In this work, carbonaceous deposits on spent HTFT catalysts were investigated. This research was required in order to better understand the observed loss in productivity observed in the industrial reactors, with the aim of improving the economy of the HTFT process. A host of complementary techniques were employed to systematically determine the composition of a typical catalyst recovered from a reactor. Spent HTFT catalysts are comprised of magnetite and a mixture of iron carbides as well as adsorbed hydrocarbon products (soft carbon) and hard carbon. Reaction initiates at the particle surface and along the promoter-rich grain boundaries toward the core of the grains. A partially reacted particle would therefore have a core-shell structure, with magnetite representing the unreacted region of the catalyst. The reacted region consists of a porous carbonaceous matrix with soft carbon and carbide crystallites nestled in this matrix. The hard carbonaceous species is a mixture of polymeric carbon and polycyclic aromatic hydrocarbons. The particle structure is linked to the sample preparation method and an alternative method yielding catalyst particle with uniformly distributed promoter elements could be beneficial. Investigating carbonaceous species is a complex process, and development of a fresh methodology would aid in the quest for insight into the nature of carbonaceous species in various systems. A new approach which entails a combination of the traditional techniques combined with MALDI-TOF MS enabled a deeper investigation. Additional aspects such as the molecular weight distributions along with known information about crystallinity and morphology of the catalyst provide a comprehensive study of carbonaceous material. Polymeric carbon and very large polycyclic aromatic hydrocarbons constitute hard carbon and can be observed with minimal sample preparation procedures. The evolution of the HTFT catalysts was investigated as a function of time-on-stream. This enabled us to study the effects of increasing amounts of hard carbon on the activity and the chemical and physical properties of the catalysts. The catalyst activity was found to decrease with increasing hard carbon content, although the effect of carbon deposition cannot be distinguished from phase transformation (oxidation) which occurs simultaneously. A method to quantify the amount of hard carbon, which progressively builds up on the catalyst, was demonstrated. This required a great deal of method development, which provides a platform for future investigations of these catalysts. Importantly, it allows predictions of the amounts of carbon that will be deposited after a certain reaction time. This allows more efficient regulation of catalyst replacement. The production of fine carbon-rich particles in the industrial reactor poses a major problem in the process. Carbon deposition leads to an increase in particle diameter with time on-stream. Permissible levels of hard carbon were identified, beyond which the mechanical strength of the catalyst particles deteriorate. This leads to break-up of the particles and therefore fines formation. The surface area and pore volume generally increase with progressive deposition of hard carbon, while the bulk density of the catalyst material exhibits a linear decrease with carbon build-up. A mechanism is proposed for hard carbon formation which apparently occurs through the dissociative adsorption of CO to form a carbon monolayer. This is followed by polymerisation of the carbon atoms. Meta-stable interstitial carbides are formed at the iron-carbon interface. Owing to a carbon concentration gradient between the top of the surface and the bottom of the metal or carbide particle, carbon diffusion across the crystal (carbide decomposition) and grows as a PAH molecule lifting the iron carbide away from the particle. As this corrosion process is intrinsic to iron-based catalysts, a catalyst that contains sulphur is proposed for future development.

