Tesi sul tema "Procédé Fischer-Tropsch"
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Renaud, Nicolas. "Hydroisomérisation de n-paraffines : valorisation des effluents du Procédé Fischer-Tropsch". Montpellier 2, 2006. http://www.theses.fr/2006MON20188.
Fischer-Tropsch process allows to obtain high quality lubricant bases and clean fuels from natural gas. In this goal, the n-paraffins produced have to be upgraded through a hydroconversion step aiming the isomerization of chains. In order to better understand the mechanisms involved, different bifunctional catalysts have been studied for the hydroconversion of n-hexadecane on a lab-scale trickle bed reactor. These catalysts are : a benchmark Pt/EMT, two commercial catalysts (Pt-Pd/SiO2-Al2O3), tungstated zirconias, as well as a new class of mordénite-based micro/mesoporous composite catalyst. A specific study highlighted the effects of mechanical treatments on activity and selectivity of tungstated zirconias. Relations between physico-chemical characterizations of the catalysts and their activities and selectivities for the hydroconversion of n-hexadecane were established
Lu, Mengnan. "New technology development for advanced "Clean" solid catalysts for Fischer-Tropsch synthesis". Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10108.
Fischer–Tropsch (FT) synthesis converts syngas into liquid hydrocarbons over cobalt catalyst for new ultraclean alternative fuels. The syngas can be produced from both fossil and renewable resources. The catalysts for FT synthesis are currently prepared by chemical ways like impregnation etc. All these routes involve toxic solvents and high temperature retreatment. Because of lower cost, reduced energy requirements and environmental pollution, the mechano-chemistry has a number of advantages for the synthesis of heterogeneous catalysis compared to conventional techniques. In this study, the mechano-chemical method was used to prepare alumina supported cobalt catalysts for FT synthesis. Differently to the conventional catalyst preparation, the deposition of active phase did not involve any solvent in the proposed method. The goal of this work is to obtain efficient FT catalysts and to simplify catalyst synthesis by reducing the number of preparation steps. The project involves innovative method of synthesis of catalysts in three different mechanical working processes in dry context. The process of mechano-chemistry to synthesize the catalyst for FT reaction was developed. The operating conditions for the control of the coating technique were identified through optimal conditions study by statistical analysis. Moreover, characterizations were studied to understand the basic mechanisms behind deposition of particles on the interface. Catalytic performance tests were estimated in a mili-fixed bed reactor; Optimization algorithm of parameters in a mechanical process was carried out via deriving target formula about energy and material size
Léonard, Stéphan. "Synthèse de Fischer-Tropsch en réacteur à alimentations séparées". Compiègne, 2001. http://www.theses.fr/2001COMP1359.
Norelus, Wesley. "Etude théorique de la réaction de fischer-tropsch : l'effet du support". Paris 6, 2013. http://www.theses.fr/2013PA066430.
The goal of this work is to study the well-known support effect in catalysis taking as an example the Fischer-Tropsch catalysis. We use a TiC(100) surface to support a an iron cluster, Fe4. When iron atoms are adsorbed, they tend to form a plat cluster and not to spread off along the surface. Carbon monoxide adsorption is modified by the support: the interaction strength between CO and the iron cluster is indeed larger in the presence of the support. In the case of supported cluster, C-O bound is more elongated, which shows an activation of CO. Then, the dissociation energy barrier for CO dissociation should be smaller on a supported Fe4 cluster than for free cluster. In addition, this study allows us to show that in our system, depending on the used functional, results can be different but the trends stay the same
Anfray, Jérôme. "Acquisition des données pour la modélisation d'une colonne à bulles Fischer-Tropsch". Lyon 1, 2005. http://www.theses.fr/2005LYO10249.
Barbier, Arnaud. "Préparation de nouveaux catalyseurs Co-SiO2 et réactivité en synthèse Fischer-Tropsch". Lyon 1, 1998. http://www.theses.fr/1998LYO10177.
Bedel, Laurent. "Structure et réductibilité de pérovskites La-Co-Fe : Application à la synthèse Fischer-Tropsch". Université Louis Pasteur (Strasbourg) (1971-2008), 2002. http://www.theses.fr/2002STR13075.
