Parmi les procédés de conversion de la biomasse, la gazéification à l’air présente l’avantage d’un rendement de conversion électrique attractif, en particulier pour les petites puissances. Cependant, l’élimination des goudrons générés reste un verrou à lever pour permettre l’émergence industrielle du procédé de gazéification. Le traitement par absorption est considérée comme technologiquement mature mais le choix du solvant de lavage, sa gestion et l’optimisation du laveur représentent un élément crucial. Afin de mettre en avant les solvants envisageables, une méthodologie rapide et robuste de choix de solvant basée sur une analyse multicritère a été développée. La comparaison de plus d’une centaine de solvants conventionnels a permis de mettre en avant deux solvants. Afin d’étudier des performances de ces solvants, un pilote de lavage de type Venturi (laveur compact présentant une aire interfaciale importante et peu de risque d’encrassement) a été dimensionné et caractérisé. L’étude expérimentale sur gaz réel a permis d’une part d’étudier l’évolution de la charge en goudron dans le solvant et d’autre part de mesurer les efficacités de traitement des solvants sur le benzène, le naphtalène, l’anthracène et le pyrène. Ces données expérimentales ont ensuite été utilisées afin de valider la modélisation du laveur Venturi effectuée dans l’optique d’une optimisation et d’une extrapolation à l’échelle industrielle de l’unité de lavage. Afin d’estimer le coût de traitement en €/MWh, le dimensionnement des équipements à l’échelle industrielle a été effectué pour les deux solvants dans différents cas de figure afin d’effectuer leur évaluation technico-économique. / Among biomass conversion processes, air gasification has the advantage of an attractive electrical conversion yield, especially for small powers. However, the elimination of the generated tar remains a lock to lift to allow the industrial emergence of the gasification process. The treatment by absorption is considered to be technologically mature but the choice of cleaning solvent, its management and the optimization of the scrubber represent a crucial element. In order to highlight possible solvents, a fast and robust solvents screening methodology based on a multi-criteria analysis was developed. Comparison of more than 100 of conventional solvents allowed to forward two solvents. To investigate performance of these solvents, a pilot scale Venturi scrubber (compact scrubber with a large Interfacial area and low risk fouling risk) has been designed and characterized. The experimental study on real raw gas allowed to study the evolution of the tar loading factor in the solvent and to measure treatment efficiencies of solvents on benzene, naphthalene, anthracene and pyrene. These experimental data were then used to validate the modelling of the Venturi scrubber in the context of optimization and extrapolation on the industrial scale of the washing unit. In order to estimate the cost of treatment in €/ MWh, the sizing of the equipment on an industrial scale has been made for two solvents in different cases in order to process to a technico-economical evaluation.

The Barton Springs salamander (Eurycea sosorum) is a federally endangered species that is endemic to Barton Springs in Austin, Texas. Development within the Barton Springs watershed threatens the continued existence of E. sosorum. A factor that may be contributing to its decline is contamination from polycyclic aromatic hydrocarbons (PAHs). Nearby asphalt parking lots paved with coal-tar and asphalt sealants can be sources of PAHs. Unaltered parent compounds of PAHs can have toxic effects, but oxidation and ultraviolet radiation can create degradation products 100 times more toxic than the parent compounds. The objective of this project was to determine if PAHs are potentially harmful to E. sosorum using two surrogate species. Adult eastern newts (Notophthalmus viridescens) and larval spotted salamanders (Ambystoma maculatum) were exposed to sediments with nominal concentrations of total PAHs that ranged from 0 to 1500 mg/kg under UV (290 - 400 nm) and visible (400 - 700 nm) light to determine concentration/response relationships. No statistically significant mortality occurred under any treatment. Exposure to both coal-tar sealant and UV light resulted in sublethal effects such as decreased righting ability and swimming speed. Difficulty in performing such movements would make it difficult to catch prey and increase susceptibility to predation. Exposure to UV light also resulted in elevated numbers of micronucleated erythrocytes and white blood cells. This study shows that simultaneous exposure to PAHs and UV light result in sublethal effects that could make the population of E. sosorum vulnerable to further decline.

