Im Rahmen der vorliegenden Arbeit wurde eine neuartige Methode und die entsprechenden Katalysatoren für die heterogen katalysierte Gasphasen-Epoxidation von Propen entwickelt und optimiert. Das Propen wurde an FeOx/SiO2-Katalysatoren mit N2O als Oxidationsmittel epoxidiert. Die Katalysatoren wurden mittels XRD, TEM, XPS, Physi- und Chemisorption, TPR/TPO, TPD und IR untersucht und charakterisiert. Der Einfluß der Reaktionsbedingungen auf die Oxidationsergebnisse wurde bestimmt und Untersuchungen zum Reaktionsablauf durchgeführt. Es wurden Selektivitäten zu Propenoxid von 40-70%, bei Propenumsätzen von 3-12%, erreicht. Die maximalen erzielten PO-Ausbeuten betrugen über 5%, und sind damit den berichteten Ergebnisse aus der Literatur überlegen.

Thesis (Ph.D.)--Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.

Petrochemical and fine chemical industries face a daunting problem in recovering acetic acid from its aqueous solutions. The recovery of acetic acid could be done through esterification reaction. However, esterification is an equilibrium limited reaction. Multi-functional reactors such as chromatographic reactor (CR) and reactive distillation column (RDC) are promising technologies mainly for equilibrium limited reactions wherein reaction and separation of products are carried out in a single equipment that tends to shift the equilibrium towards the desired direction which is not possible in a classical batch reactor. Physical and chemical characterisation of ion exchange resin catalysts such as scanning electron microscopy, Brunauer-Emmett-Teller (BET) surface area measurement, pore size distribution, elemental analysis, true density and particle size distribution were carried out to access the catalysts performance for n-hexyl acetate synthesis. Esterification of acetic acid with n-hexanol was studied with both dilute and concentrated acid in the presence of cation exchange resins (macroporous and gelular) in a jacketed stirred batch reactor to synthesise a value added ester, namely n-hexyl acetate and also to study the recovery of acetic acid from the waste aqueous streams. The effect of various parameters such as speed of agitation, catalyst particle size, feed mole ratio of n-hexanol to acetic acid, reaction temperature, catalyst loading and reusability of catalysts was studied for the optimisation of the reaction condition in a batch reactor. The non-ideality of each component in the reacting mixture was accounted for by using the activity coefficient via the use of the UNIFAC group contribution method. The kinetic data were correlated with both pseudo-homogeneous (PH) and adsorption based heterogeneous reaction rate models, e.g., Eley-Rideal (ER), Langmuir-Hinshelwood-Hougen-Watson (LHHW), and the modified LHHW (ML). Pseudo-homogeneous (PH) model gave the best representation of the kinetic data found experimentally. The feasibility of reactive distillation for the recovery of acetic acid using n-hexanol was evaluated through residue curve map (RCM) determination experiments. RCM provides information to a design engineer of the existence of separation boundaries imposed by the singular points corresponding to the reactive/non-reactive azeotropes, thus provides an insight into the feasibility of reactive distillation for this purpose. A laboratory scale batch chromatographic reactor was designed and constructed. Batch chromatographic reactor experiments were carried out using different parameters such as feed flow rate, feed mole ratio of n-hexanol to acetic acid, desorbent (n-hexanol) flow rate and reaction step to maximise the formation of n-hexyl acetate as well to achieve complete conversion of acetic acid. Continuous chromatographic reactor was designed, constructed and commissioned on the basis of the results obtained from the batch chromatographic reactor experiments. The experiments carried out in continuous chromatographic reactor correlated very well with the results from the batch chromatographic reactor for the optimised condition.

