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.

To assess the performance and future possibilities of catalytic microwave pyrolysis, laboratory-scale experiments were conducted on a widely available biomass feedstock, Eucalyptus grandis. Non-catalysed microwave pyrolysis was conducted under varying conditions to determine important factors of the microwave pyrolysis process and to conduct a basic performance evaluation. Future possibilities of microwave pyrolysis were determined by comparison to available technologies. Calcined Mg-Al LDH clay (layered double oxide or LDO) was used as catalyst to improve the quality of the pyrolysis process and its products. The heating and reaction mechanisms for microwave pyrolysis show that it offers distinct advantages over conventional pyrolysis. The main advantages are rapid and efficient volumetric heating, as well as acceptable yields at lower temperatures (much lower than those required by conventional pyrolysis), which can possibly lead to significant energy savings. Comparing the performance of a modified domestic microwave to an off-the-shelf microwave unit (Roto Synth) proved that cheap and comparative microwave research is possible. The yields from the domestic microwave products compared very closely to those of the Roto Synth unit, each having yields for char, oil and gas of 47.9%, 33.2%, 18.9% and of 46.8%, 32.7%, 20.55% respectively. The cost of the modified domestic setup was ~1% of that of the off-the-shelf unit. The use of a quartz reactor and slight adjustments to the stepper motor driver and thermocouple are recommended for future use. The pyrolysis process was found to be very dependent on power and power density. Higher powers increase the liquid and gas yields and a critical power density was identified between 800W and 1000W. The effects of power density were interesting and led to conclusions regarding the penetration depth of microwaves which could possibly play a significant role in the scale-up of microwave pyrolysis technology. Microwave pyrolysis undeniably has several advantages over conventional pyrolysis. However, for it to become competitive, microwave fast pyrolysis technologies need to be developed through the use of mixed bed reactors that can achieve fast heating rates. Possible candidates include rotating cone and fluidised bed reactors. Hybrid technology also provides unique advantages and has huge potential. Comparison of pyrolysis technologies is difficult without good data on continuous microwave pyrolysis reactors, and therefore the development of such reactors is recommended for future research. Catalysis of microwave pyrolysis with LDO proved effective. The catalyst promoted the formation of volatiles (gas and liquid), even when present in small ratios. It also promoted the formation of esters and even anhydrides and small fractions of hydrocarbons at high catalyst ratios. The catalyst activity led to increased water yields. This indicated that it removes oxygen from the pyrolysis products, thereby improving their quality. The catalyst was believed to be limited by the low temperatures used in this investigation and higher temperatures might increase the release of CO2 and should be investigated. Significant reduction in the total acid number (TAN) and an improved dry-basis heating value were also achieved by the addition of the catalyst. The water content increased from 50% to 70%, the TAN reduced from 174 mg KOH/(g oil) to 72 mg KOH/(g oil), and the calorific value increased from 19.1 MJ/kg to 21.5 MJ/kg. / Dissertation (MEng)--University of Pretoria, 2017. / Chemical Engineering / MEng / Unrestricted

Architecture is never complete. The theoretical discourse of the thesis explored the need of a building to change. This change is unpredictable, though expected. The project proposal within the informal context of Phumolong, Mamelodi, aimed to address this unavoidable nature of architecture. The focus of the project was to provide improved services within an informal settlement, whilst generating social upliftment. The thesis investigated the current and future requirements of the informal dweller. It explored the possibility of generating public space through the establishment of a catalyst. The connection of services and public amenities has been exploited to generate an environment where the building acts as generator and it supports social interaction. Inevitably the servant core provides implicit reasoning as renewed stimulus to public gathering. The project proposal addressed the integration of the informal user with a building system through the architectural process. This is achieved through phased development, investigating assembly and use of civic programmes. A quantitative approach towards the research was initially undertaken. However, the fluid nature of the informal settlement enthused a more qualitative approach. The need and right of the informal dweller to be served, and have access to public services and amenities justified the design proposal. The changing fabric, user, programme and needs of the community contribute to the rate of change of a building. The changing context of Phumolong required a flexible and adaptable design intervention allowing for future interpretation. These variables influenced architecture as a cognitive process. The design as a product within the realm of architecture represents the process of learning from the past, reacting to the present and preparing for the future. Ultimately the design intervention exists as an ongoing process of progressive change. Copyright / Dissertation (MArch(Prof))--University of Pretoria, 2010. / Architecture / unrestricted

