Cette thèse s’inscrit dans le cadre général de la dépollution d’effluents gazeux faiblement chargés en Composés Organiques Volatils (COV). L’étude concerne l'oxydation de trois COV cibles (méthane, propène, et toluène) dans l'air à la pression atmosphérique dans d'une part un réacteur plasma de décharge à barrière diélectrique (DBD) pulsée et un réacteur catalytique utilisés séparément et d'autre part, dans un réacteur hybride associant le réacteur plasma aux catalyseurs dans deux configurations: le catalyseur au coeur de la décharge et le catalyseur en post-décharge. Les catalyseurs sont à base de Pd, Mn, Cu, et Co supportés sur des billes de Al2O3. Ils ont été caractérisés par ICP-OES, TEM/EDX, XRD, XPS, et DRIFTS. L’efficacité de conversion des COV, la sélectivité en CO/CO2, ainsi que la nature et les concentrations des produits formés pour les trois molécules avec les trois systèmes ont été étudiées en fonction de la température du gaz, de l'énergie injectée, de la concentration des COV, de la taille du support, du type de métal et sa teneur, et de la vitesse volumique horaire. Dans tous les cas, l’activation des catalyseurs à basse température a été démontrée quand ces derniers sont couplés au plasma et les principaux produits de réaction identifiés et quantifiés par spectroscopie infrarouge à transformée de Fourier. Le couplage plasma-catalyseur améliore de façon significative l’efficacité de conversion du méthane, du propène, et du toluène dans l’air ainsi que la sélectivité en sous-produits. L'effet de synergie entre le plasma et les catalyseurs pour la conversion des COV a été démontré dès lors que le plasma est généré directement au sein du réacteur catalytique. / The focus of this thesis is the application of non-thermal plasma and catalysis in chemical processing, in particular for the removal of Volatile Organic Compounds (VOC) diluted in air. In a first part, the oxidation of three pollutants (methane, propene, and toluene) is studied experimentally in a pulsed dielectric barrier discharge (DBD) reactor and in a catalyst reactor working independently. In a second part, a hybrid plasma-catalyst reactor either in a single-stage or in a two-stages configuration, in which the catalyst is located inside or downstream from the plasma reactor, respectively. Catalyst materials based on Pd, Mn, Cu, and Co supported on alumina beads were tested and characterized by ICP-OES, TEM/EDX, XRD, XPS, and DRIFTS. Products were analyzed and quantified by infrared spectroscopy. Achieved VOCs removal efficiencies and CO/CO2 selectivity, as well as nature and concentrations of the formed products, were evaluated as function of many factors, particularly the specific input energy, the gas temperature, the initial VOCs concentration, the nature of catalyst (size support, metal loading), and the hourly space velocity. It has been successfully demonstrated that the combination of plasma and catalyst in the both configurations has many benefits compared to traditional thermal-catalysis and plasma alone treatment including a lowering of the catalyst operating temperature, an improvement of the conversion of VOCs at similar temperatures, and a better end-products selectivity and energy efficiency. The mutual interaction lead to a synergistic effect in plasma-catalysis especially when the discharge is in direct contact with the catalyst whatever the VOCs studied.

