Browsing by Subject "chemical engineering"

Now showing 1 - 9 of 9
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    Open Access
    A study of impact breakage of single rock specimen using discrete element method
    (2020) Oladele, Temitope Philip; Bbosa, Lawrence; Weatherley, Dion
    Comminution is a critical stage of mineral processing which aims to reduce the size of ore particles through breakage, consequently increasing the likelihood of the liberation of valuable minerals. However, comminution is highly energy-intensive and an understanding of the key breakage mechanisms has been identified as an important factor in improving the efficiency of the process. Several factors, such as pre-existing cracks, mineralogical composition, ore shape and size are known to affect ore breakage behaviour during breakage. To investigate breakage mechanisms, it is important to be able to determine how individual factor influences the breakage behaviour of rock specimens. However, isolating and investigating individual factors under experimental conditions is challenging and typically impractical. Numerical techniques such as the Bonded Particle Model-Discrete Element Method (BPMDEM) have been developed as a means of investigating in isolation, the effects of different factors on ore breakage behaviour under closely controlled breakage conditions using synthetic rock specimens. This study investigates how individual factors influence rock specimen breakage using BPM-DEM numerical methods. Numerical simulations were conducted using ESyS-particle 2.3.5, an open-source discrete element method (DEM) software package which uses Python-based libraries to generate geometries and simulations and a C++ engine for mathematical computations. Empirical calibration relationships were developed to relate microstructural model parameters to the macroscopic mechanical properties that are typically obtained from standard geotechnical breakage experiments. The robustness of the model was evaluated by considering the sensitivity of fracture measures to the variation of model resolution, size-dependency and macroscopic mechanical properties (Young's modulus and uniaxial compressive strength) of the numerical specimens. A comparative study of single rock specimen breakage using the current BPM-DEM and laboratory SILC experiments carried out by Barbosa et al. (2019) was conducted. The measured fracture force and fracture patterns at different sizes for both cylindrical and spherical synthetic rock specimens were examined. Furthermore, the model was used to study, in isolation, the influence of pre-existing cracks in rock specimens and differing mineralogical compositions upon measurable breakage properties. Numerical rock specimens with pre-existing cracks were constructed using a microcrack approach, while a unique approach with the insertion of "seed points" was developed and demonstrated to construct numerical rock specimens with varying mineralogical compositions. Results from the numerical simulations showed that a high model resolution with a sufficiently large number of DEM-spheres exhibited results with the least deviation and error with respect to fracture measures, and, was therefore considered numerically stable. The dependency of fracture measurements on specimen size showed an expected increase in the measured fracture force as the specimen size increases. The variation of the macroscopic Young's modulus and uniaxial compressive strength against the fracture measures emphasised that the locus of these mechanical properties against the fracture measure can be used to specify a calibration relationship. Results of the comparative study showed that for both cylindrical and spherical rock specimens, the DEM consistently predicted the fragment patterns as well as the increase in the measured fracture force as the specimen size increased. The investigation on the effect of pre-existing cracks revealed that an increasing number of pre-existing cracks in rock specimens necessitated lower fracture force and consequently produced a low amount of new fracture surface area. For the binary phase mineralogical composition in the study, it was found that the fracture force decreased with an increase in the concentration of the softer component due to the increased percentage of weakness in the specimen. It was concluded that, with an appropriate calibration exercise and a realistic specification of material properties from the evaluation study, the DEM as a tool was sufficient to act as a "virtual laboratory" to isolate and study the individual effects of factors that influence ore breakage. The understanding of these results highlighted two important points. Firstly, this study was able to unravel some of the possible causes of the inefficiency in comminution practices, whereby significant amounts of energy can be expended to achieve minimal gains in respect of enhancing liberation due to pre-weakening and mineralogical composition. Secondly, it emphasised some of the causes of the variation observed during ore characterisation on a laboratory breakage device, attributable to pre-weakening and mineralogical composition.
