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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

<b>Investigation of Additively Manufactured Silver Plated Stainless Steel Monolith Catalyst Beds</b>

Amelia Jane Farquharson (19180201) 19 July 2024 (has links)
<p dir="ltr">Additive manufacturing has introduced new possibilities for the design and manufacturing of monolith catalyst beds. Many hydrogen peroxide monolith catalyst beds are made of ceramics and washcoated through a complex process. However, creating a metal monolith bed with the tried-and-true silver catalyst could provide an alternative decomposition method for 90 wt.% hydrogen peroxide with easier manufacturing methods and similar or better decomposition efficiency. 91.2 wt.% hydrogen peroxide was decomposed with a lattice-type monolithic catalyst bed additively manufactured out of 316L stainless steel that was electroplated with pure silver. The variables investigated included the catalyst bed’s mass loading, chamber pressure, pressure drop, and length-to-diameter ratio (L/D). The catalyst bed had loadings of 0.1 lb<sub>m</sub>/s/inch<sup>2</sup>, 0.25 lb<sub>m</sub>/s/inch<sup>2</sup>, and 0.4 lb<sub>m</sub>/s/inch<sup>2</sup>. One catalyst bed configuration had an L/D of 2.6, while the other configuration had an L/D of 0.85. A modular throat controlled the chamber pressures for each catalyst bed loading case. The decomposition efficiency was calculated with the theoretical and expected characteristic velocity (c*) of the catalyst beds. The chamber pressures for the lowest bed loading and highest L/D ratio varied from 52 psia to 202 psia. The hydrogen peroxide decomposition efficiency was approximately 85% for the lowest chamber pressure and approximately 100% for the highest chamber pressure. The chamber pressures for the middle and highest bed loading and high L/D were 193 psia at the lowest to 325 psia at the highest. The decomposition efficiencies for all middle and highest bed loading tests with high L/D were 90% or higher for all tests. For all of the highest L/D tests, decomposition was also confirmed by observing videos of the exhaust plume, which was clear and showed no sign of flow channeling. For all of the highest L/D tests, the pressure drops in all of the middle bed loading cases were at or below 30% of the chamber pressure. The high chamber pressure, highest bed loading cases also had a pressure loss below 30% of the chamber pressure. The smallest L/D configuration performed significantly worse than expected, with efficiencies between 15-25% at chamber pressures between 33-75 psi. The silver electroplated on the stainless steel survived the 143 s of lifetime on the catalyst bed during testing with minimal to no silver loss determined by weight and visual inspection with a microscope post-test. The higher L/D catalyst bed tests prove that silver electroplated on to an additively manufactured stainless steel monolith is a viable method for creating a catalyst bed. More research is required to determine the lowest L/D possible, which resides somewhere between the two L/D cases studied, and higher bed loadings also require investigation.</p>
82

Persuasions of archaeology : the achievements and grandeur of the Omrids at their royal cities of Samaria and Jezreel

Schneider, Catharina Elizabeth Johanna 01 1900 (has links)
Our perception, of the Omrid kings of the Kingdom oflsrael in the ninth century BCE, is based on the Books of 1 and 2 Kings in the Hebrew Bible. The Biblical author's concentration, on Omrid apostasy rather than on their abilities and accomplishments, has robbed these competant monarchs of the prominence allotted to kings like David and Solomon. Recent archaeological excavations, in conjunction with extra-Biblical sources, have however projected a different image. Excavations at the royal Omrid cities of Samaria, and especially Jezreel, have indicated that Omri, and his son Ahab, had erected immense and grandiose structures. These edifices bear testimony to periods of peace, stability and great economic prosperity. The Omrids deserve new assessments as to their accomplishments, and therefore, by means of visible and tangible structural remains, I wish to promote the persuasion of archaeology as vindication of Omrid grandeur and achievement at Samaria and Jezreel. / Biblical and Ancient Studies / M.A. (Biblical Studies)
83

Synthèse de nouvelles phases monolithes versatiles à base de N-acryloxysuccinimide pour l'électrochromatographie

