High throughput and combinatorial experimentation is becoming more and more used in catalysis research. The benefits of parallel experiments are not only limited to shorten the time - to - market, but also give opportunities to study the process in more depth by performing more experiments. The influence of a parameter, for example the amount of the active metal and/or promoter, to the process is better understood with a broader parameter space investigated. To study the parameter space, multiple experiments need to be performed. It is of paramount importance to understand the variability of the data between these experiments. This is not always defined, specifically when literature gives contradictory results, most often due to the time for duplicate experiments necessary. In this project the reproducibility and variance in high throughput catalyst preparation and testing was determined and the use of parallel experimentation was demonstrated within a catalyst development study. The high throughput equipment was used for catalyst development studies for fuel processing, the production of fuel cell - grade hydrogen from hydrocarbon fuels. Fuel processing consists of three catalytic reactions, namely reforming, water - gas shift and a CO clean - up through either selective methanation or preferential oxidation. Focus has been placed on the first two reactions, steam methane reforming (SMR) and medium temperature water - gas shift (WGS), using platinum group metals (PGM). All catalysts in this study (except for the commercial WGS catalyst) were prepared using automated synthesis robot (Chemspeed ISYNTH) and the activity testing was performed on the Avantium Flowrence. For both reactions two types of studies were performed, one - to - many and many - to - many; referring to one catalyst tested in many reactors or many prepared catalysts (same composition, different batches) tested in many reactors. For the WAGS one - to - many a commercial low temperature shift catalyst was selected and for SMR a single batch of Rh/Al 2 O 3 . The many - to - many experiments comprised of eight batches of prepared catalysts for both reactions. The WGS reaction was performed with 1 wt% Pt/Al 2 O 3 catalysts and for the reforming reaction batches of 0.5 wt% Rh/Al 2 O 3 was used. It was proven that in all these studies the experimental standard deviations in the data is 6%, from preparation to activity measurements. A study on the rhodium metal loading on alumina in the steam methane reforming catalyst was studied between 0.05 and 0.6 wt%. A 0.4 wt% Rh/Al 2 O 3 was found to have the highest activity per amount of rhodium. Lower Rh content would require decreased space velocity, whereas higher metal content does not increase the conversion due to larger crystals sizes. This study has been performed up to a metal loading of 0.6 wt% and it is recommended to follow - up with studying the range of 0.6 to ~2.5 wt% to investigate the optimal metal loading. It was shown that the use of automated experimentation (parallel preparation and evaluation under same condition) for catalyst development results in highly reproducible results with a relative standard deviation of ~6% activity. The high throughput equipment was demonstrate d to be a very powerful tool in catalyst research

Bibliography: p. 179-188. / Iron antimony oxide has been known to be an active and selective catalyst for the partial oxidation of propene to acrolein and the oxidative dehydrogenation of 1-butene to 1,3- butadiene. It has become the preferred catalyst for the industrial acrolein formation from propene. The main purpose of this work was to investigate the influence of catalyst parameters such as calcination temperature, Sb:Fe ratio, type of pre-treatment, absence or presence of gaseous oxygen on the activity and selectivity in the partial oxidation of propene. Furthermore the influence of the reaction parameters temperature, space time, partial pressure, time on stream and the carbon chain length of the olefin have been studied in partial oxidation reactions using a fixed bed U-tube glass reactor. Various models have been tested for the rate of formation of products in the range of C₂ to C₆ α-olefins. Increasing the calcination temperature from 500°C to 900°C resulted in an increase of the crystallite diameter and a simultaneous decrease of the surface area which might be ascribed to high temperature sintering of the catalyst. The activity decreased proportional to the decrease of surface area. At the same time the selectivity to acrolein increased with increasing calcination temperature.

