Tightening legislation for vehicles across the world has caused the use of monolith catalysts in automotive emission control to become ubiquitous. Control of the adherence and homogeneity of the platinum group metal (PGM) coating onto the monolith block, to maximise catalytic performance for a minimum PGM loading, is therefore paramount. In this study, an automatic film application is used for coating γ–alumina slurries onto Fecralloy®, an integral component of metallic monolith catalysts, to achieve the desired coating properties. Upon coating of the Fecralloy® coupons, the samples preoxidised for 10 h gave the best performance in terms of coating loading (7.94 mass %) and adherence (< 10 mass % loss) based on ultrasonic vibration test. These conditions produced the optimal surface topography, typified by conspicuous and randomly-oriented α–alumina whiskers which promote coating adherence. The optimal coating loading and adherence were achieved at a pH of 4 and solids concentrations not exceeding 40 wt%. A newly devised technique using the electromechanical testing system showed that finest particle coatings of 40 wt% solids concentration produced the best coating adherence. At solids concentration of 45 wt% the coating adherence was poor and insensitive to the blends of different particle size distributions.

The studies of biointerfaces, interfaces between synthetic materials and biological systems, such as bacteria, represent, by definition, a highly interdisciplinary field spanning across the disciplines of physics, materials science, engineering, chemistry, biology, bioinformatics and medicine. The main approach in biointerfacial science involves the preparation and characterisation of functional surfaces for specific interactions with bio-systems, and studies of the molecular and kinetic processes occurring at such interfaces, ranging from small molecules and biomolecular interactions, to cell and bacteria adhesion. Advanced material engineering techniques, such as self-assembly can structure surfaces that allow dynamic tuning of their properties (i.e. wettability and superficial charge). Recently, switchable surfaces able to undergo conformational switching in response to an applied external stimulus were shown to be suitable platforms for controlling cellular responses. In this context, the design and fabrication of a two-component electrical switchable SAM able to undergo conformational reorientation upon an applied electrical stimulus will be described. This dynamic platform will be used for the first time to gain new insights on the non-specific bacterial adhesion to surfaces in real-time.

Moromi fermentation is an essential part of soy sauce production. This thesis aimed to characterize and control the growth and interaction of two predominant microorganisms, Tetragenococcus halophilus and Zygosaccharomyces rouxii for enhancing the aroma development during moromi fermentation. Antagonism was observed between T. halophilus and Z. rouxii, regardless of the inoculation sequence. However, sequential inoculation of Z. rouxii resulted in more complex aroma profile than simultaneous inoculation. To eliminate antagonism, chitosan-coated alginate and water-oil-water (W1/O/W2) double emulsions (DEs) were tested for their ability to encapsulate Z. rouxii and stability in high NaCl solutions. Alginate was unstable in high NaCl solutions and chitosan exhibited undesirable antimicrobial activity towards Z. rouxii. DEs minimized the antagonism between T. halophilus and Z. rouxii, by segregation in the external W2 and internal W1 phase, respectively. Physicochemical changes in the fermentation medium indicated that DEs affected microbial growth and cell physiology, contributing to the elimination of antagonism. The destabilization of DEs over 30-day storage depended on glucose concentration in W2, which indicated a possibility of sustained release mechanism of Z. rouxii into the moromi. Furthermore, the application of DEs was tested in a moromi model, formulated with reduced NaCl and/or substitution with KCl. DEs resulted in moromi with similar microbiological and aroma profile to that of high-salt. Overall, this thesis demonstrates the potential of DE for delivering mixed cultures in moromi fermentation, which could be applicable in any fermentation process where multiple species are required to act sequentially.

