supported metal catalysts.

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48

Guo, Xingwei. „Kinetic and mechanistic studies on reactions of quinones“. Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-177113.

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49

Whitmore, James Michael John. „Kinetic studies of nucleophilic displacement at heteroaromatic centres“. Thesis, University of Kent, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386135.

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50

Routledge, Carol A. „Kinetic studies on molybdenum and tungsten chalcogenide clusters“. Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308347.

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Dissertationen zum Thema „Thermochemical and kinetic studies“

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