Guerrouache, Mohamed 20 November 2009 (has links)
L’intérêt grandissant porté au cours de ces dix dernières années aux monolithes organiques pour des applications électroséparatives se justifie en partie par leur préparation aisée au sein de systèmes miniaturisés, le large choix des monomères précurseurs disponibles, ainsi que la possibilité d’ajuster les paramètres structuraux du matériau final par un contrôle judicieux des conditions opératoires. Au cours de ce travail, la synthèse de nouvelles phases monolithiques a été mise au point selon une stratégie en deux étapes. Dans une première étape, la copolymérisation radicalaire photo-initiée du Nacryloxysuccinimide avec le diméthacrylate d’éthylène glycol réalisée en présence de toluène, a permis l’élaboration de monolithes macroporeux réactifs et hautement perméables. La présence d’esters de succinimide dans la structure chimique du monolithe polymère a été mise à profit pour fonctionnaliser la surface du monolithe par des greffons de nature variée par réaction de substitution nucléophile faisant intervenir des dérivés aminés. Le choix judicieux des greffons a permis la mise au point rapide de phases stationnaires présentant des propriétés électrochromatographiques ciblées. Ainsi, le contrôle du caractère hydrophobe des supports obtenus par greffage d’alkylamines de taille variable a été mis en évidence par la séparation de dérivés benzéniques selon un mécanisme à polarité de phase inversée avec de très bonnes efficacités (200000 plateaux par mètre). L’utilisation de phases stationnaires monolithiques greffées par des sélecteurs aromatiques a été proposée comme alternative aux monolithes aliphatiques hydrophobes. La synthèse de monolithes organiques hydrophiles a été possible par la fonctionnalisation du support réactif par des alkyldiamines. La préparation d’une phase stationnaire chirale a été réalisée selon une approche originale de chimie click consistant à immobiliser un dérivé de cyclodextrine. Dans le but d’étendre l’application des monolithes à base de NAS au greffage de biomacromolécules, une nouvelle matrice monolithique incorporant dans sa structure chimique un co-monomère hydrophile a été élaborée. Les résultats préliminaires ont montré que l’augmentation du caractère hydrophile du squelette monolithique permet d’accroître sensiblement la réactivité des esters de Nhydroxysuccinimide en milieu aqueux / The continuously growing interest observed over the past ten years in the field of organic monoliths dedicated to electroseparation applications is mainly due to their easy preparation methods which are also well-suited to the development of miniaturized systems, the wide range of available monomers and the possibility of tuning the structural parameters of the final material by a judicious control of the synthesis conditions. In the present work, the synthesis of new monolithic stationary phases has been developed using a two-stage strategy. In a first step, the photo-initiated free radical copolymerization of Nacryloxysuccinimide with ethylene glycol dimethacrylate was performed in the presence of toluene allowing the preparation of reactive and macroporous monoliths with high permeability properties. The presence of succinimide esters in the chemical structure of the polymer monolith was used to functionalize the surface of the monolith by various grafts through nucleophilic substitution reaction involving amino derivatives. The judicious choice of the grafts permits the fast development of stationary phases with target electrochromatographic properties. Indeed, the tuning of the hydrophobic nature of the monolithic materials was obtained by the grafting of varied alkylamines and was demonstrated by the separation of benzene derivatives by reversed phase mechanism with very good efficiencies (200 000 plates per meter). The use of monolithic stationary phases grafted with aromatic selectors has been proposed as an alternative to the aliphatic-grafted hydrophobic monoliths. The synthesis of organic hydrophilic monoliths was possible by functionalization of the reactive support by alkyldiamines. The preparation of a chiral stationary phase was performed using an original click chemistry approach involving the immobilization of a cyclodextrin derivative. With the aim to extend the application range of NAS-based monoliths to the grafting of biomacromolecules for selective capture and enzymatic digestion applications, a new monolithic matrix incorporating in its chemical structure a hydrophilic comonomer was prepared. Preliminary results showed that the increase in the hydrophilic character of the polymeric skeleton allows increasing significantly the reactivity of N-hydroxysuccinimide esters in aqueous medium
84

Développement et mise en oeuvre de colonnes monolithiques d’affinité boronate pour des techniques séparatives miniaturisées / Boronate affinity monolithic columns for miniaturized separation techniques

