Dissertations / Theses on the topic 'Green hydrogen'

For long now, the world has been depending on the fossil-fuels; mainly oil. But a lot of businesses are moving towards a sustainable future while considering higher growth. Green hydrogen: a solution for the sustainable future has been taking over now. Being the best alternative of fossil-fuels, green hydrogen has a long way to go when it comes to production and usage. Due to many challenges, this solution has not been completely adopted yet. The case company has an innovation that can support the green hydrogen, so we will use DOI, multi-level perspective and cluster theory to identify the variables that will interrelate with the diffusion rate, which will help us to understand the diffusion process in B2B business. For our thesis research, we have followed a case study approach with the intent to highlight those opportunities and what are the challenges that are hindering the green hydrogen growth. We wanted to seek into how the Diffusion of Innovation theory can be implemented into the hydrogen industry. With the assistance of a company Scarab, who has developed an innovation called Ultrapure water which has the potential to accelerate the growth of green hydrogen adoption; we wanted to look further into the case on how such innovation can contribute for a better green future . We conducted a semi-structured interview with multiple interview guides which was used for our research with the involvement of people from ultrapure water industry and hydrogen industry. Finally, we identified the strengths and weaknesses of UPW innovation, the drivers and hinders of green hydrogen, and how all these factors will interrelate to the diffusion rate of UPW innovation into green hydrogen.

Controlling greenhouse gas emissions is essential by the introduction of renewable energysources. The island Lakshadweep in India has been dependent on non-renewable generationof electricity over the years. To make them self-sufficient in the energy sector, theintroduction of green hydrogen from wind and solar sources and its storage for sustainablefuture is a great initiative. The factors such as renewable sources, electrolyzer technology,fuel cells included in hydrogen production are optimized for this project in a cost-effectivemanner over the existing diesel power generation. The cost comparison of this greenhydrogen system with cost of diesel for next 20 years clearly illustrated the importance ofrenewable energy sources for a sustainable future.

Philosophiae Doctor - PhD
Today fossil fuels such as oil, coal and natural gas are providing for our ever growing energy needs. As the world’s fossil fuel reserves fast become depleted, it is vital that alternative and cleaner fuels are found. Renewable energy sources are the way of the future energy needs. A solution to the looming energy crisis can be found in the energy carrier hydrogen. Hydrogen can be produced by a number of production technologies. One hydrogen production method explored in this study is electrolysis of water.

This thesis concerns two aspects of microorganism behaviour. Firstly, the phenomenon of bioconvection is explored, where suspensions of motile microorganisms that are denser than the fluid in which they swim spontaneously form concentrated aggregations of cells that drive fluid motion, forming intricate patterns. The cells considered herein orientate by gyrotaxis, a balance between a gravitational torque due to uneven starch deposits causing cells to be bottom heavy and a viscous torque due to fluid flow gradients, and phototaxis, biased movement towards or away from a light source. In Chapters 2 and 3, a stochastic continuum model for gyrotaxis is extended to include phototaxis using three physically diverse and novel methods. A linear stability analysis is performed for each model and the most unstable wavenumber for a range of parameter values is predicted. For two of the models, sufficiently strong illumination is found to stabilize all wavenumbers compared to the gyrotaxis only case. Phototaxis is also found to yield non-zero critical wavenumbers under such strong illumination. Two mechanisms that lead to oscillatory solutions are presented. Dramatically different results are found for the third model, where instabilities arise even in the absence of fluid flow. In Chapter 4, an experimental study of pattern formation by the photo-gyrotactic unicellular green alga species Chlamydomonas nivalis is presented. Fourier analysis is used to extract the wavelength of the initial dominant mode. Variations in red light illumination are found to have no significant effect on the initial pattern wavelength. However, fascinating trends for the effects of cell concentration and white light intensity on cells illuminated either from above or below are described. This work concludes with comparisons between theoretical predictions and experimental results, between which good agreement is found. Secondly, we investigate the intracellular pathways and processes that lead to hydrogen production upon implementation of a two-stage sulphur deprivation method in the green alga C. reinhardtii. In Chapter 5, a novel model of this system is constructed from a consideration of the main cellular processes. Model results for a range of initial conditions are found to be consistent with published experimental results. In Chapter 6, a parameter sensitivity of the model is performed and a study in which different sulphur input functions are used to optimize the yield of hydrogen gas over a set time is presented, with the aim of improving the commercial and economic viability of algal hydrogen production. One such continuous sulphur input function is found to significantly increase the yield of hydrogen gas compared to using the discontinuous two-stage cycling of Ghirardi et al. (2000).

During the "Green Sahara" period (11,000 to 5000 years before the present), the Sahara desert received high amounts of rainfall, supporting diverse vegetation, permanent lakes, and human populations. Our knowledge of rainfall rates and the spatiotemporal extent of wet conditions has suffered from a lack of continuous sedimentary records. We present a quantitative reconstruction of western Saharan precipitation derived from leaf wax isotopes in marine sediments. Our data indicate that the Green Sahara extended to 31 degrees N and likely ended abruptly. We find evidence for a prolonged "pause" in Green Sahara conditions 8000 years ago, coincident with a temporary abandonment of occupational sites by Neolithic humans. The rainfall rates inferred from our data are best explained by strong vegetation and dust feedbacks; without these mechanisms, climate models systematically fail to reproduce the Green Sahara. This study suggests that accurate simulations of future climate change in the Sahara and Sahel will require improvements in our ability to simulate vegetation and dust feedbacks.

The modernized world is over-consuming low-cost energy sources that strongly contributes to pollution and environmental stress. As a consequence, the interest for environmentally friendly alternatives has increased immensely. One such alternative is the use of solar energy and water as a raw material to produce biohydrogen through the process of photosynthetic water splitting. In this work, the relation between H2-production and photosynthesis in the green algae Chlamydomonas reinhardtii was studied with respect to three main aspects: the establishment of prolonged H2-production, the involvement of PSII in H2-production and the electron pathways associated with PSII during H2-production. For the first time, this work reveals that PSII plays a crucial role throughout the H2-producing phase in sulfur deprived C. reinhardtii. It further reveals that a wave-like fluorescence decay kinetic, before only seen in cyanobacteria, is observable during the H2-producing phase in sulfur deprived C. reinhardtii, reflecting the presence of cyclic electron flows also in green algae.

Recently, the increasing level of atmospheric CO₂ has been widely noticed due to its association with global warming, provoking a growth in environmental concerns toward the continued use of fossil fuels. To mitigate the concentration of atmospheric CO₂, various strategies have been implemented. Among options to turn waste CO₂ into useful fuels and chemicals, carbon capture and utilisation along with renewable hydrogen production as the source materials for methanol production is more preferable. In the 1960s, the highly active and economic Cu/ZnO/Al₂O₃ catalyst was developed for CO₂ hydrogenation reaction to methanol, since then, metal nanoparticles and nanocomposites have been extensively investigated and applied. Especially, bimetallic catalysts have emerged as an important class of catalysts due to their unique properties and superior catalytic performances compared to their monometallic counterparts. This thesis presents the evolution of the catalyst development for CO₂ hydrogenation to methanol: Firstly, we introduced the CuZn-based catalysts with Zn content increased in the bimetallic CuZn system via a heterojunction synthesis approach. Secondly, we increased the active CuZn sites via introducing ultra-thin layered double hydroxide as the catalyst precursor for methanol production from CO₂ and H₂. Thirdly, a new class of Rh-In bimetallic catalysts were studied, which shows high methanol yield and selectivity under thermodynamically unfavourable methanol synthesis conditions owing to the strong synergies of Rh-In bimetallic system. Fourthly, for the renewable methanol production from H₂ and CO₂, the hydrogen source must come from the green production routes. Therefore, an in-depth study of a nanocomposite system, CdS-carbon nanotubes-MoS₂, for photocatalytic hydrogen production from water has been demonstrated. Finally, the conclusion of this thesis is given and an outlook is presented for the future development in this research area.

The present Ph.D. thesis deals with the hydrogen production via a novel process involving a biogas autothermal reforming (ATR) unit with the adoption of a catalytic wall-flow filter located downstream from the ATR processor to effectively filter and in-situ gasify the carbon emissions eventually generated. This work was aimed to produce 50 Nm3/h of green hydrogen from the ATR of a model biogas (60:40 Vol ratio) by using catalytic structured supports. Moreover, a solution for the eventual carbon formation during the biogas ATR was addressed. A nanostructured delafossite catalyst to ensure the gasification of soot in absence of O2 was synthesized. In addition, a Life Cycle Assessment (LCA) and a techno-economic analysis for the hydrogen production from biogas were also carried out. Concerning the identification of the suitable support structure to improve the coupling of exothermic and endothermic reactions during the hydrogen production from biogas ATR, homogenous SiSiC lattices composed of Cubic, Octet and Kelvin cells and the Conventional Foam structure coated with Ni based catalysts doped with noble metals were investigated. The different catalytic geometries were tested using a model biogas composed of clean methane and carbon dioxide (60:40 Vol ratio) with a steam to carbon ratio (S/C) fixed at 2.0. The effect of the space velocity, inlet temperature and oxygen to carbon ratio (O/C) on methane conversion and hydrogen yield were studied for each catalytic support. The O/C ratios evaluated was equal to 1.0, 1.1 and 1.2. Space velocity (GHSV) values from 2000 to 20000 h-1 in standard conditions (equivalent to 5000- 85000 h-1 in operating conditions), and, inlet temperatures of 500, 600 and 700°C were employed. The combined effect of chemical reaction and some properties and parameters such as: pressure drop and specific surface area on the steady-state performances of an adiabatic reactor at high flow rates has been analyzed. ASPEN simulations were performed to calculate the thermodynamic equilibrium at the different boundary conditions to validate the data and to determine the hydrodynamic properties. This study has demonstrated that the rotated cubic cell support shows the best performance in transforming the biogas into hydrogen with high CH4 conversion (<95%) and an H2 yield higher of 2.1 using an O/C ratio of 1.0, 1.1 and 1.2, S/C ratio of 2 and GHSV of 20000 h-1. Besides, this support can ensure a high reliability of the ATR process due to its lower pressure drop (6-40 Pa/m) with the lower specific surface area comparing to the other structures tested. The conventional foam has presented also good performances for all the GHSV values in terms of CH4 conversion but it is less selective for hydrogen production. With respect to the catalyst for gasification of carbon in a reducing atmosphere (H2, CO, H2O, CO2), nano-materials based on transition metal were synthesized via a solution combustion synthesis (SCS) method. LiFeO2 catalyst was selected as the most promising candidate for the soot gasification catalyst on the soot trap application close coupled to the ATR reactor for syngas post-treatment process. Afterwards, some issues in mixed atmosphere, i.e., when simultaneous carbon gasification with CO2 and steam in the presence of H2 and CO take place, were studied. It was demonstrated that the carbon gasification is inhibited during an isothermal reaction at 650°C for 40 minutes when CO and H2 are used as co-reagents. But even in these extreme reduced conditions, the LiFeO2-catalyst gasified 32.9% of the initial carbon, compared to 8% for the non-catalytic case. when H2 is used as co-reagent in the steam carbon gasification, the reaction is inhibited, the carbon conversion decreases from 73.1% to 46.6%. Analogously, when CO is a co-reactant in the carbon gasification with CO2, the reaction is inhibited, the soot conversion declines from 70.2% to 31.6 %. However, it was observed that in mixed atmosphere gasification reactions, when CO2 and H2O simultaneously reacts with carbon, there is a passive combination of steam and carbon dioxide in the gasification reaction. This means that the two gases operate on separated active sites without influencing each other. LiFeO2 was also coated on the monoliths (15/20 μm mean pore size and 45% porosity) and the coated filters’ performance was evaluated during the soot particles loading. The pressure drop across the filters was very low (<8 mbar) during loading showing that the applied coated method on the filters was successfully. On the other hand, the catalytic filter coupled with the rotated cube cell was tested at the pilot plant to examine their interaction, the effect of the coating method and the penalty in pressure drop of all system. A pressure drop of 0 – 68 mbar obtained during the test proves that the coating method did not alter the operation of the plant. As for testing at the demonstration plant, firstly, a monolith (Rh/Pt) was tested close coupled with an uncoated filter using an O/C ratio from 0.9 to 1.3, S/C ratio equal to 2.0, an inlet temperature (Tin) of 450°C with a GHSV from 5000 to 14000 h-1. The overall result fully agrees with the prediction from the simulation. The thermodynamic equilibrium was reached during the testing time with a methane conversion of 98% and hydrogen yield of 2.0. Moreover, tests with the integration of the catalyzed conventional foam and the catalytic trap downstream of the reforming reactor were performed. The boundary conditions were a space velocity of 4000, S/C= 2 and O/C=1.1. A thermodynamic equilibrium and a methane conversion higher than 98% were achieved. The plant was able to reach the predicted conversions and concentrations at nominal capacities corresponding to 50 Nm3/h (100 Kg/day) of pure hydrogen, creating a negligible pressure drop during the operation time of the processor. Finally, this thesis also deals with a comparative LCA of three different hydrogen production process from biogas. The investigated processes are: the biogas ATR, the biogas steam reforming (SR) and the water hydrolysis (a biogas-fueled internal combustion engine (ICE) followed by an electrolyzer). They were compared using environmental (GWP) and energetic (GER) impacts in order to highlight their weaknesses and strengths. H2 from biogas ATR has been demonstrated to be the most promising process in terms of the emissions reduction and energetic efficiency considering its life cycle from the extraction and processing of raw materials to the production of high purity hydrogen. The ICE + Electrolyzer process require a large amount of energy and biogas to sustain the electrochemical reactions. This feature makes such system the least energetically efficient with the most negative environmental impact. With a process efficiency of 65%, 63% and 25% for ATR, steam reforming and electrolysis process, respectively. Lastly, the economic analysis was performed to evaluate the H2 final cost. On the one hand, it was found that the process is economically favorable for H2 production higher than 100 Nm3/h. On the other hand, in 10 years of amortization using this technology, the final cost for H2 production of 100 Nm3/h from biogas is 3€/Kg H2, lower than the European target (5€/kg H2). The longer the plant life is, the more affordable the initial investment is.