Abstract The aim of the thesis was to find new information on the effect of BaO and oxygen storage capacity material on NOx reduction. A total of nine different kinds of Pd/Al2O3-based metallic monoliths were studied. Promoters such as oxygen storage capacity material (OSC material in our case Cex-1ZrxO2 mixed oxides) and stabilisers such as barium (BaO) were added into the catalyst alone or together to improve catalyst properties such as catalytic activity, selectivity, and thermal stability. The key aspects in this thesis can be divided into four parts. First, the behaviour of NO reduction and CO as well as C2H4 oxidation over Pd/Al2O3-based catalysts in rich, stoichiometric and lean conditions were studied. Secondly, the effect of BaO and the OSC material in NO reduction was considered. Thirdly, the preparation procedure, i.e. the addition order of BaO, OSC material, and Pd on the catalyst was considered. Finally, the effect of ageing on the behaviour of catalysts was investigated. Several characterization methods (in situ DRIFT, catalytic activity measurements, N2 physisorption, CO chemisorption, dynamic oxygen storage capacity measurements, and X-ray diffraction (XRD)) were utilised to find answers to the behaviour of these catalysts in the studied model reactions. The Rapid Ageing Hot in Laboratory (RAHLAB) method was used to age the catalyst. First, it was demonstrated that the CO and hydrocarbon oxidation and NO reduction reactions over the Pd/Al2O3-based catalyst behave differently. NO reduction and CO and hydrocarbon oxidation reactions were dependent on the reaction conditions and temperatures. Secondly, the effect of OSC and BaO on NO reduction was studied separately. In the case of OSC material, it was observed that the OSC material has an effect on NO reduction as well as on CO and C2H4 oxidation. In the case of BaO, it was observed that BaO has a positive effect on NO reduction as well as CO and C2H4 oxidation especially in rich conditions. Thirdly, the effects of the addition order of OSC and BaO on the catalyst was studied separately. It was shown that these have an effect on NO reduction, especially after ageing. First, on the fresh Pd/Al2O3 catalyst it was observed that the addition order of OSC on the catalyst has not an influence on catalyst performance. The effect of the BaO addition order on the Pd/OSC/Al2O3-based catalyst is found to be insignificant, especially, after the ageing process. Furthermore, it is observed that the effect of RAHLAB ageing was that the catalyst lost its catalytic activity, stability, and selectivity.

This thesis work has been conducted in the Handheld Laboratory at Husqvarna AB with the purpose of finding the parameters responsible for the performance of the catalytic converters used in the test rig. The catalytic converters are used in the test rig during the long term testing of the chain saws to reduce the hydrocarbon content from the exhaust before it enters into the environment.   To perform this research two approaches were carried out. One with Design of Experiment (DOE) and another using Scanning Electron Microscope (SEM) analysis. In Design of Experiments parameters that are suspected to be influencing the performance of the catalytic converter were refined. Using these parameters a test plan is made with the help of statistical analysis application Minitab and the tests were carried out in the test rig. Using SEM the effects of aging and its effect on microstructure and chemical composition on the catalyst surface was analyzed. The results from the DoE shows that the exhaust flow, collector diameter and distance to the muffler are responsible for the collection of exhaust. Distance to the muffler and collector length are the factors affecting the conversion of the exhaust. In addition to that exhaust flow is also responsible for the duration of heating coil running time.        The results from the SEM analysis shows that the operating temperature is high due to which there is thermal degradation of catalyst and there is also deactivation due to fouling. Another finding is that the flow on to the catalyst is not uniformly distributed

Cette étude porte sur la compréhension et l'amélioration de la réactivité des charbons pour la catalyse de la réaction du craquage du méthane. Pour ce projet, nous avons produit des charbons à partir de la gazéification de bois de peuplier à 750°C sous vapeur d'eau. Par la suite, deux traitements de fonctionnalisation ont été appliqués. D'une part, une oxygénation en phase gaz a été réalisée pour augmenter la concentration des sites oxygénés. D'autre part, une imprégnation en phase liquide dans différentes solutions de sel de nitrate (calcium et potassium) a permis d'accroître la quantité de minéraux. Les propriétés physico-chimiques (structure carbonée, sites oxygénés, minéraux et porosité/surface spécifique) des charbons bruts