Espina Benitez, Maria Betzabeth 08 October 2018 (has links)
Une partie des recherches actuelles dans le domaine de l’analyse chimique concerne la miniaturisation et l’intégration d’étapes analytiques afin de répondre, entre autres, à des besoins de portabilité, d’automatisation mais aussi d’apporter des solutions pour analyser des échantillons de plus en plus petits. Le développement et la mise en œuvre de colonnes monolithiques d’affinité boronate (µBAMC) couplées « in-line » à des techniques séparatives miniaturisées s’inscrit dans cette démarche. Ce travail de thèse s’est focalisé sur (1) une compréhension des mécanismes de rétention en chromatographie d’affinité boronate (interactions spécifiques avec les composés cis-diols, conditions de reconnaissance, interactions secondaires), (2) le développement de supports monolithiques d’affinité boronate miniaturisés et (3) leur couplage «in-line» avec une séparation électrocinétique et détection conventionnelle dans un format capillaire. Différentes voies d’élaboration de colonnes monolithiques ont été comparées (en termes d’affinité, de nombre de sites boronate actifs et de stabilité). La faisabilité du couplage en ligne de ces supports µBAMC avec une étape de séparation électrophorétique (par CZE et CIEF) a été démontrée vis-à-vis de la purification/préconcentration et séparation de 3 catécholamines contenant des groupements cis-diols (Adrénaline, Noradrénaline et Dopamine) dans l’urine. Les couplages ont été optimisés avec succès permettant l’analyse automatisée et miniaturisée de ces neurotransmetteurs dans l’urine (volume échantillon < 10 µL) avec des limites de détection de l’ordre de la dizaine de ppb et des taux de récupération proches de 100 % / Part of the current research in the field of chemical analysis concerns the miniaturization and the integration of analytical steps in order to meet, among other things, the need of portability and automation but also to provide solutions for analyzing small samples. The development and implementation of monolithic boronate affinity columns (µBAMC) in-line coupled to miniaturized separation techniques is part of this approach. This thesis work focused on (1) an understanding of the retention mechanisms in boronate affinity chromatography (specific interactions with cis-diol compounds, recognition conditions and secondary interactions), (2) the development of miniaturized boronate affinity monolithic supports and (3) their in-line coupling with electrokinetic separation and conventional detection in a capillary format. Different ways of elaboration of monolithic columns were compared (in terms of affinity, number of actives sites and stability). The feasibility of in-line coupling of these µBAMC supports with an electrophoretic separation step (by CZE and CIEF) has been demonstrated in terms of purification / preconcentration and separation of 3 catecholamines containing cis-diol groups (adrenaline, noradrenaline and dopamine) in urine. The couplings have been successfully optimized allowing the automated and miniaturized analysis of these neurotransmitters in urine (sample volume <10 µl) with limits of detection of about the tens of ppb and recovery yields close to 100 %
85

Monolithic separation media synthesized in capillaries and their applications for molecularly imprinted networks

Courtois, Julien January 2006 (has links)
<p>The thesis describes the synthesis of chromatographic media using several different approaches, their characterizations and applications in liquid chromatography. The steps to achieve a separation column for a specific analyte are presented. The main focus of the study was the design of novel molecularly imprinted polymers.</p><p>Attachment of monolithic polymeric substrates to the walls of fused silica capillaries was studied in Paper I. With a broad literature survey, a set of common methods were tested by four techniques and ranked by their ability to improve anchoring of polymers. The best procedure was thus used for all further studies.</p><p>Synthesis of monoliths in capillary columns was studied in Paper II. With the goal of separating proteins without denaturation, various monoliths were polymerized in situ using a set of common monomers and cross-linkers mixed with poly(ethylene glycol) as porogen. The resulting network was expected to present “protein-friendly pores”. Chemometrics were used to find and describe a set of co-porogens added to the polymerization cocktails in order to get good porosity and flow-through properties.</p><p>Assessment of the macroporous structure of a monolith was described in Paper III. An alternative method to mercury intrusion porosimetry was proposed. The capillaries were embedded in a stained resin and observed under transmission electron microscope. Images were then computed to determine the pore sizes.</p><p>Synthesis of molecularly imprinted polymers grafted to a core mono-lith in a capillary was described in Paper IV. The resulting material, imprinted with local anaesthetics, was tested for its chromatographic performance. Similar imprinted polymers were characterized by microcalorimetry in Paper V. Finally, imprinted monoliths were also synthesized in a glass tube and further introduced in a NMR rotor to describe the interactions between stationary phase and template in Paper VI.</p>
86