Hydrogen production and storage play a critical role in energy transformation from fossil fuels to green energy. To realize the carbon neutralization target by increasing the competitiveness of hydrogen as an energy vector, production and storage of hydrogen must be made more efficient, safer, and cheaper, which is essential for future energy security and economic development. Water splitting via electrolysis holds great promise for hydrogen production, due to its simplicity, sustainability, and high purity for industrial hydrogen production. Recently, despite tremendous efforts have been devoted, platinum (Pt)-based catalysts are still considered to be the most effective electrocatalysts for hydrogen evolution reaction (HER). However, the high cost and low reserves of platinum-based catalysts greatly limit their commercial application. To make hydrogen derived from water splitting more cost-competitive, it is thus highly desirable to exploit low-cost, highly efficient electrocatalysts to replace the expensive Pt-based catalysts. Furthermore, after hydrogen production, the gaseous hydrogen needs to be stored safely and efficiently for utilization by end-users. The current mainstream methods of solid-state hydrogen storage including molecular physisorption and atomic chemisorption, both possess either too high or too low enthalpy of hydrogen adsorption, which are not suitable for practical application. The ideal hydrogen storage materials should be reversibly ab-/desorbing hydrogen under mild temperatures with high hydrogen capacities. To this end, it is extremely essential to design and construct new solid-state hydrogen storage materials at atomic levels. Recently, the atomic metal-site (AMS) nanomaterials are found to be promising catalysts and solid-state media for both the H2 production and storage, which is not only ascribed to the maximized atomic metals utilization but also the unique electronic structure of various metal-site coordination motifs at atomic scales. The aim of this project is to develop efficient and inexpensive AMS nanomaterials that are expected to create new knowledge of atomic interface catalysis and develop practical applications of solid-state hydrogen storage materials, reducing carbon dioxide emissions and alleviating the air pollution. In summary, this thesis mainly focusses on designing and fabricating cost-effective, efficient , and scalable AMS nanomaterials for both hydrogen production and storage, and the reaction mechanisms of atomic metal sites in hydrogen production and storage are also systematically studied.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text

L'objectif principal de cette thèse est de concevoir, mettre en œuvre et comparer différentes stratégies de gestion de l'énergie et approches d'optimisation pour un système hybride impliquant l'intégration de l'énergie marémotrice flottante avec la production de l'hydrogène vert. Pour atteindre les objectifs, les composants individuels du système sont d'abord modélisés. Les capacités annuelles de performance du système de la centrale d'énergie marémotrice ont ensuite été obtenues à l'aide des profils quotidiens fréquents au poste d'amarrage de Fall of Warness dans les îles Orcades. Les modes de fonctionnement transitoires des électrolyseurs à membrane échangeuse de protons, lorsqu'elles sont soumises à l'énergie de la centrale hydrolienne, ont été analysés sur la base d'une (RBA) stratégie de gestion de l'énergie basée sur des règles. Plus tard, une évaluation préliminaire du coût de production d'hydrogène est effectuée sur la base de différentes conditions de demande quotidienne d'hydrogène et de profils de marée quotidiens. En outre, une approche d'optimisation dans le but de maximiser le profit d'exploitation du système tout en assurant un fonctionnement optimal et suffisant des deux électrolyseurs sous des contraintes réelles du système, est formulée en donnant la priorité à la production d'hydrogène par l'énergie marémotrice. Le problème d'optimisation est résolu à l'aide d'un algorithme génétique basé sur un problème non linéaire à entiers mixtes. Une analyse coûts-avantages complète basée à la fois sur les coûts fixes-variables et sur les facteurs de coûts actualisés est réalisée pour analyser le fonctionnement technico-environnemento-économique optimal d'un système hybride d'énergie marémotrice-éolienne-hydrogène connecté au réseau. Les résultats ont été comparés aux résultats de l'approche basée sur des règles. Les bénéfices annuels dans l'approche d'optimisation ont été estimés supérieurs de 41,5 % par rapport à ceux de la RBA. De plus, d'un point de vue environnemental, les meilleurs résultats d'optimisation étaient supérieurs d’environ 47 % par rapport aux résultats de la RBA en termes de réduction des émissions de carbone. Un électrolyseur dynamique capable de fonctionner à deux fois sa puissance nominale pendant une durée limitée s'avère particulièrement avantageux lorsqu'il est couplé à l'énergie marémotrice qui est de nature cyclique avec des périodes prévisibles de production d'énergie élevée et faible. Enfin, il est conclu que l'approche d'optimisation des coûts fixes-variables est relativement simple dans l'estimation des coûts. Au contraire, bien que des résultats légèrement meilleurs soient obtenus dans le cas de l'approche par coût actualisé, il est nécessaire d'avoir une meilleure connaissance préalable du fonctionnement du système pour estimer finement les facteurs de coût actualisé. Le modèle proposé peut être utilisé comme un outil générique pour l'analyse de la production d'hydrogène dans différents contextes et il est particulièrement applicable dans les sites à fort potentiel d'énergie verte avec des installations de réseau limitées
The overarching aim of this thesis is to design, implement and compare different energy management strategies and optimisation approaches for a hybrid system involving floating tidal stream energy integration with green hydrogen production. Towards reaching the objectives, the individual system components are modelled initially. The annual system performance capabilities of the tidal stream energy plant are then obtained using frequently occurring daily profiles at the Fall of Warness berth in the Orkney Islands, Scotland. The transitionary operating modes of two polymer electrolyte membrane electrolyser units, when subjected to the energy from the tidal stream plant are analysed based on a rule-based approach energy management strategy. Later, a preliminary evaluation of the hydrogen production cost is assessed based on different daily hydrogen demand and daily tidal profile conditions. Further, an optimisation approach with the objective to maximise the system operating profit ensuring optimal and sufficient operations of both the electrolyser units under real system constraints, is formulated with priority for tidal energy powered hydrogen production. The optimisation problem is solved using a genetic algorithm based on the mixed integer non-linear problem. A comprehensive cost-benefit analysis based on fixed-variable costs and levelised costs factors is performed to analyse the optimal techno-enviro-economic operation of a hybrid grid connected tidal-wind-hydrogen energy system. The outcomes are compared against the rule-based approach results. The annualised profits in the optimisation approach are estimated to be 41.5% higher compared to the rule-based approach. Further, from an environmental view, the best optimisation results are approximately 47% higher than the rule-based approach results in terms of carbon emission reductions. A dynamic electrolyser capable of working at twice of its nominal power rating for limited duration, resulted particularly advantageous when coupled with tidal energy which is cyclic in nature with predictable periods of high and low power generation. Finally, it was determined that the fixed cost (FC) optimisation approach is relatively simple in terms of cost estimation. On the contrary, while the levelised cost (LC) approach yields slightly better results, it necessitates a greater prior knowledge of system operations to reasonably estimate the cost factors. The proposed method can be used as a generic tool for electrolytic hydrogen production analysis under different contexts, with preferable application in high green energy potential sites with constrained grid facilities

The hydrogen production in the green microalga Chlamydomonas reinhardtii was evaluated by means of a detailed physiological and biotechnological study. First, a wide screening of the hydrogen productivity was done on 22 strains of C. reinhardtii, most of which mutated at the level of the D1 protein. The screening revealed for the first time that mutations upon the D1 protein may result on an increased hydrogen production. Indeed, productions ranged between 0 and more than 500 mL hydrogen per liter of culture (Torzillo, Scoma et al., 2007a), the highest producer (L159I-N230Y) being up to 5 times more performant than the strain cc124 widely adopted in literature (Torzillo, Scoma, et al., 2007b). Improved productivities by D1 protein mutants were generally a result of high photosynthetic capabilities counteracted by high respiration rates. Optimization of culture conditions were addressed according to the results of the physiological study of selected strains. In a first step, the photobioreactor (PBR) was provided with a multiple-impeller stirring system designed, developed and tested by us, using the strain cc124. It was found that the impeller system was effectively able to induce regular and turbulent mixing, which led to improved photosynthetic yields by means of light/dark cycles. Moreover, improved mixing regime sustained higher respiration rates, compared to what obtained with the commonly used stir bar mixing system. As far as the results of the initial screening phase are considered, both these factors are relevant to the hydrogen production. Indeed, very high energy conversion efficiencies (light to hydrogen) were obtained with the impeller device, prooving that our PBR was a good tool to both improve and study photosynthetic processes (Giannelli, Scoma et al., 2009). In the second part of the optimization, an accurate analysis of all the positive features of the high performance strain L159I-N230Y pointed out, respect to the WT, it has: (1) a larger chlorophyll optical cross-section; (2) a higher electron transfer rate by PSII; (3) a higher respiration rate; (4) a higher efficiency of utilization of the hydrogenase; (5) a higher starch synthesis capability; (6) a higher per cell D1 protein amount; (7) a higher zeaxanthin synthesis capability (Torzillo, Scoma et al., 2009). These information were gathered with those obtained with the impeller mixing device to find out the best culture conditions to optimize productivity with strain L159I-N230Y. The main aim was to sustain as long as possible the direct PSII contribution, which leads to hydrogen production without net CO2 release. Finally, an outstanding maximum rate of 11.1 ± 1.0 mL/L/h was reached and maintained for 21.8 ± 7.7 hours, when the effective photochemical efficiency of PSII (ΔF/F'm) underwent a last drop to zero. If expressed in terms of chl (24.0 ± 2.2 µmoles/mg chl/h), these rates of production are 4 times higher than what reported in literature to date (Scoma et al., 2010a submitted). DCMU addition experiments confirmed the key role played by PSII in sustaining such rates. On the other hand, experiments carried out in similar conditions with the control strain cc124 showed an improved final productivity, but no constant PSII direct contribution. These results showed that, aside from fermentation processes, if proper conditions are supplied to selected strains, hydrogen production can be substantially enhanced by means of biophotolysis. A last study on the physiology of the process was carried out with the mutant IL. Although able to express and very efficiently utilize the hydrogenase enzyme, this strain was unable to produce hydrogen when sulfur deprived. However, in a specific set of experiments this goal was finally reached, pointing out that other than (1) a state 1-2 transition of the photosynthetic apparatus, (2) starch storage and (3) anaerobiosis establishment, a timely transition to the hydrogen production is also needed in sulfur deprivation to induce the process before energy reserves are driven towards other processes necessary for the survival of the cell. This information turned out to be crucial when moving outdoor for the hydrogen production in a tubular horizontal 50-liter PBR under sunlight radiation. First attempts with laboratory grown cultures showed that no hydrogen production under sulfur starvation can be induced if a previous adaptation of the culture is not pursued outdoor. Indeed, in these conditions the hydrogen production under direct sunlight radiation with C. reinhardtii was finally achieved for the first time in literature (Scoma et al., 2010b submitted). Experiments were also made to optimize productivity in outdoor conditions, with respect to the light dilution within the culture layers. Finally, a brief study of the anaerobic metabolism of C. reinhardtii during hydrogen oxidation has been carried out. This study represents a good integration to the understanding of the complex interplay of pathways that operate concomitantly in this microalga.

The hydrogen production in the green microalga Chlamydomonas reinhardtii was evaluated by means of a detailed physiological and biotechnological study. First, a wide screening of the hydrogen productivity was done on 22 strains of C. reinhardtii, most of which mutated at the level of the D1 protein. The screening revealed for the first time that mutations upon the D1 protein may result on an increased hydrogen production. Indeed, productions ranged between 0 and more than 500 mL hydrogen per liter of culture (Torzillo, Scoma et al., 2007a), the highest producer (L159I-N230Y) being up to 5 times more performant than the strain cc124 widely adopted in literature (Torzillo, Scoma, et al., 2007b). Improved productivities by D1 protein mutants were generally a result of high photosynthetic capabilities counteracted by high respiration rates. Optimization of culture conditions were addressed according to the results of the physiological study of selected strains. In a first step, the photobioreactor (PBR) was provided with a multiple-impeller stirring system designed, developed and tested by us, using the strain cc124. It was found that the impeller system was effectively able to induce regular and turbulent mixing, which led to improved photosynthetic yields by means of light/dark cycles. Moreover, improved mixing regime sustained higher respiration rates, compared to what obtained with the commonly used stir bar mixing system. As far as the results of the initial screening phase are considered, both these factors are relevant to the hydrogen production. Indeed, very high energy conversion efficiencies (light to hydrogen) were obtained with the impeller device, prooving that our PBR was a good tool to both improve and study photosynthetic processes (Giannelli, Scoma et al., 2009). In the second part of the optimization, an accurate analysis of all the positive features of the high performance strain L159I-N230Y pointed out, respect to the WT, it has: (1) a larger chlorophyll optical cross-section; (2) a higher electron transfer rate by PSII; (3) a higher respiration rate; (4) a higher efficiency of utilization of the hydrogenase; (5) a higher starch synthesis capability; (6) a higher per cell D1 protein amount; (7) a higher zeaxanthin synthesis capability (Torzillo, Scoma et al., 2009). These information were gathered with those obtained with the impeller mixing device to find out the best culture conditions to optimize productivity with strain L159I-N230Y. The main aim was to sustain as long as possible the direct PSII contribution, which leads to hydrogen production without net CO2 release. Finally, an outstanding maximum rate of 11.1 ± 1.0 mL/L/h was reached and maintained for 21.8 ± 7.7 hours, when the effective photochemical efficiency of PSII (ΔF/F'm) underwent a last drop to zero. If expressed in terms of chl (24.0 ± 2.2 µmoles/mg chl/h), these rates of production are 4 times higher than what reported in literature to date (Scoma et al., 2010a submitted). DCMU addition experiments confirmed the key role played by PSII in sustaining such rates. On the other hand, experiments carried out in similar conditions with the control strain cc124 showed an improved final productivity, but no constant PSII direct contribution. These results showed that, aside from fermentation processes, if proper conditions are supplied to selected strains, hydrogen production can be substantially enhanced by means of biophotolysis. A last study on the physiology of the process was carried out with the mutant IL. Although able to express and very efficiently utilize the hydrogenase enzyme, this strain was unable to produce hydrogen when sulfur deprived. However, in a specific set of experiments this goal was finally reached, pointing out that other than (1) a state 1-2 transition of the photosynthetic apparatus, (2) starch storage and (3) anaerobiosis establishment, a timely transition to the hydrogen production is also needed in sulfur deprivation to induce the process before energy reserves are driven towards other processes necessary for the survival of the cell. This information turned out to be crucial when moving outdoor for the hydrogen production in a tubular horizontal 50-liter PBR under sunlight radiation. First attempts with laboratory grown cultures showed that no hydrogen production under sulfur starvation can be induced if a previous adaptation of the culture is not pursued outdoor. Indeed, in these conditions the hydrogen production under direct sunlight radiation with C. reinhardtii was finally achieved for the first time in literature (Scoma et al., 2010b submitted). Experiments were also made to optimize productivity in outdoor conditions, with respect to the light dilution within the culture layers. Finally, a brief study of the anaerobic metabolism of C. reinhardtii during hydrogen oxidation has been carried out. This study represents a good integration to the understanding of the complex interplay of pathways that operate concomitantly in this microalga.