M. Tech. (Chemistry Department, Faculty of Applied and Computer Sciences) Vaal University of Technology. / Benzene, toluene and xylene (BTX) are water pollutants that appear very often in chemical and petrochemical wastewaters due to gasoline leakage from storage tanks and pipelines. These BTX compounds can cause adverse health effects on humans even at very low concentrations. Amongst the available pollutant removal methods from wastewater, adsorption has been used due to its ease of operation, simplicity and cost-effectiveness. Different adsorbents have been used for BTX removal, however the use of Magnetite-organic acid composites as an adsorbent seems to offer a much cheaper alternative. This work seeks to develop a one-step microwave synthesis and optimization of magnetite-oleic (MNP-OA) and magnetite-palmitic (MNP-PA) acid) composites. Response surface methodology was used to optimize the magnetite-organic acid composites. The optimum conditions estimated for MNP-OA acid composite were 78.3 % Fe content, 1561.9 S/cm conductivity, 82.2, 84.1, 85.3 mg/g for BTX adsorption capacity. The MNP-PA composite were 75.6 % Fe content, 1325.66 S/cm conductivity, 60.55, 64.47, 63.06 mg/g for BTX adsorption capacity. The materials were characterized, and the adsorption process was optimized for BTX removal from aqueous solution. X-ray analysis confirmed the formation of magnetite by the presence of both ferric and ferrous ion states on the surface. It was noted that after modification, the magnetite-organic acids characteristics peaks became broad and the height of the peaks decreased indicating that surface modification with organic acid controls the crystallinity of the material. The average cystalline size of MNP, MNP-OA, and MNP-PA composites were 19.7, 17.1 and 17.9 nm. FTIR analysis confirmed the target materials were produced and also to determine if the organic acids were imobilised on the surface of the magnetite. TEM images presented that the MNP, MNP-OA, and MNP-PA composites were spherical in shape with particle average sizes of 18.4 ± 0.5, 15.6 ± 0.5 and 16.5 ± 0.5 nm. The magnetite-organic acids show the particles with better isolated as compared to that of the MNP. The BET isotherms of the materials were described by a type IV characteristic related to uniform mesoporous materials. The magnetic saturation value for MNP, MNP-OA, and MNP-PA composites were 62.9, 59.0 and 51.0 emu/g. The decrease in magnetization was explained by the presence of the non-magnetic layer on magnetite surface. The pHpzc of MNP, MNP-OA, and MNP-PA composites were 6.9, 6.4 and 6.1. The decrease in pHpzc aftern modification was due to the charging acid-base interaction mechanism of metal oxide nanoparticles. The optimum pH for the adsorption of BTX onto MNP, MNP-OA, and MNP-PA composites was determined to be pH 7 for benzene, pH 8 for toluene and xylene. Among the three pollutants, xylene had the highest adsorption capacity followed by toluene and benzene. The optimum adsorbent dose for the adsorbents for the adsorption process was 0.1 g/dm3. The effect of time on the uptake of BTX onto MNP, MNP-OA, and MNP-PA composites show that initial adsorption of BTX occured between 0 and 3 min of contact time. The effect of initial concentration results shows the initial concentration of BTX increases from 100 to 350 mg/dm3 with an increase in adsorption capacity. The results suggest that the adsorption process is controlled by concentration driving force. The experimental data was fitted to the pseudo-first and pseudo-second-order kinetic models for all adsorbents and all pollutants. The pseudo-second-order models showed good correlation as compared to the first-pseudo model. Desorption studies for benzene, toluene and xylene using the pure magnetite, magnetite-palmitic and magnetite oleic acid composites indicate adsorption mrchanism can be explained in relation to acid–base chemistry. Electron donation from the phenyl ring of each benzene, toluene and xylene compound to surface iron atoms of magnetite has been suggested. The CH3OH and H2O desorbing agents were used and regeneration using five cycles show that the percentage desorption decreses from Benzene < Toluene < Xylene. The reduction in adsorption capacity after the cycles are attributed to decomposition of the adsorbents active sites and mass loss of the sample.

No description available.

Increasing the efficiency of the spark-ignition engine can help to reduce the environmental impact of the transportation sector. Engine knock obstructs the increased efficiency that could be gained by increasing the compression ratio in a spark-ignition (SI) engine. A fuel’s propensity to knock is measured by the research octane number (RON) and the motor octane number (MON) in a co-operative fuel research (CFR) engine. A fuel’s octane sensitivity (OS) is the difference between the RON and MON. Modern downsized and turbocharged engines operate at what is considered to be beyond-RON conditions. Studies have shown that having a fuel with higher OS improves knock resistance at beyond-RON conditions. This study aims to gain a better understanding of the role of intermediate-temperature heat release (ITHR) in defining OS and its subsequent impact on SI operation through the experimental framework. The ITHR of toluene primary reference fuels (TPRFs) fuels with matching RON and varying OS was studied at RON-like and MON-like homogeneous charge compression ignition (HCCI) conditions for two different matching criteria. The first criterion was to control the combustion phasing by matching half of the heat release (CA50) to 3 crank angle degrees after top dead center. The second criterion was to match the compression ratios. Results showed that at RON-like HCCI conditions, TPRF fuels display decreasing ITHR with increasing OS. Furthermore, it was shown that TPRF fuels with low sensitivity displayed a greater increase in ITHR from MON-like conditions to RON-like conditions. Thus, the sensitivity of ITHR to changes in operating conditions was found to be a contributing factor to OS. In the beyond-RON conditions (relevant to current modern engines), there is a potential for improved engine efficiency by using fuels with high OS to allow for higher compression ratios. The experimental results of this work show that OS is negatively correlated with ITHR. Thus, high-sensitivity fuels can be designed by choosing components and additives that reduce the amount of ITHR.