Gas Phase And Electrocatalytic Reaction Over Pt, Pd Ions Substituted CeO2, TiO2 Catalysts and Electronic Interaction Between Noble Metal Ions And The Reducible Oxide

Sharma, Sudanshu 04 1900 (has links)
Among the various heterogeneous catalytic reactions three way catalysis (TWC), catalytic combustion of hydrogen, water gas shift reaction (WGS) and preferential oxidation of CO (PROX) in the hydrogen rich stream are some of the important reactions receiving the attention presently. Three-way catalysis (TWC) involves simultaneous removal of the three pollutants (i.e., CO, NOx, and HCs) from the automobile exhaust. Catalytic combustion of hydrogen by oxygen or hydrogen-oxygen recombination reaction is an industrially important reaction. It has variety of application such as in sealed lead acid batteries and nuclear reactors. Water gas shift (WGS) reaction is of specific importance to produce hydrogen from carbonaceous material. PROX is an important step to further purify hydrogen produced form WGS. Hydrogen purified using PROX can be directly fed to polymer electrolyte membrane fuel cells. By and large, noble metals Pt, Pd, Rh, Ru and some of their alloys are dispersed on oxide or high surface area carbon are the active catalysts. An alternative approach can be to make Pt2+, Pd2+, Rh3+, Ru4+ ions substituted in reducible support such as CeO2, Ce1-xTixO2-δ and TiO2 to increase the dispersion and bring down the cost. In this thesis we have followed this new approach and show that noble metal ionic catalysts are superior to noble metal nano particles. In the 1st chapter we present an overview of heterogeneous catalysis and important heterogeneous catalytic reactions. Monolithic catalyst and various ways to coat catalysts for application have been reviewed. Metal-support interaction till date is also reviewed. In the 2nd chapter, synthesis of noble metal ionic catalysts by solution combustion method is described. Coating of washcoat and active catalyst phase over ceramic honeycomb by a new combustion method is described. Solution combustion reaction and characterization of the catalyst by x-ray diffraction, x-ray photoelectron spectroscopy, temperature programmed reduction and reaction is given. We have fabricated experimental systems to carryout catalytic reaction and in this chapter they have been presented. In the 3rd chapter, we report a new process of coating of active exhaust catalyst over -Al2O3 coated cordierite honeycomb. The process consists of (a) growing  -Al2O3 on cordierite by solution combustion of Al(NO3)3 and oxylyldihydrazide (ODH) at 600 0C. Active catalyst phase, Ce0.98Pd0.02O2- is coated on - Al2O3 coated cordierite again by combustion of ceric ammonium nitrate and ODH with 1.2  10-3 M PdCl2 solution at 500 0C. In this way a coat layer over cordierite ceramic has been achieved and catalyst has the active sites in the form of Pd2+ ions rather than Pd metal. Weight of the active catalyst can be varied from 0.02 to 2 wt% which is sufficient but can be loaded even up to 12 wt% by repeating dip dry combustion [1]. Adhesion of catalyst to cordierite surface is via oxide growth on oxide ceramic which is very strong. 100 % conversion of CO is achieved below 80 oC at a space velocity of 880 h-1. At much higher space velocity of 21000h-1, 100 % conversion is obtained below 245 oC. Activation energy for CO oxidation is 8.4 kcal/mol. At a space velocity of 880 h-1 100% NO conversion is attained below 185 oC and 100 % conversion of ‘HC’(C2H2) below 220 oC. At the same space velocity 3-way catalytic performance over Ce0.98Pd0.02O2- coated monolith shows 100% conversion of all the pollutants below 220 o C with 15% excess oxygen. Catalytic activity of cordierite honeycomb coated by this new coating method for the oxidation of major hydrocarbons in exhaust gas is discussed further in this chapter. ‘HC’ oxidation over the monolith catalyst is carried out with a mixture having the composition, 470 ppm of both propene and propane and 870 ppm of both ethylene and acetylene with the varying amount of O2. 3-way catalytic test is done by putting hydrocarbon mixture along with CO (10000ppm), NO (2000ppm) and O2 (15000ppm). Below 350 oC full conversion is achieved [2]. A comparison of the results shows that Ce1-xPdxO2-δ far superior to other catalysts. In this method, handling of nano material powder is avoided. In the 4th chapter we present a detailed study on the catalytic combustion of hydrogen by oxygen (hydrogen oxygen recombination reaction). Ever since Michel Faraday showed H2 + O2 recombination reaction over platinum metal plates, Pt metal has remained the only room temperature recombination catalyst. In search of an alternative catalyst, we discovered a new Pt free Ti0.99Pd0.01O2- compound which shows high rates of this reaction above 45 oC compared to Ce0.98Pt0.02O2-, Pt/Al2O3 and Pd/Al2O3. High rates of H2+O2 recombination over Pt and Pd ion respectively in CeO2 and TiO2 is due to the protonic type H2+ adsorption on Pt2+ or Pd2+ and dissociative chemisorption of O2 on the electron rich oxide ion vacancies [3]. In the case of Ce0.98Pt0.02O2-, H2/Pt ratio in a TPR experiment is ~2.3 at 0 oC. In the case of Ti0.99Pd0.01O2- also, H2 adsorption occurs below 0 oC and H2 / Pd ratio is ~2.2. Thus, more than 4-5 H atoms are adsorbed per metal ion. This is attributed to hydrogen spillover. H2 is known