The burgeoning field of nanotechnology motivates comprehensive elucidation of nanoscale materials. This thesis addresses transmission electron microscope characterisation of nanoparticle morphology, concerning specifically the crystal- lographic status of novel intermetallic GaPd2 nanocatalysts and advancement of electron tomographic methods for high-fidelity three-dimensional analysis. Going beyond preceding analyses, high-resolution annular dark-field imaging is used to verify successful nano-sizing of the intermetallic compound GaPd2. It also reveals catalytically significant and crystallographically intriguing deviations from the bulk crystal structure. So-called ‘non-crystallographic’ five-fold twinned nanoparticles are observed, adding a new perspective in the long standing debate over how such morphologies may be achieved. The morphological complexity of the GaPd2 nanocatalysts, and many cognate nanoparticle systems, demands fully three-dimensional analysis. It is illustrated how image processing techniques applied to electron tomography reconstructions can facilitate more facile and objective quantitative analysis (‘nano-metrology’). However, the fidelity of the analysis is limited ultimately by artefacts in the tomographic reconstruction. Compressed sensing, a new sampling theory, asserts that many signals can be recovered from far fewer measurements than traditional theories dictate are necessary. Compressed sensing is applied here to electron tomographic reconstruction, and is shown to yield far higher fidelity reconstructions than conventional algorithms. Reconstruction from extremely limited data, more robust quantitative analysis and novel three-dimensional imaging are demon- strated, including the first three-dimensional imaging of localised surface plasmon resonances. Many aspects of transmission electron microscopy characterisation may be enhanced using a compressed sensing approach.

Hydrogen storage for stationary and mobile applications is an expanding research topic. Using liquid organic hydrides for hydrogen storage is one of the most promising alternatives as it provides simple and safe handling. Liquid organic hydrides are largely compatible with current transport infrastructure, whereas alternatives such as liquid and gaseous hydrogen and metal hydrides would require a completely new infrastructure. An attractive storage system is the so-called MTH system (Methylcyclohexane, Toluene and Hydrogen). The dehydrogenation of methylcyclohexane is a highly endothermic reaction. To improve the reaction kinetics, this research was to develop a structured catalyst with a conductive metal support (Fecralloy) which could hold an adherent catalytic washcoat (γ - Al2O3). The active phase was impregnated onto this support and the developed catalyst was tested for the dehydrogenation of methylcyclohexane. The catalyst preparation involved three key steps which were support oxidation, loading of an adherent washcoat and finally impregnation of the active phase. The oxidation and washcoat stages required significant optimisation. The optimum oxidation conditions were found to be 950 °C for 10 h. The washcoating procedure was optimised by modifying a one-step hybrid washcoating method suggested in patent literature. Characterization techniques including SEM, XRD and EDX were used to study each step of catalyst preparation. In addition the technique of STEM was used to study platinum dispersion on the catalytic washcoat. Finally the catalytic activity of the developed catalyst was compared with an in-house pelleted catalyst based on the material used to prepare the structured catalyst and commercially available platinum on γ - Al2O3. Three key factors: activity, selectivity and stability were evaluated. The activity and selectivity were studied at varied operating conditions of T = 340 °C - 400 °C, W/F = 7345 - 14690 g s/mol, H2/MCH molar ratio = 0 - 9 and P = 1.013 bar. The dehydrogenation reaction of methylcyclohexane was found to be very selective to toluene (above 99%). Compounds, which are considered coke precursors, were identified, to attempt to explain the mechanism of catalyst deactivation. By-product distribution was monitored and possible reaction pathways were postulated. To gauge the stability of the catalyst, long term life tests were also performed on the structured catalyst at 400 °C and W/F = 14690 g s/mol for approximately 400 h. The stability study investigated the different types of deactivation mechanisms. The catalyst evaluation study helped identify the effect of the alloy support, the alumina washcoat and platinum dispersion on the selectivity of the catalyst.