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    Open Access
    An investigation into the partial oxidation of C-4 alkanes over vanadyl pyrophosphate and heteropoly acids
    (1998) Robertson, Stéfan Walters
    Two different partial oxidation catalysts for paraffin functionalisation were studied: the vanadyl pyrophosphate catalyst for the conversion of n-butane to maleic anhydride and the heteropoly acid catalyst for the conversion of isobutane to methacrylic acid.
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    Open Access
    Aromatic hydroxylations over titanium-substituted crystalline silicates
    (2001) Wilkenhöner, Uwe; van Steen, Eric; Gammon, David
    This work focuses on aromatic hydroxylations over titanium-substituted zeolites of different pore sizes (TS-1, Al-free Ti-beta and Ti-HMS) using aqueous H2O2 as the oxidant. The aim was to gain a deeper understanding of the key factors controlling activity and selectivity, which implied an investigation of the reaction kinetics and the adsorption and diffusion properties of reactants and products in the various catalysts using different solvents. The role of shape selectivity inside the micropores of the solids and the reaction at their external surface was also examined.
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    Open Access
    Exploring the effects of single and dual phase culturing on the concentrations of Southern Ocean sea-ice algae and transporting living sea-ice algae from the Southern Ocean to land-based research facilities
    (2022) Hambrock, Mark; Rampai, Tokoloho; Walker, David
    Sea ice is a complex material with a significant impact on the global climate. Understanding the development of sea-ice properties based on the change in growth conditions is vital for the development of predictive models, which are key to providing forecasts of the influence global warming will have on sea ice. Algae found in sea ice form an important part of the oceanic food network, providing secondary producers with a source of food, particularly during winter, and are suspected of seeding algae blooms during spring and summer. Researching sea ice and sea-ice algae in situ is an expensive and logistically difficult undertaking, especially in the Southern Ocean. Consequently, many researchers elect to perform research on artificial sea ice, where conditions are more controlled while logistical and financial constraints are reduced. Despite the extent to which sea-ice research has been performed on artificial sea ice, relatively little research on sea-ice algae in artificial sea ice has been done. Sea-ice algae are strongly affected by the temperature, salinity, nutrient availability and intensity of photosynthetically active radiation in their environment. This makes the transportation of living sea-ice algae difficult. Little documentation of transportation of living sea-ice algae exists, with most of the laboratory research of sea-ice algae being performed on single-species liquid cultures. Such research is important but fails to address the complexity of real sea-ice algae communities. This dissertation investigates the effects of three sea-ice algae transportation methods on the concentration development of sea-ice algae, as well as the potential for experimentation with the algae transported with these methods. Two methods were adapted from literature: transportation in solid (1) and liquid (2) environments. In addition to these methods, a third method was explored: Transportation of living sea-ice algae in a hybrid solid-liquid system. The aim of transporting in the hybrid system was to minimise the changes from the natural to the artificial environment. Solid sea-ice storage was evaluated by means of an artificial sea-ice study: Artificial sea ice was grown, extracted and stored at -20 °C for 7 different durations, between 0 minutes and 35 weeks. Samples were segmented into 20 mm thick slices, melted, analysed for salinity and brine profile development was assessed. It was found that storage significantly impacted brine profiles, causing an average bulk desalination of 19% between samples stored for 1 day and 35 weeks, as well as a change in the shape of the salinity profile from a W to a C shape. Solid sea-ice transportation was thus eliminated as a transportation method for this work due to the high change algae communities would likely undergo during due to desalination and unfavourable environmental conditions associated with low temperatures. A solid-liquid hybrid system for the transportation of sea-ice algae was designed and constructed, consisting of a 30 litre Perspex tank, insulation, and a heating system. Two sea-ice cores were obtained from the Southern Ocean in winter of 2019 and transported in the hybrid system to land facilities. Issues with the system were identified, dedicated lights added, and an additional hybrid tank constructed. Six sea-ice cores were obtained from the Southern Ocean in spring of 2019 and parts of them transported in the hybrid tanks to land facilities, where they were melted and cultured in a liquid environment for 56 days. Sections of the cores were melted, and the algae preserved before transportation. Algae concentrations were determined via microscopy of preserved samples taken before transport, after transport and after liquid culturing. Taxonomic distributions of algae varied greatly between initial samples and concentrations ranged from 46 000 to 1 200 000 cells per ml. The hybrid transportation method caused the lowest degree of change in the community compositions and increased the overall concentrations of algae, whilst liquid incubation mostly decreased algae concentrations.
