Energy need in transportation and industry is mainly met by fossil fuels. This causes consumption of resources and some environmental problems. Diesel and gasoline engines are developed to consume fuel efficiently in vehicles. Since these engines work in a low fuel to air ratio, it becomes difficult to reduce nitrogen oxide emission. For this reason NO x storage/reduction (NSR) catalysts have been developed. While engines are operating under lean conditions alkaline or alkaline-earth component of NSR catalysts capture nitrogen oxides and during fuel rich period stored nitrates are reduced to nitrogen and oxygen gases. To develop this technology, different system parameters, for example system components and reaction environments have been widely investigated experimentally. To supplement the experimental findings, binding energies and structural properties of NO x on different catalyst components have been investigated theoretically. It has been experimentally observed that adding TiO2 to other conventional support materials increases resistance against sulfur poisoning, which is one of the main problems concerning NSR catalysts. For this reason, in this thesis (001) and (101) anatase surfaces have been investigated. Moreover, the effects of barium oxide units and layers on the electronic properties of the (001) anatase surface have been studied. To observe the effects of TiO2 as a support component, interactions of NO2 and SO2 on the unsupported and anatase supported (100) BaO surfaces have been compared. A clear increase in sulfur resistance has been observed in the presence of TiO2 in the catalyst under certain conditions.

En esta tesis doctoral se ha optimizado el desarrollo de catalizadores basados en cobre y óxidos mixtos BaTiO3 con estructura perovskita para ser utilizados en la eliminación de los NOx, emitidos por los vehículos diésel, mediante el proceso de almacenamiento y reducción de NOx (NSR). La actividad de los catalizadores para el almacenamiento de NOx ha sido analizada en distintas atmósferas, en condiciones de temperatura programada y mediante ciclos de adsorción y reducción de NOx a distintas temperaturas. Además, se ha llevado a cabo un estudio mecanístico del proceso de almacenamiento de NOx y se ha probado el efecto de la incorporación en la estructura de otros cationes alcalinotérreos, en la resistencia al envenenamiento por SO2 del óxido mixto.

Esta tesis doctoral se ha centrado en el diseño y la síntesis de óxidos inorgánicos con estructura macroporosa altamente activos en la combustión de carbonilla y el control de emisiones de NOx mediante el ciclo NSR. Estos materiales, que incluyen óxidos mixtos de estroncio y titanio, óxidos de cerio, praseodimio y lantano, con y sin cobre en su composición, han sido estudiados para entender la relación entre las propiedades físico-químicas de los materiales y su comportamiento catalítico, de modo que se puedan diseñar catalizadores óptimos para cada aplicación.

High fossil fuel consumption in transportation and industry results in an increase of the emission of green-house gases. To preserve clean air, new strategies are required. The main intention is to decrease the amount of CO2 emission by using lean-burn engines while increasing the combustion efficiency and decreasing the fuel consumption. However, the lean-burn engines have high air-to-fuel ratio which complicates the reduction of the oxides of nitrogen, NOx . The emission of these highly noxious pollutants, NOx , breeds both environmental and health problems. Thus, new catalytic strategies have been steadily developed. One of these strategies is the NOx storage and reduction (NSR) catalysts. Since the reduction of the NOx under excess oxygen condition is very difficult, the NSR catalysts store the NOx until the end of the lean phase that is subsequently alternated with the rich-fuel phase during which the trapped NOx is released and reduced. To develop NSR technology, different storage materials, the coverage of these metals/metal-oxides, support materials, precious metals, temperature, etc. have been widely investigated. In this thesis, the (100) surface of BaO with dopants (K, Na, Ca and La), (100) and (110) surfaces of Li2O, Na2O and K2O are investigated as storage materials. In addition, alkali metal (Li, Na and K) loaded (001) surface of TiO2 (titania) anatase is investigated as a support material for the NOx storage and reduction catalysts. The main aim is to increase the sulfur resistance. The introduction of the dopants on the BaO (100) surface has increased the stability of the NO2 . The combination of local lattice strain and different oxidation state, which is obtained by the La doped BaO (100) surface, benefit both NO2 adsorption performance and sulfur tolerance. The binding energies of NO2 adsorption configurations over the alkali metal oxide (100) and (110) surfaces were higher than the binding energies of SO2 adsorption configurations. The stability of all of NO2 adsorption geometries on the alkali metal-loaded TiO2 (001) surface were higher than the stability of SO2 adsorption geometries. Increasing basicity enhanced the adsorption of NO2 molecule.

