The threshold potentials were determined for the excitation energy necessary for low energy electrons to induce chemical reactions of carbon monoxide, and of nitric oxide adsorbed on a gold surface. The reactions were studied as a function of temperature (100 °C to 200 °C) and pressure (1.83 x 10-5 to 6.40 x 10-4 torr). The electron source was a thorium oxide coated iridium filament which was heated by a current between 1A and 3A to keep thermal distribution of the electrons to less than 0.4 ev. The reaction surface was a polycrystalline evaporated film prepared by subliming gold onto a stainless steel mesh support. Mass analysis was done by quadrupole mass spectrometry in a flow system. The general results of the research is that a technique has been developed to study the products of reactions of excited state atoms or molecules on metal surfaces. The electron-impact excitation method is an alternative to photochemical and other methods.

Dry Reforming of Methane (DRM) is a relatively new process technology that provides economic and environmental incentives for several industries that rely heavily on Hydrogen (H₂) and syngas (H₂ and Carbon Monoxide (CO)) utilization. The process utilizes Carbon Dioxide (CO₂) and Natural Gas, containing mainly Methane (CH₄), as a feedstock to produce H₂ and CO. Hydrogen intensive applications and syngas processing facilities benefit mostly by generating new revenue streams as well as achieving a reduced overall carbon footprint of their operations, since CH₄ and CO₂ are both powerful greenhouse gases. This process can be considered on a reactive basis to treat flue gases and emitted streams rich in CO₂, and it also can be a proactive approach to eliminating CO₂ emissions before they occur. The focus in this work is on the latter approach, where DRM, deposited on a low-pressure monolith, is being studied as a relatively new process to produce a pure H₂ gas stream (+99.9% purity) while maintaining carbon neutrality and prove its superiority to the dominating technology today; Steam Methane Reforming (SMR) which utilizes steam (H₂O) as a reactant instead of CO₂, and reacts with Natural Gas to produce H₂ and CO, however, they are accompanied by a large generation of CO₂ emissions. A comprehensive life cycle assessment (LCA) analysis was conducted to compare both technologies, DRM and SMR, and has demonstrated the feasibility of DRM in almost all environmental impact categories with a significant reduction in CO₂ equivalent emissions. This study assessed the performance of SMR and DRM in various indicators, including energy consumption, air emissions, global warming potential, water consumption, wastewater production, solid catalyst utilization and solid waste production. Although DRM requires higher energy in the reformer, its overall energy consumption is lower than SMR since steam generation needed is only roughly one third that of SMR. Harmful components released by DRM in air emissions are lower in all categories which reduces global warming potential to a large extent and in particular, CO₂ is reduced by approximately 61% when compared with SMR. Since SMR relies heavily on steam input and cooling purposes, water consumption and wastewater generation indicators are more adverse compared to DRM. This outcome acts as a strong driver to invest more in this research field and accelerate commercialization of this process technology. The research focus around DRM has been studied for over 20 years focusing on landfill gas (CO₂:CH₄ with a ratio of 0.8) and only few commercial testing facilities exist as of today due to major catalyst stability drawback, due to excess CH₄ causing coking issues. While most of the research body is considering DRM to process landfill gas, this research work has found out that by moving to a coke-free regime, the catalyst retains excellent initial stability properties. Thermodynamic analysis demonstrated that ratios of CO₂:CH₄ equal to and greater than 1.5, solid carbon no longer thermodynamically forms, and indeed, the experimental studies have confirmed the same conclusion evident by stable catalyst performance. Both Nickle (Ni) and Rhodium (Rh) in powder forms exhibited excellent activity and stability levels under a CO₂:CH₄ ratio of 1.5. This was the first and most important stepping stone in constructing a solid argument supporting DRM as a stable process with great potential for commercialization. This ratio is possible when separate sources of CO₂ and CH₄ are available and thus ratios can be adjusted unlike in landfills where CH₄ is always in excess. The work continued in performing several parametric experiments and screening multiple catalysts with different metal loadings. Three active metals were tested, Ni, Rh, and Ruthenium (Ru), and the results concluded that the most promising formulations are 10% Ni on Alumina (Al2O3) and 1% Rh on Al₂O₃. Those were further investigated in details for artificially aging by intentionally forming coke and successfully regenerated by steam gasification. The catalysts were coked and regenerated to essentially fresh activity. Commercial SMR is operated with a packed-bed reactor design and utilizing catalysts (most commonly Ni on alpha Al₂O₃.) in the form of pellets and rings, which lead to large pressure drops and ultimately large reactor design and increased energy requirements. To help overcome the design challenges, this research work has considered monolithic catalysts for testing and scale-up purposes. Monoliths, with their high open frontal areas and large geometric surface areas, overcome the challenges of high pressure drop, experienced in pellets, exhibit solid mechanical strength and provide large geometric surface areas of catalysts (washcoat) contact for reactions to take place, and hence, significantly reduce reactor sizes and eventually, overall capital and operating costs. The monolithic catalysts were prepared by washcoating 10% Ni and separately 1% Rh, both on gamma Al₂O₃. on their walls. The same parametric studies conducted for powders were tested for monolithic catalysts, and the results were positively surprising. Monolithic catalysts possessed extremely high activities, far better than all powders tested even at higher loadings. Moreover, their excellent stability results provide a possible road to a more compact reactor design. One conclusion; monolithic catalysts, or washcoated structured reactors as known in industry, are strong competitors that have the potential to deliver superior results when compared to packed-bed reactors. Therefore, this research is proposing the use of monolithic catalysts working under the favorable thermodynamic environment, as a potential solution to accelerate DRM advanced testing for H₂ production. To further support the thesis argument, a basic process design of the DRM was carried out to understand the various compositions of streams and the material and energy requirements for a feasible commercial plant. The design resembled very closely that of an SMR plant with the major difference in the main reactor, known as the “Reformer”. With this data on hand, a financial modelling was constructed to preliminarily prove the feasibility of this technology when compared to competitors in the market. Consequently, when compared to SMR with and without carbon capture (CC), DRM achieved relatively low H₂ prices in the range of 1.07-1.32 $/kg in the case of a Methanator design case and up to 1.91 $/kg for the CC design case, while SMR exceeded 2.1 $/kg for sustainable H₂ production; indicating that DRM, on preliminary basis, is a very profitable process technology. In conclusion, the laboratory research work combined with process design and financial feasibility, strongly supports the grounds of recommending DRM as a viable H2 production technology for a future pilot plant testing and advancement for commercialization. A more detailed engineering design and financial assessment would provide more accurate results after the successful pilot plant testing.