This article studies the impact of some environmental conditions and the nutrition of culturing medium on the growth of bacteria and theirs capacity of toluene removal. The 5 bacterial strains isolated from leaf samples of three different common houseplants in Vietnam are Gram-negative, rod-shaped bacteria. The cells are single or arranged in chains. The cell size is relatively small and ranged from 0.7 to 2.5μm. These bacteria prefer the incubating temperature from 28°C to 32°C and a neutral pH 6.5 to 7.5. They are able to assimilate different nitrogen and carbon sources. In the liquid SH1 medium containing 200ppm toluene five selected strains have shown the ability to degrade toluene at a rate of 12.8 to 75.2% in comparison with the control at 30°C at a speed of 200rpm for over 120 hours. These 5 studied strains are potentially useful in bioremediation strategies to remove airborne toluene. / 5 chủng vi khuẩn có khả năng phân giải toluene được phân lập từ lá một số cây cảnh phổ biến ở Việt Nam là vi khuẩn G (-), dạng trực khuẩn và kích thước tế bào từ 0,7 – 2,5μm. Một số điều kiện môi trường nuôi cấy thích hợp cho 5 chủng vi khuẩn nghiên cứ gồm nhiệt độ 28°C-32°C, pH 6,5- 7,5, có khả năng đồng hoá nhiều nguồn nitơ và ba nguồn carbon khác nhau. Trong điều kiện môi trường dịch SH1 chứa 200ppm toluene, 5 chủng vi khuẩn này cho thấy khả năng phân giải toluene từ 12,8 – 75,2%. Đây là các chủng vi khuẩn có tiềm năng ứng dụng để loại bỏ toluene từ không khí ô nhiễm.

La contribution de l’inhalation et de la voie percutanée à l’exposition totale à des composés organiques volatils (COV) présents dans l’eau potable est une problématique qui suscite un intérêt grandissant en santé publique et au niveau réglementaire. Jusqu’à tout récemment, seule l’ingestion était considérée dans l’évaluation du risque des contaminants de l’eau. L’objectif de ce projet était de caractériser l’impact de l’exposition multivoie sur la pharmacocinétique et la dose interne de trois COV : le toluène (TOL), le n-hexane (HEX) et le cyclohexane (CYCLO). À cette fin, un modèle expérimental animal a été utilisé et un modèle toxicocinétique à base physiologique (TCBP) a été adapté pour le TOL. Des rats Sprague-Dawley ont été exposés par voies uniques (inhalation, orale et percutanée) ou simultanées (multivoie) aux solvants. Pour le TOL, les trois voies ont été expérimentées, alors que la voie percutanée n’a pas été retenue pour le HEX et le CYCLO. Des prélèvements sanguins ont permis de caractériser les cinétiques sanguines. Les niveaux sanguins, obtenus lors des expositions multivoies, étaient généralement plus élevés que la somme des niveaux associés aux expositions par voies uniques, fait illustré par le rapport des surfaces sous la courbe expérimentale versus les prédictions (TOL : 1,30 et 2,19 ; HEX : 1,55 ; CYCLO : 0,98 et 0,99). Le modèle TCBP prédit bien la cinétique du TOL lors d’expositions par voies uniques et par multivoies. Les données expérimentales obtenues suggèrent que la dose interne résultant d’une exposition multivoie ne peut pas toujours être prédite par la somme des doses internes obtenues lors d’expositions par voies uniques. Ce phénomène serait explicable par la saturation du métabolisme. La modélisation TCBP est un outil efficace pour l’estimation du risque relatif à l’exposition multivoie aux COV présents dans l’eau potable. / The contribution of dermal and inhalation routes of exposure to volatile organic chemicals (VOCs) in drinking water is increasingly drawing attention. Until recently, ingestion was the only route considered in risk assessment of drinking water contaminants. The general objective of this study was to characterize multi-route exposures on the pharmacokinetics and internal dose of three VOCs: toluene (TOL), n-hexane (HEX) and cyclohexane (CYCLO). Towards this goal, an experimental animal model was developed and a physiologically-based toxicokinetic (PBTK) model was adapted in order to take account route-specific absorption parameters of TOL. Sprague-Dawley rats were given a single dose of VOCs by oral ingestion, inhalation or dermal route. Additional groups of rat were exposed by the three routes simultaneously. In the case of HEX and CYCLO, dermal route was not considered. Blood samples were collected in order to compare kinetics following simple and multiroute exposures. Blood levels obtained following multiroute exposures were generally higher than predictions (i.e., the sum of the blood levels obtained for single route exposures) (as revealed by area under curve ratio: TOL :1,30 et 2,19; HEX : 1,55; CYCLO : 0,98 et 0,99). The PBTK model described adequately the kinetics of TOL in rats following single and multiroute exposures. The results suggest that internal dose arising from multiple routes is not necessarely comparable to the sum of the blood levels obtained for single route exposures. This phenomenon would be attributable to degree of saturation during aggregate exposures. Furthermore, the present study demonstrated that PBTK model can be used to predict/interpret blood levels associated with multiroute exposures to VOCs in drinking water, using toluene as a model substance.