Zeolites have found widespread applications as acid catalysts for decades. By introducing transition metal ions in the cation position, the zeolite is transformed into a redox catalyst. The nature of the trivalent heteroatom influences the properties of the zeolite. Contrary to Al-zeolites, Fe-containing zeolites show redox properties, since Fe can easily change its oxidation state (Fe²⁺, Fe³⁺, or Fe⁴⁺). Catalytic function of isolated redox sites within zeolite cavities (or channels) may result in a material with specific redox properties (Kiwi-Minsker et al., 2003). The properties of transition metal exchanged zeolites have been studied from the 1960's onwards and the conversion of N₂O over Fe-Y zeolites has been studied by Fu et al. (1981) in late 1970's. In this study, the preparation of iron ZSM-5 zeolite catalysts by mechanochemical means and thermally induced solid-state ion exchange was studied. After grinding the NH4-Zeolite and ferrous chloride, no x-ray reflections characteristic of ferrous chloride are detected. After heating the sample to 120 and 200 °C reflections characteristic of ferrous chloride are visible but disappear upon further heating to 300 °C. No porosity is observed after grinding and heating up to 200 °C as a result of pore mouth blocking. Moreover, upon heating up to 500 °C porosity starts to develop with pore volumes and pore sizes slightly lower than those of the parent zeolite. From the thermogravimetric analysis it is evident that the ion exchange takes place during calcination from 150 and 420 °C in agreement with the literature. In the second part of the study commercial Fe-ZSM-5 catalyst samples with different N₂O conversion activities (in the presence of H₂O and NO at 425 °C), ranging between 70 and 90 % (high, mid and low activity) are studied and characterised. The effect of temperature during calcination of the plant produced and laboratory calcined extrudate catalyst material was investigated. Panov et al. (1996) reported in the literature that the Fe²⁺ is oxidised to Fe³⁺ in the presence of N₂O forming what they called the α-oxygen, a form of active surface oxygen, with the evolution of molecular nitrogen. During the conversion, two surface α-oxygen atoms migrate, combine and desorbs as molecular oxygen from the surface. The α-oxygen forms between 200 and 350 °C and desorbs as molecular oxygen above 350 °C (Taboada et al., 2005). In this study, no correlation to N₂O conversion activity could be found for the α-oxygen content and correspondingly the concentrations of the respective iron oxides and iron hydroxides in the Fe-ZSM-5 samples.

Includes bibliographical references (pages 99-107). / Two deposition-precipitation style methods of preparing zinc oxide supported dispersed gold materials for use as water-gas shift catalysts were examined, with some of the better formulated materials being tested for catalytic activity, and compared to World Gold Council Au/TiO₂ reference material and a commercial copper-based WGS catalyst (Cu/ZnO/AlO₃ - C 18-7 from Sud-Chemie). Materials Synthesis: The classical deposition-precipitation synthesis from the group of Haruta (Tsubota et al., 1995) - where the support is added to a pH adjusted solution of HAuCl₄ and the system aged at constant pH and temperature - was examined, using ZnO as the support. Gold uptake by the support was confirmed to decrease with ageing pH, tending to zero as the IEPS of ZnO (~ 9) is approached. Such behaviour is both qualitatively and quantitatively consistent with theory, which proposes that the magnitude and polarity of the charge on the support surface will determine the effective carrying capacity of that surface for an (an)ionic solution phase gold species. Decreasing post-calcination (120°C) gold crystallite size with increasing ageing pH [as reported by Haruta (1997)] was also observed (figure 11.2) - but it is not clear whether this resulted from pH dependent crystallization dynamics, from crystallite size being simply determined by the amount of deposited gold (which clearly decreases with increasing pH), or from chloride induced sintering during heat treatment (with chloride uptake by the support decreasing with increasing pH [Kung et al., 2003)). Nevertheless, gold deposition at pH 8 produced highly dispersed gold crystallites around 3.5 nm in diameter. It emerged that an inherent trade-off exists with this, the classical depositionprecipitation method, in that acidic ageing pH promotes a high degree of gold uptake by the support, but produces large gold crystallites, and vice versa. To overcome this, a modified method - where HAuCI₄ and the base (ammonium carbonate) were simultaneously added dropwise to a slurry of the support, maintaining a constant pH of 8 (Fu et al., 2003b) - was investigated. This method was attractive because it is claimed to simultaneously achieve total gold uptake and post-calcination Au crystallite size in the range 5 - 6 nm. Since it was not clear from the published description whether a constant pH was maintained across the ageing period (practiced here as MDP1 ), or if the pH was rather allowed to drift (practiced here as MDP2), both alternatives were investigated. When a constant pH was maintained across the ageing period (MDP1 ), gold uptake by the support was found to reach a maximum (of ~ 60 %) when operating at a pH of ~ 8. The degree of gold uptake was found to be independent of both gold loading and support surface area. Furthermore, the degree of gold uptake achieved using this variation was increased to unity by allowing the pH to drift during the ageing period (after being initially held constant at 8 during HAuCI₄ addition) [= MDP2], instead of being maintained at a constant value via addition of nitric acid (as is done in MDP1). In terms of the size of the gold crystallites produced, after calcination in air at 400°C, a mean diameter of 3.8 ± 1.5 nm was observed for a sample 1.9 wt % in Au, increasing slightly with increasing gold loading [to 4.6 ± 1. 7 nm by 5.1 wt %Au].