Las esmectitas como hectorita o saponita, son silicatos laminares. Tienen múltiples aplicaciones (catálisis, nanocomposites, adsorbentes) e interesa tener un material reproducible y sin impurezas. Los métodos convencionales de síntesis comportan tratamientos largos o a altas temperaturas. La introducción del microondas puede disminuir ambos. El objetivo de esta tesis es estudiar la síntesis de hectorita y saponita con microondas y su aplicación como soportes catalíticos de Ni en la hidrogenación de óxido de estireno para la obtención de 2-feniletanol (componente principal de la esencia de rosas) y en la preparación de composites con poliuretano. Se obtienen hectoritas y saponitas reproducibles. Cuando se emplean como soportes de catalizadores de Ni se obtienen conversión y selectividad total hacia el 2-feniletanol. Cuando se utilizan las arcillas obtenidas en preparación de composites sus propiedades son comparables a los de la bibliografía. / Smectites like hectorite or saponite, are phyllosilicates. They can be applied for many purposes (catalysis, nanocomposites, adsorbents) but a reproducible, pure material is necessary. Classical methods of synthesis involve long synthesis times at high temperatures. The use of microwaves can be an interesting alternative. The scope of this thesis is to study the synthesis of hectorites and saponites with microwaves and their application as supports of Ni catalysts in the hydrogenation of styrene oxide to obtain 2-phenylethanol (main component of rose oil) and in the preparation of composites with polyurethane. We obtained reproducible hectorites and saponites. When used as supports of Ni catalysts we obtained total conversion and selectivity to 2-phenyethanol. When obtained clays were used in the preparation of polyurethane composites, their properties were comparables to those of the bibliography

Die Immobilisierung homogener Katalysatoren ist eine wichtige Methode zur Realisierung der Abtrennbarkeit und Wiederverwendbarkeit aktiver Spezies. Im Rahmen dieser Arbeit wurde durch die Komplexierung von Palladium mit 1,4-Bis-(4′-pyrazolyl)benzen ein neues mikroporöses Koordinationspolymer generiert und dieses als heterogener Katalysator in der Suzuki-Miyaura-Kreuzkupplungsreaktion erfolgreich eingesetzt. Dabei konnten vollständige Umsätze und hohe Selektivitäten erzielt werden, die vergleichbar zu bereits kommerziell erhältlichen homogenen Katalysatoren sind. Die Besonderheit des Katalysators ist, neben dessen außergewöhnlich hohen chemischen Stabilität, die Variation seiner Struktureigenschaften durch die Wahl der Synthesebedingungen und die damit verbundene Steuerung seiner katalytischen Aktivität.

To meet the new challenges of the chemical indutries, the developpement of new heterogeneous catalytic reactors and their understanding are mandatory. From these perspectives, new reactor designs based on structuring at micro or millimeter scales have emerged. They have sparked interest for their ability to decrease physical limitations for heat and mass transfers. Thus, two advanced reactor technologies for gas-liquid-solid catalysed reactions are studied. The first reactor is a micro-structured falling film (FFMR) in which vertical sub millimetric grooves are etched and coated with a catalyst. This structuration allows stabilizing the gas-liquid interface of a down flow liquid phase. A thin liquid film is generated leading to high specific surface areas. Commercially available, it represents a very good potential for performing demanding reactions (i.e.fast, exothermic) for small scale productions such as pharmaceuticals. In a second part, a new reactor concept is proposed. Open cell foams are used as catalyst support and inserted in a milli-square channel. The reactor is then submitted to a preformed gas-liquid Taylor flow. In both cases, hydrodynamics features are studied by using microscopy based methods. Their potential in terms of mass transfers are also studied by performing catalyzed α-methylstyren hydrogenation. For both reactors, it comes out that the particular flow induced by micro or milli structures leads to at least one order of magnitude higher mass transfers performances than mutliphase reactors currently used in the industry albeit it remains to be demonstrated at such scale. From all these studies, correlations, models and methods for chemical engineers (hydrodynamics, pressure drops, mass transfer) are proposed for the two reactors