Ces derniers temps, des procédés commerciaux basés sur la technologie photocatalytique, sont arrivés sur le marché, afin de satisfaire la demande croissante du traitement de l’air intérieur. L’objectif de ce présent travail est de développer une nouvelle méthodologie pour évaluer l’efficacité de ce nouveau procédé. Pour l’étude de l’application de la photocatalyse au traitement de l’air intérieur, un dispositif expérimental a été mis au point et deux méthodes analytiques ont été développées (ATD-GCMS et GC-PDHID). La performance de la dégradation photocatalytique du 2-propanol et du toluène à faibles concentrations (ppbv) a été étudiée. L’influence des différents paramètres (humidité relative, débit, concentration initiale, etc.) et leurs interactions sur la conversion, la formation des intermédiaires et la minéralisation au CO2 a été établie / Many commercial systems based in the photocatalytic technology have reached the market recently in order to address the growing demand for improve poor indoor air qualities. The present work deals with the development of a new methodology in order to evaluate the efficiency of this process. For the study of photocatalytic oxidation for indoor air applications, an experimental set-up was designed and two analytical tools (ATD-GC-MS and GC-PDHID) were developed. The performance of the photocatalytic treatment of 2-propanol and toluene at indoor air concentrations levels (ppbv) were realised. The influence of several parameters and their interactions effects on the conversion, by-product formation and mineralization to CO2 were established

La production de l'hydrogène à partir de biomasse est actuellement à l'étude mais la méthode de valorisation du biogaz (mélange H2/CO2) par réactions catalytiques, autres que la simple combustion, n'a pas encore été retenue. Par conséquent, le principal objectif de ce travail est d'explorer les autres voies. L'effet du CO2 sur le système catalytique est mal connu et seulement un effet négatif sur la dissociation de l'hydrogène a été mentionné. L'hydrogénation du toluène sur un catalyseur Pt a d'abord été étudiée sans CO2 pour suivre son comportement et éventuellement sa perte d'activité. En présence de CO2, l'inactivité complète du catalyseur pour l'hydrogénation du toluène a été mis en évidence. La modification de la surface du catalyseur par le CO2 est quantifiée par DRIFT et un mécanisme à deux sites a été montré. La réaction de Reverse Water Gas Shift produisant du CO se trouve être la principale cause de la désactivation de la surface de catalyseur avec le CO2. Donc la compétition d'adsorption entre le CO et des acides carboxyliques a été mise à profit pour favoriser sélectivement la conversion des acides. Pour l'alumine, elle est polluée par des carbonates complexes venant du CO2. La silice étant aussi connue pour promouvoir la décomposition, ces supports ont été rejetés. L'oxyde de titane a été utilisé pour catalyser une autre gamme de produits. Sur ce catalyseur, le changement de sélectivité entre le RWGS et la conversion de l'acide a été observé. Quant à l'oxyde de fer (catalyseur moins actif), il n’est pas capable de produire du CO à partir du CO2. La chimie de surface de l'oxyde de fer joue un rôle important sur la sélectivité du produit parmi les cétones et les aldéhydes. Un mécanisme à deux sites peut réutiliser pour l'oxyde de fer, montrant qu'un fonctionnement stable peut être trouvé si la réduction par l'hydrogène est continue. Si l'oxyde de fer est totalement oxydé par le CO2, produit de réaction, la production des cétones cesse. Énergiquement, le procédé de production d'acétone peut être autosuffisant et l'acétone peut être utilisée comme une molécule de stockage d'énergie. Le procédé va aussi compenser le nouveau procédé de production de phénol qui ne produit pas l'acétone / Hydrogen potential from biomass is currently being studied but ways of valorization of such biogas (H2/CO2 mix) via catalytic reaction, other than simply burning has not yet been considered. Thus the main objective of this work is the exploration of such methods. Effect of CO2 over catalytic system was not well known and only hydrogen dissociation inhibition is reported. Toluene hydrogenation over Pt catalyst is studied and