This thesis is based on research in Cu-catalyzed electrophilic trifluoromethylation and exploiting Cu/Cu2O nanowires with novel catalytic reactivity for developing of catalytic and greener synthetic methods. A large number of biological active pharmaceuticals and agrochemicals contain fluorine substituents (-F) or trifluoromethyl groups (-CF3) because these moieties often result in profound changes of their physical, chemical, and biological properties, such as metabolic stability and lipophilicity. For this reason, the introduction of fluorine or trifluoromethyl groups into organic molecules has attracted intensive attention. Among them, transition metal-catalyzed trifluoromethylation reactions has proved to be an efficient and reliable strategy to construct carbon-fluorine (C-F) and carbontrifluoromethyl (C-CF3) bond. We have developed a catalytic process for the first time for trifluoromethylation of terminal alkynes with Togni’s reagent, affording trifluoromethylated acetylenes in good to excellent yields. The reaction is conducted at room temperature and exhibits tolerance to a range of functional groups. Derived from this discovery, the extension of work of copper catalyzed electrophilic trifluoromethylation were investigated which include the electrophilic trifluoromethylation of arylsulfinate salts and electrophilic trifluoromethylation of organotrifluoroborates. Because of growing environmental concern, the development of greener synthetic methods has drawn much attention. Nano-sized catalysts are environment-friendly and an attractive green alternative to the conventional homogeneous catalysts. The nano-sized catalysts can be easily separated from the reaction mixture due to their insolubility and thus they can be used recycled. Notably, because of the high reactivities of nano-sized metal catalysts, the use of ligands can be avoided and the catalysts loadings can be reduced greatly. Moreover, the nano-sized catalysts can increase the exposed surface area of the active component, thereby enhancing the contact between reactants and catalyst dramatically. Based on the above-mentioned concepts and with the aim of achieving one “green and sustainable” approach, C-S bond formation and click reactions catalyzed by Cu/Cu2O nanowires were investigated. It was found that the recyclable core-shell structured Cu/Cu2O nanowires could be applied as a highly reactive catalysts for the cross-coupling reaction between aryl iodides and the cycloaddition of terminal alkynes and azides under ligand-free conditions. Furthermore, these results were the first report for the crosscoupling reaction and click reaction catalyzed by one-dimensional (1D) copper nanowires.

Heterogeneous catalysis is a powerful chemical technology because it can enhance the conversion of reactants, promote selectivity to a desired product, and lower the reaction temperature requirements. The breaking and forming of chemical bonds in heterogeneous catalysis is facilitated on a solid surface where adsorbed gas-phase species react and form products. This study is concerned with utilizing heterogeneous catalysis in the automobile industry via the generation and utilization of hydrogen to reduce NOx emissions. In spark ignition engines, the three-way-catalyst technology is ineffective at the more efficient, lean-burn conditions. In compression-ignition engines, an ammonia-based technology is implemented but has associated high cost and ammonia slip challenges. This motivates providing an alternative technology, such as hydrogen selective catalytic reduction (H2-SCR). In this study, four catalysts were investigated for the lean-burn selective catalytic reduction of NO using hydrogen. The catalysts were platinum (Pt) and palladium (Pd) noble metals supported on cerium oxide (CeO2) and magnesium oxide (MgO). Additionally, finding a source of hydrogen for H2-SCR on board a vehicle is a challenge due to the issues associated with hydrogen storage. A numerical study was performed to investigate the utilization of the partial oxidation of natural gas on a rhodium surface to synthesis gas, CO and H2. A kinetic understanding of natural gas demands an understanding of its components. While methane and ethane have been extensively studied, propane partial oxidation on rhodium has only been kinetically examined at low temperatures. The aim of the numerical study was to obtain an improved understanding of propane partial oxidation kinetics by extending the surface reactions mechanism to high temperatures and developing a gas phase mechanism to capture the effects of gas-phase reactions. Moreover, the optimal temperature and pressure for H2 generation were determined, and the kinetic simulation results were analyzed by temperature sensitivity, chemical path flux and hydrogen production sensitivity analyses.