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    Open Access
    On the selective flotation of pentlandite from pyrrhotite in Sheba's Ridge ores
    (2009) Mbonambi, Mduduzi Justice; Franzidis, J. P.; Bradshaw, Dee; Becker
    Metal sulphides are the raw material for most of the world's supplies of non-ferrous metals and can be considered one of the most important group of ore minerals. In the context of South Africa, the Bushveld Igneous Complex (BIC) sulphides play a very important role in that they are largely associated with the valuable platinum group elements (PGEs) and platinum group minerals (PGMs). Typically, the base metal sulphide (BMS) content in the BIC is comprised of pentlandite, pyrrhotite and chalcopyrite. Sheba's Ridge, one of the ore deposits found in the BIC, is exploited for its PGEs and PGMs. For typical PGE processing operations like the Merensky reef, the valuable PGEs and PGMs are associated with the base metal sulphides pentlandite, pyrrhotite and chalcopyrite. Unusually, in the case of the Sheba's Ridge ore, not all the sulphides contain associated PGEs and PGMs, and pyrrhotite has been observed to show little or no association. Therefore, this study was carried out to develop a methodology for the selective flotation of pentlandite from pyrrhotite using the polysaccharide depressants that are already in use in the flotation of BIC ores to control the naturally floating gangue minerals such as talc. Microflotation tests were conducted on a high grade Nkomati massive sulphide ore sample as a probe ore, to investigate the flotation response of pentlandite and pyrrhotite to four different chain length xanthate collectors (SEX, SNPX, SIBX and PAX) and to different types of polysaccharide depressants (guar, CMC and starch). The effect of oxygen addition and pH modification were also studied. Laboratory batch flotation tests were then carried out using the Sheba's Ridge ore, to evaluate the optimum reagent suite and flotation conditions determined in the microflotation tests. The results showed that using the different chain length xanthates or polysaccharide depressants on their own did not produce any pentlandite selectivity over pyrrhotite, but, when these reagents were used in conjunction with one another, some pentlandite selectivity was obtained. The best combination was found to be an intermediate chain length xanthate (SNPX) with guar depressant, where a balance between collector hydrophobicity and selectivity was obtained. Adjustment of the pH to 10, using lime instead of NaOH, together with artificial pre-oxidation showed further improvement in the selective flotation of pentlandite. This was attributed to the faster oxidation rate of pyrrhotite at these conditions, which led to selective depression of pyrrhotite while pentlandite floatability was maintained. The optimum reagent regime for pentlandite/pyrrhotite selectivity, as determined from the microflotation testwork using the Nkomati massive sulphide probe ore, was used as the basis of the batch flotation tests. The batch flotation tests represented a scale up of the microflotation tests, in terms of sample size (1 kg vs. 2 g) and were a closer representation of real operations, as silicate gangue minerals (e.g. talc) were present, as well as a froth phase. The variables that were found to be key in the microflotation testwork in terms of improving metallurgical performance for pentlandite selectivity were pH, collector and depressant type and dosage. These were the same variables identified as key in the batch flotation tests. However, the differences between these parameters were observed to be more subtle in the case of batch flotation tests compared to what was observed in the microflotation testwork. Nevertheless, it can be concluded that results from microflotation test work can used as a good basis to study of the interactions of different minerals in ores in a batch flotation system. Translating the results from microflotation testwork to batch flotation testwork was not so straight forward, and further work still needs to be done to prove that this can be done successfully. It was also found that there needs to be a synergistic interpretation of the interactions present in the reagent – mineral system. Finally, the study showed that the reagents used in flotation cannot be evaluated independently but rather a holistic approach needs to be employed.