Hydrogen is considered one of the means by which to store energy coming from renewable and intermittent power sources. With the growing capacity of renewable energy sources, a storage system is required to not waste energy. PEM electrolysis provides a sustainable solution for the production of hydrogen and is well suited to couple with energy sources such as solar and wind. This work reports the development of simulation software to estimate the performance of a proton exchange membrane electrolyzer working at atmospheric or low pressure conditions connected to a solar energy source. The electrolyzer is defined from a validated reference semi-empirical model, which allows for simulating the electrochemical, thermal and H2 output flow behaviours with enough precision for engineering applications. An algorithm for a fitting procedure to characterize commercial products, and functions for power modulation have been implemented. A series of simulations have been carried on, starting from real photovoltaic data of input power, and the output values have been discussed, with particular attention to output flow rate, thermal behaviour and the cooling demand in order to preserve the operation of the electrolyzer.

Hydrogen peroxide (H2O2) is a versatile environmentally friendly oxidizing agent that has many practical applications. H2O2 has countless qualities and it is one of the world’s most important bulk inorganic chemicals. Most of the world’s H2O2 is produced by auto-oxidation process (AO). The AO process involves indirect oxidation of H2 to yield H2O2. The first commercial anthraquinone (AQ) process was operated by I.G. Farbeinindustrie in Germany during the second world war. The AO process is successfully used to produce most of the world’s H2O2 because it avoids explosive H2/O2 gas mixture. However AO process suffers from several drawbacks, such as the use of a complex and toxic solvent system, the periodic replacement of costly quinone-derivative due to non-selective hydrogenation, the deactivation of the hydrogenation catalyst, high requirements of energy and intensive process steps for the removal of organic impurities. Also, it is known to have high capital and operating costs, thus it economically viable only for large scale productions (>4*104 tons per year). Therefore, H2O2 is produced in few locations and then transported to the customers. Transportation of H2O2 creates additional safety concerns since concentrated H2O2 can decompose explosively. A process where H2O2 forms from the direct combination of its elements (H2 and O2) could be preferred, especially for small scale productions at the end-user site, if control of the sequential hydrogenation can be achieved, but none of the presently available processes has solved the productivity vs. safety dilemma. Traditionally, the attention of the scientists focused on the identification of an active and particularly selective catalyst, overlooking the impact of safety and multiphase issues. Both aspects may benefit from continuous operations and suitable feeding policies, along with kinetics studies as we are currently investigating. Three reactor set-ups were developed and realized for hydrogen peroxide direct synthesis: two of them are based on batch reactors of different volumes to perform catalytic tests and kinetics studies, and one is based on a novel trickle bed reactor (TBR). Most of the work presented here is focused on the continuous reactor, far more attractive from an industrial perspective. In the TBR set up different catalysts were chosen to investigate H2O2 direct synthesis. A systematic study on operative conditions was performed, varying liquid and gas flow rates (contact time between liquid,gas and solid phases), changing H2/O2 ratio, investigating conditions for H2O2 decomposition and the effect of pressure. With this work very high values of selectivity were achieved (up to 90%), improving catalytic performances compared to those previously obtained in batch reactor set-ups. The best results were accomplished with a Pd and Au catalyst supported on sulfated zirconia. Despite an extensive body of research on the direct synthesis process, very little has been published about kinetic rate expressions of the full reaction network, and in this study experimental kinetics in a batch reactor and their relative modeling are treated for the first time.
Il perossido di idrogeno è un ossidante “verde” e non tossico, che non genera sottoprodotti inquinanti per l’ambiente, poiché si decompone a dare solamente acqua ed ossigeno. Il perossido di idrogeno viene utilizzato principalmente nelle cartiere come sbiancante, nell’industria tessile e metallurgica, come intermedio nella sintesi chimica, come disinfettante e additivo per detergenti, e molto altro. L’H2O2 viene attualmente prodotto con il processo dell’antrachinone, il quale necessita di numerose operazioni per la produzione e la purificazione del prodotto finale, con il conseguente elevato consumo energetico, a cui sono associati notevoli costi di esercizio, e la formazione di sottoprodotti inquinanti. La sintesi diretta di H2O2 è un’alternativa interessante, che si propone di eliminare i sottoprodotti inquinanti e ridurre drasticamente i costi di impianto e di esercizio, per produzioni su piccola scala direttamente in situ presso l’utilizzatore finale (che non è Berlusconi). In questo modo sarebbe possibile abbattere anche i costi di trasporto e i rischi ad esso connessi. Negli ultimi anni particolare attenzione è stata data al processo di sintesi diretta di acqua ossigenata, tuttavia i lavori pubblicati e brevettati vertevano per lo più sullo sviluppo di un catalizzatore che potesse avere delle caratteristiche tali da favorire la formazione di perossido di idrogeno a dispetto delle reazioni di decomposizione e idrogenazione dello stesso, anch’esse facenti parte del network di reazione. Scarso interesse è invece stato rivolto allo studio sistematico delle condizioni operative e allo sviluppo di un processo continuo. Ad esempio, lo studio in reattori batch non è stato mai approfondito con cinetiche di reazione e con lo studio degli equilibri liquido-vapore che si instaurano all’interno del sistema di reazione. In questo lavoro sono stati sviluppati e realizzati due reattori di tipo batch (di due volumi differenti) e un reattore in continuo: dei due reattori batch, uno è stato utilizzato per testare i catalizzatori e condurre studi preliminari, mentre nell’altro si sono svolti studi di cinetiche di reazione, che sono stati successivamente utilizzati per sviluppare un modello cinetico relativo all’intero network di reazioni. Il reattore continuo, invece, è un reattore a letto fisso (trickle bed reactor) in cui viene caricato il catalizzatore. Un notevole interesse dalle realtà industriali è rivolto all’operazione in continuo, per cui in questo progetto particolare attenzione è stata data allo sviluppo di un tale processo, ottimizzandone le condizioni operative per massimizzare la produzione di acqua ossigenata. Numerosi catalizzatori mono- e bi- metallici sono stati studiati, supportati su diversi materiali, sia inorganici che organici, e per ognuno di essi sono state studiate le migliori condizioni operative. Nel Capitolo 1 è presentato lo stato dell’arte della ricerca sulla sintesi diretta del perossido di idrogeno, e viene spiegato come la ricerca effettuata fin d’ora abbia posto l’attenzione sullo studio di un catalizzatore che potesse essere adatto alla sintesi diretta, trascurando però lo studio reattoristico del sistema impiegato. Nel Capitolo 2 è descritto lo sviluppo dei reattori in seguito utilizzati nella sperimentazione, ed i sistemi di analisi implementati. Vengono presentati gli schemi di impianto e gli studi preliminari condotti sia sui reattori batch, che sul reattore continuo. Il Capitolo 3 affronta temi di cinetica con la relativa modellazione. Sono stati condotti esperimenti di sintesi diretta in un reattore batch ad alta pressione, e da questi dati è stato ricavato un primo approccio di modello cinetico ancora assente in letteratura. Nel Capitolo 4 si è studiato un catalizzatore al palladio su un supporto di ceria sulfatata, con il quale sono stati condotti esperimenti di decomposizione e idrogenazione del perossido di idrogeno. Partendo da questi risultati si è svolto uno studio teso ad identificare le migliori portate di gas e di liquido per ottenere la massima produttività e la massima selettività. Un’altra condizione operativa indagata è stata la pressione ed il suo effetto sulla produzione di acqua ossigenata. Nel Capitolo 5 sono stati scelti 4 catalizzatori a base di palladio, supportati su diversi materiali inorganici. Variando le condizioni operative di sistema si è studiato il comportamento di questi catalizzatori in relazione alla produzione di H2O2 e alla loro selettività. I vari catalizzatori, a seconda del supporto, hanno proprietà differenti e le condizioni operative devono essere ottimizzate di conseguenza per ottenere il massimo rendimento sulla sintesi diretta. Il Capitolo 6 tratta lo studio di catalizzatori bimetallici a base di palladio e oro e catalizzatori a base di solo palladio. Diversi supporti inorganici sono stati utilizzati ed è stato introdotto un nuovo supporto organico. I catalizzatori sono stati confrontati tra di loro variando le condizioni operative di sistema. È stato inoltre studiato l’effetto della concentrazione di idrogeno immesso come reagente e il suo effetto sulla sintesi diretta di H2O2. Il Capitolo 7 riassume i migliori risultati ottenuti e fornisce indicazioni relativamente agli sviluppi futuri. In Appendice è fornito un approccio per la modellazione termodinamica del sistema.

The energy transition taking place in various parts of the world will have many effects on the current energy systems as an increasing amount of intermittent power supply gets installed every year. In Sweden, just as many other countries, this will cause both challenges and opportunities for today´s energy producers. Challenges that may arise along with an increasingly fluctuating electricity production include both power deficits at certain times and regions but also hours of over-production which can cause electricity prices to drop significantly. Such challenges will have to be met by both dispatchable power generation and dynamic consumption. Conversely, actors prepared to adapt to the new climate by implementing new technologies or innovative business models could benefit from the transition towards a fully renewable energy system.  This thesis evaluates the techno-economic potential of green hydrogen production at a combined heat and power plant with the objective to provide decision support to a district heat and electricity producer in Sweden. It was in the company’s interest to investigate how hydrogen production could help reduce the production cost of district heat as well as contribute to the reduction of greenhouse gases.  In the project, two separate business models: Power-to-gas and Power-to-power were evaluated on the basis of technical and economic performance and environmental impact. To do this, a mathematical model of the CHP plant and the hydrogen systems was developed in Python which optimizes the operation based on costs. The business models were then simulated for two different years with each year representing a distinctly different electricity market situation.  The main conclusions of the study show that Power-to-gas could already be profitable at a hydrogen retail price of 40 SEK per kg, which is the projected retail price for the transportation sector. The demand today is however limited but is expected to grow fast in the near future, especially within heavy transportation. Another limiting factor for hydrogen production showed to be the availability of storage space, as hydrogen gas even at pressures up to 200 bar require large volumes.  Power-to-power for frequency regulation was found to not be economically justifiable as the revenue for providing grid services could not outweigh the high investment costs for any of the simulated years. This resulted in a high levelized cost of energy at over 3000 SEK per MWh which was mostly due to the low capacity factor of the power-to-power system.  Finally, green hydrogen has the potential of replacing fossil fuels in sectors that is difficult to reach with electricity, for example long-haul road transport or the shipping industry. Therefore, green hydrogen production in large scale could help decarbonize many of society’s fossil-heavy segments. By also serving as a grid-balancer, hydrogen production in a power-to-gas process has the potential of becoming an important part of a renewable energy system.
Energiomställningen som äger rum i olika delar av världen kommer att ha många effekter på de nuvarande energisystemen eftersom en ökande mängd väderberoende kraftproduktion installeras varje år. I Sverige, precis som många andra länder, kommer detta att medföra både utmaningar och möjligheter för dagens energiproducenter. Utmaningar som kan uppstå tillsammans med en alltmer fluktuerande elproduktion inkluderar både kraftunderskott vid vissa tider och regioner men också timmar av överproduktion som kan få elpriserna att sjunka avsevärt. Sådana utmaningar måste mötas av både planerbar kraftproduktion och dynamisk konsumtion. Omvänt kan aktörer som är beredda att anpassa sig till det nya klimatet genom att implementera ny teknik eller innovativa affärsmodeller dra nytta av övergången till ett helt förnybart energisystem.  Denna rapport utvärderar den tekno-ekonomiska potentialen för produktion av grön vätgas vid ett kraftvärmeverk med målet att ge beslutsstöd till en fjärrvärme- och elproducent i Sverige. Det var i företagets intresse att undersöka hur vätgasproduktion kan bidra till att sänka produktionskostnaden för fjärrvärme samt bidra till att minska växthusgaser.  I projektet utvärderades två separata affärsmodeller: Power-to-gas och Power-to-power baserat på teknisk och ekonomisk prestanda samt miljöpåverkan. För att kunna göra detta utvecklades en matematisk modell i Python av kraftvärmeverket och vätgassystemen som optimerar driften baserat på kostnader. Affärsmodellerna simulerades sedan för två olika års elpriser för att undersöka modellens prestanda i olika typer av elmarknader.  De viktigaste slutsatserna i studien visar att Power-to-gas redan kan vara lönsamt till ett vätgaspris på 40 SEK per kg, vilket är det förväntade marknadspriset på grön vätgas for transportsektorn. Efterfrågan är idag begränsad men förväntas växa snabbt inom en snar framtid, särskilt inom tung transport. En annan begränsande faktor för vätgasproduktion visade sig vara tillgången på lagringsutrymme, eftersom vätgas även vid tryck upp till 200 bar kräver stora volymer.  Power-to-power för frekvensreglering visade sig inte vara ekonomiskt försvarbart, eftersom intäkterna för att tillhandahålla nättjänster inte kunde uppväga de höga investeringskostnaderna under några av de simulerade åren. Detta resulterade i en hög LCOE på över 3000 SEK per MWh, vilket främst berodde på Power-to-power-systemets låga utnyttjandegrad.  Slutligen kan det sägas att grön vätgas har stor potential att ersätta fossila bränslen i sektorer som är svåra att elektrifiera, exempelvis tunga vägtransporter eller sjöfart. Därför kan storskalig grön vätgasproduktion hjälpa till att dekarbonisera många av samhällets fossiltunga segment. Genom att dessutom fungera som balansering har väteproduktion i en Power-to-gas-process potential att bli en viktig del av ett system med stor andel förnybar energi.