et fonctionnalisés ont été caractérisées. Les résultats ont montré que les deux traitements de fonctionnalisation ont augmenté la concentration des sites actifs visés. Par ailleurs, les évolutions des propriétés texturales et de la structure carbonée lors des deux fonctionnalisations ont été mises en évidence. Les tests catalytiques du craquage du méthane sur les différents charbons, à 700°C, ont montré que les minéraux sont les sites les plus réactifs vis-à-vis de cette réaction. Les fonctions oxygénées basiques et les défauts de structure sont également des sites actifs. Une diminution de l'efficacité lors du craquage a été observée due à la désactivation progressive de la surface des biochars. Le développement d'un modèle, à l'échelle du pore, a permis de montrer que la concentration initiale de sites actifs à la surface et leur différence de réactivité étaient deux paramètres importants dans la prédiction du comportement de désactivation de la surface. / This study is focused on the reactivity of biochar to catalyze the methane cracking reaction. Biochar was produced from steam gasification of poplar wood (750°C, 30 min, 20°C/min, 90%H2O/10%N2, fluidized bed) and then functionalized by an O2 gas-phase treatment and a wet impregnation into nitrate salts solutions to increase oxygen functions and minerals (calcium and potassium) concentrations at the biochar surface respectively. A set of characterization was performed on the raw and functionalized biochars to evaluate their surface physico-chemical properties. The oxygenated functions, the mineral particles, the carbonaceous structures and the textural properties (specific surface area and porosity) were analyzed. Results showed that the two functionalization treatments increased the concentration of the targeted functions and modified the carbon structures and the textural properties as well. Methane cracking tests were then performed on the biochars to compare their activities and correlate with their physico-chemical properties. It has been highlighted the minerals particles of potassium and calcium are the main active sites of the biochar surface. In fact, the reactivity of the impregnated biochars was twice to 4 times higher than the one of the raw biochar. The porosity of the biochar is the second most important criteria to notably obtain a good dispersion of the minerals particles. Basic oxygenated functions and disordered carbonaceous structures (defaults into the graphene sheets) are reactive as well. However, coke deposition progressively deactivated the biochars surface over the reaction in any case. A model at the pore scale has been proposed to better understand the surface deactivation.

L’oxydation sélective des alcools en aldéhydes, acides ou cétones est une transformation très importante en chimie. L’emploi d’oxygène moléculaire comme oxydant permet de se placer dans une perspective de chimie verte, avec la production d’eau comme seul sous-produit principal. L’oxydation d’alcools primaires (1-octanol et géraniol) et d’alcools secondaires (2-octanol, 1-phénylethanol et alcools hétéroaromatiques dérivés de la pyridine) a été étudié en présence de catalyseurs au platine supportés sur charbon sous pression d’air, en solvant organique ou mélange à de l’eau. Les résultats ont montré une forte influence du solvant sur l’activité catalytique, avec un effet promoteur très important de l’eau sur la réaction. Cet effet a été discuté sur la base de différentes hypothèses. La promotion des catalyseurs au platine par le bismuth a permis d’observer des modifications de l’activité avec un effet positif en particulier dans l’oxydation des alcools hétéroaromatiques secondaires. La désactivation observée lors de l’oxydation de certains substrats a été analysée et des solutions ont été proposées pour la surmonter. / The selective alcohols oxidation to aldehydes, acids and ketones is an important transformation in chemistry. The use of molecular oxygen as oxidant is in adequation with a green chemistry perspective, since water is the only by-product. The oxidation of primary alcohols (1-octanol and geraniol) and secondary alcohols (2-octanol, 1-phenylethanol and pyridine substituted alcohols) has been studied in the presence of platinum supported carbon catalysts under air pressure in organic or mixed organic/aqueous media. The results have shown a strong influence of the solvent on the catalytic activity, with an important promoting effect of water on the reaction. This effect has been discussed based on several hypotheses. The promotion of platinum supported catalysts by bismuth has shown some modifications of the activity, with a positive effect in particular in the oxidation of secondary heteroaromatic alcohols. The deactivation observed during the oxidation reaction of some substrates has been analyzed and some solutions have been proposed to overcome the problem.