Electrochemical devices, such as fuel cells and electrolysers, are said to be at the forefront of a renewable energy technology revolution centred on hydrogen as an energy carrier. These devices rely on the chemical reactions of oxygen, namely the oxidation of water to evolve oxygen (oxygen evolution reaction, OER) and hydrogen , carried out in electrolyser applications or the reverse reaction, the reduction of oxygen to water (oxygen reduction reaction, ORR) producing electricity in the case of fuel cells . Th e reactions of oxygen are however still hindered by extremely slow reaction kinetics. The resultant low efficiencies and associated high cost of electrocatalysts required hinder the widespread commercial success of these devices. In addition, current state - of - the - art electrocatalyst technologies suffer from severe corrosion during operation, presenting an additional barrier to commercialisation and ultimately delaying the successful implementation of a sustainable hydrogen economy. One primary goal of electrocatalysis research is thus the rational design of new materials with higher efficiencies. The fundamental understanding of the behaviour of the electrocatalyst materials towards these reactions will enable greater strides to be achieved in this area. To date much research has been conducted towards this end, however further progress is still required. This thesis details work towards the understanding of a new generation of electrocatalyst technologies for the OER and ORR. This study particularly explore s the use metal oxide based electrocatalyst materials for the oxygen evolution and reduction r eactions as employed in electrolyser and fuel cell applications respectively. The thesis is divided in two parts focusing individually on the OER and ORR respectively. New theoretical and experimental insight into the understanding of oxide electrocataly sts for the OER are discussed in Part I. Part II explores the ORR by studying metal oxides as both catalysts and catalyst support materials in alkaline and acidic environments respectively. Here the emphasis is placed on activity and durability of oxide ma terials under fuel cell operating conditions. The study confirms the promise of oxide based materials and highlights some of the challenges still present in their development for fuel cell applications. The final chapter presents a summary of the thesis. This study provides important insight and contributes towards the further understanding of the use of metal oxides for the OER and ORR. From this study several interesting and promising results were also obtained which warrant further intensive research and investigation. Directions for future research are discussed. [Please note: the full text of this thesis has been deferred until January 2018]

The direct methanol fuel cell (DMFC) is identified as a promising fuel cell for portable and micro fuel cell applications. One of the major benefits is that methanol is an energy dense, inexpensively manufactured, easily stored and transported, liquid fuel (Hamann et al., 2007). However, the DMFC's current efficiency and power density is much lower than theoretically possible. This inefficiency is predominantly due to the crossover of methanol from the anode to the cathode, Ru dissolution and Ru crossover from the anode to the cathode. In addition, the DMFC has a high manufacturing cost due to expensive catalyst costs and other materials. Catalyst expenses are further increased by catalyst loading due to low activity at the anode of the DMFC (Zhang, 2008). Hence, with increasing activity and stability of the Pt-Ru/C catalyst, catalyst expenditure will decrease due to a decrease in catalyst loading. In addition, performance will increase due to a reduction in ruthenium dissolution and crossover. Therefore, increasing the activity and stability of the Pt-Ru/C catalyst is paramount to improving the current DMFC performance and viability as an alternative energy conversion device. Pt-Ru/C catalyst synthesis method, precursors, reduction time and temperature play a role in the activity for methanol electro-oxidation and stability since these conditions affect structure, morphology and dispersivity of the catalyst (Wang et al., 2005). Metal organic chemical deposition methods have shown promise in improving performance of electro-catalysts (Garcia & Goto, 2003). However, it is necessary to optimise deposition conditions such as deposition time and temperature for Pt(acac)₂ and Ru(acac)₃ precursors. This study focuses on a methodical approach to optimizing the chemical deposition synthesis method for Pt-Ru/C produced from Pt(acac)₂ and Ru(acac)₃ precursors. Organo-metallic chemical vapour deposition (OMCVD) involved the precursor's vapourisation before deposition and a newly developed method which involved the precursors melting before deposition. An investigation was conducted on the effects of precursor's phase before deposition. The second investigation was that of the furnace operating temperature, followed by an exploration of the furnace operating time influence on methanol electro-oxidation, CO tolerance and catalyst stability. Lastly, the exploration of the Pt:Ru metal ratio influence was completed. It was found that the catalyst produced via the liquid phase precursor displayed traits of a high oxide content. This led to an increased activity for methanol electro-oxidation, CO tolerance and catalyst stability despite the OMCVD catalyst producing smaller particles with a higher electrochemically active surface area (ECSA).