The FTS is one of the most interesting way to valorize the natural gas. After reforming the natural gas toward syngas (CO+H2), this process leads to the obtainment of sulfur-free hydrocarbons catalyzed by Coʿ and/or Feʿ. In this work, both Co and Fe have been integrated in a perovskite-type structure well known for its flexibility. LaCoxFe1-xO3 series was prepared by a sol-gel like method. Depending on the Co content x, perovskites crystallize either in the orthorhombic system if x<0. 5 or in the Rrhombohedral one if xđ0. 5. The reduction process study of these materials revealed that their partial reduction is possible and that only the orthorhombic perovskites allow the formation of Coʿ particles. During the reducing treatment the initial oxide crystalline structure is preserved. The extractable metal amount can be enhanced either by decreasing the calcination temperature of the raw oxide or by introducing, when preparing, a lanthanum deficiency in order to generate some defects in the crystalline lattice. The study by XRD and Mössbauer spectroscopy of the La(1-y)Co0. 4Fe0. 6O3-d series pointed out a core-shell phenomenon. The perovskite B cation excess is rejected through Fe as small size cores of g-Fe2O3 (cubic). On these cores crystallizes by epitaxy a cubic Co-rich perovskite-type phase without any La-deficiency. The partial reduction at 450ʿC of these nano-composites remains possible and generates a (Co-Fe)0 alloy in which the iron comes from the g-Fe2O3 cores reduction. An iron enrichment of the perovskite phase is observed during the reducing treatment. The partially reduced oxides catalytic reactivity has been studied under pressure with an on-stream set up. Catalysts are very selective toward light olefins formation, have a remarkable life time and produce a very few CO2 amount
Karaca, Héline. "Propriétés catalytiques et versatilité des catalyseurs à base de cobalt lors du procédé Fischer-Tropsch". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10070/document.
This PhD thesis focuses on the investigation of different phenomena which occur during activation of the industrial catalysts for Fischer-Tropsch synthesis and during the reaction under realistic conditions. The first approach was to study the impact of different operational and structural parameters on the catalytic performances. Various ex-situ characterization techniques combined with catalytic tests uncovered a few correlations between the catalyst structure and operating conditions. Nevertheless, because of limitations of ex-situ characterization, there remained a lack of information on the evolution of catalyst structure during the reaction. Then, an innovative operando study of the evolution of catalyst structure under reaction conditions in the Fischer-Tropsch process, which represents a significant experimental challenge due to the severe reaction conditions (high temperature, high pressure, multiphase environment ...), has fill this information gap.This work has finally revealed the significant versatility of studied solids in the Fischer-Tropsch process, and provided new insights into understanding catalyst activation and deactivation phenomena such as cobalt reduction/oxidation, sintering or carbidization of the metallic phase often discussed in the literature
Chakkingal, Anoop. "Réglage de la sélectivité de la synthèse Fischer-Tropsch : aperçu de la modélisation microcinétique et de l'apprentissage automatique". Electronic Thesis or Diss., Centrale Lille Institut, 2022. http://www.theses.fr/2022CLIL0015.
Striving towards a circular economy has led to the re-investigation of many existing processes, with the target of developing more sustainable variants. In our present economy, plastics form an important and omnipresent material affecting our daily lives. They are inexpensive, durable, corrosion resistant, and light weight leading to their use in a wide variety of applications.Within the plastic chemical recycling scheme, Fischer-Tropsch synthesis (FTS) could play a key role as the syngas feedstock that is converted in it, can be generated via the gasification of the considered plastics. This syngas is then chemo-catalytically converted into hydrocarbons such as paraffins and light olefins. Typical FTS catalysts are based on supported cobalt or iron species.Among the mechanistic kinetic models, the comprehensive variant based on the Single Event MicroKinetics (SEMK) concept has been widely applied in the field of oligomerization, autoxidative curing, etc. and has proven to be a versatile tool to simulate Fischer-Tropsch synthesis. However, developing mechanistic models for every chemical engineering challenge is not always feasible due to their complexity and the in-depth knowledge required to build such models.A detailed evaluation on the potential of using machine learning approaches to match the performance of results obtained using the Single-Event MicroKinetic model was carried out. Initially, the focus was on a single dominant output scenario (methane selective catalyst). The current work thus shows that more widely applied techniques in data science can now be applied for systematic analysis and interpretation of kinetic data. Similar analysis using experimental data can also help experimenters in their preliminary analysis, to detect hidden trends in the data, and thus to identify importance features. After gaining confidence on the investigated interpretation techniques, for the FTS reaction with single dominant output, a similar investigation on the potential of iron based catalysts with enhanced light olefin selectivity is carried out next
Tymowski, Benoît de. "Fischer Tropsch synthesis on conductive silicon carbide based support". Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAF019/document.
The Fischer-Tropsch synthesis (FTS) allows the transformation of a mixture of synthesis gas, i.e. H2 and CO, into valuable liquid hydrocarbons. The catalysts generally used in FTS are based on iron or cobalt supported on alumina or silica. ln the present work, silicon carbide (SiC) has been proposed as a replacement media to traditional supports. The results obtained indicate that the mesoporous SiC containing cobalt catalyst exhibits a good FTS activity and an extremely high selectivity towards liquid hydrocarbons compared to other FTS catalysts supported on alumina or silica. The FTS activity on the Co/SiC catalyst can be improved by changing the impregnation solvent or by promoting the cobalt phase with trace amount of noble metal. The doping of the SiC support with Ti02 phase also significantly improves the FTS activity keeping a similar high selectivity thanks to the formation of small cobalt particles in contact with the Ti02 phase
Helali, Zeineb. "Etude de la coadsorption de H et CO sur une série de méteaux supportés par le rutile TiO2 (110)". Paris 6, 2013. http://www.theses.fr/2013PA066089.