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    Open Access
    Selection of bacterial species from wastewater for potential production of poly (γ-glutamic acid): isolation, characterisation and growth kinetics
    (2013) Madonsela, Ziningi; Harrison, Sue
    Wastewater treatment plants represent a source of nutrients for microbial growth and product formation. In an approach in which bioresource productivity is maximised, it is desirable to not only achieve water treatment to the desired standard, but at the same time to harness the value in these resources. Wastewaters are a source of nutrients such as carbon, nitrogen and phosphates. Macronutrients typically comprise the major share of the operating costs of commodity bioprocesses, such as the production of alcohols, organic acids and polymers. The nutrient loads in municipal wastewaters are dilute, but add up to significant daily loads because of the massive volumes generated in urban populations. The effluent of most wastewater treatment plants in South Africa is released back into either rivers, lakes or the ocean without reuse. For many, there is a concomitant failure to comply with the country's effluent requirements. This has resulted in the need to move towards more sustainable water treatment systems, including more efficient and innovative solutions to treat wastewater. Additionally, by recovering value from waste, there is potential to improve plant operation; releasing water which is better treated, more compliant and can be reused, while simultaneously improving resource productivity and minimising environmental burden; thereby changing the economics of the wastewater treatment plant. This includes the recovery or the production of valuable resources, whilst in turn recovering clean water. Bioprocessing to reduce these nutrient loads in wastewater while producing a range of byproducts have conventionally included biogas and compost, produced with minimal modification of existing plants. In extending the potential product range of these ‘wastewater biorefineries', key design factors include using waste resources in a non-sterile environment, thus requiring a positive selection pressure for the product of interest, and ideally producing a product readily separated from the wastewater through a phase change such as precipitation. Stress and storage polymers satisfy both these requirements. In this project, we explore such a wastewater biorefinery approach in which we aim to use the nutrient component of partially treated domestic wastewater for the production of poly (γ-glutamic acid) (γPGA). γ-PGA, a polymer of D- and L-glutamic acid monomers connected by amide linkages, is a naturally occurring biopolymer, synthesized by a variety of micro-organisms. Most commonly, γ-PGA production has been studied in Bacillus species, such as B. subtilis and B. licheniformis. Bacillus species are ubiquitous in the environment, including an association with domestic wastewater treatment. Its enrichment has been associated with improved treatment processes. The favourable properties of this very promising polymer include its water solubility, anionic nature, biodegradability and non-toxicity towards humans, animals and the environment. Potential applications of γ-PGA are reported in the medical, food, cosmetic, wastewater treatment, plastic,agricultural and textile industries. In this project, we consider the production of γ-PGA by Bacillus-enriched species for the Synopsis iii partial treatment of domestic wastewater and concomitant production of the polymer for soil improvement and water treatment. To design and optimise a process using wastewater for γ-PGA production, it is important to understand the growth kinetics of Bacillus-like microorganisms that can be found in a domestic wastewater treatment plant. The base case for growth, substrate utilisation and biomass production has been presented for a Bacillus licheniformis type culture strain in this dissertation. In presenting this base case, a complete experimental methodology using both shake flasks and deep well plates is developed and appropriate analytical protocols selected. The second objective of this project was to characterise the growth kinetics of the microorganisms isolated from the wastewater obtained from the Mitchell's Plain wastewater treatment plant. Following enrichment of wastewater