to be adsorbed as hydride ion (H-) over Pt, Pd, Rh, Ru, Os and Ir metals. Proton NMR studies of H2 adsorbed on Pd metal have shown upfield i.e. negative shift of 12 ppm with respect to TMS. We have studied proton NMR of Ti0.99Pd0.01O2- + H2 which show a downfield shift of 11.35 ppm confirming H+ or H2+ kind of species over Pd2+ ion in Ti0.99Pd0.01O2-. In Ce0.98Pt0.02O2- also H2 adsorption led to H2+ like species observed at 8 ppm and DFT calculations indeed showed H2+ kind species. H2+ is a precursor for dissociation and can readily induce O2 dissociation leading to high rates of recombination. In the 5th chapter we report water gas shift reaction (WGS) and preferential oxidation of CO (PROX) over Ti0.99Pt0.01O2-, Ce0.83Ti0.15Pt0.02O2- and Ce0.98Pt0.02O2-δ. The water gas shift reaction (WGS) is an important reaction to produce hydrogen. In this study, we have synthesized nano crystalline catalysts where Pt ion is substituted in the +2 state in TiO2, CeO2 and Ce1-xTixO2-δ. The catalysts have been characterized by X-ray diffraction and X-ray photoelectron spectroscopy (XPS) and it has been shown that Pt2+ ions in these reducible oxides of the form Ti0.99Pt0.01O2-, Ce0.83Ti0.15Pt0.02O2- and Ce0.98Pt0.02O2-δ are highly active. These catalysts were tested for the water gas shift reaction both in presence and absence of hydrogen. It is shown that Ti0.99Pt0.01O2- exhibits higher catalytic activity than Ce0.83Ti0.15Pt0.02O2- and Ce0.98Pt0.02O2-δ [4]. Further, experiments were conducted to determine the deactivation of these catalysts by performing the daily startup and shutdown of the reactor for over 24 hours. There was no sintering of Pt and no carbonate formation and, therefore, the catalyst did not deactivate even after prolonged reaction. There was no carbonate formation because of the highly acidic nature of Ce4+, Ti4+ ions in the catalysts. Further, PROX activity of these catalysts has been studied. Ce0.83Ti0.15Pt0.02O2- and Ce0.98Pt0.02O2-δ showed high activity, large operating temperature window and low working temperature proving them to be highly effective PROX catalysts. In the 6th chapter we study the electrocatalysis of formic acid electro-oxidation and simultaneously mapping the electronic states of the electrodes by X-ray photoelectron spectroscopy (XPS). Ionically dispersed platinum in Ce1-xPtxO2-δ and Ce1-x-yTiyPtxO2-δ is very active towards oxygen evolution and formic acid oxidation. Higher electro-catalytic activity of Pt2+ ions in CeO2 and Ce1-xTixO2 compared to Pt0 in Pt/C is due to Pt2+ ion interaction with the supports, CeO2 and Ce1-xTixO2 respectively [5]. Further, ionic platinum does not suffer from CO poisoning effect unlike Pt0 in Pt/C. Utilization of lattice oxygen from the electrodes during the reaction has been demonstrated. This lattice oxygen exchange is responsible to convert CO to CO2 in the lower potential region to remove CO poisoning effect. In 7th chapter we repeat our study on the noble metal ion reducible oxide interaction in Ce1-xPtxO2- and Ce1-xPdxO2- (x= 0.02) system by a novel electrochemical method combined with XPS. Working electrodes made of CeO2 and Ce0.98Pt0.02O2- mixed with 30% carbon are cycled between 0.0-1.2 V in potentio-static (chronoamperometry) and potentio-dynamic (cyclic voltametry) mode with reference to saturated calomel electrode (SCE). Reversible oxidation of Pt0 to Pt2+ and Pt4+ state due to the applied positive potential is coupled to simultaneous reversible reduction of Ce4+ to Ce3+ state. CeO2 reduces to CeO2-y (y= 0.35) after applying +1.2 V which is not reversible. But Ce0.98Pt0.02O2- reaches a steady state with Pt2+: Pt4+ in the ratio of 0.60: 0.40 and Ce4+: Ce3+ in the ratio of 0.55: 0.45 giving a composition Ce0.98Pt0.02O1.74 at 1.2 V which is reversible [6]. Composition of Pt ion substituted compound is reversible between Ce0.98Pt0.02O1.95 to Ce0.98Pt0.02O1.74 within the potential range of 0.0-1.2 V. Thus, Ce0.98Pt0.02O2- forms a stable electrode for oxidation of H2O to O2 unlike CeO2. A linear relation between oxidation of Pt2+ to Pt4+ with simultaneous reduction of Ce4+ to Ce3+ is observed demonstrating Pt-CeO2 metal support interaction is due to reversible Pt0/Pt2+/Pt4+ interaction with Ce4+/Ce3+ redox couple. Similar studies have been performed with Ce0.98Pd0.02O2- catalyst to show the redox coupling between Pd2+/Pd0 and Ce4+/Ce3+ redox couples. We expect similar redox coupling for Pd, Pt ions substituted TiO2, and Ce1-xTixO2. In the final chapter 8, a critical review and conclusion on the results presented in the thesis is presented. The combustion synthesized catalysts reported in this thesis stabilizes the Pt and Pd metals in their ionic state rather than zero valent metallic state. Thus, the catalysts are uniform solid catalysts. High activity and stability of these catalysts are shown to be due to the electronic interaction between noble metal ions and the reducible oxide. Redox couples Pt0/Pt2+, Pt2+/Pt4+ and Pd0/Pd2+ interact with Ce4+/Ce3+, Ti4+/Ti3+ couples such that metal is oxidized and the support is reduced. This has been established in the thesis by a combined use of electrochemistry and XPS thus solving a long standing problem of metal support interaction in catalysis. We hope that the results presented in the thesis is a worthwhile contribution to catalysis. (For mathematical equations pl refer pdf file.)
87