Pollution from automobile exhaust is one of the most major environmental problems because of increasing usage of engine technologies. Diesel and lean burn gasoline engines operate under oxygen rich (lean) conditions and they emit harmfull gases to the atmosphere (CO,CO2, NO, NO2). The control of NOx emission from exhaust has become a challenging issue in engine industry because of the worldwide environmental regulations. Therefore lean-burn NOx emission control technologies have been developed to reduce emission of harmfull gases from exhausts, and the NOx storage/reduction (NSR) catalysts is one of the most promising candidates to reduce the pollution caused by lean-burn engines. In NSR systems, NO from the emission is first oxidized to NO2 over noble metal sites (Pt, Rh, Pd) during lean-burn engine operation. After that NO2 is stored as nitrites and nitrates in alkali earth oxides (BaO,MgO, CaO) particles or monolayer which is well dispersed on a substrate (Gamma-Al2O3, TiO2, SiO2). Finally, stored NOx compound are broken into N2 and O2 on noble metal sites. The Pt/BaO/Gamma-Al2O3 system is one of the most popular subjects in literature both experimentally and theoretically since this system is known to be catalytically more active and ecient in interactions between NOx and Pt-BaO components are still not clearly explained. For this reason, in this thesis, the interaction between catalytic redox components, Pt and Rh, and the support material Gamma-Al2O3 and the eects of Pt and Rh in atomic and diatomic clusters forms on the adsorption of the NO2 molecule on the Gamma-Al2O3(100) surface have been investigated by using density functional theory (DFT).

Le catalyseur quatre voies est destiné à diminuer simultanément les émissions d'hydrocarbures, de monoxyde de carbone, d'oxydes d'azote et de suies par l'intermédiaire d'un seul monolithe catalytique. Plusieurs études sur ce type de catalyseur ont montré que la présence d'oxydes d'azote entraîne une diminution de la température d'oxydation des suies. Cependant, l'effet de la présence d'eau sur l'adsorption des oxydes d'azote n'est pas encore clair, surtout en présence de suies. Les travaux présentés dans ce manuscrit ont pour but de mettre en évidence l'influence de la présence d'eau et/ou de suies sur le fonctionnement de catalyseur "piège à NOx". Les résultats obtenus montrent que la présence d'eau entraîne une inhibition de la fonction oxydante du catalyseur, une diminution de la quantité de stockage des oxydes d'azote, et une inhibition de la formation des espèces adsorbées de surface. Ces phénomènes ont été attribués à la voix réactionnelle spécifique en présence d'eau associée à l'adsorption des oxydes d'azote. Les résultats obtenus sur le mélange noir de carbone et catalyseur montrent que la présence de noir de carbone induit une diminution de stockage des oxydes d'azote. De plus, cet effet se trouve plus important en contact fort. Les expériences réalisées sur l'adsorption des oxydes d'azote en présence simultanée de noir de carbone et d'eau ont montré un effet non cumulé de l'eau et du noir de carbone. Ce phénomène a été attribué à une compétition entre l'action de l'eau qui favorise la formation de nitrate de cœur à partir des nitrates faiblement liés et l'action du noir de carbone qui tend à déstabiliser les nitrates faiblement liés pour former les carbonates.

The aim of this thesis was to study the Baltic Sea Region (BSR) Programme and the North Sea Region (NSR) Programme within the Transnational Interreg IV B Programme for the period 2007-2013, by making a comparison between Sweden and Denmark. The thesis looked at the level of involvement of both National Planning Authorities in the designing process of the programmes and projects, and investigated whether the Interreg programmes influence the authorities in their work with future policy-making, and the national spatial planning policies in general. The ambition of the thesis was also to clarify the links between the Interreg Programmes, the ESDP document, the Territorial State and Perspectives of the European Union and the Territorial Agenda, and how these documents have influenced the EU Territorial Cohesion debate and the creation of the EU Baltic Sea Strategy. The reason was to better understand the role of the National Planning Authorities in the implementation of the transnational programmes and their work towards territorial cohesion. The methods used for the thesis consisted of secondary research and analysis of the intergovernmental “Territorial Documents”, the Interreg programmes and their specific projects, and not least, the study of books, articles, and other documents and sources of interest for this topic. Interviews were made with people working at Swedish “Boverket”, Danish “By- og Landskabsstyrelsen” (BLST) and “Danske Regioner” (Danish Regions). Some of the main findings have been the different approaches among the Planning Authorities towards their potential leadership in the Interreg projects, the little time dedicated to the Interreg work in general at Swedish Boverket, and Boverket’s scarce intervention in the development-process of the EU Baltic Sea Strategy. On the Danish side there is very little priority given to the diffusion and transfer of knowledge, while in Sweden on the other hand, this is one of the main issues for all the authorities involved. The conclusion is that, even if Sweden and Denmark are close neighbours and are collaborating in many fields, there are some substantial differences in attitude and action towards their role as participators of the Transnational Interreg projects, differences which, if emphasised, could be useful knowledge for both parts in order to develop their own Interreg-work, responding to the growing interest of the EU in territorial concerns. / m.bengtsson@tiscali.it