Im Hinblick auf eine spätere Anwendung als Katalysatorträger in Hydrierungsreaktionen wurden in dieser Arbeit Adsorptionseigenschaften von Metall-Organischen Gerüstverbindungen (MOFs) in der Flüssigphasenadsorption untersucht. In den Experimenten wurden Materialien gegenübergestellt, bei denen entweder freie Koordinationsstellen am Metallatom (MIL 101, DUT 9, HKUST 1) oder eine abgeschlossene Koordinationssphäre (MOF 5, Zn4O(btb)2, Zn2(bdc)2dabco, ZIF 8, DUT 4, DUT 6) in der Struktur vorlagen. Die Substrate und Lösungsmittel wurden hinsichtlich auf die spätere Verwendung als Edukte in der Hydrierungsreaktion ausgewählt. Neben dem polaren Zimtsäureethylester kamen unpolare Substrate wie Styrol, cis-Cyccloocten und Diphenylacetylen zum Einsatz. Die Materialien wurden desweiteren auf ihre Eignung und Stabilität in der Flüssigphasenhydrierung getestet. Da die untersuchten Metall-Organischen Gerüstverbindungen selbst nicht hydrieraktiv sind, wurden sie als Matrix für die Synthese von Palladium-Nanopartikeln (mittels Incipient Wetness Infiltration) verwendet. Als Referenzkatalysatoren kamen kommerziell erhältliche Pd-Trägerkatalysatoren (Pd@C, Pd@NoritA) und Pd@MOF 5 zum Einsatz. Bei den Experimenten erwies sich Pd@MIL 101 als besonders stabil gegenüber den Reduktions- und Reaktionsbedingungen, sowohl in Gasphasen- als auch Flüssigphasenhydrierungen. Die erzielten Ergebnisse zeigen den starken Einfluss des spezifischen Porenvolumens, der Form der Pore bzw. des Poreneingangs, der Polarität des Substrates und des verwendeten Lösungsmittels auf die adsorbierte Substratmenge. Sie verdeutlichen die Relevanz von Adsorptionsuntersuchungen an neuen Materialien. Das Verständnis der Wechselwirkungen zwischen den verwendeten Lösungsmitteln, Substraten und Adsorbentien ist ein entscheidender Faktor bei der Optimierung von Adsorptionsprozessen und bei der Verwendung von MOFs in heterogen katalysierten Reaktionen. Diese Arbeit zeigt das hohe Potential von Metall-Organischen Materialien im Bereich der heterogenen Katalyse. Unter Verwendung dieser Verbindungen als Trägermaterialien für Palladium können sehr hohe Aktivitäten in Hydrierungsreaktionen erreicht werden, welche z.T. auch industriell genutzte, Aktivkohle basierte Pd-Trägerkatalysatoren übertreffen.