This thesis investigates how the properties of foams can be modulated by the addition of particles to the foam solution. As a model system hydrophobic and hydrophilic silica particles were used. The de-agglomeration of hydrophilic silica particles in water and surfactant solutions was studied. Two methods are investigated: ultrasound cavitation (UC) and mechanical agitation (MA). The efficiency of these two methods was compared with respect to their ability to produce foams and to de-agglomerate both hydrophilic and hydrophobic silica particles. The same particles were used as additions to protein and surfactant foaming solutions. In the experiments, the amount and types of particles, proteins and surfactants were varied in the foaming dispersions. Then UC and MA were used to foam the dispersions and the drainage, breakage and microstructure of the resulting foams were examined. In the protein foaming solutions, both casein and whey protein foams were considered. In the surfactant foaming solution, C12LAS and CTAB were used. Partially hydrophobic silica particles were used in pure water to generate foam. Foamability and foam stability both increased with increasing concentration of particles. Moderately hydrophobic particles gave optimum foamability whilst no foam could be produced with fully hydrophilic particles. In the foam rheology test, a transition from solid-like to liquid-like behaviour was found while the foam with addition of SCMC exhibited no such transition.

In this thesis testing of solid oxide cells in fuel cell and electrolysis operation have been performed. Attempts to fabricate fuel cells are described, equipment for testing solid oxide electrolysis cells has been constructed and the development process for this described. Cells of a number of different types have been tested in which initial work was performed using microtubular cells. Work on the fabrication of planar solid oxide cells is described, anode supports were prepared by pellet pressing however the application of a suitably dense electrolyte was unsuccessful which resulted in a poor cell OCV. The initial degradation of commercial solid oxide cells has been investigated. During cyclic testing at low current density the cells were found to degrade at twice the rate in electrolysis operation compared to fuel cell operation. This leads to the conclusion that the degradation observed in electrolysis is reversible and that there is a disconnect between the electrolysis and fuel cell degradation processes. During testing at different current densities the cells were found to undergo severe degradation when operated with very low water content supplied to the cells. The degradation was 512 mV kh\(^{−1}\) at 2.5 vol% H2O and reduced to 45mV kh\(^{−1}\) at 50 vol% H2O. Over the timescales investigated in this work and due to the reversible nature of the electrolysis degradation identifying a degradation mechanism was very difficult.

Catalytic deactivation caused by coking was studied in ZSM5 and zeolite Y catalysts during the isomerisation of 1-hexene under sub and supercritical conditions. The effects of varying temperature and pressure, from 220–250 °C and 10-70 bar respectively, on conversion and coke deposition were studied in both zeolites. TGA, DRIFTS, nitrogen sorption isotherms for fresh and coked catalysts and catalyst acidity measurements were compared. In ZSM5 the catalyst was stable for 96 hours. TGA and DRIFTS results show coke deposits were mainly polyolefinic and the amount decreases considerably from 18.8 wt% in the subcritical region to 10 wt% in the supercritical region. In zeolite Y, decay in conversion was observed with the rate of deactivation being slower at supercritical conditions at 235 °C and 40 bar. Naphthalene hydrogenation on NiMo/γ-Al2O3 catalyst was also studied. The effect of temperature, pressure, varying naphthalene feed concentration and operating in sub and supercritical conditions were studied. Coke deposit decreased by 38 wt% in the supercritical region. SC CO2 (Tc 31.04 °C, Pc 73.8 bar) was also used to re-activate the coked catalysts. This resulted in recovering 93% of the catalytic activity and 37% of the coke was effectively extracted by SC CO2.

This thesis pursues an enhanced understanding of flow dynamics and mixing within Sulzer SMX mixers. A number of techniques were used, with the main focus on Positron Emission Particle Tracking (PEPT), as well as Particle Image Velocimetry (PIV) and high speed image capture. PEPT tracer location data was processed to derive properties such as local velocity fields, mixing efficiencies, occupancies and changeover efficiencies, for a number of model Newtonian and non-Newtonian fluids, under industrially relevant flow conditions. It was demonstrated that velocity fields within SMX mixers are not adversely affected by the fluid rheology. Comparable velocity maps were also obtained using PIV, where transparent 3D printed mixer elements were successfully used with the technique for the first time. The assessment of the mixing patterns illustrated that the concentric feed orientation offers the fastest reduction in variance across the mixer cross-section, when compared to side-by-side feed patterns. Analysis of occupancies demonstrated a sharp breakthrough front, reminiscent of plug flow, while the assessment of the changeover patterns further emphasised the resemblance to plug flow within the mixer. A model was derived predicting the time required to achieve a desired level of changeover within a system with known rheological properties and geometry.