L’objectif de ce travail était de démontrer la possibilité de coupler sur un même catalyseur, la fonction de stockage et réduction des NOx (sur le baryum) avec un effet électrochimique reposant sur un système micropile. Ce système micropile est composé de nanoparticules catalytiques (Pt et Rh) déposés sur conducteur ionique par les ions O2- (YSZ) en contact avec un support conducteur électronique (SiC dopé) de façon à pouvoir générer, sous mélanges réactionnels, une force électromotrice capable de réduire électrochimiquement une partie des NOx sur le Pt et d’oxyder le CO, les hydrocarbures imbrûlés et H2 sur le Rh. L’effet micropile a été observé sur un catalyseur Pt/Ba (matériau de stockage)/YSZ/Rh enduit dans les canaux d’un filtre à particule en carbure de silicium dopé, en condition essence pauvre à 400°C et en condition Diesel à plus basse température (300°C). Une augmentation de la conversion des NOx d’environ 10% a été observé sur les catalyseurs micropile. L’effet électrochimique a été détecté par une surproduction de CO2, en milieu riche (très peu ou pas de O2) provenant de la réaction d’oxydation électrochimique du CO (produit par vaporeformage) en réagissant avec les ions O2- provenant de YSZ. De plus, des tests catalytiques ont montré que YSZ peut être utilisée comme matériau de stockage des NOx. En effet, un traitement réducteur préalable augmente fortement sa capacité de stockage des NOx / The main objective of this study was to demonstrate the coupling between NOx storage/reduction process on barium, with an electrochemical reduction of NOx (micro fuel cell effect) on the same catalyst. The micro fuel cell effect is ensured by a an electromotive force (potential) which is created between catalytic nanoparticules (Pt and Rh) in contact with an ionic conductor (YSZ) and an electronic conductor (doped SiC). The micro fuel cell effect was observed, during the regeneration phase of the catalysts (rich period), on a Pt/Ba/doped α-SiC-YSZ/Rh monolithic system under lean-burn gasoline conditions at 400°C with an enhancement of about 10 % of the NOx conversion over a complete cycle lean/rich. This electrochemical effect was characterized by the electrochemical oxidation of CO (produced by steam reforming) into CO2 by using O2- ions coming from YSZ. Under Diesel conditions, the micro fuel cell system was found to work at low temperature especially at 300°C. In the second part of the work, a new generation of NOx Storage and reduction catalyst was developed consisting only of noble metals (Pt and/or Rh) deposited on YSZ support (Ba free catalyst). The catalytic measurements revealed that YSZ can be used as a NOx storage material in lean burn conditions (Gasoline and Diesel) especially when it was previously reduced under hydrogen. The storage mechanism would take place on the oxygen vacancies created by the removal of O-2 ions from the YSZ structure

The new fact that the environment is becoming the main factor of geopolitical transformations in the Arctic region has been triggered mainly by climate change. In the North, this recent aspect of geopolitics, in correlation with the environment, leads sometimes to tensions between countries, but also to a need for cooperation. The question brought by such conditions is, to which extent will this climate change provoke cooperation or conflicts between the Arctic states. The purpose of addressing the problem is to understand what kind of challenges would be facing the international relations between circumpolar countries and how the environment is playing a geopolitical role in them. The objective of the main research question is to assess the importance of climate change over the geopolitics of the Arctic through several spheres of geopolitics: environment and bio-diversity, economic activity of the region, sovereignty and territoriality, security of the circumpolar states, and international and diplomatic relations. The trans-border and transnational nature of environmental issues is another important factor, since nature does not respect human-made boundaries and an environmental concern, such as climate change and its aftermaths, cannot be exclusive to a state along the lines of its borders.