samples collected, 18 isolates were obtained and characterised in terms of morphology. Further, using DNA sequence data for the enzymes involved in PGA synthesis, primers were designed to identify strains carrying γ-PGA synthesis potential through molecular biology studies. Two different media; namely Medium E, containing glutamic acid, citric acid and glycerol as carbon sources, as well as a modified Medium E, in which the glutamic acid was replaced with glucose, were used for these experiments. Isolates showing reproducible growth and evidence of polymer production were selected for detailed screening in terms of growth. Based on this, six isolates were chosen. These experiments were performed in both shake flasks as well as deep well plates with the growth kinetics and biomass production by the various strains carefully analysed. Biomass concentrations varied from 2 to 8 g.L-1 while specific growth rates varied from 0.11 to 0.26 h-1 in these cultures. The results of the growth studies showed that the growth rates and biomass production of the different isolates varied greatly under identical cultivation conditions. Cultivation of the isolates in deep well plates generally yielded higher biomass concentrations in comparison to shake flask cultivation. A quantitative analysis of the data on carbon substrate utilisation in the media showed that glucose was the preferred of these, most consumed by the isolates for cell growth. Preliminary media optimisation was undertaken to identify optimal C:N:P ratios in the modified growth Medium E and to assess the impact of these medium components by using two-level Plackett-Burman factorial design. The dependence of biomass accumulation on C levels and maximum specific growth rate on N is illustrated. Response surfaces revealed the insignificant effect on the microorganism growth of varying P concentrations. Influence of P was attributed when P acted in tandem with C and N. Identification of the isolates selected for detailed screening was confirmed using 16S rRNA sequencing. There were two major families present – Proteobacteriaceae and Enterobacteriaceae – which grouped accordingly when analysed phylogenetically. The Bacillus, and opportunistically pathogenic enteric bacteria Klebsiella and Enterobacter, were reflective of genuses which have a high Synopsis iv probability of being present in a treatment plant which predominantly treats domestic wastewater containing high sewage loads, such as Mitchell's Plain. A suitable reactor configuration, capable of treating wastewater and simultaneously producing γ-PGA, was proposed for integration into Mitchell's Plain wastewater treatment plant after studying the selected Bacillus isolate in a laboratory-scale bioreactor in optimal medium. The sustained biomass production and growth rate, even at lower medium carbon inputs, shows a great potential for application by enrichment, growth and product production of this Bacillus subtilis strain in a wastewater treatment plant. Although this work was able to make a substantial contribution to the current knowledge of microbial growth kinetics in various media and bioreactor systems, the study limitations related to growth profiling in more dilute and variable nutrient concentrations, non-sterile environments and mixed culture dynamics are acknowledged. These present a scope and opportunity for further research in this exciting field. Analysis of extracted and purified γ-PGA showed a polymer composed of a combination of polysaccharides and protein (in roughly equal proportions in three of four of the isolates) in which histidine, homoserine and glutamic acid were typically the most dominant amino acids. The impure nature of this γ-PGA remains suitable for wastewater applications, but not for areas which require a product composed of specific, high molecular weight stereoisomers such as the medical industry. This study illustrates the importance of developing new experimental techniques for more γ-PGA-specific purification and improved analysis. Further it demonstrates the shortcoming of the gravimetric analysis of the crude extract typically reported in the literature. The findings of this project are intended to be used in a system which applies wastewater as an economical and sustainable source of nutrients with the aim of producing valuable products through bioprocessing applications.