Rhodium diesel-reforming catalysts for fuel cell applications

Karatzas, Xanthias January 2011 (has links)
Heavy-duty diesel truck engines are routinely idled at standstill to provide cab heating or air conditioning, and in addition to supply electricity to comfort units such as radio and TV. Idling is an inefficient and unfavorable process resulting in increased fuel consumption, increased emissions, shortened engine life, impaired driver rest and health, and elevated noise. Hydrogen-fueled, polymer-electrolyte fuel-cell auxiliary power unit (PEFC-APU) as a silent external power supply, working independently of the main engine, is proposed as viable solution for better fuel economy and abatement of idling emissions. In a diesel PEFC-APU, the hydrogen storage problem is circumvented as hydrogen can be generated onboard from diesel by using a catalytic reformer. In order to make catalytic diesel PEFC-APU systems viable for commercialization research is still needed. Two key areas are the development of reforming catalyst and reformer design, which both are the scope of this thesis. For diesel-reforming catalysts, low loadings of Rh and RhPt alloys have proven to exhibit excellent reforming and hydrogen selectivity properties. For the development of a stable reforming catalyst, more studies have to be conducted in order to find suitable promoters and support materials to optimize and sustain the long-term performance of the Rh catalyst. The next step will be full-scale tests carried out at realistic operating conditions in order to fully comprehend the overall reforming process and to validate promising Rh catalysts. This thesis can be divided into two parts; the first part addresses the development of catalysts in the form of washcoated cordierite monoliths for autothermal reforming (ATR) of diesel. A variety of catalyst compositions were developed containing Rh or RhPt as active metals, CeO2, La2O3, MgO, Y2O3 as promoters and Al2O3, CeO2-ZrO2, SiO2 and TiO2 as support materials. The catalysts were tested in a bench-scale reactor and characterized by using N2-BET, XRD, H2 chemisorption, H2-TPR, O2-TPO, XPS and TEM analyses. The second part addresses the development and testing of full-scale reformers at various realistic operating conditions using promising Rh catalysts. The thesis shows that a variety of Rh on alumina catalysts was successfully tested for ATR of diesel (Papers I-IV). Also, zone-coating, meaning adding two washcoats on specific parts of the monolith, was found to have beneficial effects on the ATR catalyst performance (Paper II). In addition, RhPt supported on CeO2-ZrO2 was found to be one of the most active and promising catalyst candidates for ATR of diesel. The superior performance may be attributed to higher reducibility of RhiOx species and greater dispersion of Rh and Pt on the support (Paper IV). Finally, two full-scale diesel reformers were successfully developed and proven capable of providing high fuel conversion and hydrogen production from commercial diesel over selected Rh catalysts (Papers II-III, V-VI). / QC 20110418
88