With increasing global populations and demand for energy, greater strain is placed on the limited supply of fossil derived fuels, which in turn drives the need for development of alternative energy sources. The discovery of biophotolysis in Chlamydomonas reinhardtii and the development of a spectral-selective photosystem I activating/photosystem II deactivating light (PSI-light) method provides a promising platform for commercial hydrogen production systems. The PSI-light method allows electrons to pass through the photosynthetic electron transport chain while reducing radiation available for photosynthetic oxygen evolution that inactivates hydrogenase. Exploring the physiology of photohydrogen production using the PSI-light method can provide insight on how to optimize conditions for maximum hydrogen production. Through the use of photosynthetic mutant strains of C. reinhardtii, it was possible to suppress photosynthetic oxygen evolution further than using photosystem I light alone to extend photohydrogen production longevity and total yield. A preliminary investigation of an iterating light treatment revealed that longevity and yield could be increased further by providing a period of darkness to allow cells to consume evolved oxygen and resynthesize hydrogenase. Work with these mutants provided understanding that a balance of radiation was required to provide electrons to hydrogenase while limiting oxygen evolution, and that when no light was provided, fermentation of stored starch was the major contributor of electrons to hydrogen production. To determine the role of starch during hydrogen production, wild type cells were exposed to different media and light treatments and monitored for starch consumption and hydrogen production. The results indicated that starch was required for hydrogen production in the dark, but for photohydrogen production, starch likely played a minor role in contributing electrons to hydrogenase. The experiments also showed the importance of acetate in the medium during the hydrogen production phase to allow any significant photohydrogen production. The role of acetate was further investigated as a growth medium constituent that stimulates metabolic activity while reducing photosynthetic oxygen evolution when added to cells grown auto- or mixotrophically. By exposing cells to CO₂ during growth, photohydrogen production was significantly increased over cells grown only in the presence of acetate.

Concerns over green house gas emissions and their climate change effects have lead to a concerted effort into environmental friendly technologies. One such emphasis has been on the implementation of the hydrogen economy. There are four major impediments to the implementation of a hydrogen economy: hydrogen production, distribution, storage and conversion. This thesis is focused on exploring the hydrogen storage problem. Hydrogen can be stored by a wide range of methods. One of these methods involves using a secondary material that stores hydrogen by either physisorbing hydrogen onto its surfaces or by reacting with it to form a new compound. Of the wide variety of materials that can interact with hydrogen, three different materials were chosen; (1) nano-structured materials of high surface area; mesoporous silica (MCM-41) and titanate nanotubes, and (2) hydrides of Ti-Mg-Ni alloys. Results of the hydrogen on mesoporous silica (MCM-41) showed 1 wt.% H[subscript]2 to a maximum of 2 wt.% H[subscript]2 for 500 to 1060 m2/g surface area, respectively, at 77 K. Doping these samples with Al or Zn did not make an appreciable difference but rather they reduced the surface area available for hydrogen adsorption. Adorption of hydrogen at room temperature was neglifible (0.1 wt.% up to an equilibrium pressure of 5 MPa). Sodium titanate nanotubes showed hydrogen adsorption that increased with increasing hydrogen pressure at 77 K. Hydrogen adsorption reached 0.4 wt.% at an hydrogen equilibrium pressure of 2.6 MPa. Exchange of sodium ions in the titanate nanotubes with Zn and Li did not have an impact on hydrogen adsorption.However, partial substitution of Na ions for H ions resulted in an increase in hydrogen adsorption from 0.4 wt.% to 0.8 wt.% while decreasing the pressure required for maximum hydrogen uptake from 2.6 MPa to 0.5 MPa at 77 K. Desorption from this sample also showed strong hysteresis indicating hydrogen adsorption into the interlayer spacing of the nanotube wall. Hydrogen adsorption at room temperature was negligible for all samples being below 0.1 wt.%, up to a hydrogen equilibrium pressure of 5 MPa. Ti-Mg-Ni alloys are interest as 11 wt.% hydrogen has been reported in the literature; specifically for Ti53Mg47Ni20. Samples with various stoichiometries of Ti, Mg and Ni were produced via balling and their hydrogen sorption properties examined. Measured hydrogen absorption ranged from 2.5 wt.% to 5.0 wt.%. Measurements were hindered by the high temperature (723 K) used during the activation process. The high temperature ensured decomposition of titanium hydride but resulted in the vaporisation and deposition of magnesium on the sample cell filter. This had the duel effect of reducing the total hydrogen absorption and to sporadically block the sample cell filter. However, in those cases where the hydrogen flow was not impeded, absorption kinetics were measured to be extremely rapid. For example, greater than 95 % of the total hydrogen uptake of 3.7 wt.% for the sample ball-milled in the molar ratio of 65:133:20 (Ti:Mg:Ni) occurred within 60 seconds at room temperature.However, the low equilibrium pressure meant a negligible amount of hydrogen could be desorbed at this temperature. X-ray diffraction revealed that after hydriding, the samples comprised varius mixtures of MgH[subscript]2, TiH[subscript]2 and hydrides of the intermetallic compounds Mg[subscript]2Ni and Ti[subscript]2Ni. The amount of each of these hydride phases changed according the intial starting stoichiometries of each sample.

Background: Green hydrogen energy systems can address environmental and societal concerns within the energy sector. Therefore, increased attentions from both public and private stakeholders has led to the general perception that hydrogen systems can serve as a disruptive innovation.  Given that disruption innovation theory has seen increased entrepreneurial involvement over recent years, the study focuses on assessing the role of green entrepreneurs within the implementation of hydrogen systems through cross-collaborative efforts and disruptive innovation drivers.    Purpose: The development of a theoretical matrix that interconnects disruptive innovation, entrepreneurial involvement, and cross-collaborative initiatives to establish entrepreneurial positioning roles within the energy market.    Method: The epistemology chosen was interpretivist, and its ontology subjectivism. The research followed an inductive approach. The research was qualitatively conducted and adopted a case study approach. The data was collected through semi-structured interviews, and followed a theoretical sampling approach.   Conclusion: The study proposes a theoretical matrix that extended disruptive innovation theory to green entrepreneurship and concluded that high levels of cross-collaboration, and a high innovation impact, serve as key drivers for green entrepreneurial implementations of disruptive energy. Results highlight the need for entrepreneurial involvement across all stages of market implementations.

Today the development of sustainable processes in the chemical industry is critical, and Green Chemistry represents an evolution from the conventional concepts of process efficiency. Twenty years ago, Paul Anastas and John Warner introduced this concept within the twelve principles. In this work, many aspects the twelve principles are applied, developing sustainable methods involving the use of metal catalysis and biocatalysis through one pot and cascade reactions.
In the first part of the PhD period, the use of the micellar catalysis was investigated, to perform reactions in water avoiding (or limiting) the use of the traditional organic solvents. The possibility to apply the micellar conditions for the hydrogen borrowing (HB) reaction to prepare amines was explored. Different Ru catalysts were screened using water as medium, under Microwave (MW) dielectric heating. Once optimized, the scope of the reaction was investigated using differently substituted amines and alcohols. Besides, the use of a biomass-derived solvent (GVL) was explored in Pd/C catalysed transformations to avoid the arching phenomena frequently observed using conventional solvents (e.g. toluene). A sustainable protocol for the synthesis of benzimidazoles employed different aliphatic and aromatic amines through a hydrogen transfer Pd/C. A heating profile and various studies of stability have been reported. A biocatalytic approach to pyridine and furans is also reported. These heterocycles are fundamental building blocks for the synthesis of pharmaceuticals, agrochemicals and organic material. Furthermore, these compounds are also employed in flavour and fragrance industry owing to their peculiar olfactory properties. Classical methodologies for their synthesis are based on low-yielding multistep methods, which involve the use of harsh conditions. Therefore, novel mild and greener methodologies for the preparation of heterocycles compounds are highly desirable. Aromatization of substituted 1,2,3,6-tetrahydropyridines (THPs) was performed using whole-cell monoamine oxidase MAO-N (variants from Aspergillus niger) catalyst. The aromatization of the tetrahydropyridine starting materials into the pyridine products was monitored through 1H NMR spectroscopy. During the optimization, different pyridine compounds are prepared to screen the best co-solvents and MAO-N variants. The kinetic profile of the biocatalytic transformation by MAO-N was also monitored via in situ 19F NMR experiments. Aromatization of different 2,5-dihydrofurans into corresponding furans was also performed using the Laccase/TEMPO catalytic system using mild conditions. A chemo- enzymatic cascade reaction starting directly from acyclic aliphatic precursor has been developed showing that metathesis Grubb's catalyst and the Laccase/TEMPO system can be used in combination for an efficient protocol.

With a surge in future demand for hydrogen as a renewable fuel, the specific aim of this study was to develop a novel strategy in photosynthetic hydrogen production from green algae, which is one of the cleanest processes among existing hydrogen-production methodologies currently being explored. The novel strategy designed was a spectral-selective PSI-activation/PSII-deactivation protocol that would work to maintain a steady flow of electrons in the electron transport system in the light-dependent part of photosynthesis for delivery of electrons to hydrogenase for photo-hydrogen production. The strategy would work to activate PSI to assist in driving the electron flow, while partially deactivating PSII to a degree that it would still supply electrons, but would limit its photosynthetic oxygen production below the respiratory oxygen consumption so that an anoxic condition would be maintained as required by hydrogenase. This study successfully showed that the implementation of the spectral-selective PSIactivation/ PSII-deactivation strategy resulted in actual and relatively sustained photohydrogen production in Chlamydomonas reinhardtii cells, which had been dark-adapted for three hours immediately prior to exposure to a PSI-spectral selective radiation, which had a spectral peak at 692 nm, covering a narrow waveband of 681-701 nm, and was applied at 15 W m⁻². The optimal condition for the PSI-spectral-selective radiation (692 nm) corresponded with low cell density of 20 mg chlorophyll L⁻¹ ("chl" henceforth) with cells grown at 25⁰C. At this condition, the PSI-spectral-selective radiation induced the maximal initial hydrogen production rate of 0.055 mL H² mg⁻¹ chl h⁻¹ which statistically the same as that achieved under white light of 0.044 mL H² mg⁻¹ chl h⁻¹, a maximal total hydrogen production of 0.108 mL H² mg⁻¹ chl which significantly exceeded that under white light of 0.066 mL H² mg⁻¹ chl, and a maximal gross radiant energy conversion efficiency for hydrogen production of 0.515 μL H² mg⁻¹ chl L⁻¹ that statistically matched that under white light of 0.395 μL H² mg⁻¹ chl L⁻¹. The study also successfully demonstrated the reversibility feature of the novel strategy, allowing for the cells to alternately engage in photo-hydrogen production and to recover by simply switching on or off the PSI-spectral-selective radiation.

A problem that has become apparently growing in the deployment of renewable energy systems is the power grids inability to accept the forecasted growth in renewable energy generation integration. To support forecasted growth in renewable generation integration, it is now recognised that Energy Storage Technologies (EST) must be utilised. Recent advances in Hydrogen Energy Storage Technologies (HEST) have unlocked their potential for use with constrained renewable generation. HEST combines Hydrogen production, storage and end use technologies with renewable generation in either a directly connected configuration, or indirectly via existing power networks. A levelised cost (LC) model has been developed within this thesis to identify the financial competitiveness of the different HEST application scenarios when used with grid constrained renewable energy. Five HEST scenarios have been investigated to demonstrate the most financially competitive configuration and the benefit that the by-product oxygen from renewable electrolysis can have on financial competitiveness. Furthermore, to address the lack in commercial software tools available to size an energy system incorporating HEST with limited data, a deterministic modelling approach has been developed to enable the initial automatic sizing of a hybrid renewable hydrogen energy system (HRHES) for a specified consumer demand. Within this approach, a worst-case scenario from the financial competitiveness analysis has been used to demonstrate that initial sizing of a HRHES can be achieved with only two input data, namely – the available renewable resource and the load profile. The effect of the electrolyser thermal transients at start-up on the overall quantity of hydrogen produced (and accordingly the energy stored), when operated in conjunction with an intermittent renewable generation source, has also been modelled. Finally, a mass-transfer simulation model has been developed to investigate the suitability of constrained renewable generation in creating hydrogen for a hydrogen refuelling station.

Les organismes photosynthétiques participent à la régulation du climat terrestre en utilisant l'énergie lumineuse pour séquestrer le dioxyde de carbone (CO2), un processus auquel les algues ou les cyanobactéries contribuent largement dans les milieux aquatiques. Une fixation efficace du carbone par la photosynthèse repose sur un équilibre entre la production d'énergie par la photosynthèse et sa consommation. Plusieurs mécanismes de régulation contribuent à limiter les déséquilibres, soit en dissipant l'excès d'énergie, soit en détournant le flux photosynthétique d’électrons vers l'oxygène (O2). Dans les cyanobactéries, des protéines flavodiiron (FLV) ont été identifiées comme étant les principaux protagonistes de la photoréduction de l’O2. Des gènes FLV ont été identifiés dans les algues vertes, mais n’ont pas encore été caractérisés. Dans cette thèse, nous avons exploré le rôle des FLVs durant la photosynthèse chez la microalgue verte Chlamydomonas reinhardtii. En mesurant les échanges gazeux à l’aide d’un spectromètre de masse à introduction par membrane sur des mutants dépourvus de FLVs, nous montrons que ces enzymes sont impliquées dans une photoréduction massive d'O2 lors de transitions de l'obscurité à la lumière en aérobiose et en anaérobiose. En mesurant les échanges de monoxyde d’azote (NO) et d'oxyde nitreux (N2O) dans différentes souches et espèces d'algues, nous démontrons l'existence d'une réduction du NO en N2O médiée par les FLVs. Nous discutons du rôle physiologique des FLVs et de leur implication dans la régulation de la photosynthèse chez les microalgues et proposons un modèle explicatif de la disparition des FLVs durant l'évolution des plantes à fleurs
Photosynthetic organisms regulate the earth’s climate by using light energy to sequester carbon dioxide (CO2), a phenomenon to which algae and cyanobacteria substantially contribute in aquatic ecosystems. Efficient carbon fixation by photosynthesis relies on a proper balance between energy production by photochemical reactions and energy consumption, a balance that can be challenged during sudden environmental shifts. Several regulatory mechanisms contribute to limiting such imbalances, either by dissipating excess energy or by diverting the photosynthetic electron flow electrons towards oxygen (O2). The O2 photoreduction potential is important in green microalgae, but both physiological significance and molecular mechanisms remain elusive. In cyanobacteria, flavodiiron proteins (FLVs) are the main protagonists of O2 photoreduction. FLV genes have been identified in green algal genome but are so far uncharacterized. In this thesis, we have explored the role of FLVs during photosynthesis in the model green microalga Chlamydomonas reinhardtii. By measuring gas exchange with a Membrane Inlet Mass Spectrometer on mutants devoid of FLVs, we show that FLVs are involved in a massive O2 photoreduction during aerobic and anaerobic dark to light transition. By measuring nitric oxide (NO) and nitrous oxide (N2O) exchange in different algal strains and species, we that a light-dependent NO reduction into N2O is driven by photosynthesis and mediated by FLVs. We discuss the physiological relevance of the mechanisms described and their involvement in regulating CO2 fixation in microalgae. We finally propose a model for the disappearance of FLVs during the evolution of flowering plants