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    Open Access
    The synergistic interaction between dithiophosphate and frothers at the air-water and mineral-water interface
    (2022) Pienaar, Dandré; Mcfadzean, Belinda; O'connor Cyril
    Collectors and frothers are reagents in the flotation process that are thought to have separate roles. Collectors selectively hydrophobized the mineral surface and frothers adsorb onto bubbles inhibiting bubble coalescence and stabilizing the froth. Interactions between these molecules have been previously reported in literature (Leja & Schulman, 1954; Lekki & Laskowski, 1971; Dai, Bradshaw & Harris, 2001; Jordaan, 2018). These interactions have been shown to improve sulphide mineral recovery. Dithiophosphate (DTP) is a collector in sulphide mineral flotation which has been shown to synergistically increase flotation recovery in the presence of frothers (Pienaar et al., 2018) but it has also been shown that DTP does not adsorb onto the sulphide mineral surface (Nagaraj & Brinen, 2001; McFadzean & O'Connor, 2014; Petrus et al., 2011; Grano et al., 1997; Guler et al., 2006; Taguta, O'Connor & McFadzean, 2017) as occurs with conventional collectors. If DTP does not adsorb onto the mineral surface and improve hydrophobicity it was not clear what the role of DTP is in the flotation process. The main objective of this research was to identify the role of DTP in sulphide mineral flotation. Each of the respective interfaces were investigated for the adsorption of dithiophosphate (DTP). The adsorption of DTP on galena, pyrite, chalcopyrite and chalcocite was measured by UV-Vis spectrophotometry and isothermal titration calorimetry. Adsorption tests in the presence of aeration were used to determine if DTP dynamically transferred from the air-water to the mineral-water interface. At the air-water interface a regular solution theory approach, critical coalescence experiments and foam stability tests were used to quantify the interactions between DTP and frothers and compare them to xanthate and frothers. Microflotation and induction time experiments were performed to determine the effect of the collectors, frothers and their mixtures on mineral recovery and bubble-particle attachment It was found that DTP in the presence of a non-ionic frother synergistically improved sulphide mineral recovery. This improvement was attributed to attractive molecular interactions which were found to occur between the collector and the frother at the air-water interface. The interaction facilitated the transfer of the frother between the air-water and mineral-water interface, which destabilised the film between the bubble and the particle, improving film thinning kinetics and synergistically enhanced mineral recovery. When DTP did not adsorb onto the mineral surface, the collector co-adsorbed with the frother at the air-water interface and transferred with the frother onto the mineral surface during bubble-particle collision.
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    Towards identifying platinum anchor sites on carbon via a model electrochemical system
    (2018) Fortuin, Adrian Charles; Levecque, Pieter; Scherer, Günther
    The interaction between Pt and its carbon support was investigated by a model electrochemical system. This entailed aggressively oxidising a two-dimensional carbon substrate, i.e. highly orientated pyrolytic graphite (HOPG) and mirror finish graphite (MFG) quartz crystal, to incorporate oxygen terminated groups into the graphitic matrix. This study focusses on potential cycling to determine the mobility of Pt across these carbon surfaces and the effect of the Pt anchoring to carbon on the electrocatalyst durability. This work incorporates both a conventional three electrode electrochemical setup and the use of the electrochemical quartz crystal nano-balance (EQCN). The objectives of this study were to better understand the Pt mobility across the carbon substrate surface and to gain insight into the solid-liquid interface of Pt dissolution due to potential cycling. Initial results on HOPG as discussed in chapter 2, indicated minimal Pt dissolution of between 13% and 15% of total electrochemical active surface area loss. These results, however, did not provide adequate evidence to conclusively determine the extent of Pt mobility on the carbon surface and the effect of oxygen terminated groups in hindering Pt dissolution. In order to gain a more thorough understanding of the Pt dissolution processes, the use of the EQCN technique was utilised. Firstly, it was shown that the mirror finished graphite quartz crystals used in the EQCN technique, are qualitatively comparable to the electrochemical measurements recorded with the HOPG samples. Secondly, potential cycling under the same conditions as HOPG produced similar electrochemical results. The frequency response curves from the EQCN yielded the most promising results. This study showed, qualitatively, that the surface of Pt is non-monotonic, and that the surface charge changes with increased potential cycling. Pt/MFG-A had consistent frequency responses over the entire potential range during Pt dissolution, thus, with the above understanding of surface charge, it is concluded that acid treated carbon substrates show a stronger affinity for Pt anchoring.