La conversion thermochimique à haute température (>700°C) de la biomasse en double lit fluidisé circulant est une voie alternative aux énergies fossiles (pétrole, charbon) pour la production d’un gaz de synthèse à haute valeur énergétique, utilisable dans de nombreuses applications. L’objectif de cette thèse est de développer des méthodologies et des outils théoriques et expérimentaux permettant d’accéder aux cinétiques des transformations élémentaires (pyrolyse de la biomasse, gazéification et combustion du char, craquage et reformage des goudrons) présentes dans le procédé de gazéification de la biomasse en double lit fluidisé circulant. Dans un premier temps, un mini-réacteur à lit fluidisé fonctionnant entre 300 et 1000°C avec une alimentation en gaz parfaitement contrôlée (N2, O2, H2, H2O et goudrons) a été conçu et mis au point au Laboratoire de Génie Chimique de Toulouse. Un système d’échantillonnage et d’analyse de la phase gaz permet de quantifier en continu les fractions molaires des gaz incondensables et des goudrons produits. Une étude hydrodynamique et thermique a permis de déterminer les points de fonctionnement du réacteur pour chaque transformation élémentaire étudiée. Dans un second temps, les études de gazéification et de combustion du char ont été réalisées dans le mini-réacteur à lit fluidisé. L’influence de nombreux paramètres opératoires (température, pression partielle des différents constituants) a permis de comprendre la formation des différents produits et de modéliser les cinétiques de transformation du solide. Dans le cas de la combustion du char, un mécanisme réactionnel a également été établi et la cinétique obtenue en lit fluidisé a été comparée à celle déterminée par analyse thermogravimétrique. Enfin, une étude sur le reformage d’un goudron modèle (toluène) en lit fluidisé a mis en évidence l’effet de l’atmosphère réactionnelle sur le mécanisme de dégradation du toluène sur l’olivine et le char. / The thermochemical conversion of biomass at high temperature (>700°C) in Fast Internally Circulating Fluidized Bed (FICFB) is a promising alternative route to fossil fuels (oil, coal) to produce syngas which can be used in several applications. The aim of the present work is to develop methodologies as well as theoretical and experimental tools for determining the intrinsic kinetic of biomass transformations (biomass pyrolysis, char gasification and combustion, cracking and reforming of tars). Firstly, a fluidized bed reactor has been designed and built at the Laboratory of Chemical Engineering (LGC). This reactor can operate for temperatures between 20 and 1000°C with a well-defined gas supply (N2, O2, H2, H2O and tars). A sampling and analysis gas system enables the continuous quantification of the non-condensable gases and tars molar fractions. A hydrodynamic and thermal study enabled the determination of the operating conditions for each experimental study. Secondly, the char gasification and combustion was performed in the fluidized bed reactor. The influence of the operating conditions (temperature and compounds partial pressure) led to the modelling of the different solid transformation kinetics. Besides, in the case of char combustion, a reaction scheme was proposed and the kinetic obtained in the fluidized bed was compared to that obtained in a thermogravimetric analyzer. Finally, a study on the tar reforming in a fluidized bed reactor highlighted the effect of the reactive atmosphere on the reaction scheme of toluene conversion over olivine and char.

In the spring of 2016, a wildfire consumed the boreal forest that encircles the municipality of Fort McMurray, Alberta. Notwithstanding the severity of the blaze, known as “The Beast,” attention turned to the community because of its link to Canada’s largest industrial project – the Athabasca tar/oil sands in northern Alberta. A moment of controversy erupted in May 2016 when commentary pinned the cause of the wildfire on climate change, a charge that was quickly judged insensitive. With this context in mind, Fort McMurray holds scholarly value in the investigation of discourse related to today’s dominant form of energy – fossil fuels. Using a dataset of opinion discourse (N=40) sourced from four Canadian newspapers (The Globe and Mail, the National Post, the Calgary Herald, and the Edmonton Journal), this thesis presents a critical discourse analysis of how commentators and editorial boards articulated the relationship between the 2016 Fort McMurray wildfire and concerns about the tar/oil sands contribution to climate change. The opinion pages are free from the journalistic pressure of objectivity and thus offer a place for argumentative narratives to reside. As such, my analysis focuses on the use of storylines in the dataset to give meaning to the wildfire and the tar/oil sands industry. The analysis reveals that the storylines cast environmentalist groups as ideologically motivated radicals while the oil industry was positioned as Alberta’s economic champion, thereby fusing the petro-state with the common good.