Monolithic separation media synthesized in capillaries and their applications for molecularly imprinted networks

Courtois, Julien January 2006 (has links)
The thesis describes the synthesis of chromatographic media using several different approaches, their characterizations and applications in liquid chromatography. The steps to achieve a separation column for a specific analyte are presented. The main focus of the study was the design of novel molecularly imprinted polymers. Attachment of monolithic polymeric substrates to the walls of fused silica capillaries was studied in Paper I. With a broad literature survey, a set of common methods were tested by four techniques and ranked by their ability to improve anchoring of polymers. The best procedure was thus used for all further studies. Synthesis of monoliths in capillary columns was studied in Paper II. With the goal of separating proteins without denaturation, various monoliths were polymerized in situ using a set of common monomers and cross-linkers mixed with poly(ethylene glycol) as porogen. The resulting network was expected to present “protein-friendly pores”. Chemometrics were used to find and describe a set of co-porogens added to the polymerization cocktails in order to get good porosity and flow-through properties. Assessment of the macroporous structure of a monolith was described in Paper III. An alternative method to mercury intrusion porosimetry was proposed. The capillaries were embedded in a stained resin and observed under transmission electron microscope. Images were then computed to determine the pore sizes. Synthesis of molecularly imprinted polymers grafted to a core mono-lith in a capillary was described in Paper IV. The resulting material, imprinted with local anaesthetics, was tested for its chromatographic performance. Similar imprinted polymers were characterized by microcalorimetry in Paper V. Finally, imprinted monoliths were also synthesized in a glass tube and further introduced in a NMR rotor to describe the interactions between stationary phase and template in Paper VI.
89

Persuasions of archaeology : the achievements and grandeur of the Omrids at their royal cities of Samaria and Jezreel

Schneider, Catharina Elizabeth Johanna 01 1900 (has links)
Our perception, of the Omrid kings of the Kingdom oflsrael in the ninth century BCE, is based on the Books of 1 and 2 Kings in the Hebrew Bible. The Biblical author's concentration, on Omrid apostasy rather than on their abilities and accomplishments, has robbed these competant monarchs of the prominence allotted to kings like David and Solomon. Recent archaeological excavations, in conjunction with extra-Biblical sources, have however projected a different image. Excavations at the royal Omrid cities of Samaria, and especially Jezreel, have indicated that Omri, and his son Ahab, had erected immense and grandiose structures. These edifices bear testimony to periods of peace, stability and great economic prosperity. The Omrids deserve new assessments as to their accomplishments, and therefore, by means of visible and tangible structural remains, I wish to promote the persuasion of archaeology as vindication of Omrid grandeur and achievement at Samaria and Jezreel. / Biblical and Ancient Studies / M.A. (Biblical Studies)
90

Stavebno technologický projekt administratívnej budovy v Šumperku. / Building technology project office building in Šumperk.

Puczok, Daniel January 2017 (has links)
This diploma thesis is deals with construction-technological project for administrative building in Šumperk. This thesis is concerned with technological regulation of monolith structure, its inspection and test schedule and its risks plan. This project includes construction - technological study of building stages, suggestion of machine composition, solution of traffic routes, technical report of construction site, budget, plan of maintenance, timetable of construction and financial plan of building.

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