We propose a fundamental study aimed to determine the most favorable thermodynamically first step of the Fischer-Tropsch reaction based on the nature of M =K…Zn. The results showed that M interacts more strongly with the TiO2(110) perfect surface. We have examined in detail the electronic structures by applying a Hubbard correction. This allowed us to have more localized states. This correction does not influence by much the interaction if the penalty applied remains moderate. Therefore, we concluded that the energetic study which will be conducted later will be in PW91 and using the perfect surface as a support. The H adsorption on these supported metals showed that a strong M-H interaction requires at least two electrons available for the transfer. In the case of the CO adsorption, the interaction force increased particularly for Cr and Cu : the support can empty antibonding levels of M and stabilizes the interaction. We have also studied the formation of hydrogenated complexes, HCO and HOC, which may be a beginning or an end of this catalysis. We have shown that the elementary first step depends on the nature of the metal. For Sc, Ti and V, the most likely mechanism is the hydrogenation of CO in the first place followed by the dissociation of the CO bond. On the contrary, for M = Fe- Ni, this mechanism seems to be more difficult. Finally, we proposed a new methodology to improve the modeling of TiO2 slab. We have therefore proposed a saturated slab of the unreactive side by a dissociated H2O molecule. The results showed a significant reduction of the allowing faster convergence compared to other models proposed in the literature
Saidane, Lamia. "Synthèses Fischer Tropsch : Optimisation des paramètres réactionnels en mode lit fixe". Strasbourg, 2009. http://www.theses.fr/2009STRA6150.
In the GTL process, the FTS is the step which transforms the syngas into liquid HC. In catalysis, the interest of using Co/SiC was demonstrated. This work consists in studying the influence of parameters: Treduction, promoters or the nature of the support on the activity. Modifications of the active phase particles size, its reducibility as well as its crystallinity are followed by diverse characterization techniques: XRD, TPR and SEM. The Ru effect on the Co/SiC system enhanced the Co dispersion and consequently the activity. In order to illustrate the best macroscopic shape of β−SiC (foam, pellets and powder), a comparative study on supports was also realized. A second study deals with the chemical nature of supports eg. SiC, Al2O3/SiC and Al2O3. In term of environmental protection, the base idea of this work was to enhance the catalyst life time by its regeneration and its recycling
Butel, Aurore. "Optimisation de catalyseurs pour la synthèse Fischer-Tropsch à partir de biosyngaz". Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10128/document.
The work exposed in this manuscript concerns the preparation of monometallic and bimetallic catalysts containing cobalt and iron supported on alumina and silica for the synthesis Fischer-Tropsch. The catalysts denoted xCoyFe/Al2O3 or SiO2 have a total mass content of 10% for various values of the Co/Fe ratio (x and y = 0; 2.5; 5; 7.5; 10 and x+y = 10%). Thus, these catalysts were prepared by wetness impregnation and were characterized at different stages of their preparations by various physicochemical and spectroscopic techniques of characterization. The major part of this study concerns the germination of the oxides phases and the genesis of the active phases of mixed materials. The samples monometallic represent the solid references for this study. From decompositions of XANES and XPS spectra, we proposed the presence of a CoFe alloy on mixed catalysts after calcination for the low cobalt contents. A better dispersion is observed for iron compared with cobalt whatever the support used. Moreover, on the alumina support, iron and cobalt are better dispersed with lower crystallite sizes. The originality of this work consists with the Operando study, which allowed to confirm the characteristic of our mixed materials CoFe. Indeed, the latter, have a low sensitivity of sintering of the cobalt metal particles, contrary to materials monometallic. These mixed materials present an intermediate activity compared with those of monometallic materials for the Fischer-Tropsch reaction
Liu, Chang. "Effect of sulphur on Fischer-Tropsch synthesis : promoted molybdenum and cobalt catalysts". Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10134/document.
This thesis focuses on the study of promoted molybdenum catalysts supported on alumina or carbon nanotubes for the synthesis of olefins from synthesis gas obtained from biomass. The catalysts were studied at every stage of their preparation by different characterization techniques and tested in fixed bed reactor. The results showed that both types of sites are present on the K-MoS2 catalysts: MoS2, which leads to the production of methane and a mixed K-Mo-S phase which leads to the synthesis of olefins. The decrease in activity observed with catalysts supported on carbon nanotubes was attributed to the low rate of sulphidation. The basicity of the promoters and the size of the molybdenum sulphide crystallites are important parameters influencing the olefins synthesis. A moderate basicity as well as large size of molybdenum crystallites are favorable to the synthesis of light olefins
Sadeqzadeh, Majid. "Deactivation modeling of cobalt Fischer-Tropsch catalysts in different reactor configurations". Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10172/document.