Abstract Biomass gasification as a thermochemical treatment method is typically used for heat and power production. Instead of burning the producer gas, it can be converted to added-value products, i.e to fuels and chemicals. One such conversion is the catalytic Fischer-Tropsch synthesis (FTS) which converts synthesis gas to a chain of aliphatic hydrocarbons (FT diesel) as studied in this thesis. This requires, however, proper cleaning steps of producer gas, such as the removal of tar compounds and other impurities. These cleaning steps are not considered in this thesis. The first goal of the thesis was to determine the tar content in the producer gas from a small scale biomass gasifier. This subject is discussed in Paper I. The second and main goal of the thesis was the preparation and characterization of cobalt (or iron) catalysts for catalytic conversion of a gas mixture close to the synthesis as discussed in Papers II-V. The overall aim of the second part was to study the effects of promoters on the reducibility of cobalt and the effects of different calcination conditions on the degree of reduction and size of the metallic cobalt particles. In this later part different catalytic supports were used. According to the results of the thesis, naphthalene and toluene were the main tar compounds in the producer gas representing almost 80 % of the GC detected tar compounds. Only traces of polycyclic aromatic compounds were detected and no phenolic compounds were found in the gas. Further, a number of supported heterogeneous catalysts for FTS using cobalt (Co) or in some cases iron (Fe) as the active metal were prepared and characterized. These catalysts were supported on alumina (Al2O3), titanium dioxide (TiO2) or silicon carbide (SiC). Catalysts were promoted with Ru, Re or Rh in the concentrations of 0, 0.2, 0.5, and 1.0 mass-%. Several characterization methods (such as H2-TPR, catalytic activity measurements, N2 physisorption, CO chemisorption, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD)) were used to find answers to the behaviour of these catalysts under selected conditions and in the model reaction of FTS. Based on the results, there are significant differences in the characteristics of the catalysts, the differences are dependent of the supports used, promoters added and calcination conditions used. The properties of the support, especially the pore size distribution will effect the distribution of products formed in the Fischer-Tropsch synthesis. Addition of promoters and variatons in calcination conditions will effect the dispersion and the particle size of the active metal. / Tiivistelmä Biomassan kaasutus on termokemiallinen prosessi, jota käytetään pääosin sähkön- ja lämmöntuotannossa. Polton sijaan kaasutuksessa muodostuva synteesikaasu voidaan puhdistaa ja hyödyntää edelleen katalyyttisesti polttoaineiden ja kemikaalien valmistuksessa. Eräs mahdollisuus synteesikaasun hyödyntämiseen on Fischer-Tropsch synteesi (FTS), jossa koboltti- tai rautakatayyteillä voidaan tuottaa alifaattisia hiilivetyketjuja (FT-dieseliä), mitä on tutkittu tässä työssä. FT-synteesi vaatii kuitenkin puhtaan tuotekaasun ja sen vuoksi tervayhdisteet ja muut epäpuhtaudet on poistettava kaasusta. Kaasun puhdistusta ei ole kuitenkaan tutkittu tässä työssä. Työn ensimmäisenä tavoitteena oli määrittää biomassan kaasutuksessa käytettävän pienikokoisen myötävirtakaasuttimen kaasun koostumus ja tervayhdisteet ja niiden pitoisuudet (julkaisu I). Toisena, ja tämän työn päätavoitteena oli Fischer-Tropsch -synteesissä käytettävien koboltti- ja rautakatalyyttien valmistus ja karakterisointi sekä käyttö synteesikaasun katalyyttisessä konvertoinnissa (julkaisut II-V). Erityisesti tutkittiin promoottorimetallien ja kalsinointiolosuhteiden vaikutusta koboltin pelkistymiseen ja kobolttimetallipartikkelien kokoon. Lisäksi tutkittiin ja vertailtiin erilaisia tukiaineita. Työn tulosten perusteella naftaleiini ja tolueeni olivat pääasialliset tervayhdisteet myötävirtakaasuttimen tuotekaasussa ja niiden osuus oli yli 80 % kaasukromatografisesti havaittavista tervayhdisteistä. Lisäksi havaittiin pieniä määriä polysyklisiä aromaattisia yhdisteitä, kun taas fenolisia yhdisteitä ei havaittu tuotekaasussa. Työssä valmistettiin ja karakterisoitiin lukuisa määrä erilaisia FT-katalyyttejä, joissa aktiivisena metallina oli koboltti tai rauta. Katalyyteissä tukiaineena oli alumiinioksidi (Al2O3), titaanidioksidi (TiO2) tai piikarbidi (SiC) ja promoottorimetallina joko Ru, Re tai Rh (pitoisuudet 0, 0.2 tai 1.0 massa-%). Katalyyttien karakterisointiin käytettiin useita menetelmiä, kuten H2-TPR, N2-adsorptio, CO-kemisorptio, XPS, XRD ja lisäksi määritettiin katalyyttien aktiivisuus ja selektiivisyys valituissa olosuhteissa FT-synteesin mallireaktioissa. Tulosten perusteella katalyyttien välillä havaittiin selkeitä eroja riippuen käytetystä tukiaineesta, promoottorista ja kalsinointiolosuhteista. Tukiaineen ominaisuudet, erityisesti huokoskokojakauma vaikuttavat FT-synteesin tuotejakaumaan. Promoottorien lisäys katalyyttiin sekä kalsinointiolosuhteet vaikuttavat lisäksi dispersioon ja aktiivisen metallien partikkelikokoon.