A wash-coating method which had originally been used for wash-coating a Rh/Al₂O₃ catalyst onto stainless steel micro-channels (MC) for the reforming of propane [24] was tested in the steam reforming of methane. The robustness of this method was unknown and was therefore tested for its possible application in methane steam reforming, which has far harsher reaction conditions. A 1 wt% Rh/Al₂O₃ catalyst was wash-coated onto heat treated MC reactor plates and tested at 700 °C with steam to carbon ratio of 3 at a number of catalyst mass specific space velocities (scc᛫(gcat᛫h)⁻¹). The MC tests yielded conflicting results with some tests having stable catalysts and the majority have unstable catalysts due to poor wash-coat adhesion. The unsuccessful cases were due to a loss of catalyst. The change in catalyst stability was postulated to be the result of the wash-coating suspension size being reduced too much. In the cases where catalyst instability due to poor adhesion and ultimately loss of the catalyst the suspension batch size was reduced such that the surface tension of the viscous suspension now exceeded the intermolecular forces in the liquid. This resulted bubble formation and due to the high viscosity of the suspension due to the presence of the polyvinyl alcohol (PVA) binder the bubbles remained during the wash-coating process which is thought to have adversely affected the wash-coats adhesion. Another possible cause which is thought to have amplified the poor adhesion of the unstable catalyst runs is the thermal expansion of the stainless-steel reactor plates. The results of this study could not give outright and straightforward conclusions as to why there were 2 stable runs and unstable runs due to a loss of catalyst. As a result, further work is required to confirm the postulations and trends seen in this study. Future work should concentrate on using a larger batch of suspension to mitigate bubble formation, adding an alumina primer layer before wash-coating the catalyst to aid adhesion through additional oxide bond formation and the use of a more thermally stable stainless steel reactor plate to mitigate thermal expansion.

In this thesis, the lateral interactions involved in conversion of synthesis gas, a mixture of H2 and CO, to methane over Fe(100) and the effect they have on the kinetics of the process is explored. Understanding the methanation of syngas allows for a better understanding of the initial stages of Fischer-Tropsch synthesis. Density functional theory was used to calculate the energies and properties of simple methanation adsorbates on an Fe(100) surface. All of the parameters were tested and optimized in order to find a balance between efficiency and accuracy. A number of configurations were calculated to investigate nearest neighbour and next nearest neighbour interactions. An energetic break down of the lateral interactions is postulated using the components of the Hamiltonian. The charges associated with the different atoms in each configuration were identified using the Mulliken population analysis and the Bader population analysis. These gave insights into configurations which displayed large electrostatic lateral interactions. Lateral interactions were investigated using larger unit cells than typically utilized in molecular modelling up to now (viz. p(4x4) and p(3x2) unit cells) to enable the estimation of nearest neighbour and next nearest neighbour interactions. When using larger p(4x4) unit cells for CO adsorption on Fe(100), the results showed that the heat of adsorption can differ by as much as 0.24 eV at 0.25 ML. It was concluded that lateral interactions are a function of local coverage (i.e. number of nearest and next nearest neighbours) and not necessarily global coverage. Nearest neighbour interactions are typically repulsive and much larger than next nearest neighbour interactions, which varied between repulsive and attractive interactions. While this is not a unique conclusion it did allow for the creation lateral interaction matrices that vary with temperature. The study has shown that lateral interactions can be broken down into kinetic and potential energy and an inverse relationship exists between these component energies. If this relationship is truly understood, then the total energy can be calculated knowing either kinetic or potential energy instead of both. This would then give additional value to well explored electrostatic interaction models. The lateral interactions were empirically related to nearest neighbour and next nearest neighbour interactions. Two kinetic studies were investigated in this thesis and in both cases, mean field approximations and quasi chemical approximation (QCA) were used and compared to incorporate lateral interactions into the kinetics. The mean field approximation over estimates the lateral interactions and considers global coverage while the QCA approximation considers probability of local combinations. The first kinetic study was a simulated CO TPD experiment on Fe(100). The mean field approximation was an improvement on systems which considered no lateral interactions but did not describe all the aspects observed in the experimental TPD. The prediction by the quasi-chemical approximation shows good agreement for the desorption of associatively bound CO. The deviation observed for the dissociatively adsorbed CO is attributed to the presence of alternative pathways for the adsorbed species (specifically the diffusion of oxygen into the lattice of the solid). A microkinetic model for the methanation of syngas over Fe(100) was also created. The results showed that different methods of lateral interaction incorporation resulted in significantly different coverage profiles and reaction energy profiles. Both methods showed a build-up of oxygen on the surface towards the end of the simulation. The build-up of oxygen on the surface of Fe(100) may indicate that iron-based catalysts need to undergo phase changes to complete the catalytic cycle.