Orientadores: Reginaldo Guirardello, Cristiane Barbieri Rodella, Fábio de Ávila Rodrigues / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-25T22:54:30Z (GMT). No. of bitstreams: 1 SepulvedaLanziano_CarlosAlberto_M.pdf: 2488855 bytes, checksum: f2b18af4d9c9b44b4d3596ab297bbcda (MD5) Previous issue date: 2014 / Resumo: O presente trabalho teve como objetivo avaliar catalisadores de titânia-zircônia na reação de isomerização de glicose para frutose. Foram testados catalisadores puros de titânia e zircônia, além de mistos desses óxidos em proporções em massa de 25:75, 50:50 e 75:25. Os catalisadores foram caracterizados por adsorção de nitrogênio a 77 K, difração de raios X e dessorção a temperatura programada de CO2 e NH3. A atividade catalítica dos catalisadores foi testada em reator de batelada, a temperaturas de 393, 403, 413 e 423 K e tempos de reação de 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7 e 8 h. Os resultados mostraram que os catalisadores puros possuem estrutura cristalina, no caso da titânia fase anatásio e mistura de fase monoclínica e tetragonal no caso da zircônia. A área superficial dos catalisadores puros foi menor em comparação com os catalisadores mistos que mostraram ser materiais amorfos. Além disso, os catalisadores mistos apresentaram maior concentração de sítios ácidos e básicos. Todos os catalisadores permitiram a reação de isomerização, contudo favoreceram reações secundárias que transformaram a frutose em HMF e/ou ácido lático. A isomerização de frutose é atribuída às características básicas, enquanto a formação de HMF às características ácidas. Já a formação de ácido lático é considerada como a intervenção de sítios básicos e ácidos. Finalmente, considerando esses resultados foram supostas rotas de reação sobre os catalisadores e modeladas matematicamente. Os parâmetros reacionais foram determinados ajustando os dados experimentais aos modelos matemáticos usando a metodologia de ajuste de parâmetros de equações diferenciais ordinárias / Abstract: In this work, titania-zirconia catalyst were evaluated in the reaction of glucose into fructose. Pure Titania and Zirconia and mixed oxides in mass proportions 25:75, 50:50 and 75:25 were tested. The catalysts were characterized by nitrogen adsorption at 77K, X-ray diffraction and temperature programmed desorption of \ce{CO2} and \ce{NH3}. The catalytic activity was measured in batch reactor at temperatures of 393, 403, 413 and 423 K and reaction times of 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7 and 8 h. The results showed that pure catalyst structure is crystalline, Titania phase was anatase and Zirconia was mixture of monoclinic and tetragonal phase. The surface area of pure catalysts was lower that the mixed catalysts, these showed properties of amorphous solids. Similarly, the mixed catalysts showed higher concentration of acidic and basic sites. The catalysts allowed the isomerization reaction, but favored side reactions that convert fructose to HMF and lactic acid. Basic sites favored the reaction of isomerization of glucose into fructose and acid sites favored the reaction of dehydration of fructose to HMF. Basic and acid site favored lactic acid formation. Finally taking into account these results were supposed routes of reaction on the catalysts and modeled mathematically. The reaction parameters were determined by fitting the experimental data to mathematical models. The methodology used was parameter estimation for differential equations / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Recently a large amount of interest has developed around separating out impurities of small size; pertinent examples are found within fuel and solvent processing. For such applications a leading candidate process is nanofiltration. This thesis focuses on SRNF (solvent resistant nanofiltration) composite membranes consisting of a dense polymer active layer bonded to a stronger, but ultimately more porous, support layer. The composite membranes that have been produced during the course of this work consist of a PDMS (polymdimethylsiloxane) active layer bonded to a commercially available support layer of PAN (polyacrylonitrile). To create the membrane a monomer was spread over the support layer and then polymerised to form the matrix which was responsible for separation. Commercially, either heat or radiation is often applied to cause polymerisation, however the membranes in the current work have been formed by the used of a homogeneous catalyst. This thesis investigates the transport and separation dynamics of the produced membranes for a series of fuel simulants composed of organometallics and poly-nuclear aromatic solutes dissolved in aromatic and alkane solvents. Membrane composition and the extent of polymer swelling were found to be the two key factors which had the greatest influence on solvent flux and solute rejection. By increasing catalyst concentration it was found that the dual effects of increased rejection and reduced flux occurred, with the converse also being true. The effective pore size of the membrane could also be controlled by varying the catalyst amount during manufacture as this directly affected the limit of crosslinking which formed. Polymer swelling was the most pronounced using solvents with a solubility parameter close to that of the polymer. The membrane transport mechanism was most accurately forecast by the solution diffusion model for flux predictions and the convection diffusion model for rejection predictions, however all the models tried were in close agreement. This was postulated to be due to the swelled polymer matrix which allows for both convective and diffusive transport to occur.