Ce travail de thèse a comporté deux parties distinctes : l'une porte sur l'étude du complexe TAR/Tat/cycline T1 impliqué dans la transactivation de la transcription de l'ARN du virus HIV-1, l'autre concerne différentes facettes de la régulation de l'épissage de l'ARN du virus HIV-1. L'interaction de la protéine virale Tat avec l'élément TAR présent à l'extrémité 5' des ARN du virus HIV-1 d'une part, et la cycline T1, composant du complexe p-TEFb responsable de l'hyperphosphorylation de l'ARN polymérase II d'autre part, est primordial pour obtenir des ARN viraux de pleine longueur. Dans l'objectif de réaliser une étude structurale du complexe TAR/Tat/cycline T1, l'ARN TAR et un fragment de la cycline T1 ont été produits en grandes quantités. De nombreuses tentatives de complexation des trois partenaires (TAR, Tat et cycline T1) ont été effectuées, mais la qualité des cristaux n'était pas suffisante pour une étude radiocristallographique du complexe. L'épissage est une étape majeure du cycle de multiplication du virus HIV-1. Son ARN comporte 5 sites donneurs et 8 sites accepteurs dont l'utilisation combinée permet la production des 9 ORF virales. Les variations de l'épissage alternatif de l'ARN du virus HIV-1 en fonction de l'expression de protéines virales Tat et Nef ont été étudiées. Nous avons par ailleurs étudié l'effet des protéines SR sur l'utilisation des sites accepteurs A2 et A3. L'étude fine de l'élément régulateur ESEt du site A3 a révélé l'implication de la protéine SR 9G8 dans le schéma complexe de régulation de ce site. / This work of thesis contained two different parts : the one concerns the study of the TAR/Tat/cycline T1 complex involved in the transactivation of the transcription of the HIV-1 RNA, the other one concerns various facets of the regulation of the splicing of the HIV-1 RNA. The interaction of the viral protein Tat with the TAR element present in the 5 ' extremity of the HIV-1 RNA on one hand, and the cycline T1, composing of the complex p-TEFb responsible for the hyperphosphorylation of the RNA polymerase II on the other hand, is essential to obtain viral RNA of full length. In the objective to realize a structural study of the complex TAR/Tat/cycline T1, TAR RNA and a fragment of the cycline T1 were produced in appropriate quantities. Numerous attempts of complexation of three partners (TAR, Tat and cycline T1) were made, but the quality of crystals was not sufficient for a radiocristallographic study of the complex. Splicing is a major stage of the cycle of reproduction of the virus HIV-1. His RNA contains 5 donor splice sites and 8 acceptor splice sites whose combined use allows the production 9 viral ORF. The variations of the alternative épissage of HIV-1 RNA according to the expression of viral proteins Tat and Rev were studied. We besides studied the effect of proteins SR on the use of acceptor splice sites A2 and A3. The fine study of the regulating element ESEt of the site A3 revealed the involvement of the SR protein 9G8 in the complex regulation of this site.

