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.

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Medicine (Pharmaceutical Affairs). Johannesburg 2012 / Global warming has stimulated research into alternative energy carries and fuels. Hydrogen is one of these alternative fuels that are recognized as a promising future energy source. Historically, it is produced by water electrolysis and the gasification of coal. Hydrogen is a natural though transient by-product of several microbial driven biochemical reactions, including anaerobic digestion and fermentation. Microorganisms degrade complex molecules to produce butyrate and alcohols with CO2 and hydrogen as the only by- products. Hydrogen produced by microorganisms is known as biohydrogen. This study aimed to identify biohydrogen- producing bacteria in three Anaerobic Fluidised Bed Bioreactors (AFBRs), which are capable of producing hydrogen under anaerobic and thermophilic conditions, by using PCR-DGGE analysis of the 16 S rDNA genes. Sewage sludge from anaerobic digester and cow- dung were used as inoculum to isolate potential H2- producing organisms. The operational conditions were manipulated to removing mesophilic bacteria and non- spore forming bacteria by gradually increasing the temperature to thermophilic conditions and the pH maintained at acid conditions to allow acidotolerant bacteria to survive. The bioreactors were operated for a period of forty days for each research cycle. Bioreactor One was operated at 55°C for eight days and then the temperature kept at a constant 65°C for the remainder of the research cycle. Bioreactor Two was operated for 8 days at each temperature ranging from 45°C - 65°C, with increments of 5 °C. Bioreactor Three was operated at each temperature for ten days ranging from 55- 70°C, also with increments of 5°C. Samples for microbial community identification were taken at 55°C and 65°C. The bacterial morphologies and structural properties were evaluated by examining the hydrogen- producing granules, isolated at 65°C, using scanning electron microscopy. Species of the families Bacillus, Enterobacteria, Actinomyces, Clostridium and Veillonella were identified. Clostridium thermopalmarium, Bacillus coagulans and Bacillus thermoamylovorans were the culturable species at the desired operational temperature of 65°C. C. thermopalmarium and B. coagulans are major H2 producers with theoretical values of 4mol H2/ g glucose and 3mol H2/ mol sugar, respectively. Sewage sludge is the best source of biohydrogen producing bacteria in comparison to cow dung as an inoculum in AFBRs. Bioreactor 1 with a constant operational temperature of 65°C and at a HRT of 6.5 allowed for the desired Clostridium sp. to be the predominant H2 producer.

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In general, the velocity of inversion of sucrose ie a function of several variables; namely, the temperature, the viscosity, and the concentrations of hydrogen ions, undissociated acid, sucrose, added salts, and non-electrolytes. It can readily be seen, then, that this reaction offers a broad field for research with decidedly varied and diversified lines of attack.

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