Abstract The aim of this thesis is the knowledge of the most relevant deactivation mechanisms of Pd/Rh three-way catalysts under different ageing conditions, the deactivation correlation of laboratory scale ageing and engine bench/vehicle ageings, and the evaluation of the deactivation correlation. In the literature review, the phenomena involved in the three-way catalyst operation and its deactivation are considered. In the experimental section, ageing-induced phenomena in the catalyst are studied and deactivation correlations between laboratory scale and engine bench/vehicle ageings are presented, based on the results of several surface characterization techniques. The effects of ageing atmosphere and temperature, and time are considered in particular. Fresh and aged catalysts used in this study were metallic monoliths designed for Euro IV emission limits. Thermal ageings were carried out in the reductive, oxidative and inert atmospheres in the temperature range of 800°C to 1200°C, and in the presence of water vapour (hydrothermal ageing). The engine ageing was carried out in the exhaust gas stream of a V8 engine during a 40 hour period. The ageing procedure composed of rich and stoichiometric air-to-fuel ratios carried out consecutively. The vehicle ageing was accomplished under real driving conditions (100 000 kilometres). According to the results, deactivation of a Pd/Rh monolith is a combination of several ageing phenomena. The most important deactivation mechanisms are the sintering of active phase, the collapse in surface area and ageing-induced solid-solid phase transitions in the bulk washcoat. Furthermore, poisoning is a relevant deactivation mechanism of the vehicle-aged catalyst. High ageing temperature, gas phase composition and exposure time are essential variables to the deactivation of a Pd/Rh three-way catalyst. This thesis presents an approach to discover the deactivation correlation between the laboratory scale ageing and under the vehicle's operation in an engine bench or on-road. Based on the characterization results, the accelerated laboratory scale air ageing does not correspond to the ageing-induced changes in the catalyst under the vehicle's operation. Therefore, there is a need for a modified ageing cycle and according to the results, a deactivation correlation between the laboratory scale ageing and the engine bench ageing can be presented as a function of ageing temperature and atmosphere, and time. Instead, after the vehicle operation, the deactivation correlation cannot be presented based solely on the studied variables because, after 100 000 kilometres of driving, the role of poisoning should be taken into account in the ageing cycle. The results of this thesis can be utilized and applied in the development of laboratory scale ageing cycles, which corresponds closely to the ageing-induced changes in the catalyst during the vehicle operation. This enables a rather fast testing of the catalyst's performance and reduces the cost during the manufacturing of catalysts.

Abstract Protein disulfide bonds are covalent links formed between the thiol groups of cysteine residues. In many proteins, they have an important role in stabilizing the three-dimensional conformation of the polypeptide chain. Usually proteins are physiologically active and functional only when they are correctly folded. Protein folding takes place very soon after the synthesis of a new polypeptide chain. Proteins which are to be secreted from the cell fold in a specialized compartment, the endoplasmic reticulum (ER). Folding and disulfide bond formation in the ER does not happen spontaneously, there are proteins which are specialized in assisting in these processes. Protein disulfide isomerase (PDI) is a multifunctional protein, which is capable of catalysing both of disulfide bond formation and folding of a protein. In addition, it has other functions: it is an essential part of two protein complexes: collagen prolyl 4-hydroxylase (C-P4H) and microsomal triglyceride transfer protein. C-P4H is an enzyme essential in the formation of collagens, proteins found in connective tissue. The function of C-P4H is to catalyse the hydroxylation of prolines, which is essential for the structural stability of collagens. C-P4H is a tetramer, formed of two catalytic α subunits and two β subunits, which are identical to PDI. The function of PDI in C-P4H is apparently to keep it in a soluble, functionally active conformation. In mammals there are several proteins similar to PDI, together forming a PDI family of proteins. They share both structural and functional similarities. One of these proteins is ERp57. It is specialized in assisting in the folding and disulfide bond formation of glycoproteins. PDI consists of four domains, two of which contain a catalytic site for disulfide bond formation. One domain is the main site of interaction with other proteins and one domain is of unknown function. In this study, the role of these domains in the activities of PDI was investigated. The peptide-binding domain was characterized in detail. In addition, structural similarities of PDI and ERp57 were studied by formation of hybrid proteins containing domains of both and comparing the activities of these recombinant proteins to those of PDI.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15389号 / 工博第3268号 / 新制||工||1492(附属図書館) / 27867 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 江口 浩一, 教授 井上 正志, 教授 垣内 隆 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17522号 / 工博第3681号 / 新制||工||1560(附属図書館) / 30288 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 辻 康之, 教授 大江 浩一, 教授 松原 誠二郎 / 学位規則第4条第1項該当

