Uma das desvantagens dos bio-óleos precursores do biodiesel é a alta carga de compostos oxigenados que diminuem seu poder de combustão, reduzindo sua eficiência e inviabilizando seu uso em larga escala. Nesse contexto, o processo de hidrodesoxigenação (HDO) é relevante, dado que elimina esses compostos através de uma reação catalítica e, portanto, aumenta o poder calorífico do combustível. Neste trabalho, estudou-se a HDO do guaiacol (2-metoxifenol) como composto modelo dos bio-óleos derivados da biomassa e avaliou-se o desempenho de catalisadores de Ni e Mo no processo. Estudou-se a performance de um catalisador suportado em SBA-15 - um material mesoporoso de sílica de alta área superficial - em comparação a de um catalisador tradicional suportado em gama-alumina. Para tal, utilizou-se um sistema contínuo em fase gasosa e reator de leito fixo. Utilizaram-se técnicas de caracterização de catalisadores, como adsorção de N2, MEV, MET, DRX, TPR-H2, FTIR, TPO-O2, Raman e TGA. Através das análises DRX e MET, comprovou-se que se formaram partículas de NiO e MoO3 de menor tamanho e mais dispersas no caso do catalisador de SBA-15, devido à menor interação com o suporte e maior área superficial, o que resultou em um grau de redução de 91,6 % deste catalisador, em comparação a 73,4 % do outro, analisados por TPR-H2. Os testes catalíticos mostraram que o catalisador de NiMo/SBA-15 supera o de alumina em termos de conversão no intervalo de 200 a 300 °C, com ciclohexeno e ciclohexano como principais produtos, em face à maior seletividade a catecol e fenol no NiMo/?-Al2O3. A 300 °C, o catalisador suportado em sílica alcançou taxas de 66,5 % para a HDO e 35,3 % HDA (hidrodesaromatização), enquanto o de alumina obteve somente 30,8 e 2,7 %, respectivamente. Finalmente, comprovou-se que o SBA-15 teve uma taxa de desativação por coque de 1,14 mgcoque gcat-1 h-1, 31 % menor que a taxa do catalisador de alumina, cujos depósitos foram de carbono grafítico bem estruturado e irreversível. Em vista dos resultados obtidos, esta dissertação apresenta as rotas e mecanismos de reação do guaiacol nos catalisadores estudados, conhecimento que é relevante para o desenvolvimento e aprimoramento de futuros catalisadores da HDO. / A key disadvantage of the bio-oils precursors of biodiesel is the high load of oxygenated compounds that reduce their heat of combustion, dropping their efficiency and making them unfeasible on a large scale. In light of that, the hydrodeoxygenation process (HDO) is relevant, since it eliminates these compounds through a catalytic reaction, thus increasing the calorific value of the fuel. In this work, the HDO of guaiacol (2-methoxyphenol) as a model compound of the bio-oils derived from biomass was studied and the performance of Ni-Mo catalysts was evaluated. A catalyst supported on SBA-15 - a high surface area mesoporous silica material - was compared to a traditional gamma-alumina-supported catalyst. For this purpose, a continuous gas phase setup with fixed bed reactor was employed. The catalysts properties were identified by N2 adsorption, SEM, TEM, XRD, H2-TPR, FTIR, O2-TPO, Raman and TGA techniques. Through XRD and TEM, it was verified that smaller and more dispersed NiO and MoO3 particles were formed in the case of the SBA-15 catalyst, due to the lower interaction with the support and the greater surface area, which resulted in a degree of reduction of 91.6% for this catalyst, as opposed to 73.4% for the other one, both analyzed by H2-TPR. The catalytic tests showed that the NiMo/SBA-15 outperforms the alumina catalyst in terms of conversion in the range of 200 to 300 °C, with cyclohexene and cyclohexane as main products, in contrast with major selectivity to catechol and phenol on NiMo/?-Al2O3. At 300 °C, the silica-supported catalyst achieved rates of 66.5% for HDO and 35.3% for HDA (hydrodearomatization), whereas alumina reached only 30.8 and 2.7%, respectively. Finally, it was shown that the SBA-15 catalyst had a coke deactivation rate of 1.14 mgcoke gcat-1 h-1, 31% lower than the alumina catalyst, whose coke deposits consisted of well-structured irreversible graphitic carbon. In view of the results, this dissertation proposes the routes and reaction mechanisms of guaiacol on the studied catalysts, knowledge that is pertinent for the development and improvement of future HDO catalysts.