La déshydratation du glycérol en acroléine en phase gazeuse sur catalyseur solide a été étudiée pour comprendre la formation des sous-produits, déterminer un mécanisme réactionnel et expliquer la désactivation du catalyseur. Les expériences ont été réalisées dans un réacteur isotherme à lit fixe sous différentes conditions opératoires. Pour déterminer les chemins réactionnels de la réaction, de nombreux sous-produits ont été passés séparément sur le catalyseur. Une chromatographie gazeuse en ligne, en continu et originale a été utilisée pour analyser tous les produits de la réaction simultanément. Deux produits ont été quantifiés par chromatographie liquide et de nouveaux composés ont été identifiés par chromatographie gazeuse couplée à un spectromètre de masse. Un mécanisme réactionnel a été proposé. Pour comprendre la désactivation du catalyseur, les produits responsables du dépôt carboné ont été identifiés et la chute de la conversion du glycérol au cours du temps a été modélisée / Glycerol dehydration to form acrolein in gas phase over a solid acid catalyst was studied to understand by-products formation, to determine a detailed mechanism and to explain the deactivation process. Experiments were run in an isothermal fixed bed reactor under different operating conditions. To understand the multiple pathways of the glycerol dehydration mechanism, many by-products of the reaction were passed separately over the catalyst. An original multivalve on-line gas chromatography was used to analyze the whole reaction products continuously and simultaneously. Two products were quantified by high performance liquid chromatography, and the unknown products were identified by gas chromatography-mass spectrometry. A detailed reaction mechanism was then proposed. In order to understand the deactivation process, compounds responsible of carbon deposit were identified and the glycerol conversion fall during an experiment was modelled

PetrÃleo Brasileiro S/A / O objetivo principal à determinar a atividade catalÃtica residual e as causas da desativaÃÃo de amostras de catalisadores de uma unidade de HDT de lubrificantes. Foram realizadas corridas em unidade piloto, caracterizaÃÃo dos catalisadores e coletados dados do histÃrico operacional da unidade industrial. A atividade catalÃtica foi determinada atravÃs das conversÃes das reaÃÃes de HDA, HDS e HDN bem como pelos parÃmetros cinÃticos aparentes de um modelo de lei das potÃncias e lei de Arrhenius. Os catalisadores dos leitos principais de entrada e saÃda dos reatores industrial foram os mais desativados e o menos desativado o do leito intermediÃrio sendo estabelecida a seguinte ordem de atividade catalÃtica residual: R1L3 (meio) > R1L2 (topo)  R2L2 (fundo). Os resultados de teor e caracterÃsticas do coque, contaminantes e propriedades texturais sugerem que mecanismos distintos tenham causado a desativaÃÃo desses catalisadores: deposiÃÃo de metais e deposiÃÃo de coque. Os mecanismos de desativaÃÃo foram fortemente influenciados pelo posicionamento das amostras no interior do leito catalÃtico. No inÃcio do leito, a contaminaÃÃo por metais (notadamente Si e As) revelou-se o principal mecanismo de desativaÃÃo. Jà no final do leito, a deposiÃÃo de coque foi o mecanismo preponderante e a temperatura de reaÃÃo identificada como a principal causa para o maior envelhecimento do coque. / The main objective of this work is to study the residual catalyst activity and the mechanisms of deactivation of catalyst from a lube-oil hydroprocessing industrial unit. In order to accomplish this, pilot plant tests were carried out followed by spent catalysts characterization. The residual catalytic activity was determined by HDA, HDS and HDN conversions and adjusted by a power law apparent kinetic model. Pilot plant tests revealed different levels of residual activity for spent catalyst samples. Catalyst samples taken from the first and last of the five catalytic beds showed higher deactivation than others. Catalyst characterization results pointed out two mechanisms as the main reason for the catalytic deactivation through the industrial reactor: poisoning by metal deposition (mainly Si and As) and coke deposition. Poisoning was the main deactivation mechanism for the first bed spent catalyst sample, while coke deposition was predominant at the last catalytic bed sample. Reactor temperature was identified as the most important operational parameter considering coke aging.