Les goudrons, composés lourds limitant le fonctionnement optimal des procédés thermochimiques de valorisation de la biomasse, ont été étudiés pour mieux comprendre leur formation, leur maturation et leur décomposition. L’étude détaillée de la décomposition des trois molécules modèles représentant les goudrons issus de la biomasse a été réalisée en réacteur auto agité par jets gazeux. Les molécules étudiées étaient l’anisole et le guaiacol, représentant les goudrons primaires issus de la lignine ainsi que le 5-méthylfurfural représentant les goudrons primaires issus de la cellulose. L’étude expérimentale de pyrolyse et d’oxydation a été réalisée à pression atmosphérique, pour un temps de passage de 2 s, à haute dilution et sur une large gamme de températures. L’oxydation a été étudiée dans les conditions stœchiométriques ([phi]=1). Les produits de réaction pour chacun des composés ont été quantifiés par chromatographie en phase gazeuse et identifiés par couplage avec la spectrométrie de masse. Des mécanismes cinétiques détaillés de pyrolyse et d’oxydation, basés sur un modèle de combustion des aromatiques légers, ont été développés pour toutes les molécules étudiées et validés à partir des résultats expérimentaux. Les trois modèles prédisent correctement la conversion des réactifs et la formation des produits majeurs. / Tars are compounds limiting the optimal operation of thermochemical processes of biomass conversion. The reactions of these compounds were studied to better understand their formation, maturation and decay. The study of the decomposition of three model compounds from biomass was conducted with a jet stirred reactor. The studied compounds were anisole and guaiacol, representing the primary tars from lignin and the 5-methylfurfural, representing the primary tars from cellulose. The pyrolysis and the oxidation of these compounds were performed at atmospheric pressure, at a residence time of 2 s and at high dilution, and for a wide range of temperatures. The oxidation was carried out in stoichiometric conditions ([phi]= 1). Reaction products were quantified by gas chromatography and identified using mass spectrometry. Detailed kinetic mechanisms for the pyrolysis and oxidation (based on a combustion model for light aromatics) have been developed for each compound. Models predict well the conversion of reactants and the formation of the main products.

This diploma thesis deals with impurities in waste gases and syngas. Those gases usually have low heating value and contain impurities which are the main issue of those gas fuels. Waste gases and syngas can replace natural gas after right gas treatment. First part is theoretical. It starts with description of biomass and gasification technology. Then the waste gases are described – their origin and usual composition. Next part is dedicated to impurities and is followed by impurities treatment technologies. For removing of almost every type of impurity wet scrubber can be used which is described in detail in following part. There are other types of gas cleaning technologies, so they are described too but not in such detail as wet scrubber. In second part the wet scrubber is designed, and its function is tested by cleaning syngas from fluidized-bed gasifier called Biofluid. During gas cleaning in wet scrubber the influence of water temperature on efficiency of tar removal is examined.

Gasification is a process which produces gas of low heating value, however, generated gas contains several pollutants. This thesis is dealing with the issue of purity and cleaning of generated gas. Theoretic part of thesis consists of research, describing the very process of gasification itself, mapping of possible pollutants appearing during gasification and particular ways of purifying gas, looking in detail at wet scrubbing with several scrubbing liquids. Further, it looks into proposition of conditions for wet scrubbing and balance of scrubbing liquids. Next part deals with calculation of purifying line. Main goal of calculations, is to determine the length of the pipeline, transfering polluted gas from the gasifier to the filter for elimination of solid particles and wet scrubber. Key aspect of length calculation was the input and output temperature of the gas, determined by characteristics of the filter. Calculation for wet scrubber istelf is also included, to detremine if the output temperature of the scrubbing liquid after the passage of the gas needs to be modified by additional cooling or heating. For experimental purposes, syngas generated by gasification of biomass, is gathered from the atmospheric gasifier Biofluid 2. Experiment itself inquires into the purity of the gas before and after the passage through solid particles filter and through the wet scrubber. The purpose of this thesis is to determine the chemical composition of gas before and after wet scrubbing, the difference of composition of tar gathered from purified and nonpurified gas and using gathered data to evaluate the effectiveness of wet scrubbing.

The aim of the diploma thesis is to discuss the gasification of biodegradable waste. The theoretical part deals with gasification with focus on gasification phases, types of gasification reactors and pollutants contained in the generated gas, especially tar. Further, there is listed the characteristic of alternative biomass fuels, namely digestate and sludge waste. The practical part is devoted to gasification on a fluidized bed reactor with the aim to test the possibilities of gasification of these fuels, to determine their specifications and the influence of various gasification media. In the final part there are discussed the results of the collected gases and tar.