L’hydrogène vert est le vecteur d’énergie du futur le plus prometteur car il est d’une part capté par des sources renouvelables et inépuisables qui sont les énergies éolienne et/ou solaire et d’autre part permet de meilleurs transport et stockage de l’énergie sur le long terme en bouteilles haute pression par un électrolyseur pour produire ensuite de l’électricité par des piles à combustible sans émission d’aucun polluant. La nature intermittente des SER dégrade la performance et le fonctionnement dynamique des électrolyseurs PEM et leur couplage doit être étudié afin d’assurer la disponibilité opérationnelle et la pérennité du fonctionnement des équipements par une détection précoce des défauts et l’estimation de leurs durées de vie mais aussi le suivi en ligne des performances technico économiques.L’objectif de la thèse réalisé dans le cadre du projet Européen Interreg-2 Mers E2C est de développer un modèle dynamique multi-physique d’un électrolyseur PEM, basé sur une approche Bond-Graph pour une utilisation générique pour d’autres types d’électrolyseur non seulement pour l’analyse mais aussi pour la conception de systèmes de supervision en ligne pour la détection et localisation de défauts. La modélisation des divers composants de l’électrolyseur a été réalisée sous forme de capsules Bond-Graph. Ces capsules peuvent être connectées en tenant compte de la structure du diagramme d’instrumentation pour obtenir un modèle dynamique global. Ce modèle est capable de représenter différentes configurations, du pilote de laboratoire jusqu’à l’échelle industrielle, et également de suivre l’efficacité en temps réel. Le modèle a été converti en MATLAB® Simulink pour implémentation, puis validé expérimentalement sur une cellule alimentée par une Plateforme Multi-Source Hybride comprenant des sources d’énergie solaire et éolienne. Le modèle a été adapté pour représenter et étudier la performance d’un électrolyseur à Membrane Echangeuse d’Anions, dont la configuration et l’architecture sont similaires, en collaboration avec l’Université d’Exeter. Le modèle permet également de développer des algorithmes de commande, diagnostic et pronostic ; ainsi, un diagnostic robuste des défauts est présenté dans ce travail. Une Interface Utilisateur Graphique pour la supervision en ligne incorpore le modèle et les algorithmes de diagnostic
Renewable Energy Sources (RES) have emerged as a sustainable alternative to carbon-based energy sources as the world is struggling in limiting the greenhouse effect in the coming years. The use of RES, such as solar and wind, alone is non-reliable due to their intermittent nature. The surplus electricity generated during off-peak hours must be stored to tackle the problem of the unavailability of energy. Green Hydrogen (GH$_2$) generation using electrolyser running on RES has seen an increase in recent years for the storage of this surplus energy due to its advantages over conventional methods (such as batteries and ultra-capacitors) for long term storage and transport. Proton Exchange Membrane (PEM) based electrolysers are better suited for the coupling with RES as compared to the alkaline electrolysers due to their faster start-up times and fast dynamic load changing capability. The intermittent nature of RES affects the performance and operation dynamics of the PEM electrolyser and must be analysed and studied in order to make these systems more reliable and safer to use. Mathematical modelling is one of the possible solutions for studying their behavior and developing supervision algorithms.Under the framework of the E2C project of the European Interreg 2-Seas program, a generic dynamic multi-physics model of a PEM electrolyser has been proposed in this work based on Bond Graph (BG) approach. Various components of the PEM electrolyser have been modelled in the form of BG capsules. These capsules can be connected based on the piping and instrumentation diagram of the PEM electrolyser system to have a global model of the system. The developed model is capable of representing different configurations of PEM electrolysers ranging from laboratory scale to industrial scale. The model is also capable of facilitating efficiency tracking in real-time. The developed model in the BG form has been converted into MATLAB® Simulink block diagram from the implementation point of view.The model was then validated using a single cell PEM electrolyser powered by a Hybrid Multi-source Platform (HMP) running on solar and wind energy at the University of Lille. The proposed model was also extended for the modelling and performance study of Anion Exchange Membrane (AEM) electrolysis cell, in collaboration with the University of Exeter of England, which shares a similar configuration and architecture.The developed model for the PEM electrolysis system is also suitable for the development of control, diagnosis, and prognosis algorithms. Therefore, a model-based robust fault diagnosis for PEM water electrolyser has been proposed in this work. The proposed diagnosis algorithms and model have been then utilized for developing the graphical user interface for online supervision

Ce mémoire porte sur la synthèse de matériaux composites nanostructurés à base de polyoxométallates pour la conversion de l’énergie et des applications à des problèmes environnementaux. Pour atteindre ces objectifs, de nombreux composés nouveaux de cette famille d’oxydes moléculaires ont été synthétisés puis ont été associés à différentes matrices éco-compatibles dans le respect des principaux critères de la Chimie Verte. Les principales techniques d’étude sont l’électrochimie, la photochimie et la spectroscopie UV-visible. Dans le domaine de l’énergie, les catalyseurs obtenus se sont révélés très efficaces dans des réactions très importantes mais difficiles à réaliser, comme la production de l’hydrogène, la réduction de l’oxygène et l’oxydation de l’eau. De même, parmi les applications aux problèmes de dépollution, ces nanomatériaux ont montré une forte activité électrocatalytique et photocatalytique pour la réduction des oxydes d’azote, des bromates et la photodégradation d’un colorant textile toxique, l’Acide Orange 7. Les performances de ces nouveaux catalyseurs sont comparables à celles des meilleurs systèmes connus
This thesis focuses on the synthesis of nanostructured composite materials based on polyoxometalates for energy conversion and applications to environmental problems. To achieve these goals, many new compounds of this family of molecular oxides were synthesized and were associated with different nature friendly matrices, in agreement with the main criteria of Green Chemistry. In the field of energy, the new catalysts have proved very effective in important but difficult to achieve reactions, such as producing hydrogen, oxygen reduction or water oxidation. Similarly, among applications to pollution problems, these nanomaterials have shown a strong electrocatalytic and photocatalytic activity for the reduction of nitrogen oxides, bromate and for the photodegradation of a toxic textile dye, Acid Orange 7. The performances of these new catalysts are comparable to those of the best known systems

Cyanobacteria belong to the oldest organisms of our planet. They use photosynthesis to produce ATP and gain biomass from carbon dioxide. The cyanobacteria Nostoc punctiforme is a filamentous bacterium that consists of two different types of cells, vegetative cells and heterocysts. The type of cell it differentiates into depends on the media they grow in. In an ammonium-rich medium, the N.punctiforme consists of vegetative cells that differentiate into heterocysts when in the medium is changed to a low-concentration ammonium medium. The ammonium-binding nitrogenase in the heterocysts does not work in an oxidative environment. During oxidative stress, N.punctiforme produces Dps (DNA binding protein from starved cells) which protects DNA. In the heterocysts the nitrogenase produces hydrogen as a side product. The hypothesis is that Dps is cell specific. In order to study this protein, a fusion of the promotor of Dps and GFP (Green Flourescent Protein) was constructed. To detect GFP, optimization of a Western Blot (WB) for GFP was performed. Protein samples were analyzed in strains of N.punctiforme. In strain 12A, the production of GFP was visualized but the band was not specific. Several attempts of optimization of the WB procedure were performed, but none of them showed clear specific protein detection in the N.punctiforme strains. Further optimization of the WB protocol is needed.

Mestrado Bolonha em Economia Internacional e Estudos Europeus
A economia de hidrogénio verde surge como uma alternativa sustentável à atual economia de base fóssil e às suas consequências negativas para o meio ambiente. De modo a contrariar este cenário, diferentes economias comprometem-se a realizar a transição energética assente em hidrogénio limpo, através da publicação de Estratégias Nacionais para o Hidrogénio. Estas, para além de estabelecerem ambiciosas metas para a descarbonização interna, revelam a intenção de comercializar e cooperar a nível internacional, tanto na esfera pública como privada. Assim, o objetivo deste trabalho é identificar as dinâmicas da emergente economia de hidrogénio verde para, posteriormente, procurar compreendê-las segundo os principais aspetos teóricos referentes à teoria de comércio internacional e sobre o envolvimento económico internacional das empresas, de forma a verificar o seu poder explicativo e de previsão. Ao realizar este exercício foi possível concluir que as dotações fatoriais são capazes de explicar os futuros fluxos comerciais de hidrogénio verde e, simultaneamente, a inserção internacional das empresas através das alianças. Contudo, o poder explicativo de modelos teóricos assentes nas dotações fatorais apresentam limitações, sendo necessário considerar outras contribuições teóricas.
The green hydrogen economy emerges as a sustainable alternative to the current fossil-based economy and its negative consequences for the environment. To counter this scenario, different economies made commitments to promote a clean hydrogen society by announcing theirs National Strategies for Hydrogen. In addition to setting ambitious decarbonisation goals, these documents also reveal the desire to trade and cooperate internationally, in both the public and private sectors. Thus, the objectives of this work are to identify the dynamics of the emerging green hydrogen economy and, afterward, try to understand them according to the main theoretical aspects: international trade theory and internationalization of firms’ theoretical framework. This approach will allow to verify their explanatory and predictive power. This work allows to conclude that the factor endowments can explain the future international trade of green hydrogen and other forms of firms’ internationalization, namely alliances. However, the explanatory power of theoretical models based on factor endowments faces limitations, making it necessary to consider other theoretical frameworks.
info:eu-repo/semantics/publishedVersion

In recent years, the need for personal urban mobility has increased a lot especially in emerging and developing countries. It becomes increasingly important to explore propulsion systems that use alternative energy sources and are related to the chain of production, storage and use of renewable energy. Several studies have been conducted in this area, but very few have achieved solutions for the interaction of the vehicle with the building by which it is parked in terms of a multi-energy exchange. Technological innovation of house plant parts, of large residences / hotels, of shelter stations for vehicles, it is now crucial to implement the integration of more renewable energy sources within the same building structure: this is one of the aspects covered by the most general definition of "Smart Housing". Sustainable mobility is perceived as a strong need to match individual urban and sub-urban mobility, to the least environmental and social impact of such personal need. This research project proposes a possible scenario for energy integration between smart housing and smart mobility using a common energy platform that allows self-generation, storage and energy exchange between residential district buildings and smart vehicles. The project integrates multidisciplinary approaches with the aim of designing, evaluating technical and industrial feasibility for the development of: 1) Modular and scalable energy storage devices dedicated to a smart house. 2) a modular city vehicle, with high flexibility of use, with energy storage system and energy-efficient switching capabilities with smart building.

The exigent need to address climate change and its adverse effects is felt all around the world. As pioneers in tackling carbon emissions, the European Union continue to be head and shoulders above other continents by implementing policies and keeping a tab on its carbon dependence and emissions. However, being one of the largest importers of Natural Gas in the world, the EU remains dependent on a fossil fuel to meet its demands.  The aim of the research is to investigate the barriers and constraints in the EU policies and framework that affects the natural gas decarbonization and to investigate the levelized cost of hydrogen production (LCOH) that would be used to decarbonize the natural gas sector. Thus a comprehensive study, based on existing academic and scientific literature, EU policies, framework and regulations pertinent to Natural gas and a techno economic analysis of possible substitution of natural gas with Hydrogen, is performed. The motivation behind choosing hydrogen is based on various research studies that indicate the importance and ability to replace to natural gas. In addition, Portugal provides a great environment for cheap green hydrogen production and thus chosen as the main region of evaluation.  The study evaluates the current framework based on a SWOT ((Strength, Weakness, and Opportunities & Weakness) analysis, which includes a PESTEL (Political, Economic, Social, Technological, Environmental & Legal) macroeconomic factor assessment and an expert elicitation. The levelized cost of hydrogen is calculated for blue (SMR - Steam Methane Reforming with natural gas as the feedstock) and green hydrogen (Electrolyzer with electricity from grid, solar and wind sources). The costs were specific to Portuguese conditions and for the years 2020, 2030 and 2050 based on availability of data and the alignment with the National Energy and Climate Plan (NECP) and the climate action framework 2050. The sizes of Electrolyzers are based on the current Market capacities while SMR is capped at 300MW. The thesis only considers production of hydrogen. Transmission, distribution and storage of hydrogen are beyond the scope of the analysis.  Results show that the barriers are mainly related to costs competitiveness, amendments in rules/regulations, provisions of incentives, and constraints in the creation of market demand for low carbon gases. Ensuring energy security and supply while being economically feasible demands immediate amendments to the regulations and policies such as incentivizing supply, creating a demand for low carbon gases and taxation on carbon.  Considering the LCOH, the cheapest production costs continue to be dominated by blue hydrogen (1.33 € per kg of H2) in comparison to green hydrogen (4.27 and 3.68 € per kg of H2) from grid electricity and solar power respectively. The sensitivity analysis shows the importance of investments costs and the efficiency in case of electrolyzers and the carbon tax in the case of SMR. With improvements in electrolyzer technologies and increased carbon tax, the uptake of green hydrogen would be easier, ensuring a fair yet competitive gas market.
Det starka behovet av att ta itu med klimatförändringarna och deras negativa effekter är omfattande världen över. Den europeiska unionen utgör en pionjär när det gäller att såväl hantera sina koldioxidberoende och utsläpp som att implementera reglerande miljöpolitik, och framstår därmed som överlägsen andra stater och organisationer i detta hänseende. Unionen är emellertid fortfarande mycket beroende av fossilt bränsle för att uppfylla sina energibehov, och kvarstår därför som en av världens största importörer av naturgas.  Syftet med denna forskningsavhandling är att undersöka befintliga hinder och restriktioner i EU: s politiska ramverk som medför konsekvenser avkolningen av naturgas, samt att undersöka de utjämnande kostnaderna för väteproduktion (LCOH) som kan användas för att avkolna naturgassektorn. Därmed utförs en omfattande studie baserad på befintlig akademisk och vetenskaplig litteratur, EU: s politiska ramverk och stadgar som är relevanta för naturgasindustrin. Dessutom genomförs en teknisk-ekonomisk analys av eventuella ersättningar av naturgas med väte. Valet av väte som forskningsobjekt motiveras olika forskningsstudier som indikerar vikten och förmågan att ersätta till naturgas. Till sist berör studien Portugal. som tillhandahåller en lämplig miljö för billig och grön vätgasproduktion. Av denna anledning är Portugal utvalt som den viktigaste utvärderingsregionen.  Studien utvärderar det nuvarande ramverket baserat på en SWOT-analys ((Strength, Weakness, and Opportunities & Weakness), som inkluderar en PESTEL (Political, Economical, Social, Technological, Environmental och Legal) makroekonomisk faktoranalys och elicitering. Den utjömnade vätekostnaden beräknades i blått (SMR - Ångmetanreformering med naturgas som råvara) och grönt väte (elektrolyser med el från elnät, sol och vindkällor). Kostnaderna var specifika för de portugisiska förhållandena under åren 2020, 2030 och 2050 baserat på tillgänglighet av data samt anpassningen till den nationella energi- och klimatplanen (NECP) och klimatåtgärdsramen 2050. Storleken på elektrolyserar baseras på den nuvarande marknadskapaciteten medan SMR är begränsad till 300 MW. Avhandlingen tar endast hänsyn till produktionen av vätgas. Transmission, distribution och lagring av väte ligger utanför analysens räckvidd.  Resultaten visar att hindren är främst relaterade till kostnadskonkurrens, förändringar i stadgar och bestämmelser, incitament och begränsningar i formerandet av efterfrågan på koldioxidsnåla gaser på marknaden. Att säkerställa energiförsörjning och tillgång på ett ekonomiskt hållbart sätt kräver omedelbara ändringar av reglerna och politiken, såsom att stimulera utbudet, att skapa en efterfrågan på koldioxidsnåla gaser och genom att beskatta kol.  När det gäller LCOH dominerar blåväte beträffande produktionskostnaderna (1,33 € per kg H2) jämfört med grönt väte (4,27 respektive 3,68 € per kg H2) från elnät respektive solenergi. Osäkerhetsanalysen visar vikten av investeringskostnader och effektiviteten vid elektrolysörer och koldioxidskatten för SMR. Med förbättringar av elektrolys-tekniken och ökad koldioxidskatt skulle upptagningen av grön vätgas vara enklare och säkerställa en rättvis men konkurrenskraftig gasmarknad.