Overall goal: “The overarching aim of the Programme is to promote a sense of dignity in the public real, targeting the poorest and most disadvantaged parts of the city, by providing each local area with a place where individual circumstances of poverty are not starkly visible, where people can meet and gather or just sit in a place that is as attractive and comfortable as any other well-made, positive place in the city.” [Southworth, 2003:125] Problem identification: The form and structure of the city is driven by the urban legend that almost all users will move through the city by car, bus or taxi. This produced a low-density, disorganized expansion which forces users to commute between spread out facilities. Public space in the city has largely been neglected, with green areas fenced of [e.g. the Union buildings green space] and existing squares and arcades taken over by commercial interests. The perception is created that these vital areas are extravagant squander of money both to create and maintain. This resulted in neglected and derelict spaces scattered around the city, often only used as parking. The focus of designers has largely been on individual buildings only, neglecting their impact on their neighbours, the street and their interaction on public space. Project aims and objectives: Explore and analyse the interconnected systems inherent in the city. In order to obtain a comprehensive understanding of some of the systems and processes that are active in the city, analysis needs to be done on several levels.Regional scale: The city systems as part of the larger Tswane Megacity. City scale: Explore the interaction of these processes within the CBD. Local scale: Placing the study area within the north-eastern quarter of the CBD to create a master program for the area. Create a master program for the north-eastern quarter of the city incorporating these systems and processes. Study the workings of the north-eastern quarter to develop guidelines for its improvement. Place an urban catalyst within the study area to promote regeneration on social, economic and urban levels. Design an architectural response to the new urban catalyst. Approach: The creation of a public space, linking isolated city blocks. To use buildings to fill gaps in the existing street edges, as well as defining the new public space. This will lead to economic and social regeneration of the area. Develop guidelines for function selection of building linked to the street and public space. Design an architectural response to the new public space. / Dissertation (MArch(Prof))--University of Pretoria, 2008. / Architecture / unrestricted

Linear alkylbenzenes (LAB) are key intermediates in the synthesis of linear alkylbenzene sulfonate surfactants that are used in the manufacture of detergents. Production of LAB with traditional Lewis acids as catalysts, such as hydrofluoric acid, results in the formation of large amounts of toxic wastes and corrosion of industrial equipment. Phosphotungstic acid (PTA) has gained much attention in recent years as a solid catalyst for various alkylation reactions. This research work aims to develop a novel material based on PTA-containing silica gel, which can effectively catalyze LAB synthesis. Sol-gel synthesis of silica gel in the presence of PTA and tetraethyl orthosilicate as precursors produced a mesoporous aterial containing covalently embedded PTA clusters. Obtained superacidic catalyst demonstrated high catalytic activity in liquid-phase alkylation of benzene by various alkenes. Covalent embedding of catalytically active HPA clusters prevents their leaching from the catalyst surface, which enabled its excellent catalytic properties.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21589号 / 理博第4496号 / 新制||理||1645(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 竹腰 清乃理, 教授 吉村 一良 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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Thesis advisor: Masayuki Wasa / Thesis advisor: Amir H. Hoveyda / This dissertation describes the development of cooperative catalyst systems that contain an achiral Lewis acid and a chiral Lewis acid that may have overlapping functions but play their independent roles to promote enantioselective C–C bond formations. Chapter 1 provides a summary of recent advances made in the field of enantioselective cooperative catalysis that served as intellectual foundations for this dissertation research. As it will be discussed in the first chapter, key limitations of cooperative catalysis are: (1) undesirable catalyst deactivation which occurs due to acid/base complexation, (2) requirement for base sensitive pronucleophiles and acid sensitive electrophiles, and (3) poor reaction efficiency. In an effort to overcome these fundamental limitations, we have developed “frustrated” Lewis pair (FLP)-based catalyst systems that consist of potent and sterically encumbered Lewis acids used in pair with bulky N-containing Lewis bases. To demonstrate the potential of the novel FLP catalyst system, we describe our work involving the enantioselective Conia-ene-type cyclization (Chapter 2). In the subsequent chapter (Chapter 3), we discuss the application of the FLP catalysts for enantioselective β-amino C–H functionalization reactions. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.