L'accès à de nouvelles techniques de synthèse simples permettant l'obtention d'architectures macromoléculaires complexes et bien définies demeure un enjeu permanent. Les réactions de couplage dites " click " permettent de relever en parti ce défi et dans cette catégorie, les γ-thiolactones sont apparues comme un nouvel outil important. Dans ce contexte, nous avons développé un nouveau procédé de synthèse de mono- et bis(γ-thiolactones) fonctionnelles basé sur la chimie radicalaire des xanthates, permettant l'accès à une bibliothèque de thiolactones porteuses de groupements fonctionnels divers. La réactivité de ces molécules a été testée au travers de la réaction amine-thiol-ène avec la fonctionnalisation d'extrémités de chaînes polymères et la polymérisation par étapes. Un exemple d'utilisation de ces polymères est présenté avec la stabilisation de nanoparticule de gadolinium en milieu aqueux. Enfin, une série de thiolactones portant des groupements susceptibles de jouer le rôle d'amorceurs et d'agents de contrôle en polymérisation radicalaire par désactivation réversible ont permis l'obtention de polymères fonctionnalisés thiolactone en bout de chaîne. Ces polymères ont par la suite été utilisés dans des réactions de modifications post-polymérisation permettant l'incorporation de groupements possédant des propriétés de fluorescences par exemple. / The development of simple synthetic protocols allowing the construction of complex and well-defined macromolecular architectures remains an ongoing challenge. The so-called "click" coupling reactions make it partially possible. Among these reactions, the use of γ-thiolactones has emerged as a new important tool. In this context, we have developed a new procedure for the synthesis of functional mono- and bis(γ-thiolactones) based on the radical chemistry of xanthates, allowing access to a library of thiolactones bearing various groups. The reactivity of these molecules was tested with the amine-thiol-ene conjugation for the functionalization of polymer chain-ends and step-growth polymerization. An application of these functionalized polymers was presented with the stabilization of gadolinium nanoparticles in water. Finally, a series of thiolactone-functional initiators or control agents for reversible-deactivation radical polymerization techniques allowed us to obtain thiolactone-terminated polymers. These polymers were then used for post-polymerization modification reactions with the incorporation of a new fluorescent group for example.

Chapter one reviewed the development of sol-gel stationary phase for gas chromatograph (GC). Inorganic sol-gel precursor creates the substrate support for stationary phase bind to silica surface through the condensation of silanol groups, the rough surface with enhanced surface area enlarger the capacity of the sol-gel stationary phase, the porosity of sol-gel structure decreases the mass transferring coefficient, the term C in Van Deemter equation, which makes sol-gel stationary phase thicker coating up to 1 um but keeps the high resolution for gas chromatography. Chemical bound stationary phase significantly improve GC column with better thermal stability and solvent stability. Partial derivatizations of known polymers have not increased the column performance but remained at the same level of 3200 plates per meter. The sol-gel chemistry with essential structure rebuilding will make sol-gel stationary phase to a new level. The chapter two reported the non-silica-based metal alkoxide oxide as the new building block, cooperated with known polymer poly(dimethyldiphenylsilanoxan), developed the original nonpolar feature of the stationary phase to broad the polarity from the nonpolar to extreme polar, overcome the thermal stability for other types of polar column. The theoretical plate number reached the 3200 plates per meter, and the optimized plate number arrived at the top level at 3800 plates per meter. The basic recipe and preparation of sol-gel process were verified by tungsten alkoxide incorporated with poly(dimethyldiphenylsilanoxan) as the stationary phase which arrived the same plate number level at 3800 per meter. Chapter three demonstrated the preparation of core-shell particle for HPLC. Conventional silica core particles were prepared with stÖbe methods. The extended layer of germanium oxide coating was made with acid and alkaline as a catalyst. EDS characterize the extended layers of germanium oxide has been coated at ratio 12/1(Ge/Si). Then the carbon loading with C 18 for surface derivatization were also confirmed with EDS testing. 