L'objectif de cette thèse est d'étudier les phénomènes d'import et d'export de la pollution gazeuse et particulaire au-dessus du Bassin Méditerranéen (BM). Ce travail consiste dans un premier temps à étudier l'évolution de l'ozone (O3) de surface dans un contexte de changement climatique au-dessus du BM entre 2000 et 2100, en exploitant les sorties issues de 13 modèles participant à l'exercice ACCMIP (Atmospheric Chemistry and Climate Model Intercomparison Project). Nous avons montré que l'ozone de surface diminue entre 2000 et 2030 (2100) pour 3 RCPs (Representative Concentration Pathway) : -14% (-38%) pour le RCP2.6, -9% (-24%) pour le RCP4.5 et -10% (-29%) pour le RCP6.0, alors que pour le scénario RCP8.5, l'ozone de surface reste stable au cours du XXIème siècle. Dans un second temps, nous avons identifié les sources et les chemins de transport de l'O3 et du monoxyde de carbone (CO) représentatifs des différentes régions du BM : l'Est, l'Ouest et le Centre entre 2012 et 2014, en utilisant une approche statistique qui combine des observations de surface et des rétro-trajectoires issues du modèle HYSPLIT (Hybrid Single Particle Lagrangian Trajectory). En général, l'O3 et le CO sont transportés, respectivement, depuis l'Europe continentale et l'Europe de l'Est vers le BM. Finalement, nous avons étudié les phénomènes d'import et d'export de la pollution au-dessus du BM, en utilisant le modèle MOCAGE (Modèle de Chimie Atmosphérique à Grande Échelle) et le modèle HYSPLIT, et en exploitant les observations récoltées lors des deux campagnes de mesures TRAQA (TRAnsport à longue distance et Qualité de l'Air) (été 2012) et GLAM (Gradient in Longitude of Atmospheric constituents above the Mediterranean basin) (août 2014) réalisées dans le cadre du programme ChArMEx (The Chemistry-Aerosol Mediterranean Experiment). Nous avons mis en évidence le transport à longue distance des masses d'air enrichies en O3 et l'impact du Mistral sur le mélange des masses d'air. Le bilan d'O3 et de CO a été aussi réalisé sur le BM pour l'année 2012 à partir des simulations du modèle MOCAGE. Les résultats montrent que le CO est importé vers le BM pendant le printemps et l'été alors que l'O3 est importé vers le BM durant la période janvier-juin puis exporté le reste de l'année. / The objective of this thesis is to study the import and the export processes of gaseous and particulate air pollution over the Mediterranean Basin (MB). Firstly, we investiga- ted the evolution of surface ozone (O3) over the MB over the time period 2000-2100 in a context of climate change, using the Atmospheric Chemistry and Climate Model In- tercomparison Project (ACCMIP) outputs from 13 models. Compared to the reference period (2000), we found a net decrease in the ensemble mean surface O3 over the MB in 2030 (2100) for 3 RCPs (Representative Concentration Pathway) : -14% (-38%) for RCP2.6, -9% (-24%) for RCP4.5 and -10% (-29%) for RCP6.0. For the RCP8.5 scenario, the ensemble mean surface O3 is almost constant over the MB from 2000 to 2100. Se- condly, we identified the geographical sources and the transport pathways of polluted air masses inducing high levels of surface O3 and carbon monoxide (CO) concentrations in di erent regions of the MB, representative of the west, the center and the east of the MB between 2012 and 2014, using several backward trajectory statistical analyses combining in situ measurements and back trajectories obtained from the HYSPLIT (HYbrid Single- Particle Lagrangian Integrated Trajectory) model. In general, O3 and CO are transported to the MB from continental Europe and Eastern Europe, respectively. Finally, we studied the import and export processes of pollution over the MB using the chemical transport model MOCAGE (MOdele de Chimie Atmosphérique à Grande Échelle) and the HYS- PLIT model. We also investigated in situ measurements carried out during both TRAQA (TRAnsport à longue distance et Qualité de l'Air) (2012) and GLAM (Gradient in Longi- tude of Atmospheric constituents above the Mediterranean basin) (2014) field campaigns performed within the framework of the ChArMEx (The Chemistry-Aerosol Mediterranean Experiment) program. We highlighted the long-range transport of air masses rich in O3 and the impact of the Mistral wind on the air mass mixing. The budget of O3 and CO was also performed over the MB for the year 2012 using the MOCAGE model simulations. We found that the MB is an import area for CO during the spring-summer period, whilst tropospheric O3 is imported to the MB during the January-June period and exported the rest of the year.