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    Understanding the promotion of aerobic oxidation of benzyl alcohol over Pt-based catalysts
    (2022) Kunene, Avela; Van Steen, Eric
    The combination of metal catalyst with molecular oxygen (which is the cheapest and the most environmental-friendly oxidant) is undoubtedly a more benign alternative to the existing methodologies for the oxidation of alcohol substrates to aldehydes, ketones and/or carboxylic acid products. However, a potential risk is apparent upon the use of volatile and flammable organic solvents, specifically in the presence of molecular oxygen. This makes the liquid-phase oxidation of alcohols a non-trivial chemical reaction that requires safety considerations. As such, designing a new alcohol oxidation procedure should carefully incorporate safety and sustainability principles while maintaining overall reaction efficiency. The solvent system should be considered carefully to limit potential risk associated with the oxidation of organic substrates using air/O2 as an oxidant at elevated temperatures. The use of H2O (as a non-flammable solvent) would not only present safety measure in alcohol oxidation (with O2 as an oxidant), but also has a potential to enhance overall catalytic performance. In this study the influence of H2O on the liquid phase benzyl alcohol oxidation is explored using a Pt/TiO2(P25). The rate of reaction at 90°C is significantly enhanced when using H2O as a solvent (TOF of 677.4 ± 23 hr-1 compared to the TOF obtained in solvent-free system, 27 ± 6 hr-1, in m-xylene as a solvent, 23 ± 2 hr-1, or in n-heptane as a solvent, 20 ± 2 hr-1). The promotional effect of H2O is associated with the mole fraction of H2O in the organic phase rather than fugacity of H2O in the system. It is thought that the precise role of H2O in the organic phase is thought to facilitate the H-transfer reactions. A DFT study suggests that the presence of H2O facilitates the dissociation of molecularly adsorbed O2 over Pt(111) surface resulting in the formation of surface hydroxyl species in addition to surface oxygen. The catalytic activity of platinum in the benzyl alcohol oxidation is suppressed significantly upon alloying Pt with Ni (forming Pt-skin Ni subsurface alloy). This is ascribed to a weakening of the chemical bond between Pt and adsorbed atomic oxygen due to the suppression of surface-states on the Pt surface layer, due to the presence of Ni atoms in the subsurface layer. In contrast to the effect associated with the presence of Ni in alcohol oxidation, the addition of Bi enhances the rate of the benzyl alcohol oxidation (but to a lesser extent the oxidation of the non-aromatic analogue, cyclohexyl methanol). The addition of bismuth results in the formation of Bi2Pt (together with some amorphous Bi2O3), which is partially oxidized upon exposure to oxygen. Bismuth is thought to be a sink for oxygen which may be involved in the selective oxidation of alcohols. The resulting surface hydroxyl groups are thought to be rapidly eliminated from the bismuth surface. Furthermore, bismuth is thought to induce electron backdonation in benzyl alcohol substrate, thus weakening the O-H bond of the alcohol; electron backdonation induced by Bi is improbable with cyclohexyl methanol as the substrate. Typically, the active metal, in heterogeneous catalysis immobilized on a metal oxide support. Platinum-based catalysts were synthesized by incipient wetness impregnation of TiO2(P25), CeO2, g-Fe2O3, g-Al2O3 and MoO3. The turnover frequency is strongly dependent on the type of support used indicating a strong involvement of the support on the benzyl alcohol oxidation. With the exception of Pt/g-Fe2O3, it is apparent that the reducibility of the oxide support together with the ability to form OH on the oxide plays an important role. It is thought that the alcohol substrate may interact with oxygen on the support, which may result in the formation of a surface hydroxyl species on the reducible support, which can be eliminated generating an oxygen vacancy on the oxide. This ultimately improves the overall TOF for benzyl alcohol oxidation. Hence, support materials which can generate surface hydroxyl groups, and eliminate them under reaction conditions in the form of water, will be enhance the benzyl alcohol oxidation.