This thesis focuses on the atomic structure of Platinum-based nanoclusters, and covers two main areas: Binary platinum-titanium clusters, and pure platinum clusters. Both were produced with a magnetron sputtering, gas-aggregation cluster beam source, and imaged with a Scanning Transmission Electron Microscope (STEM) with detailed image analysis. For the study of Pt-Ti clusters, identifying their overall morphology is key. For oxidised clusters, a Pt core with a TiOx shell is found for smaller clusters, whereas for larger clusters multiple Pt cores are seen within the TiOx shell. The Pt-Ti clusters have been transferred under nitrogen, to reduce oxidation. Here, the morphology of the clusters is more amorphous, with the Pt and Ti atoms forming an alloy core within the cluster. Experimentally, clusters were produced containing 10- 600 Pt atoms. The structural motif of these clusters shows that the large clusters (> 250 Pt atoms) typically present with a cubic structure which matches that of bulk FCC Pt. This experimental work has been complemented by theoretical modeling, to identify dominant motifs within a large size range from 55-10,000 Pt atoms, using empirical potentials. The results show that there is a persistent switching between the decahedral and octahedral motifs.

Emulsions are a vital part of many products in everyday use, such as foods, cosmetics, and even construction materials. Membrane emulsification is a technique which has been used to produce emulsions in a manner contrary to the traditional methods where droplets are broken and re-broken to make smaller and smaller droplets, and instead each droplet is individually formed at a pore on the surface of the membrane. This research compared two of the most favoured membrane emulsification techniques; cross-flow and rotating membrane emulsification. Two systems were built for producing emulsions using tubular microporous membranes, made from shirasu porous glass, polymer, ceramic and stainless steel. One device employed a cross-flow system providing shear to detach the nascent droplets from the membrane pores whilst the other system employed a rotated membrane to produce both shear and potentially centripetal force at the membrane surface. Both systems were used to create emulsions, and the effects of various settings of the systems were investigated. A direct comparison between cross flow membrane emulsification and rotating membrane emulsification were achieved for the first time, as the same membranes were available for both systems. The modular interchangeable nature of the membranes in the systems also allowed direct comparison between the various different membrane types tested. The distinct differences in the structure and materials of the membranes tested was compared, and its effects elucidated, as the different membrane types each showed different advantages and disadvantages when producing droplets. It was shown that the membrane pore size is a major factor on the size of the droplets produced, and the membrane pore size distribution span affects the size distribution span of the droplets. Increasing the emulsifier concentration decreases droplet size, as does increasing the shear force applied to the forming droplets, either by increasing the cross-flow velocity or the rotation rate. Increasing the pressure applied to force the dispersed phase through the membrane increases flux rate, but also increases droplet size slightly. The relative viscosity of the two phases being emulsified has an effect on the droplet size; increasing the continuous phase viscosity decreases droplet size, and increasing dispersed phase viscosity increases droplet size. The systems performed equally well making water in oil, as oil in water emulsions. Although the rotating membrane system produces lower shear rates than the cross-flow system, similar droplet diameters were produced, implying that detachment is enhanced by the rotation, showing a clear advantage to rotating membrane emulsification. The systems were also used to produce various more complex particles, including double emulsions and gelled beads, and the level of control over the phases afforded by membrane emulsification was shown to be an advantage in the production of such microstructures.

Twin screw extruder (TSE) has been studied extensively as a granulator because it allows continuous processing. Initial work was carried out by comparing the TSE with conventional granulator shows that the mechanism of TSE granulation is different from conventional granulation with the absence of the consolidation stage. PEPT was also utilised and it reveals that the flow stream of the material is not only due to the conveying capacity but also the granulator fill, in particularly for the 90o mixing zone which is believed to be a dispersion type of mechanism driven by the granulator fill gradient. Residence time distribution was measured and simulated by fitting the experimental data using a continuous stirred tank reactors model. The model describes the experimental curves reasonably well when a plug flow fraction was considered. Generally the mean residence time (MRT) of the system is proportional to the mixing zone angle and is inversely proportional to the screw speeds and flowrate. A study using the variance reduction ratio demonstrates that the TSE granulator used in the present study is able to remove the feed instability given that the ratio of the frequency of the input stream fluctuation to the MRT is high.