Recent work indicates that microorganisms present in soils can remove carbon monoxide from the atmosphere and as such constitutes a major sink. B.E.T. adsorption studies were carried out on representative soils from the Willamette Valley River Basin in order to determine their adsorptive characteristics for carbon monoxide and other gases. Attempts were made to isolate, through a non-soildestructive sterilization, the adsorptive characteristics of the soil microorganisms as well as of the test soil. The carbon monoxide studies show physical adsorption equivalent to the coverage of a few per cent of the surface area at 25.0° and 76 cm-Hg. Adsorption studies also shows that the soil rather then the microorganisms adsorbs most of the carbon monoxide. On sterilized soil, chemical sorption of oxygen was present and was probably caused by the oxidation of dead or damaged soil microorganisms. Hysteresis effects were present in all adsorption studies at 25.0° and appears to be a characteristic of the constituents of the soil and represents a new and as yet unexplained phenomenon.

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Heme oxygenase (HMOX) catalyzes first and rate-limiting step in heme degradation. By its action, carbon monoxide (CO), ferrous iron and biliverdin which is subsequently reduced to bilirubin are produced. Before discovery of HMOX reaction mechanism, CO was considered only a toxic waste product without any significant importance for human organism. Bilirubin, marker of liver dysfunction, has been also exposed to similar perception. But results from past decades show that HMOX and its metabolic products play an important role in number of physiological as well as defense against pathophysiological processes. The aim of this thesis was to clarify the role of HMOX and its metabolic products, presumably CO and bilirubin, in vivo and in vitro. We focused on the role of CO in a rat model of lipopolysaccharide-induced cholestasis. We were first to describe tissue distribution and pharmacokinetics of inhaled CO in this animal model and found out that CO inhalation is associated with anti-inflammatory and hepatoprotective effects. In a rat model of ethinylestradiol-induced cholestasis, we demonstrated the anticholestatic effect of HMOX. The induction of HMOX by its substrate heme increased the expression of liver transporters thereby increasing bile flow and simultaneously facilitated effective clearance of...

Gold-based catalysts can be replaced with platinum group catalysts in catalytic automotive exhaust aftertreatment if their thermal stability and durability issues can be resolved. Hence, one of the potential markets for gold catalysis is the automotive after treatment market, our interest is to synthesize a gold-based catalyst which has practical applications in automotive industry specifically for diesel-methane dual fuel low-temperature combustion strategy where the exhaust temperature is varying from ~ 200 to400° C. Our research focused on synthesizing a bimetallic gold-copper catalyst which is not only highly active for CO oxidation reaction but also sinter-resistant at temperatures normally observed at LTC engine exhaust. The Au-Cu@SiO2 catalyst exhibited excellent efficacy for CO oxidation with >95% conversion to CO2 achieved at 300 °C. While the presence of Cu enhanced CO conversion at low to intermediate temperatures (50-300 °C), silica encapsulation of the Au-Cu nanocomposites facilitated for remarkable stability of the catalyst. Moreover, the catalyst exhibited remarkable stability at high reaction temperatures which could be attributed to the SiO2 encapsulation of nanoparticles. The activity and stability of Au-Cu@SiO2 catalyst are suitable for its application in automotive after treatment devices, especially in low-temperature combustion engine exhaust.

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