Master of Science / Department of Mechanical and Nuclear Engineering / Kirby S. Chapman / In the natural gas production industry, recent legislation has mandated new emission regulations for low horsepower reciprocating internal combustion engines. One method to achieve compliance of the new regulations is the use of non-selective catalytic reduction. Nonselective catalytic reduction utilizes a three-way catalyst and an air-to-fuel ratio controller to oxidize carbon monoxide and unburned fuel while reducing oxides of nitrogen. Testing of a non-selective catalytic reduction system was preformed on a typical exploration and production engine, a Compressco GasJack. To fully test the unit, exhaust gas samples were taken with an ECOM gas analyzer both before and after the catalyst over typical engine speeds and powers. By sampling the exhaust gas concentration before and after the catalyst, the catalyst efficiency or percent reduction in exhaust gas specific concentrations were calculated. Additionally by testing throughout the engine's typical operation range, conditions under which the non-selective catalyst reduction system fails were determined. After testing, it was found that the three-way catalyst was effective at reducing oxides of nitrogen by 98% at all speeds and power conditions. Carbon monoxide was reduced by 90% under all conditions except for maximum speed and power. At maximum speed and power, the conversion efficiency for carbon monoxide was recorded as low as 32%. One reason for the low conversion efficiency at maximum speed and power was that the oxygen concentration entering the catalyst was not sufficient to oxidize the carbon monoxide to carbon dioxide. These results indicate the three-way catalyst was effective at reducing emissions when the controller correctly maintained the pre-catalyst oxygen concentration. However, the controller was unable to maintain engine operation at the ideal airto- fuel ratio at all test conditions. The controller failed to keep the pre-catalyst oxygen concentration in the correct range because the oxygen sensor was not accurate and consistent in its output. Future work on the development of a more robust oxygen sensor is recommended.

Philosophiae Doctor - PhD / Direct methanol fuel cells (DMFCs) are attractive power sources as they offer high conversion efficiencies with low or no pollution. One of the major advantages DMFCs has over PEMFCs is that methanol is a liquid and can be easily stored where in the case for PEMFCs storing hydrogen requires high pressures and low temperatures. However, several challenging factors especially the sluggish oxygen reduction reaction (ORR) and the high cost of Pt catalysts, prolong their commercialization. With the aim to search for more active, less expensive more active ORR catalysts and methanol tolerant catalysts than pure Pt, this dissertation focuses on the development of low loading Pt electrocatalyst and the understanding of their physical and electrochemical properties. Pt-Sn/C electrocatalsyts have been synthesized by a modified polyol reduction method. The effect of temperature, pH, water, sonication and addition of carbon form were studied before a standard polyol method was established. From XRD patterns, the Pt-Sn/C peaks shifted slightly to lower 2Ө angles when compared with commercial Pt/C catalyst, suggesting that Sn is alloying with Pt. Based on HRTEM data, the Pt-Sn/C nanoparticles showed small particle sizes well-dispersed onto the carbon support with a narrow particle distribution. The particle sizes of the different as-prepared catalysts were found to be between 2-5 nm. The Pt-Sn/C HA Slurry pH3 catalysts was found to be the best asprepared catalyst and was subjected to heat-treatment in a reducing atmosphere at 250-600 °C which led to agglomeration yielding nanoparticles of between 5-10 nm. The Methanol Oxidation Reaction (MOR) on the as-prepared Pt-Sn/C HA Slurry pH3 catalyst appeared at lower currents (+7.11 mA at 860 mV vs. NHE) compared to the commercial Pt/C (+8.25 mA at +860 mV vs. NHE) suggesting that the Pt-Sn/C catalyst has „methanol tolerance capabilities‟. Pt-Sn/C HA Slurry pH3 and Pt-Sn/C 250 °C catalysts showed better activity towards the ORR than commercial Pt/C with specific and mass activities higher than Pt/C at +0.85 V vs NHE. The Tafel slopes of Pt-Sn/C HA Slurry pH3 catalyst was -62 and -122 mV dec-1 for the low and high current regions respectively and suggests that the ORR mechanism is similar to that of commercial Pt/C indicating that the ORR kinetics was not negatively influenced by the addition of tin. It was found that the electrochemical oxidation reduction reaction follows first order kinetics of a multi-electronic (n=4ē) charge transfer process producing water. All the Pt-Sn/C catalysts showed resistance towards MOR and it was found for the heat-treated catalysts that an increase in temperature resulted in an increase in methanol tolerance. The synthesized Pt-Sn/C HA Slurry pH3 catalysts were also tested in a fuel cell environment. Electrodes were prepared by either spraying on Toray carbon paper with the Asymtek machine or by VI spraying directly on the membrane with a hand spray gun the catalysts coated membrane (CCM) technique. Polarization curves obtained in DMFC with CCM showed superior performance than electrode prepared by spraying on the carbon paper with the machine. In our study, the Pt-Sn/C catalyst appears to be a promising methanol tolerant catalyst with activity towards the ORR in the DMFC.