Catalyst deactivation remains a major challenge in Fischer-Tropsch synthesis; as it reduces the catalyst lifetime as well as its productivity. Deactivation can be attributed to certain mechanisms according to the literature. Sintering is proposed in this work to be responsible for the initial deactivation whereas coking is suggested to be the main cause of long-term deactivation. The final objective of this thesis is to develop the mechanistic models which could predict the extent of catalyst deactivation with time. In the first step, the change in the catalyst physico-chemical properties with time on stream is considered. A three-step sintering model is proposed which involves the effect of water acceleration through the formation of surface cobalt oxide layer. This mechanism allows correlating the crystallites growth with certain operating conditions especially the H2O/H2 molar ratio inside the reactor. We have also developed a mechanism for the active site poisoning by carbon deposition for the long-term deactivation. This mechanism helps to evaluate the change in the active sites coverage with time as well the CO, H2, and H2O mole fractions. The two microscopic models are then integrated in the reactor models in order to correlate the change in the catalytic activity with the catalyst properties. We have developed the models dedicated to fixed bed and slurry reactors. The effect of operating conditions on the crystallite size, active sites fraction, and conversion is considered by the simulations. The models are then employed in the laboratory scale reactors to fit the experimental data and to optimize the deactivation constants
Peña, Zapata Diego. "Identification of deactivation mechanisms of cobalt Fischer-Tropsch catalysts in slurry reactor". Electronic Thesis or Diss., Lille 1, 2013. http://www.theses.fr/2013LIL10149.
The Fischer-Tropsch Synthesis (FTS) produces ultra-clean liquid fuels and chemicals via conversion of syngas from a wide range of feedstocks: natural gas, shale gas coal and biomass. Supported cobalt-based catalysts are the best option for the low temperature FTS, due to their high stability and selectivity toward heavy paraffinic hydrocarbons. Nevertheless, cobalt catalysts deactivate with time on stream. This leads to a decrease in catalyst lifetime and productivity. Hence, catalyst deactivation remains a major challenge of FTS. In this work we identified cobalt sintering, catalyst attrition and carbon deposition as the most relevant catalyst deactivation mechanisms in slurry reactor; the deactivation rate being influenced by the operating conditions. The experimental results suggest that catalyst attrition is strongly affected by water partial pressure in the catalytic reactor. High water partial pressure favours mobility of cobalt nanoparticles on surface and cobalt sintering. Both cobalt agglomerates of micron size located on catalyst grains and detached cobalt metal particles were observed in the spent catalysts. The formation of cobalt agglomerates was favoured at lower gas space velocity and in H2-deficient syngas. Syngas dilution at the beginning of reaction decreases the degree of attrition and reduces cobalt agglomerate formation. Hydrocarbons, alcohols, ketones, aldehydes, organic acids were detected in the spent catalysts; α-olefins being the most abundant species. Carboxylic acids and alpha-alkyl cinnamic aldehyde seem to be most detrimental for the catalytic performance. A tentative schema of formation of different carbon species in cobalt catalysts during FTS in slurry reactor has been proposed in the manuscript
Madani, Behrang. "Synthèse de Fischer-Tropsch sur catalyseur à base de cobalt supporté sur carbure de Silicium". Université Louis Pasteur (Strasbourg) (1971-2008), 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/MADANI_Behrang_2005.pdf.
The Fischer-Tropsch synthesis (FTS) leads to various products, mainly alkanes as well as olefins and alcohols, starting with precise mixture of CO and H2. Currently, natural gas is recovered as a by-product of oil extraction and directly burnt, which leads a non negligible economic loss as well as an atmospheric pollution due to the production of CO2. The reaction of FTS is one of the ways permitting valorisation of natural gas after its transformation in gas of synthesis (mixture of CO and H2). The SFT reaction is exothermique and requires fast evacuation of heat from the catalytic sites in order to avoid the problem of hot spots formation and subsequent cracking of formed products. The supports used traditionally for the FTS are insulating supports, such as alumina and silica, which does not permit a good evacuation of heat. In this work, we replaced the insulating support by a conducting support based on SiC, which permits a better homogenisation of the temperature in the catalytic bed. In this study, different reaction parameters- the Co content, the total pressure and contact time, have been optimized in order to obtain the best activity, selectivity and stability of the catalysts. We also studied the influence of the morphology of the support on the catalyst performance. Among the different shapes of support based on SiC (grain, extrudes and foam), the support as foam seems to have the best performance. We finalised the procedures of regeneration of the catalyst as well as the doping by molybdenum. The thus obtained catalysts present the best activity and selectivity
Azib, Hédi. "Catalyseurs fischer-tropsch a base de cobalt : influence de la dispersion du cobalt et promotion par le titane". Paris 6, 1996. http://www.theses.fr/1996PA066017.
Carlu, Jean-Claude. "Synthèse et caractérisation de polymères poreux : applications catalytiques". Lille 1, 1985. http://www.theses.fr/1985LIL10109.
Soyez, Alain. "Hydrocondensation du monoxyde de carbone catalysée en phase liquide par des espèces à base de fer". Lille 1, 1985. http://www.theses.fr/1985LIL10104.
Balloy, Dominique. "Etude des propriétés de catalyseurs à base de carbures de tungstène et de molybdène dans les réactions CO + H2". Lille 1, 1986. http://www.theses.fr/1986LIL10059.
Sablier, Michel. "Réactivité en phase gazeuse des cations des métaux de transition avec des espèces atomiques ou radicalaires". Paris 6, 1992. http://www.theses.fr/1992PA066318.