Hydrogen peroxide is a versatile oxidizing agent with several industrial applications. It is also one of “greenest”, since its oxidation by-product is only water. The global demand of the peroxide is increasing, due to its recent usage in new large scale oxidation processes, such as the epoxidation of propylene to propylene oxide and the synthesis of caprolactam. Nowadays most of the world production of H2O2 is carried out by the anthraquinone autoxidation process. Though very safe (H2 and O2 are never in direct contact), the costs related to the high energy consumption for the extraction and purification of the peroxide produced, together with the usage and periodic replacement of toxic and expensive solvents, stimulated the interest in new production paths. Among the several alternatives proposed, the most fascinating one is the direct synthesis (DS) from H2 and O2. It is a environmentally friendly process that would be economically profitable for an in-situ production, requiring lower investments and operating costs. During the last thirty years this system has been under intensive study both by industries as well as academia. However, it has not been commercialized yet, mainly because of poor selectivity and safety concerns. While most of the efforts on improving DS must address the catalyst, there are reaction engineering aspects that deserve attention. DS is frequently carried out in solvents other than water, both to improve H2 solubility and isolate the undesired product (H2O). Further, CO2 is used for safety, H2 solubility and H2O2 stability. However, the lack of information about the solubility of the reagents makes it difficult to develop a realistic kinetic description of the reactions involved in the DS process. Hence, the first step of the research presented herein dealt with solubility measurements, at temperatures in the range 268-288 K and pressures between 0.37 and 3.5 MPa. Measurements were focused on H2, i.e. the limiting reagent during the reaction. At all conditions investigated a linear relation between hydrogen partial pressure and concentration was observed. Increasing the temperature resulted in an enhanced H2 solubility at the same H2 partial pressure. At constant H2 fugacity, the presence of CO2 favored the dissolution of hydrogen in the liquid phase. Correlation and generalization of the measurements were provided through an EoS-based thermodynamic model for the estimation of H2 solubility at reaction conditions. A batch apparatus for the direct synthesis of hydrogen peroxide was developed, to carry out activity measurements on new catalysts and develop a quantitative model of the kinetics. Hydrogenation, disproportionation and direct synthesis reactions were studied on a commercial 5 wt.% Pd/C catalysts at temperatures in the range 258-313 K and pressure up to 2 MPa. Separate experiments were performed to highlight the role of each reaction. An enhanced H2O2 production was obtained adopting different H2 feeding policies, although selectivity did not exceeded 30%. A model of the gas bubbling, batch slurry reactor for H2O2 direct synthesis was developed. A sensitivity analysis on the mass transfer coefficients excluded any limitations occurring at experimental conditions. Comparable temperature dependence was observed for H2O production, hydrogenation and disproportionation (activation energies close to 45 kJ mol-1), while H2O2 synthesis had a much lower activation energy (close to 24 kJ mol-1), suggesting that a higher selectivity is achievable at low temperature. Disproportionation reaction had a very limited influence on the overall peroxide production rate, while hydrogenation was the most rapid side reaction. Water formation was significant, prevailing at higher temperatures. Following these results, Pd and PdAu catalysts supported on SBA15 were prepared and investigated for H2O2 direct synthesis. Catalysts were doped with bromine, a promoter in the H2O2 direct synthesis. Productivity and selectivity decreased when bromine was incorporated in the catalysts, suggesting a possible poisoning due to the grafting process. A synergetic effect between Pd and Au was observed both in presence and absence of bromopropylsilane grafting on the catalyst. Three modifiers of the SBA15 support (Al, CeO2 and Ti) were chosen to elucidate the influence of the surface properties on metal dispersion and catalytic performance. Higher productivity and selectivity were achieved incorporating Al into the SBA15 framework, whereas neither Ti nor CeO2 improved H2O2 yields. The enhanced performance observed for the PdAu/Al-SBA15 catalysts was attributed to the increased number of Brønsted acid sites. Supported catalysts were also synthesized depositing Pd on a highly acidic, macroporous PS-DVB resin (Lewtit K2621). Catalysts with active metal content in the range 0.3-5 wt.% were tested batchwise for the direct synthesis of H2O2. Preliminary H2O2 measurements and X-ray photoelectron spectroscopy (XPS) analysis revealed that the reduced form of Pd was more selective than PdO towards the peroxide. Transmission electron microscopy (TEM) images showed that smaller nanoclusters favored the production of H2O, likely due to their O-O bond breaking aptitude
Il perossido di idrogeno è un potente agente ossidante, molto usato nella pratica industriale. E’ uno dei meno tossici, dal momento che l’unico sottoprodotto della sua ossidazione è l’acqua. A livello mondiale, la domanda di H2O2 è in costante aumento, non da ultimo grazie a recenti usi in nuovi processi ossidativi, quali l’epossidazione del propilene e la sintesi del caprolattame. Attualmente l’acqua ossigenata viene prodotta quasi esclusivamente attraverso l’auto-ossidazione dell’antrachinone. Sebbene molto sicuro (non vi è mai contatto diretto tra idrogeno ed ossigeno), questo processo presenta alcuni svantaggi, quali ad esempio gli alti costi di esercizio, dovuti in particolare all’alta richiesta energetica per la separazione e la purificazione del perossido prodotto. Si tratta inoltre di un processo potenzialmente inquinante, in quanto fa uso di costosi solventi tossici, e dagli alti costi d’investimento, essendo economicamente vantaggioso solo per grandi produzioni (>4*104 tonnellate all’anno). Pertanto l’H2O2 è attualmente prodotta in pochi grandi impianti e trasferita per grandi distanze all’utente finale. Il trasporto aggiunge costi e rischi, in quanto soluzioni concentrate di H2O2 possono decomporre violentemente. Nelle ultime decadi vi è stato un notevole interesse nella ricerca di nuovi processi di produzione del perossido di idrogeno, che fossero contemporaneamente meno costosi ed inquinanti. Tra le varie alternative proposte, la più affascinante è sicuramente la sintesi diretta a partire da H2 ed O2. Si tratta di un processo “verde”, che si propone di eliminare i sottoprodotti inquinanti e, allo stesso tempo, ridurre i costi di produzione, rendendo economicamente vantaggiosa la produzione in situ presso l’utilizzatore finale. Nonostante il grande interesse sia industriale che accademico suscitato da tale processo negli ultimi trent’anni, a tutt’oggi non vi è nessuna applicazione industriale. Il motivo di ciò è da ricercarsi principalmente nei problemi di sicurezza e selettività che a tutt’ora restano irrisolti. La mancanza di informazioni sulla solubilità dei reagenti alle condizioni di reazione rende difficoltoso ottenere una descrizione cinetica precisa delle reazioni coinvolte nella sintesi diretta. Pertanto i primi passi della ricerca qui presentata sono stati mossi con l’obiettivo di raccogliere dati di solubilità alle condizioni di reazione (temperatura compresa tra i 268 e i 288 K e pressione tra 0.37 e 3.5 MPa). In particolare, si era interessati all’H2, in quanto reagente limitante del processo. A tutte le condizioni indagate, è stata riscontrata una relazione lineare tra la pressione parziale e la concentrazione di H2. Contrariamente a quanto normalmente avviene, l’incremento di temperatura ha avuto l’effetto di aumentare la solubilità nella fase liquida (a parità di pressione parziale). Inoltre, a parità di fugacità di H2, la presenza di CO2 ha favorito la concentrazione dell’H2 nel liquido. I risultati ottenuti sono stati generalizzati sviluppando un modello per stimare la solubilità dell’H2 alle condizioni di reazione. E’ stato poi realizzato un apparato batch per la sintesi diretta di acqua ossigenata. Un catalizzatore commerciale a base di Pd (5 wt.%) su carbone è stato utilizzato per studiare le reazioni di idrogenazioni, dismutazione e sintesi a temperature comprese tra 258 e 313 K e pressioni fino a 2.0 MPa. Il ruolo di ciascuna reazione è stato studiato attraverso esperimenti specifici. Appropriate politiche di alimentazione dell’H2 hanno permesso di realizzare un aumento di produzione rispetto a condizioni tipicamente batch. Tuttavia il catalizzatore testato ha rivelato limiti di selettività, non superando valori del 30% ca. Per studiare le cinetiche di reazione, è stato sviluppato un modello per il reattore batch. Un’analisi di sensitività sui coefficienti di trasporto di materia (sia dalla fase gassosa alla liquida che dalla liquida al catalizzatore) ha permesso di escludere ogni limitazione tra le fasi coinvolte nelle reazioni. Le reazioni indesiderate (formazione di H2O, dismutazione ed idrogenazione) hanno rivelato una simile dipendenza dalla temperatura (con un’energia di attivazione di circa 45 kJ mol-1). Una minore energia di attivazione è stata ottenuta per la reazione di sintesi diretta di H2O2 (24 kJ mol-1), il che suggerisce che la selettività è favorita alle basse temperature. Un confronto tra le velocità delle reazioni coinvolte ha permesso di identificare la dismutazione come la reazione più lenta di distruzione del perossido. Inoltre, la formazione di acqua era sempre significativa, compromettendo la selettività. A seguito di questi risultati, si è deciso di focalizzare l’attenzione sul catalizzatore. Catalizzatori mono e bi-metallici sono stati realizzati depositando Pd e PdAu su SBA15, una silice macroporosa e strutturata. Tali catalizzatori sono stati anche dopati con l’aggiunta di bromo, un noto promotore della reazione di sintesi diretta. Sia la selettività che la produttività sono diminuite modificando i catalizzatori con l’alogenio, probabilmente a causa di un avvelenamento durante la procedura di innesto del bromo. Una sinergia tra i metalli Pd e Au è stata osservata sia nei catalizzatori con e che senza bromo. Tre modifiche sono state apportate al miglior catalizzatore sviluppato (PdAu/SBA15) per evidenziare l’influenza delle proprietà superficiali sulla reazione di sintesi diretta. Tre modificatori sono stati incorporati nel supporto: Al, CeO2 e Ti. Un aumento sia di selettività che di produttività è stato riscontrato solo con l’aggiunta di Al. Tale risultato è stato attribuito al maggior numero di siti acidi di Brønsted riscontrati su questo catalizzatore. Un'altra famiglia di catalizzatori, con un contenuto di metallo attivo variabile tra lo 0.3 ed il 5 wt.%, è stata sintetizzata depositando del Pd su una resina acida e macroporosa, miscela di PS e DVB. I risultati preliminari dei test catalitici e delle analisi di spettroscopia fotoelettronica a raggi X (XPS) hanno rivelato che lo stato di ossidazione del palladio più selettivo verso il perossido è quello ridotto, mentre il PdO porta più facilmente alla formazione di H2O. Le immagini al microscopio elettronico a trasmissione (TEM) hanno mostrato che i nanocluster di Pd più piccoli portato alla formazione preferenziale di H2O, il che è probabilmente legato alla loro propensione alla rottura del legame O-O

Afin de palier à l’intermittence des énergies renouvelables, l’utilisation d’un vecteur énergétique tel que l’hydrogène semble une solution idéale. Il permet de stocker massivement de l’énergie sur une longue période de temps, convient à une large gamme d’utilisation (mobilité, chaleur, procédés) et son impact carbone est très intéressant selon sa production. Cette source d’énergie apparait donc comme une bonne alternative aux énergies fossiles dont nous sommes très dépendants. Cependant, 95 % de l’hydrogène est actuellement produit par la technique de vaporeformage du gaz naturel qui conduit à une production importante de dioxyde de carbone (CO2) ! Il est donc nécessaire de le produire par d'autres techniques et, parmi les différentes technologies disponibles, la production par photocatalyse (procédé utilisant la lumière du soleil et l'eau) semble tout à fait appropriée compte tenu de la possibilité de coupler cette technique à une source d'énergie renouvelable comme la lumière du soleil. Le photocatalyseur le plus connu et le plus utilisé actuellement est le dioxyde de titane (TiO2) mais sa synthèse requiert des températures élevées de l’ordre de plusieurs centaines de degrés. De plus, l’activité photocatalytique du TiO2 est limitée et ce dernier est en général dopé avec des métaux nobles afin d’augmenter son pouvoir photocatalytique. Compte tenu de cette problématique, dans le cadre de ce doctorat, un nouveau procédé de synthèse du TiO2 en conditions douces à 50°C a été mis en place. Les matériaux obtenus ont alors été dopés au moyen de métaux non nobles de types zinc (Zn), magnésium (Mg), aluminium (Al). Des tests de dopage sous pression ont aussi effectués et les résultats de production d’hydrogène obtenus en lumière visible sont très prometteurs
To circumvent the intermittency of the renewable energies, the use of an energy vector like Hydrogen seems to be an ideal solution. It represents a good way to store energy massively over long periods to be later employed in a wide variety of systems such as mobility, heating or industrial processing, with no impact on the carbon footprint. This source of energy then appears then to be a good alternative to fossil fuels on which we are very dependent. However, 95% of hydrogen is currently produced by the technique of steam reforming of natural gas, which leads to a significant production of carbon dioxide (CO2)! It is therefore necessary to produce it by other techniques and, among the various technologies available, the production by using photocatalysis (a process using only sunlight and water) seems quite appropriate given the possibility of coupling this technique to a renewable energy source such as sunlight. The best-known and most currently used photocatalyst is titanium dioxide (TiO2), but its synthesis requires high temperatures on the scale of several hundreds of degrees. Moreover, its photocatalytic activity is limited and it is generally doped with noble metals in order to increase its photocatalytic power. Given this problem, as part of this doctorate, a new process for TiO2 synthesis under mild conditions at 50°C has been implemented. The materials obtained were then doped with non noble metals such as zinc (Zn), magnesium (Mg), aluminum (Al). Pressure doping tests were also carried out and the hydrogen production results obtained under visible light are very promising

The aim of this research is the analysis of socio-economic factors that wouldinfluence consumer buying process of electric vehicles in Iceland. The purpose of the researchis to detect the most crucial factors influencing Icelanders decisions for and againstpurchasing an electric vehicle, instead of car with internal combustion engine. This researchverified people‟s opinions and can bring companies closer to real mindsets of Icelandicpotential buyers. Moreover, this paper might give a possibility to eliminate wrong thinkingand barriers by better adjusted marketing. Additionally, analyzed advantages might showwhat the main reason of shifting to this alternative technology is. Moreover, it shows whatmight be the customer acceptance price range.