activity loss transition behavior is observed with no CO2 where as complete catalyst inactivity for toluene hydrogenation is found in presence of CO2. Catalyst surface change by CO2 is quantified by DRIFT analysis and two-site mechanism is found to prevail. Reverse water gas shift reaction producing CO is found to be the main cause behind such catalyst surface response to CO2. Adsorption competition between CO and carboxylic acids is exploited for selectivity shift in favor of acids conversion. Alumina support is fouled by carbonates complexes with CO2 while silica is reported to promote decomposition, thus both were rejected and titanium oxide is used instead with a range of products produced. The required selectivity shift between reverse water gas shift and acid conversion is thus observed. Less active iron oxide catalyst further suppresses CO2 conversion. Iron oxide surface chemistry plays an important role over product selectivity among ketones and aldehydes. Two sites mechanism still prevails over iron and stable continuous operation requires simultaneous iron reduction via hydrogen, if totally oxidized by CO2–a reaction product, will cease to produce ketones. Energetically the process devised for acetone production is self sufficient and acetone not only act as an energy storage molecule but can also compensate new phenol production process producing no acetone

The proton exchange membrane fuel cell generates electricity from hydrogen and oxygen (from air) through electrocatalytic reactions in an electrochemical cell. The Pt/C catalyst, commonly used in PEM fuel cells, is very sensitive to impurities that can interact with the active catalyst sites and limit fuel cell performance. Unfortunately, most hydrogen is currently produced from fossil sources, and inevitably contains impurities. The subject of this thesis is the effect of hydrogen impurities on the operation of a PEM fuel cell using a Pt/C anode. The impurities studied are carbon monoxide (CO), carbon dioxide (CO2), and selected hydrocarbons. Particular focus is given to the interaction between the impurities studied and the anode catalyst. The main method used in the study involved performing cyclic voltammetry and mass spectrometry, simultaneously. Other electrochemical techniques are also employed. The results show that all the impurities studied adsorb to some extent on the Pt/C catalyst surface, and require potentials comparable to that of CO oxidation, i.e., about 0.6V, or higher to be removed by oxidation to CO2. For complete oxidation of propene, and toluene, potentials of above 0.8, and 1.0V, respectively, are required. The unsaturated hydrocarbons can be desorbed to some extent by reduction, but oxidation is required for complete removal. Adsorption of ethene, propene, and CO2 is dependent on the presence of adsorbed or gaseous hydrogen. Hydrogen inhibits ethene and propene adsorption, but facilitates CO2 adsorption. Adsorption of methane and propane is very limited and high concentrations of methane cause dilution effects only. The adlayer formed on the Pt/C anode catalyst in the presence of CO2, or moderate amounts of hydrocarbons, is found to be insffuciently complete to notably interfere with the hydrogen oxidation reaction. Higher concentrations of toluene do, however, limit the reaction. / Polymerelektrolytbränslecellen genererar elektricitet fran vätgas och syrgas (fran luft) genom elektrokatalytiska reaktioner i en elektrokemisk cell. Den platina-baserade katalysator som oftast används i dessa bränsleceller är känslig mot föroreningar, då dessa kan interagera med katalysatorns aktiva yta, och därmed begränsna bränslecellens prestanda. Tyvärr produceras dagens vätgas huvudsakligen fran fossila källor och innehåller därför oundvikligen föroreningar. Denna avhandling behandlar hur olika vätgasföroreningar påverkar katalysatorns aktivitet och bränslecellens drift. De föroreningar som studeras är kolmonoxid (CO) och koldioxid (CO2), samt ett antal mindre kolväten. Störst fokus ligger på hur dessa föroreningar interagerar med anodens Pt/C katalysator. Den metod som huvudsakligen används är cyklisk voltammetri kombinerat med masspektrometri, men flera elektrokemiska metoder har använts. Resultaten visar att alla