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No. of bitstreams: 1 santos_cf_me_sjrp.pdf: 2242337 bytes, checksum: fa2ed2aede3ab1105b17fe2fc10b76c3 (MD5) Previous issue date: 2018-05-23 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / RESUMO Pesquisa destinada a melhorar e gerar rotas de produção de biocombustíveis como fonte alternativa a combustíveis derivados do petróleo está se tornando mais frequente. Nesta área, desenvolver novas técnicas que facilitem, ou ajudem a otimizar processos como a transesterificação de óleos vegetais ganham espaço no meio científico. Óxidos provenientes de materiais semelhantes a hidrotalcitas pertencentes à família de argilas aniônicas foram estudados recentemente como um substituinte para catalisadores básicos na síntese de biodiesel. Para testar estes catalisadores, a síntese de materiais de hidrotalcita como (HDLs) com fórmula molecular MgxXAly (CO3)(OH)16.4H2O em diferentes proporções x / y foi realizada com substituição total de Na2CO3 por amido de milho e amido de milho acidificado pelo ozono. A síntese dos HDLs foi realizada pelo método de coprecipitação e os materiais secados pela técnica de pulverização e para gerar os óxidos estes precursores foram calcinados a 450 e 600 °C . A caracterização do HDLs foi realizada por difração de raios-X (XRD), espectroscopia vibracional (ATR-FTIR) e decomposição térmica (TGA) e dos óxidos por XRD, BET, adsorção de CO2 (basicidade) e n-butilamina (acidez) e microscopia eletrônica de varredura (MEV). As reações de transesterificação foram processadas por 12 horas a 120 ° C na proporção molar de óleo de soja /etanol (1/20) com 20% (m / m) de catalisador em relação à massa, e os produtos foram quantificados por GC-FID. Com a introdução de amido de milho ou amido de milho acidificado no sólido, características físico-químicas típicas de HDLs foram alteradas com base nos dados obtidos das caracterizações. Foi observado o aumento nas áreas superficiais dos óxidos (800m2 g-1) e nas propriedades de acidez e basicidade. Nos testes iniciais o precursor sem a presença de amido (3:1 Mg:Al) alcançou 36,1% de conversão. Embora o melhor resultado de conversão tenha sido alcançado a partir do sólido sem amido de milho, existe uma correlação interessante entre as atividades catalíticas e as propriedades físico-químicas dos sólidos com os materiais modificados e seus respectivos homólogos. Estudos suplementares buscando melhorar o rendimento destes óxidos foram realizados resultando com resultados próximos a 50% de rendimento de biodiesel. / Research to improve biofuel production routes as an alternative source of petroleumderived fuels has been matter of recent efforts. In this area, developing new techniques that facilitate or help optimize processes such as transesterification of vegetable oils have been gaining attention. Oxides from hydrotalcite-like materials belonging to the anionic clays family were recently studied as substitute for basic catalysts in the synthesis of biodiesel. In order to test these catalysts, the synthesis of hydrotalcite materials (HDLs) with molecular formula MgxXAly(CO3)(OH)16.4H2O in different x/y ratios was carried out with total substitution of Na2CO3 by corn starch and corn starch acidified by ozone. The synthesis of the HDLs was performed by the coprecipitation method and the materials dried by the spray technique and the oxides generated by calcination at 450 and 600 °C. The characterization of HDLs was performed by XRD, vibration spectroscopy (ATR-FTIR) and thermal decomposition (TGA) and the oxides by XRD, BET, CO2 adsorption (basicity) and nbutylamine (acidity), and scanning electron microscopy (SEM). The transesterification reactions were carried out for 12 hours at 120 °C in 1/20 molar ratio of soybean / ethanol with 20% (w/w) of catalyst and the products were quantified by GC-FID. With the introduction of corn starch or acidified maize starch into the solid, typical physico-chemical characteristics of HDLs were successfully modified based on the characterization data. It was observed the increase in the surface areas of the oxides (800 m2 g -1 ) and in the acidity and basicity properties. In catalytic assays the precursor without the presence of starch (3:1 Mg:Al) reached 36.1% conversion. Although the best conversion result has been achieved from the solid without cornstarch, there is an interesting correlation between the catalytic activities and the physico-chemical properties of the solids with the modified materials and their respective counterparts. Further studies to improve the yield of these oxides were performed resulting in results close to 50% biodiesel yield. / 380762/2016-1.

Cette thèse porte sur la modélisation multi-échelle des réactions en catalyse hétérogène de polyols sur une surface de platine 111, en phase aqueuse. Ce travail s’inscrit dans l’utilisation de la biomasse lignocellulosique. Les réseaux réactionnels issus du traitement de cette matière première sont très grands en taille, et en complexité. D’autre part, la nature même des molécules la composant impose une chimie en phase aqueuse. Il n’est donc pas possible de cartographier l’ensemble des ces chemins réactionnels avec des méthodes de calcul ab initio, tant les conditions aqueuses et le grand nombre de simulations que cela impliquerai demanderaient d’effort computationnel. Le changement d’échelle de simulation peut répondre à ce problème. Nous avons ainsi développé un modèle d’additivité par groupes permettant la prédiction des propriétés thermodynamiques de réactions de polyols sur platine 111 en phase aqueuse, à partir de la seule structure topologique des réactifs. Ce modèle a été construit sur un jeu de données issus de calculs en théorie de la fonctionnelle de la densité. Nous avons également étudié la cinétique de réactions de mêmes types, afin d’en prédire l’énergie d’activation à partir de leur thermodynamique. En parallèle, nous avons décrit l’influence de la micro-solvatation par rapport à un modèle de solvant implicite sur la réactivité d’alcools sur platine 111, ce qui couplé avec le modèle d’additivité par groupe permettra des simulations micro cinétiques complètes. Enfin, la réactivité des isomères du butanediol a été traitée afin de comprendre l’influence de l’espacement des fonctions alcools sur la réactivité d’un polyol. / This thesis focuses on multi scale simulations heterogeneous catalysis reactions of polyols on platinum (111) in aqueous phase. This work is about lignocellulosic biomass valorisation. The reaction networks raising from these materials are extremely large and complex. Also, the properties of the molecules forming this biomass make aqueous conditions mandatory. Ab initio methods as we know them forbids us to treat entire networks at the finest calculation level, the computational cost would be way beyond feasibility. Changing the simulation scale can tackle this problem. Thus, we developed a group additivity model assessing for thermochemical properties of polyols at a platinum (111) surface under aqueous conditions, with a topology as the only input. This model was built upon a density functional theory set. Kinetics of reactions was also covered, and the difference in terms of impact was investigated between implicit and explicit micro solvation models, in order to predict reaction barriers. The two models might be used together in order to feed a micro kinetic simulation, allowing a drastic decrease of reaction networks complexity. Finally, the influence on reactivity and selectivity, of hydroxyl groups on butanediol isomers was investigated.