Sammanfattning I dagens samhälle ställs det stora krav på att ett företags IT-system skall vara tillgängligt för kommunikation. Kommunikationen kan ske inom och mellan företag. Då dessa kommunicerande aktörer kan ha olika system och arkitekturer som gör det komplicerat att kommunicera med varandra, krävs även någon applikation som hanterar detta problem. Dessa applikationer går under namnet integrationsplattformar. Då dessa plattformar fungerar som ett centralt nav i kommunikationen är det viktigt att säkerheten i dessa är av hög nivå. Problemet är, vilka säkerhetsrisker kan tänkas dyka upp vid användandet av integrationsplattformar i ett informationssystem? Denna fråga ledde oss in på två forskningsfrågor som presenteras nedan: • Kan denna teknik för applikationsintegration få konsekvenser för säkerheten och i så fall på vilket sätt? • Hur ser den bakomliggande tekniken för säkerhet ut hos två viktiga integrationsplattformar på marknaden, är dessa likvärdiga så att de säkerhetsrisker som identifieras är giltiga för integrationsplattformar generellt? Vi började med att definiera termen säkerhet utifrån tidigare kursböcker. När detta var klart kunde vi identifiera potentiella problem som företag kunde ställas inför vid implementation av integrationsplattformar. Därefter använde vi oss av Internet och olika typer av databaser och tidskrifter för att lokalisera fakta och information som behandlar integrationsplattformar för att få en bredare förståelse för hur dessa fungerar. Vi bestämde oss för att använda primärdata vid empiriinsamlingen och valde därför att genomföra intervjuer med leverantörer, tillverkare och kunder av integrationsplattformar för att kunna få olika perspektiv från hela kedjan. En analys har gjorts av teorin och resultat av intervjun. Analysen ger ett svar på våra två forskningsfrågor utifrån våra emperiska resultat. Vi har dragit slutsatsen att det finns säkerhetsrisker med användandet av integrationsplattformar vid applikationsintegration. De säkerhetsrisker som kan dyka upp vid användandet av integrationsplattformar i ett IS är ett flertal och väldigt beroende av hur integrationsplattformens miljö är sammansatt. Vid införandet av en ny teknik finns det risk att man ärver säkerhetsproblem från den föregående tekniken. i

This study aimed to investigate whether there was evidence of variation in the quality of School-Based Assessment (SBA), with specific reference to Grade 9 mathematics. Assessment has been a prime focal point for educational reform in recent years. In the South African context, there are common external assessments carried out below Grade 12. However, assessments are placed entirely in the hands of individual teachers. Moderation and monitoring as quality assurance mechanisms are also conducted internally at varying degrees, which raises the issues regarding the validity, reliability, and credibility of SBA tasks. Learner achievement in mathematics had recently been a debated issue in national and international assessments. Furthermore, South Africa's Grade 9 learners have been performing below the expected levels in mathematics as compared to the rest of the world. A qualitative research approach was used within a case study research design. Purposeful sampling was employed, and five schools with 15 participants were selected. The data were collected through questionnaires, semi-structured interviews, observations and field notes, and were triangulated by document analysis in order to make the findings and conclusions more reliable. This study revealed that there is a varying degree in the quality of mathematics SBA tasks, and a lack of knowledge about quality assurance mechanisms. In addition, the study revealed that the participating teachers lacked knowledge on how to develop high quality SBA tasks. This study followed Scheeren's input-process-output model (2004), which was further adapted to provide an opportunity to identify enhancing or impeding issues associated with the quality of SBA and learner achievement at Grade 9 level. / Dissertation (MEd)--University of Pretoria, 2016. / Science, Mathematics and Technology Education / MEd / Unrestricted

This thesis deals with the study of several catalysts for the Fischer-Tropsch synthesis in the Biomass-To-Liquid process. In this work two groups of catalysts were tested. On the one hand, two series of catalysts with cobalt loadings of 6 and 12 wt% over SiO2 and some of them containing 5wt% of TiO2 were tested. One the other hand, other two series of mesoporous short channel SBA-15, all of them with cobalt loadings of 12wt% and some with 5wt% of titania. The first series was supported on SBA-15 DeWitte and the second one on SBA-15 Martinez. On the one hand, the influence of water addition to the feed, titania content and cobalt loading to the catalyst and was studied, as well as the consequences of a GHSV. The FT reaction was carried out along 5 periods of 24 hours each, in which conditions such as feed and water content were modified, enabling the study of these parameters. It was found that water provokes an increase of the CO conversion and has a positive kinetic effect on the rate to hydrocarbons. However, this fact reaction is followed by a quick deactivation, enhanced by high water partial pressures. Most of that deactivation is irreversible since it is not completely recovered after water removal. On the other hand, differences between the supports were studied. Some SBA-15 supported catalysts show CO diffusion limitations at longer channel lengths than what applies for conventional 3D porous supports. Titania grafting increases the rate to hydrocarbons, showing positive results for FT catalysts development.