In dieser Dissertation werden ab initio Theorien zur Beschreibung der Zustände von perfekten halbleitenden und nichtleitenden Kristallen, unter Berücksichtigung elektronischer Korrelationen, abgeleitet und angewandt. Als Ausgangsbasis dient hierzu die Hartree-Fock Approximation in Verbindung mit Wannier-Orbitalen. Darauf aufbauend studiere ich zunächst in Teil I der Abhandlung den Grundzustand der wasserstoffbrückengebundenen Fluorwasserstoff und Chlorwasserstoff zick-zack Ketten und analysiere die langreichweitigen Korrelationsbeiträge. Dabei mache ich die Basissatzextrapolationstechniken, die für kleine Moleküle entwickelt wurden, zur Berechnung von hochgenauen Bindungsenergien von Kristallen nutzbar. In Teil II der Arbeit leite ich zunächst eine quantenfeldtheoretische ab initio Beschreibung von Elektroneneinfangzuständen und Lochzuständen in Kristallen her. Grundlage hierbei ist das etablierte algebraische diagrammatische Konstruktionsschema (ADC) zur Approximation der Selbstenergie für die Bestimmung der Vielteilchen-Green's-Funktion mittels der Dyson-Gleichung. Die volle Translationssymmetrie des Problems wird hierbei beachtet und die Lokalität elektronischer Korrelationen ausgenutzt. Das resultierende Schema wird Kristallorbital-ADC (CO-ADC) genannt. Ich berechne damit die Quasiteilchenbandstruktur einer Fluorwasserstoffkette und eines Lithiumfluoridkristalls. In beiden Fällen erhalte ich eine sehr gute Übereinstimmung zwischen meinen Resultaten und den Ergebnissen aus anderen Methoden
In this dissertation, theories for the ab initio description of the states of perfect semiconducting and insulating crystals are derived and applied. Electron correlations are treated thoroughly based on the Hartree-Fock approximation formulated in terms of Wannier orbitals. In part I of the treatise, I study the ground state of hydrogen-bonded hydrogen fluoride and hydrogen chloride zig-zag chains. I analyse the long-range contributions of electron correlations. Thereby, I employ basis set extrapolation techniques, which have originally been developed for small molecules, to also obtain highly accurate binding energies of crystals. In part II of the thesis, I devise an ab initio description of the electron attachment and electron removal states of crystals using methods of quantum field theory. I harness the well-established algebraic diagrammatic construction scheme (ADC) to approximate the self-energy, used in conjunction with the Dyson equation, to determine the many-particle Green's function for crystals. Thereby, the translational symmetry of the problem and the locality of electron correlations are fully exploited. The resulting scheme is termed crystal orbital ADC (CO-ADC). It is applied to obtain the quasiparticle band structure of a hydrogen fluoride chain and a lithium fluoride crystal. In both cases, a very good agreement of my results to those determined with other methods is observed

La synthèse de glycomonomères à base d'oligoalginate (AlgiMERs) et leur polymérisations conventionnelles et RAFT en solution aqueuse ont été étudiés. Premièrement, l'oligoalginates de départ ont été transformés soit dans le glycosylamines correspondant ou en amino alditols (via une amination réductrice). A cette étape, l'optimisation des protocoles d'amination ont été identifiées par la réalisation d'une étude systématique sur un simple acide uronique (acide D-glucuronique). Deuxièmement, les sucres aminés ont été obtenus a réagi avec une électrophile portant un groupe vinyle polymérisable à céder AlgiMERs. Le glycomonomères résultant n'a pas homopolymérisé même en haute force ionique et pour temps de réaction longs, mais leur copolymérisations radicalaire conventionnelles avec N-(2-hydroxyéthyl)méthacrylamide (HEMAm) donne de glycopolymères avec de haute mass molaires (Mw ≈ 1.500.000 Da) contenant jusqu'à 50% en masse de oligoalginate. Une étude cinétique a confirmé que la consommation des deux monomères suivi une cinétique de premier ordre et que les AlgiMERs ont été intégrées tôt dans le processus de polymérisation. Basé sur ces résultats, l'enquête a été étendue à la copolymérisation radicalaire vivante en milieu aqueuse et glycopolymères gradient bien définies ont été obtenues (Mn = 12 000 Da - 90 000 Da; PDI ≤ 1,20). Enfin, j'ai pu prouver qu'un polymère synthétique portant des résidus d'oligo (1→4)-α-L-guluronan conduit des gels en présence d'ions Ca2+ et offre un hydrogel transparent et stable.

Afin de développer une chimie plus respectueuse de l'environnement, l'accès à de nouveaux procédés est nécessaire. Plus spécifiquement, dans le domaine de l'oxydation, l'utilisation d'oxydants toxiques doit être bannie, l'utilisation de solvants limitée et l'utilisation de catalyseurs recyclables développée. Dans ce contexte, deux approches " vertes " ont été explorées. La première d'entre elle consiste à éliminer ou remplacer l'acide acétique, additif qui, en présence de H2O2 et de complexes de Mn ou de Fe, favorise la formation exclusive d'époxydes lors d'oxydation d'alcènes. Pour cela, deux stratégies ont été testées. La première consiste à introduire dans la seconde sphère de coordination de complexes de Fe(III) et de Mn(II) des fonctions fluoroalcools devant faciliter l'activation d'H2O2. Comparés aux complexes analogues non modifiés, aucune amélioration de l'activité catalytique pour l'oxydation de cyclooctène n'est observée. Cependant, des complexes de Ni(II) et de Co(II) à ligands non modifiés ont démontré une activité catalytique élevée pour la photoproduction d'hydrogène. La seconde stratégie est basée sur le remplacement de l'acide acétique. Pour cela, en utilisant des billes de silice fonctionnalisées par des fonctions COOH (SiO2@COOH) comme co-réactif, une sélectivité significative en faveur de l'époxyde est observée lors de l'oxydation d'alcènes en présence de complexes de Mn(II) et de Fe(III) à ligand BPMEN. La seconde approche concerne des réactions d'(ép)oxydation sans solvant et utilisant des catalyseurs recyclables à base de polyoxométallates (POMs). Les catalyseurs SiO2@PMo et SiO2@PW, respectivement obtenus par greffage ionique de H3PMo12O40 ou H3PW12O40 sur des billes de silices fonctionnalisées par des fonctions pendantes NH2 (SiO2@NH2). Avec une faible charge catalytique, les deux catalyseurs sont efficaces lors de réactions d'oxydation avec une meilleure sélectivité que les POM libres. De plus, les deux catalyseurs réutilisés ont donné des conversions et des sélectivités similaires après deux recyclages
In order to develop a chemistry more respectful of the environment, access to sustainable processes is mandatory. More specifically, in the field of oxidation chemistry, use of toxic oxidants has to be banished, use of solvents limited and reusable catalysts developed. In this context, two types of greener approaches have been explored. The first approach concerns removal or replacement of acetic acid, an additive - in association with H2O2, favoring exclusive formation of epoxides with Mn and Fe metal complexes as catalysts. For this objective, two strategies have been explored. The first one consists in introducing fluoroalcohol functions in the second coordination sphere of metal complexes with pyridinophane-based ligand to easily activate H2O2. Those complexes did not enhance the catalytic activity for cyclooctene oxidation reactions in comparison to analogous Mn(II) and Fe(III) complexes with unmodified ligands. However, Ni(II) and Co(II) metal complexes with unmodified ligands display interesting catalytic activity for H2 photoproduction. The second strategy aimed to replace acetic acid. Using silica beads functionalized with COOH pendant arms (SiO2@COOH) as additive and H2O2 as oxidant, catalytic epoxidation reactions catalyzed by Mn(II) and Fe(III) metal complexes with BPMEN ligand displayed significant selectivity towards epoxide. The second approach concerns organic-solvent free (ep)oxidation processes with catalysts based on polyoxometalates (POMs). Catalysts SiO2@PMo and SiO2@PW, respectively obtained by ionic grafting of H3PMo12O40 or H3PW12O40 on silica beads functionalized with NH2 pending functions (SiO2@NH2), have been fully characterized. With low catalyst loading, both catalysts displayed efficient oxidation activity and better selectivity than the free POMs. Moreover, recovered beads gave similar conversion and selectivity after two recycling processes

L’histoire des événements accidentels dans les industries chimiques montre que leurs conséquences sont souvent graves sur les plans humain, environnemental et économique. Cette thèse vise à proposer une approche de détection et de diagnostic des défauts dans les procédés chimiques afin de prévenir ces événements accidentels. La démarche commence par une étude préalable qui sert à identifier les causes majeures responsables des événements industriels chimiques en se basant sur le retour d’expérience (REX). En France, selon la base de données ARIA, 25% des évènements sont dus à l’emballement thermique à cause d’erreurs d’origine humaine. Il est donc opportun de développer une méthode de détection et de diagnostic précoce des défauts dus à l’emballement thermique. Pour cela nous développons une approche qui utilise des seuils dynamiques pour la détection et la collecte de mesures pour le diagnostic. La localisation des défauts est basée sur une classification des caractéristiques statistiques de la température en fonction de plusieurs modes défectueux. Un ensemble de classificateurs linéaires et de diagrammes de décision binaires indexés par rapport au temps sont utilisés. Enfin, la synthèse de l'acide peroxyformique dans un réacteur discontinu et semi-continu est considérée pour valider la méthode proposée par des simulations numériques et ensuite expérimentales. Les performances de détection de défauts se sont révélées satisfaisantes et les classificateurs ont démontré un taux de séparabilité des défauts élevés
The history of accidental events in chemical industries shows that their human, environmental and economic consequences are often serious. This thesis aims at proposing an approach of detection and diagnosis faults in chemical processes in order to prevent these accidental events. A preliminary study serves to identify the major causes of chemical industrial events based on experience feedback. In France, according to the ARIA database, 25% of the events are due to thermal runaway because of human errors. It is therefore appropriate to develop a method for early fault detection and diagnosis due to thermal runaway. For that purpose, we develop an approach that uses dynamical thresholds for the detection and collection of measurements for diagnosis. The localization of faults is based on a classification of the statistical characteristics of the temperature according to several defectives modes. A multiset of linear classifiers and binary decision diagrams indexed with respect to the time are used for that purpose. Finally, the synthesis of peroxyformic acid in a batch and semi batch reactor is considered to validate the proposed method by numerical simulations and then experiments. Faults detection performance has been proved satisfactory and the classifiers have proved a high isolability rate of faults