Strossi, Pedrolo Débora Regina. "Synthesis of metal-zeolite composite materials for bifunctional catalytic reactions". Thesis, Université de Lille (2018-2021), 2021. https://pepite-depot.univ-lille.fr/LIBRE/EDSMRE/2021/2021LILUR065.pdf.
Zeolite-based catalysts have been widely used in the conversion of biomass. The catalytic yields of the desired products are strongly limited due to the relatively small size of the pores in zeolites and the catalyst preparation by impregnation usually leads to relatively large metal nanoparticles and low contact between metal and acid sites. The purpose of this work is the design of metal-zeolite nanocomposite catalysts containing ruthenium nanoparticles uniformly distributed in the hierarchical BEA and ZSM-5 zeolites. Use of ruthenium avoids formation of inert hardly reducible inert metal silicates and metal aluminates, while carbon nanotubes with supported metal oxide nanoparticles play a role of sacrificial template, which allows creating mesoporosity and bringing metallic functionality inside the zeolite matrix. Compared to the conventional zeolite supported metal catalysts the synthesized hierarchical ruthenium-zeolites exhibited much higher activity and lower methane selectivity in Fischer-Tropsch synthesis. Characterization of the prepared catalysts has indicated initiation of crystallization of zeolites over metal nanoparticles. This effect has been further used to increase the dispersion of metal nanoparticles by secondary crystallization of Ru supported over ZSM-5. Our results show significant re-dispersion of embedded metal oxide nanoparticles and increase in the activity of model reactions. In addition, a synthetic strategy was developed for the preparation of hierarchical metal and zeolite nanocomposite catalysts for direct synthesis of iso-paraffins from syngas. The nanocomposites are synthesized in three steps. In the first step, the parent (core) zeolite is etched with an ammonium fluoride solution. The etching creates small mesopores inside the zeolite crystals. In the second step, the Ru nanoparticles prepared using water-in-oil microemulsion are deposited in the mesopores of the zeolite. In the third step, a zeolite shell of MFI-type zeolites (silicalite-1 or ZSM-5) is grown on the parent zeolite crystals coating both the etched surface and metallic nanoparticles. Thus, the metal nanoparticles become entirely encapsulated inside the zeolite matrix. Most important parameters such as ruthenium content, zeolite mesoporosity, and more particularly, the acidity of the catalyst shell, which affect the catalytic performance of the synthesized nanocomposite materials in low-temperature Fischer−Tropsch synthesis were identified in this work. The higher relative amount of iso-paraffins was observed on the catalysts containing a shell of ZSM-5. The proximity between metal and acid sites in the zeolite shell of the nanocomposite catalysts is a crucial parameter for the design of efficient metal zeolite bifunctional catalysts for selective synthesis of gasoline-type fuels via Fischer−Tropsch synthesis, while the acidity of the catalyst core has only a limited impact on the catalytic performance
Bundhoo, Adam. "Contribution à l'étude mécanistique de la synthèse Fischer-Tropsch: préparation et caractérisation de catalyseurs de cobalt et de nickel". Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210084.
Les objectifs de ce travail s’articulent autour de deux méthodes originales, respectivement de préparation et de caractérisation des catalyseurs. La première permet la formation in situ de catalyseurs par voie oxalique, alors que la seconde est une méthode de cinétique transitoire chimique appliquée à la réaction CO + H2.
Dans un premier temps, la préparation de catalyseurs « modèles » de cobalt et de nickel a été réalisée en faisant intervenir un oxalate comme précurseur à la formation in situ du catalyseur. L’étude de cette méthode de préparation par « voie oxalique » nous a tout d’abord permis de discuter du mécanisme de formation de l’oxalate, que nous envisageons comme une polymérisation faisant intervenir des ligands oxalate tétradentates établissant des ponts entre les atomes métalliques.
La décomposition thermique de l’oxalate de cobalt a été étudiée dans un second temps. Nous nous somme penchés en particulier sur l’influence de l’atmosphère de la décomposition sur la nature du catalyseur obtenu in fine. Utiliser l’hydrogène comme gaz réducteur permet d’obtenir des catalyseurs purement métalliques développant une surface spécifique intéressante.
Ces catalyseurs ont été utilisés pour les études cinétiques transitoires chimiques de la réaction CO + H2. Les phénomènes transitoires observés ont permis de corréler les hypothèses formulées pour l’élaboration d’un mécanisme original initialement proposé par A. Frennet. En particulier, la dépendance des vitesses réactionnelles aux pressions partielles de CO et d’hydrogène permet d’envisager un mécanisme d’allongement de chaîne basé sur la réactivité d’un intermédiaire réactionnel avec les réactifs en phase gazeuse. Au vu des recouvrements de surface sous conditions réactionnelles ainsi que des phénomènes transitoires observés, cet intermédiaire est constitué de plusieurs atomes (carbone, oxygène et hydrogène), et est à l’origine de la formation des produits de la réaction (CH4 et alcanes à plus longues chaînes), dont la désorption en phase gazeuse suit un processus en deux étapes lors duquel l’influence de l’hydrogène est primordiale.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Peña, Zapata Diego. "Identification of deactivation mechanisms of cobalt Fischer-Tropsch catalysts in slurry reactor". Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10149/document.