undersökta föroreningar adsorberar på Pt/C katalysatorns yta i större eller mindre utstreckning. For att avlägsna det adsoberade skiktet genom oxidation till CO2 krävs potentialer jämförbara med CO oxidation, dvs ca 0,6V, eller högre. Fullständig oxidation av propen eller toluen kräver potentialer högre än 0,8V respektive 1,0V. De omättade kolvätena kan delvis avlägsnas genom reduktion, men fullständig avlägsning kräver oxidation. Närvaron av väte, i gasform eller adsorberat pa katalysatorn, hämmar adsorptionen av eten och propen, men främjar CO2 adsorption. Metan och propan adsorberar i mycket begränsad utstreckning på Pt/C katalysatorns yta. De prestandaförluster som uppstår av höga koncentrationer av metan förklaras av utspädning av vätgasen. Det adsorberade skiktet som bildas när Pt/C katalysatorn exponeras för CO2 eller måttliga koncentrationer av studerade kolväten, är inte tillräckligt heltäckande for att märkbart påverka vätgasreduktionen. Däremot kan höga koncentrationer av toluen begränsa reaktionen. / <p>QC 20161010</p>

L'objectif est de produire un antioxydant puissant, l'acide 3,4-dihydroxyphénylacétique (3,4-DHPA) à partir de la L-tyrosine chez l'archée hyperthermophile et acidophile, Sulfolobus solfataricus 98/2. Les microorganismes extrêmophiles possèdent des enzymes particulièrement résistantes et intéressantes pour l'industrie.Des cultures ont donc été réalisées en fermenteur contrôlé dans 4 conditions : (i) en présence de glucose avec ou sans L-tyrosine, (ii) en présence de phénol avec ou sans L-tyrosine. Il a été montré que le 3,4-DHPA est synthétisé seulement en présence de phénol et de L-tyrosine. Les gènes codant pour les enzymes impliquées dans cette voie métabolique et potentiellement responsables de la synthèse du 3,4-DHPA ont été identifiés par homologie de séquence chez cette archée.Des études transcriptomiques et protéomiques ont donc été initiées pour confirmer ces hypothèses et tenter de caractériser les enzymes impliquées dans ces voies métaboliques. Plusieurs toluène-4-monooxygénases (T4MO) et une catéchol 2,3-dioxygénase, impliquées dans le métabolisme du phénol et potentiellement dans la voie de dégradation de la L-tyrosine ont été identifiées. Leur production est soumise à une régulation transcriptionnelle dépendant de la présence de phénol. L'analyse des régions génomiques correspondantes a permis de mettre en évidence une région consensus qui pourrait être impliquée dans la fixation d'un facteur de transcription lors de la régulation par le phénol. Ces différentes études ont permis, de déterminer d'une part dans quelles conditions le 3,4-DHPA est synthétisé, d'autre part d'identifier les enzymes qui interviendraient dans le métabolisme de la L–tyrosine. / The aim is to produce a powerful antioxidant, 3,4-dihydroxyphenylacetic acid (3,4-DHPA) from L-tyrosine in the hyperthermophilic and acidophilus archaea, Sulfolobus solfataricus 98/2. Extremophiles microorganisms have resistant enzymes and interesting for industry. Cultures have been carried out in controlled bioreactor four conditions: (i) in the presence of glucose with or without L-tyrosine, (ii) in the presence of phenol with or without L-tyrosine. It has been shown that 3,4-DHPA is synthesized only in the presence of phenol and L-tyrosine. The genes encoding enzymes involved in the metabolic and potentially responsible for the synthesis of 3,4-DHPA pathway have been identified by sequence homology in S. solfataricus.Des transcriptomic and proteomic studies have therefore been initiated to confirm these hypothesis and attempt to characterize the enzymes involved in these pathways. Several toluene-4-monooxygenase (T4MO) and catechol 2,3-dioxygenase involved in the metabolism of phenol and potentially in the degradation pathway of L-tyrosine were identified. Their production is subjected to a dependent transcriptional regulation of the presence of phenol. The analysis of the corresponding genomic regions has highlighted a consensus region that could be involved in the binding of a transcription factor in the regulation of phenol. These studies helped to determine the one hand the conditions under which 3,4-DHPA is synthesized, secondly to identify enzymes that intervene in the metabolism of L-tyrosine.