2 um core-shell particles were successfully prepared from the external composition (1.7 um core, 0.3 um shell). The function of the core-shell particles was slurry packed with 5cm regular steel column and the capillary column with sol-gel frit. The preliminary HPLC testing showed the core-shell particles had more retention ability compare with 4 um commercial core particles. The backpressure of the short steel column and capillary both were beyond the pressure limit of conventional HPLC pump. Chapter three demonstrates the new ideal of the surface sol-gel process for GC stationary phase. Without the catalyst, the sol solution has constant viscosity and gelation time is much longer, the sol-gel reaction was taking on the silica surface only, to accomplish the thinner coating for sol-gel stationary phase. From the retention time of the grob mixture, the surface sol-gel coated 2 meters of column acquired the half retention time, grob mixture analytes were eluted within 7 minutes, compared with conventional sol-gel coated column eluted within 14 minutes. Without the TFA as the catalyst, the sol-gel matrix may not form effective surface area and porosity to support the functional polymer for separation, the column performances were two third of the protocol column, at 1500-2500 plate number per meter. The coating results proved the sol-gel stationary phase could be fulfilled with diluted sol solution by static coating. Basic parameters for dynamic coating and static coating with conventional coating and surface sol-gel were acquired for further development. The germania and niobium precursor is highly active, the water amount in the solvents used as received without drying process can meet the surface sol-gel coating without precipitates and gelation formed before finishing coat. For germania -PDMDPS column, thermal stability is very important because of the temperature for remaining the low residual OH- group in silica and germania film at 350 °C.

In der vorliegenden Habilitationsarbeit wurden die Ionenkanäle von Mikrogliazellen mit Hilfe der Patch-clamp-Technik untersucht, nachdem die Mikrogliazellen in den deaktivierten Zustand überführt worden waren. Die Deaktivierung der Mikroglia erfolgte durch die Zugabe des astrozytenkonditionierten Mediums. Nach der Deaktivierung exprimierten die Mikrogliazellen einwärts- und auswärtsgleichrichtende sowie Ca2+-aktivierte Kaliumkanäle. Der auswärtsgleichrichtende Kaliumkanal wurde erst nach Zugabe des astrozytenkonditionierten Mediums exprimiert, wobei das durch die Astrozyten freigesetzte Zytokin transformierender Wachstumsfaktor für diesen Prozeß verantwortlich gemacht werden konnte. Zusätzlich wurden Chloridkanäle an deaktivierten Mikrogliazellen nachgewiesen, die an den Ramifizierungsprozessen der Zellen, d.h. dem Übergang von der amöboiden in die ramifizierte Zellmorphologie, beteiligt waren. Die an Mikrogliazellen exprimierten Protonenkanäle spielen offensichtlich eine wichtige Rolle bei der Generierung von reaktiven Sauerstoffradikalen und wurden im Prozeß der Deaktivierung der Mikrogliazellen herunterreguliert. / The current work describes patch clamp recordings in cultured murine microglial cells, which had been deactivated following exposure to astrocyte-conditioned medium. Deactivated microglial cells expressed inwardly rectifying, outwardly rectifying and calcium-activated potassium channels. The outwardly rectifying potassium channels were upregulated following treatment of microglial cells with the astrocyte-conditioned medium. The anti-inflammatory cytokine transforming growth factor was released by astrocytes and appeared to be responsible for the observed upregulation of outwardly rectifying potassium channels in deactivated microglia. In addition, deactivated microglial cells expressed chloride channels, which were found to be involved in microglial ramification, i.e., in the transformation of microglial cells from ameboid into ramified morphology. Voltage-gated proton channels, which are involved in processes of oxygen radical generation, were downregulated in deactivated microglial cells.