Durante los últimos tiempos, una de las preocupaciones sociales ha estado relacionada con las consecuencias del consumo de tabaco sobre la salud de los fumadores activos y pasivos. De este modo, se han generado múltiples debates enfocados hacia la importancia de erradicar esta práctica. Sin embargo, las acciones adoptadas por los diferentes gobiernos, claramente no han sido suficientes. Éstas no han sido capaces de evitar los efectos negativos del tabaco y tampoco han alcanzado los valores esperados en la reducción del consumo. En este sentido, los procesos de adsorción y catálisis pueden proporcionar una alternativa valiosa para reducir la toxicidad del humo del tabaco, lo cual puede constituir un campo importante para una nueva aplicación en el uso de catalizadores. Nuestro grupo de investigación ha estado trabajando durante años en el uso de catalizadores, como la SBA-15, para reducir los niveles de compuestos tóxicos generados en el proceso de fumado y ayudar al consumidor a minimizar su adicción. Los trabajos realizados por el grupo anteriormente se centraron en la descripción del efecto de tales catalizadores en la química del humo del tabaco y su capacidad de reducción de tóxicos. También se ha estudiado el efecto sobre la nicotina y varios aditivos del tabaco. Son varios los autores que trabajan en esta vía, centrándose en las nitrosaminas y otros compuestos específicos. Sin embargo, en todos los trabajos de investigación, no se ha considerado la influencia de las propiedades de textura del catalizador en el rendimiento de la aplicación. En este sentido, el objetivo del presente trabajo es preparar materiales SBA-15 a diferentes temperaturas, tiempos y velocidades de agitación en las diferentes etapas de la síntesis, así como la simplificación de los equipos necesarios para el proceso. Se ha estudiado, además, el efecto de reducir el volumen de medio de reacción en el tratamiento hidrotérmico. De este modo, se pretende analizar la influencia de estas variables en la capacidad de reducción de compuestos tóxicos en el humo del tabaco. Asimismo, también se pretende analizar el efecto del reactivo fuente de sílice. En este trabajo se muestran datos de gran interés para seleccionar las condiciones de síntesis y ajustar las propiedades de materiales tipo SBA-15 para esta aplicación práctica de enorme repercusión potencial. Además de discutir aspectos que pueden simplificar y economizar su proceso a gran escala, se muestran los resultados preliminares de un proceso de producción de estos materiales a escala de kilogramos, lo que permite avanzar en la puesta a punto del proceso de fabricación a escala industrial.

Over the past decades, there have been worldwide efforts to synthesize new types of ordered porous materials for catalysis, separations, etc. Among those, mesoporous material with microporous walls are promising in a sense that while mesopores act as channels for the reactant transport with little diffusion limitation, micropores in the wall act as active sites for reactions or storage of the molecules. In this study, we focused on the SBA-15 material, which is a highly ordered mesoporous silica material with micropores present in the wall. We have studied the synthesis of the material by manipulating various factors that are known to have influence on the porous characteristic of the material. We have aimed our studies particularly on the micropores present in the material. Unlike zeolite materials, which have regular, well characterized pore structures, micropores in the SBA-15 are not ordered, thus may have a very broad pore size distribution. We have synthesized sets of mesoporous silica materials that have characteristics similar to those reported in the literature. Using microwave heating, we were able to synthesize the target material within a short period of time, about 10 to 12-fold reduction of the conventionally known synthesis time. The synthesized materials were initially characterized using XRD and SEM. Adsorption studies were then undertaken on the materials to determine the surface area and pore structure. The interpretation of micropores has heretofore been problematic and the models are ambiguous. Relatively simply ordered, 1-dimensional channel type, zeolite materials were also studied; MTW, MTT, TON, ATS, VET frameworks. Adsorption isotherms of these materials were obtained and simple empirical models were developed to determine the pore size distribution. Further, a sequential adsorption technique, using n-nonane as a preadsorbate, was used to evaluate the realistic external surface areas of zeolite materials and mesopore surface areas of micro-mesoporous materials. Applying this technique to “multidimensional pore system” will provide another way to obtain the realistic surface area and mesopore size distribution.

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