[ES] En este trabajo de tesis doctoral, la investigación se ha centrado en el desarrollo de diferentes procesos catalíticos heterogéneos empleando materiales híbridos orgánico-inorgánicos porosos (MOFs y sílices funcionalizadas) y materiales orgánicos aromáti-cos (PAFs), que se han estudiado en diversas reacciones orgánicas. Tras la preparación de los MOFs en estudio, se han caracterizado sus propiedades estructurales y se han determinado sus centros activos en los clústeres metálicos (circonio, hafnio o cerio). La reactividad de estos MOFs y de los materiales híbridos sílice-aminas se ha estudia-do teniendo en cuenta sus centros catalíticos; estas reacciones se han optimizado lle-vando a cabo un estudio de los mecanismos de reacción. Finalmente, se han preparado sólidos homoquirales de tipo PAF que presentan el sistema binaftilo, cuya reactividad también ha sido probada. Más específicamente, en el capítulo 3 se ha estudiado la esterificación de amidas, que permite convertirlas en ésteres, grupos funcionales más versátiles. Esta transfor-mación se ha abordado desde la catálisis heterogénea via MOFs basados en circonio, hafnio y cerio de las series MOF-808, UiO-66 y MOF-801. El catalizador más eficien-te para la esterificación de amidas ha sido el MOF-808-Zr. Mediante análisis TGA y la adsorción de una molécula sonda básica (CO) estudiada utilizando espectroscopia FT-IR, se han determinado los centros ácidos de Lewis y Brönsted presentes en ellos. De los MOFs preparados en este trabajo, el MOF 808-Zr posee una menor conectividad de los clústeres metálicos y un mayor tamaño de poro mayor que el UiO-66 y el MOF-801; además, tiene el balance adecuado de centros ácidos y básicos de Brönsted y Lewis para activar los sustratos de la reacción. El alcance de la alcoholisis con n-butanol se ha extendido a un gran número de sustratos (amidas primarias, secundarias y terciarias; aromáticas y alifáticas). La reacción también se ha estudiado en condicio-nes no solvolíticas con alcoholes más complejos. El catalizador es estable durante la reacción y puede ser reutilizado fácilmente. El mecanismo de reacción en la esterifica-ción de benzamida con n butanol catalizada por MOF-808-Zr se ha investigado me-diante el análisis cinético empleando el modelo de LHHW y el estudio in situ de las interacciones moleculares por FT-IR. En el capítulo 4, se ha investigado la deuteración por intercambio isotópico deute-rio/hidrógeno catalizada por aminas soportadas en sílice comerciales empleando D2O como fuente de deuterio. Este procedimiento es aplicable a una gran gama de sustra-tos, como compuestos carbonílicos, sales de organofosfonio, nitrocompuestos e, inclu-so, hormonas esteroideas. La estabilidad del catalizador, SiO2-(CH2)3-NH2, se mantie-ne hasta en 10 usos de reacción sin pérdidas significativas de la actividad. Por último, en el capítulo 5, se afronta la síntesis y aplicación de PAFs homoquira-les donde se ha integrado el esqueleto del BINOL (1,1′-binaftil-2,2′-diol) y del BIN-BAM (1,1' binaftil-2,2'-disulfonimida) generando tres nuevos PAFs activos en catáli-sis asimétrica: PAF-3,3'-(S)-BINOL, PAF-6,6'-(R)-BINOL y PAF 3,3'-(S)-BINBAM. En concreto, el PAF-6,6'-(R)-BINOL ha demostrado su actividad catalítica en la reacción de alquilación de aldehídos aromáticos con dietil-zinc y el catalizador PAF-3,3'-(S)-BINBAM es activo en la reacción aldólica de Mukaiyama y la reducción del doble enlace de compuestos carbonílicos a,b-insaturados.
[CA] En aquesta tesi doctoral, la investigació s'ha centrat en el desenvolupament de dife-rents processos catalítics heterogenis emprant materials híbrids orgànic-inorgànics porosos (MOFs i sílices funcionalitzades) i materials orgànics aromàtics (PAFs), que s'han estudiat en diverses reaccions orgàniques. Després de la preparació dels MOFs en estudi, s'han caracteritzat les seues propietats estructurals i s'han determinat els seus centres actius en els clústers metàl·lics (zirconi, hafni o ceri). La reactivitat d'aquests MOFs i dels materials híbrids sílice-amines s'ha estudiat tenint en compte els seus cen-tres catalítics; aquestes reaccions s'han optimitzat duent a termini un estudi dels meca-nismes de reacció. Finalment, s'han preparat sòlids homoquirals de tipus PAF que presenten el sistema binaftilo, la reactivitat del qual també ha sigut provada. Més específicament, en el capítol 3 s'ha estudiat l'esterificació d' amides, que per-met convertir-les en èsters, grups funcionals més versàtils. Aquesta transformació s'ha abordat des de la catàlisi heterogènia via *MOFs basats en zirconi, hafni i ceri de les sèries MOF-808, UiO-66 i MOF-801. El catalitzador més eficient per a l'esterificació d'amides ha sigut el MOF-808-Zr. Mitjançant anàlisi TGA i l'adsorció d'una molècula sonda bàsica (CO) estudiada utilitzant espectroscopia FT-IR, s'han determinat els cen-tres àcids de Lewis i Brönsted presents en ells. Dels MOFs preparats en aquest treball, el MOF 808-Zr posseeix una menor connectivitat dels clústers metàl·lics i una major grandària de porus que el UiO-66 i el MOF-801; a més, té el balanç adequat de centres àcids i bàsics de Brönsted i Lewis per a activar els substrats de la reacció. L'abast de l'alcoholisi amb n-butanol s'ha estés a un gran nombre de substrats (amides primàries, secundàries i terciàries; aromàtiques i alifàtiques). La reacció també s'ha estudiat en condicions no solvolítiques amb alcohols més complexos. El catalitzador és estable durant la reacció i pot ser reutilitzat fàcilment. El mecanisme de reacció en l'esterifica-ció de benzamida amb n-butanol catalitzada per MOF-808-Zr s'ha investigat mitja-nçant l'anàlisi cinètica emprant el model de LHHW i l'estudi in situ de les interaccions moleculars per FT-IR. En el capítol 4, s'ha investigat la deuteració per intercanvi isotòpic deuteri/hidrògen catalitzada per amines suportades en sílices comercials emprant D2O com a font de deuteri. Aquest procediment és aplicable a una gran gamma de substrats, com a com-postos carbonílics, sals d'organofosfoni, nitrocompostos i, inclosa, hormones esteroi-dals. L'estabilitat del catalitzador, SiO2-(CH2)3-NH2, es manté fins a 10 usos de reac-ció sense pèrdues significatives de l'activitat. Finalment, en el capítol 5, s'afronta la síntesi i aplicació de PAFs homoquirals on s'ha integrat l'esquelet del BINOL (1,1′-binaftil-2,2′-diol) i del BINBAM (1,1'-binaftil-2,2'-disulfonimida) generant tres nous PAFs actius en catàlisi asimètrica: PAF-3,3'-(S)-BINOL, PAF-6,6'-(R)-BINOL i PAF 3,3'-(S)-BINBAM. En concret, el PAF-6,6'-(R)-BINOL ha demostrat la seua activitat catalítica en la reacció d'alquilació d'aldehids aromàtics amb dietil-zinc i el catalitzador PAF-3,3'-(S)-BINBAM és actiu en la reacció aldólica de Mukaiyama i la reducció del doble enllaç de compostos carbonílics a,b-insaturats.
[EN] In this Doctoral Thesis, the research has been focused on the development of different heterogeneous catalytic processes using hybrid porous organic-inorganic materials (MOFs and functionalized silicas) and organic aromatic materials (PAFs), which have been studied in various organic reactions. After the preparation of the MOFs under study, their structural properties have been characterised and their active centres in the metal clusters (zirconium, hafnium or cerium) have been determined. The reactivity of these MOFs and the hybrid silica-mine materials has been studied considering their catalytic centres; these reactions have been optimised by carrying out a study of the reaction mechanisms. Finally, homochiral PAF-type solids have been prepared with the binafil system, whose reactivity has also been tested. More specifically, the esterification of amides has been studied in Chapter 3. This reaction allows to convert the amides into esters, which are more versatile functional groups. This transformation has been approached from the heterogeneous catalysis via MOFs based on zirconium, hafnium and cerium of the MOF-808, UiO-66 and MOF-801 series. The most efficient catalyst for amide esterification has been MOF-808-Zr. Using TGA analysis and the adsorption of a basic probe molecule (CO) studied using FT-IR spectroscopy, the acid centres of Lewis and Brönsted present in them have been determined. Among the MOFs prepared in this work, MOF 808-Zr has a lower metal cluster connectivity and a larger pore size than UiO-66 and MOF-801; it also has the appropriate balance of acid and basic Brönsted and Lewis centres to activate the reaction substrates. The scope of n-butanol alcoholysis has been extended to a large number of substrates (primary, secondary and tertiary amides; aromatic and aliphatic). The reaction has also been studied in non-solvolitic conditions with more complex alco-hols. The catalyst is stable during the reaction and can be easily reused. The reaction mechanism in the esterification of benzamide with n-butanol catalysed by MOF-808-Zr has been investigated through kinetic analysis using the LHHW model and the in situ study of molecular interactions by FT-IR. In Chapter 4, the deuteration by isotopic deuterium/hydrogen exchange catalysed by commercial silica-supported amines using D2O as a source of deuterium has been investigated. This procedure is applicable to a wide range of substrates, such as carbonylic compounds, organophosphonium salts, nitro compounds and, even, steroid hormones. The stability of the catalyst, SiO2-(CH2)3-NH2, is maintained for up to 10 reaction uses without significant loss of activity. Finally, in Chapter 5, the synthesis and application of homochiral PAFs, in which the structure of BINOL (1,1′-binaftil-2,2′-diol) and BIN-BAM (1,1' binaftil-2,2'-disulfonimide) has been integrated, is discussed. Three new PAFs active in asymmetric catalysis has been generated: PAF-3,3'-(S)-BINOL, PAF-6,6'-(R)-BINOL and PAF 3,3'-(S)-BINBAM. In particular, PAF-6,6'-(R)-BINOL has demonstrated its catalytic activity in the alkylation reaction of aromatic aldehydes with diethyl zinc and the catalyst PAF-3,3'-(S)-BINBAM is active in the Mukaiyama aldolic reaction and the reduction of the double bond of carbonylic a,b-unsaturated compounds.
Villoria Del Álamo, B. (2021). Síntesis de catalizadores sólidos orgánicos e híbridos orgánicos-inorgánicos y su aplicación [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/163789
TESIS

Carbonate minerals play a very important role in nature, they represent some of the most diverse and common mineral species on the Planet. They are directly involved in the carbon dioxide (CO2) cycle acting as relatively stable long term chemical storage reservoirs, moderating both global warming trends and oceanaquatic chemistry through carbonate buffering systems. A range of synthetic metal carbonates have been synthesised for analysis under multiple experimental conditions, in order to study the variation in physical and chemical properties such as phase specificity, metal substitution, hydration/hydroxy carbonate formation under varying partial pressures of CO2 and thermal stability. Synthetic samples were characterised by a variety of instrumental analysis techniques in order to investigate chemical purity and phase specificity. Some of the techniques included, vibrational spectroscopy (IR/Raman), thermal analysis (TGA-MS) (thermal Raman), X-Ray diffraction (XRD) and electron microscopy (SEM-EDX). From the instrumental characterisation techniques, it was found that single phase smithsonite, hydrozincite, calcite and nesquehonite could successfully be synthesised under the conditions used. Minor impurities of other minerals and / or phases were found to form under specific chemical or physical conditions such as in the case of hydrozincite / simonkolleite if zinc chloride was used during hydrothermal synthesis.

Carbonate minerals play a very important role in nature, they represent some of the most diverse and common mineral species on the Planet. They are directly involved in the carbon dioxide (CO2) cycle acting as relatively stable long term chemical storage reservoirs, moderating both global warming trends and oceanaquatic chemistry through carbonate buffering systems. A range of synthetic metal carbonates have been synthesised for analysis under multiple experimental conditions, in order to study the variation in physical and chemical properties such as phase specificity, metal substitution, hydration/hydroxy carbonate formation under varying partial pressures of CO2 and thermal stability. Synthetic samples were characterised by a variety of instrumental analysis techniques in order to investigate chemical purity and phase specificity. Some of the techniques included, vibrational spectroscopy (IR/Raman), thermal analysis (TGA-MS) (thermal Raman), X-Ray diffraction (XRD) and electron microscopy (SEM-EDX). From the instrumental characterisation techniques, it was found that single phase smithsonite, hydrozincite, calcite and nesquehonite could successfully be synthesised under the conditions used. Minor impurities of other minerals and / or phases were found to form under specific chemical or physical conditions such as in the case of hydrozincite / simonkolleite if zinc chloride was used during hydrothermal synthesis.

Nous présentons des évaluations théoriques et
numériques de contributions de l'électrodynamique quantique (QED) aux
niveaux d'énergie des ions à un et deux électrons.

Nous donnons tout d'abord un aperçu des mesures de niveaux d'énergie
dans les systèmes simples formés d'un noyau et de quelques électrons
(en nous concentrant sur l'hydrogène, les ions hydrogénoïdes, l'hélium
et les ions héliumoïdes, y compris très chargés). De tels niveaux
permettent entre autres des mesures très précises de constantes
fondamentales (comme par exemple la constante de structure
fine alpha ou le Rydberg).

Nous faisons le point sur une méthode d'évaluation formelle des
niveaux d'énergie prédits par QED : la méthode "de la fonction de
Green à deux temps", et nous en donnons une présentation très
détaillée. Cette méthode permet d'obtenir de QED les énergies de
niveaux atomiques, y compris lorsque ceux-ci sont dégénérés ou
quasi-dégénérés (dans l'approximation d'électrons ne subissant que
l'attraction du noyau) --- ce qu'il n'est possible de faire qu'avec
une seule autre méthode, très récente. Nous montrons qu'il est
possible de résoudre les difficultés de principe que pose la méthode
de la fonction de Green à deux temps, grâce à une étude (restreinte au
problème considéré) du lien entre les propriétés analytiques d'une
fonction méromorphe et de son développement perturbatif. Afin de
pouvoir utiliser de façon pratique la méthode de la fonction de Green
à deux temps pour l'obtention des niveaux d'énergie prédits par QED,
nous introduisons de plus la méthode graphique "de la particule
fantôme", qui permet de calculer systématiquement un hamiltonien
effectif pour les niveaux considérés. Enfin, nous présentons un calcul
détaillé d'une contribution (la "self énergie écrantée") au
hamiltonien effectif, qui montre que la méthode de la particule
fantôme peut être appliquée de façon générale à l'évaluation des
déplacements en énergie dûs à n'importe quel diagramme de Feynman.

Enfin, nous étendons par des formules analytiques la méthode
actuellement la plus précise de calcul du déplacement le plus
important de QED (la self énergie), dans l'hydrogène et les ions
hydrogénoïdes. Cette méthode numérique permet d'obtenir le déplacement
de self énergie de niveaux de moment cinétique quelconque (elle était
auparavant restreinte à j <= 3/2). Nous montrons qu'il est ainsi
possible de calculer numériquement le déplacement de self énergie de
nombreux niveaux excités, avec une très bonne précision.

碩士
明新科技大學
土木工程與環境資源管理系碩士班
105
In the 4.6 billion years of the formation of the Earth, the climate has been influenced by many factors, and mankind is forcing the natural environment to make destructive changes in order to survive and to pursue a more comfortable life. Human beings making a lot of carbon dioxide in life, pollution also makes the hole of the ozone layer expanding, global warming, melting glaciers also caused by the crisis of survival, so we must be guarded To prevent global warming, it will begin to improve global warming. Now, most of countries in the world to promote energy-saving and carbon reduction, The green building is one of them, our Government has been promoted for many years, in recent years has been promoting hydrogen energy to reduce CO2 action. The application of hydrogen energy in green building can effectively reduce CO2 emissions, minimize environmental damage, and build the safest, healthy, efficient and sustainable development of the environment. The green building emphasizes the reduction of CO2 production, this thesis has sorted out the response to the greenhouse effect and comparing the advantages and disadvantages of various energy sources, using the most favorable hydrogen energy for the environment in green building to do research, and making suggestions on the disadvantages of hydrogen energy, and finally recommended the use of hydrogen energy in green building can effectively reduce the production of CO2.