Afin de répondre aux nouveaux challenges de l'industrie chimique, le développement de nouveaux réacteurs catalytiques hétérogènes plus efficaces et plus sûrs ainsi que leur compréhension sont nécessaires. Dans cette optique, des réacteurs micro ou milli-structurés ont vu le jour et suscitent un intérêt croissant de par leur capacité à diminuer les phénomènes physiques de limitations aux transferts de mantière et de chaleur. Dans ce travail, deux concepts de réacteurs structurés dédiés au milieu gaz-liquide solide sont étudiés. Le premier est un réacteur à film tombant microstructuré (FFMR) dans lequel des canaux sub-millimétriques, rectilignes et verticaux permettent de stabiliser et d'amincir un film liquide en écoulement, générant des aires d'interfaces très importantes. Disponible commercialement, il présente un très bon potentiel pour la mise en oeuvre de réactions à fortes contraintes mais pour de petites productions. Le second réacteur est quant à lui nouveau. Des mousses à cellules ouvertes métalliques sont utilisées comme support de catalyseur structurant confiné dans un canal de section millimétrique carrée et soumis à un écoulement de Taylor G-L préformé. Pour chaque réacteur, l'hydrodynamique des écoulements est étudiée par le développement de techniques microscopiques et leurs aptitudes aux transferts de masses sont évaluées par la mise en oeuvre de la réaction catalytique d'hydrogénation de l'α-methylstyrène. Il en ressort que les écoulements particuliers rencontrés dans ces deux objets permettent d'atteindre des capacités de transferts de matières supérieurs d'au moins un ordre de grandeur aux technologies usuelles pour un coût énergétique, lié à l'écoulements des fluides, faible. Par ailleurs, des éléments de dimensionnement (hydrodynamique, perte de charge et transferts de matière) ont été construits pour les deux réacteurs / To meet the new challenges of the chemical indutries, the developpement of new heterogeneous catalytic reactors and their understanding are mandatory. From these perspectives, new reactor designs based on structuring at micro or millimeter scales have emerged. They have sparked interest for their ability to decrease physical limitations for heat and mass transfers. Thus, two advanced reactor technologies for gas-liquid-solid catalysed reactions are studied. The first reactor is a micro-structured falling film (FFMR) in which vertical sub millimetric grooves are etched and coated with a catalyst. This structuration allows stabilizing the gas-liquid interface of a down flow liquid phase. A thin liquid film is generated leading to high specific surface areas. Commercially available, it represents a very good potential for performing demanding reactions (i.e.fast, exothermic) for small scale productions such as pharmaceuticals. In a second part, a new reactor concept is proposed. Open cell foams are used as catalyst support and inserted in a milli-square channel. The reactor is then submitted to a preformed gas-liquid Taylor flow. In both cases, hydrodynamics features are studied by using microscopy based methods. Their potential in terms of mass transfers are also studied by performing catalyzed α-methylstyren hydrogenation. For both reactors, it comes out that the particular flow induced by micro or milli structures leads to at least one order of magnitude higher mass transfers performances than mutliphase reactors currently used in the industry albeit it remains to be demonstrated at such scale. From all these studies, correlations, models and methods for chemical engineers (hydrodynamics, pressure drops, mass transfer) are proposed for the two reactors