Synthetic graphite is an important industrial material, used in nuclear reactors, electrodes and many other applications. Graphitisation of coke is the solid-state transformation of the disordered carbon atoms into a well-ordered hexagonal graphite structure, requiring temperatures as high as 2 600 ºC. Catalytic graphitisation using metals or metal compounds allows the rearrangement of atoms to occur at lower temperatures. The extent of catalytic graphitisation is markedly dependent on the structural ordering of the parent coke, the catalyst concentration and the reaction conditions. Solvent extraction of coal using dimethylformamide (DMF) as a solvent yields a refined coal solution referred to as Refcoal solution. Cokes of solvent-refined Tshikondeni coal derivatives have been found to be graphitisable. The activity of acetylacetonate and hydroxyquinolinate complexes of Al, Ca, Cu, Fe and Zr for catalysing the graphitisation of Refcoal cokes at 1 600 and 2 000 ºC was investigated. The effect of residence time on the catalytic graphitisation of Refcoal cokes was investigated by heat-treating cokes for two and six hours at 1 600 °C. For iron(III)acetylacetonate, the effect of metal concentrations was studied. Samples were analysed using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and optical microscope techniques. The results show that calcium(II)acetylacetonate catalyses the graphitisation of Refcoal cokes. The degree of graphitisation increases with an increase in the iron concentration. However, iron promotes localised graphitisation, probably in the vicinity of the catalyst particles. / Dissertation (MSc (Chemistry))--University of Pretoria, 2008. / Chemistry / unrestricted

The objective of this work was the development of structured zeolite catalysts by growing of ZSM-5 and Y zeolites layers on the pre-treated FeCrAlloy wires, which could now offer technical advantage in catalytic application. The advantages of implementation of zeolitic coatings in industrial applications are that they have; lower pressure drop, high heat and mass transfer rates compared to standard pelleted or extruded catalysts. The key focus of this research was the generation of thin films of zeolite ZSM–5 and Y zeolite catalysts on the surface of a FeCrAlloy metal substrate. Using in-situ hydrothermal synthesis, the influence of the synthesis parameters such as substrate oxidation and crystallisation time on the zeolite crystallisation process in both the bulk phase (powder) and on the structured zeolite was studied and optimised. Then powder and structured Na-ZSM-5 and Na-Y were treated by calcination and ion exchange in post-synthesis treatment. Further post-synthesis modification was required in the zeolite Y case to improve the catalytic properties. The post synthetic modification of zeolite Y was carried out using acidified ammonium nitrate which was optimised to produce dealuminated zeolite Y with good crystallinity and a Si/Al = 8. Characterisation was performed after each stage of this work to optimise catalyst development using XRD, SEM, EDAX, BET, MAS-NMR, and TGA. Once the optimised zeolite Y and ZSM-5 structured catalysts prepared, cracking of n-heptane was carried out to assess the in catalytic performance compared with Y and ZSM-5 pellets in a fixed-bed reactor under the same operation conditions. The cracking of n–heptane over the pellets and structured catalysts for both ZSM–5 and Y zeolite showed very similar product selectivities for similar amounts of catalyst with apparent activation energy of around 60 kJ mol-1. This research demonstrates that structured catalysts can be manufactured with excellent zeolite adherence and when suitably activated/modified give comparable cracking results to the pelleted powder forms. These structured catalysts will improve temperature distribution in highly exothermic and endothermic catalysed processes.