The Fischer-Tropsch Synthesis (FTS) produces ultra-clean liquid fuels and chemicals via conversion of syngas from a wide range of feedstocks: natural gas, shale gas coal and biomass. Supported cobalt-based catalysts are the best option for the low temperature FTS, due to their high stability and selectivity toward heavy paraffinic hydrocarbons. Nevertheless, cobalt catalysts deactivate with time on stream. This leads to a decrease in catalyst lifetime and productivity. Hence, catalyst deactivation remains a major challenge of FTS. In this work we identified cobalt sintering, catalyst attrition and carbon deposition as the most relevant catalyst deactivation mechanisms in slurry reactor; the deactivation rate being influenced by the operating conditions. The experimental results suggest that catalyst attrition is strongly affected by water partial pressure in the catalytic reactor. High water partial pressure favours mobility of cobalt nanoparticles on surface and cobalt sintering. Both cobalt agglomerates of micron size located on catalyst grains and detached cobalt metal particles were observed in the spent catalysts. The formation of cobalt agglomerates was favoured at lower gas space velocity and in H2-deficient syngas. Syngas dilution at the beginning of reaction decreases the degree of attrition and reduces cobalt agglomerate formation. Hydrocarbons, alcohols, ketones, aldehydes, organic acids were detected in the spent catalysts; α-olefins being the most abundant species. Carboxylic acids and alpha-alkyl cinnamic aldehyde seem to be most detrimental for the catalytic performance. A tentative schema of formation of different carbon species in cobalt catalysts during FTS in slurry reactor has been proposed in the manuscript
Brabant, Cathy. "Promotion par le lanthane des catalyseurs à base de cobalt pour la réaction Fischer-Tropsch". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10046/document.
The work exposed in this manuscript concerns the study of cobalt supported catalysts on alumina modified by lanthanum addition for Fischer-Tropsch synthesis (FT). Modified supports are prepared by wetness impregnation of alumina with a lanthanum nitrate solution (La: 0-20 wt%). After a calcination step, modified support is impregnated with a cobaltous nitrate solution (Co: 10 wt%) followed by a calcination step at 400°C in air. The catalysts were then activated by reduction in hydrogen at 400°C and the catalytic performance was evaluated. The effect of the La/Co ratio and calcination conditions of the modified supports (400°C or 800°C, in air or under vacuum) on the nature and dispersion of species before and after reduction has been studied. Then the major part of this study concerns the characterization of supports and catalysts at each preparation step by various physicochemical and spectroscopic techniques. The results showed that a calcination at 800°C of the modified support does not limit the interaction of cobalt with the support and leads to low activity. The formation of a perovskite structure is proposed. For the catalysts prepared from modified supports calcined at 400°C, a strong impact of the La/Co ratio on the structure and the reducibility of the phases is observed. A surface analysis by XPS and LEIS leads to propose a distribution scheme of oxide species on the surface. A content of 10% of lanthanum allows to reduce the formation of cobalt aluminate and get a low methane selectivity
Lorito, Davide. "Cinétique transitoire pour l'identification des voies de production de méthane sur des catalyseurs Fischer-Tropsch". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1305/document.
The Fischer-Tropsch synthesis (FTS) converts a mixture of hydrogen and carbon monoxide (syngas) selectively into hydrocarbons with a large chain length distribution. Syngas can be produce from different resources such as natural gas, coal and biomass. In the light of energy resource diversification, FTS can make a contribution to the production of liquid fuels. However, methane formation as byproduct has a large impact on the process economic feasibility. This study aims at the understanding of the methane formation over syngas conversion catalysts, such as nickel and cobalt. To this purpose, Steady-State Isotopic Transient Kinetic Analysis (SSITKA) and step-transient experiments over different nickel and cobalt samples have been carried out and the data have been used to develop a microkinetic model describing methane formation. By using these methodologies, it was found that the CO conversion to methane proceeds through two different surface intermediate species. The microkinetic model is developed on the hypothesis of two reacting paths leading to methane: the unassisted CO dissociation and the H-assisted CO decomposition. It is proposed that these two reacting intermediates are related to the structure of the catalyst particle, specifically to the distribution of the catalyst surface sites on terraces and steps
Li, Di. "Direct synthesis of long-chain hydrocarbons by plasma-catalysis from syngas and CH4-CO2 mixtures". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM059.
This thesis deals with the study of Fischer-Tropsch synthesis (FTS) and the direct conversion of CO2 and CH4 into value-added liquid products by a process coupling non-thermal plasma and heterogeneous catalysis. A coaxial dielectric barrier discharge (DBD) plasma-catalytic reactor was designed and tested in this thesis with its analysis and diagnostic devices. The reactor operates under ambient conditions, the catalyst and its support are under the form of granules packaged in the reactor. The support is in silica aerogel and was synthesized by surface treatment and ambient drying. Chapter 3 is dedicated to the experimental study of plasma-catalytic Fischer-Tropsch synthesis. In this chapter, the experiments were first conducted in plasma alone without catalyst, paying particular attention to the influence of the gas flow rate, the H2/CO ratio and the electrical excitation frequency on the syngas conversion. Then, in a second step, the catalyst/support couple (Co/SiO2) was introduced into the reactor in order to study the results of the conversion under plasma-catalytic combination. Chapters 4 and 5 deal with the direct plasma-catalytic conversion of CO2 and CH4 into liquid products and syngas. In Chapter 4, the same approach as in Chapter 3 was used, a comparative study of experiments with and without catalyst was done. The two catalyst/support couples used successively in this chapter are Co/SiO2 and Fe/SiO2. Chapter 5 extends the study by proposing a plasma-catalytic combination with two catalysts at the same time. The effects of packing composite catalysts (Co/SiO2 or Fe/SiO2 with HZSM-5, Co/HZMS-5 and Fe/HZSM-5) were studied. The combination of catalysts has made it possible to increase the liquid products selectivity and to produce new liquid products compared to Chapter 4. Thus alcohols, carboxylic acids and C5+ hydrocarbons were synthesized. The thesis ends with a comparison of the results with those of the literature from close processes; energy efficiency and gross productivity were compared. Some possible ways of reaction have also been proposed to initiate a more theoretical reflection. Finally, recommendations for optimization/improvement of FTS and direct conversion of CO2/CH by plasma-catalytic route are provided and discussed
Truong, Huu Tri. "Détermination des grandeurs hydrodynamiques et thermiques d’un support à base de mousse alvéolaire de carbure de silicium beta pour la synthèse de Fischer-Tropsch : de la modélisation vers l’application". Strasbourg, 2011. http://www.theses.fr/2011STRA6050.
It has been observed that the Fischer-Tropsch synthesis can be carried out at high conversion (> 65%) per pass along with high selectivity (> 85%) towards liquid hydrocarbon on the cobalt-based catalyst supported on a silicon carbide foam. In this context, the present work focuses on the investigation of transport properties within silicon carbide (β-SiC) foams in order to explain these results. Using a regular pentagonal dodecahedron model, we established equations relating to the different foam morphological parameters (strut side, pore diameter, cell size and porosity). From this model, a new correlation has been developed to estimate the external mass transfer coefficient within foams. Then, two systems for thermal measurements have been developed. In the first system, from the interpretation of axial and radial temperature profiles by using the -pseudo-homogeneous 2D model, we were succeeded to quantify: 1. The effective radial heat conductivity. 2. The influence of the intrinsic thermal conductivity, the foam morphology as well as the fluid flow pattern on the effective radial thermal conductivity. The second system has been developed in order to measure directly the effective radial heat conductivity of β-SiC foam saturated with a layer of immobilized fluid. The last part is devoted to the radial mass dispersion within foams. The results obtained in this work allow one to verify the analogy between heat and mass transfer processes in foams, as well as to confirm that the foam behavior is similar to that of standard peaked beds at high Reynolds number
Colson, Didier. "Modélisation des équilibres gaz-liquide en solution diluée : caractérisation d'un réacteur triphasique et application à l'étude de la sélectivité de la synthèse de Fischer-Tropsch en phase liquide". Lyon 1, 1990. http://www.theses.fr/1990LYO10017.
Balloy, David. "Étude et mise en oeuvre des catalyseurs Co et Co+Ru/Al2O3 pour la synthèse de carburants diesel". Compiègne, 1997. http://www.theses.fr/1997COMP1011.
Jean-Marie, Alan. "Contrôle du dépôt et de la décomposition des précurseurs de cobalt dans la conception de catalyseurs Fischer-Tropsch". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10174/document.
This thesis focuses on the design of new cobalt catalysts supported by alumina for Fischer-Tropsch synthesis. A large number of catalysts were prepared by wetness impregnation and by sol-gel method. They were studied at different stages of their preparation by various physicochemical and spectroscopic methods and a certain number was tested in fixed bed and slurry reactors under pressure.The major part of this study addresses sub-stoichiometric introduction of organic additives during catalyst preparation. According to the conditions of preparation, these compounds had a major impact on the dispersion and reducibility of cobalt and therefore on the catalytic performances in Fischer-Tropsch synthesis. Various parameters affecting the catalytic behaviour were identified such as the chemical nature of these compounds, their mode of introduction, conditions of their decomposition, etc. We noticed that these organic agents can have multiple functions. These compounds, by interacting with cobalt ions, may modify the nature of cobalt precursor deposited on the support and thus modify the process of “nucleation-growth” of cobalt oxide aggregates during decomposition of precursor. In addition, these organic molecules can modify the physicochemical properties of support (texture, PZC point, etc.) and consequently, change the cobalt dispersion on the support during impregnation
Kocic, Stefan. "La perte d’activité et de sélectivité des catalyseurs Fischer-Tropsch à base de Cobalt". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1219.
Loss of catalyst activity and selectivity with time-on-stream are one of the greatest limitations for the Fischer-Tropsch (FT) industrial process. There is a lack of consensus about the reasons leading to catalyst deactivation and many different paths towards those inevitable events have been evoked in the literature. Among them, some of the most common hypotheses are oxidation and carburation of active sites. Besides, the diminution of Co catalyst activity during time-on-stream exhibits non-uniform behavior, indicating that this phenomenon might be a result of multiple distinctive events. In this thesis, we concentrate on those paths that concern the active phase only, particularly hydrocarbon-species deposition, active phase oxidation and hydrocarbon-induced surface reconstruction as a function of hydrogen, oxygen and carbon coverage effects. With the aid of periodic Density Functional Theory (DFT) calculations, we determine the Gibbs free energy for a large set of key reactions leading to the formation of CαHβOγ surface species on the Co(111) surface uner FT reaction conditions and we identify intermediates and transition states that may lead to activity and selectivity loss of Co-based catalysts. Hence, we propose here to study how the structure of the cobalt surface evolves as a function of the carbon, hydrogen and oxygen chemical potentials under FT reaction conditions. These calculations allowed us to propose an atomistic structure of some experimentally identified coke precursors and to identify favorable reaction conditions towards their formation. Depending on the (C, H, O) coverages, we identify three structural domains containing surface species related with activity and selectivity trends discussed in the literature so far: firstly, a low C coverage domain, where CHβ monomers are formed, the impact of O atoms is the strongest and leads to adsorbed CO, OH or water as well as to oxidized Co sites; an intermediate C coverage domain, where CαHβ linear oligomers and branched hydrocarbon chains are formed and where reconstruction of Co may take place upon subsurface C migration; and thirdly, a high C coverage domain, where we find the formation of longer branched hydrocarbon chains together with the genesis of a carbon overlayer (graphitic coke-like) that is expected to be the main source of deactivation. For intermediate and high carbon coverages, the impact of O atoms on the surface is weaker and its deposition occurs on top of the carbon overlayer without direct contact with Co sites. With the aid of periodic DFT transition state calculations and microkinetic modeling, we offer some new understandings and ideas related to the mechanism of a carbon induced deactivation phenomenon. Our study shows that surface ethynyl species CCH may be regarded as thermodynamically and kinetically the most plausible deactivation initiators. Moreover, we propose 2+2+2 cycloaddition and some CHβ / CHβ reactions as a mechanism for detrimental coke formation leading to a progressive deactivation by a site-blocking effect. This deactivation mechanism has been integrated to an existing deactivation-free micro-kinetic scheme from the literature. The resulting, two-site deactivation model has been optimized and compared to some experimental observations. Our multiscale (DFT and microkinetic model) reproduces well known experimental trends. Hence, we expect that our work will provide the FT community some valuable insights into this intricate and elusive problem, the kinetics of deactivation, as well as some rational guidelines about how to optimize the catalyst process
Razzouk, Antonio. "Contribution à la séparation des produits issus d'un réacteur Fischer-Tropsch : tension de vapeur de paraffines lourdes, étude des équilibres polyphasiques de systèmes à multiconstituants". Lyon 1, 2006. http://www.theses.fr/2006LYO10158.
Bonnin, Charles. "Evaluation de l’expérimentation haut débit en milli lit fixe pour le screening de catalyseurs Fischer-Tropsch". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10111.
Nowadays, catalyst screening for a Fischer-Tropsch application in slurry bubble column reactors is often a slow process, performed in small autoclave reactors. High throughput experimentation in micro packed bed reactors could accelerate it and provide activity and selectivity for a large number of catalysts, in a short time. This research thesis work aimed at addressing the numerous issues related to the comparison of results obtained in these two different reactors
Rebmann, Edouard. "Étude Mécanistique de la Synthèse Fischer- Tropsch sur des Catalyseurs au Cobalt supporté". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1037.
The Fischer-Tropsch synthesis (FTS) converts a mixture of hydrogen and carbon monoxide (syngas) selectively into hydrocarbons with a large chain length distribution. Syngas can be produce from different resources such as natural gas, coal and biomass. In the light of energy resource diversi fication, FTS can make a crucial contribution to the production of liquid fuels. Alumina supported cobalt catalysts are used to produce heavy waxes. The activity and selectivity depend on the structural and textural properties of the catalyst. This study aims at establishing a link between the structural properties of alumina supported cobalt catalysts and specific kinetic parameters. To this purpose, the steady-state and SSITKA kinetics over different cobalt samples have been carried out. By using this met hodology, it was found that the CO conversion over 5 cobalt catalysts only depends on the initial number of reduced cobalt surface atoms. No influence of the cobalt particle size, phase orientation or promotor could be identified. SSITKA experiments during long-term catalyst testing allowed estimating the number of active sites under working conditions. Further modelling showed that the most abundant surface species is adsorbed carbon monoxide and that two distinct surface intermediates lead to the production of methane and higher hydrocarbons
Schweicher, Julien. "Kinetic and mechanistic studies of CO hydrogenation over cobalt-based catalysts". Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210036.
Two different types of catalysts have been investigated during this thesis: cobalt with magnesia used as support or dispersant (Co/MgO) and cobalt with silica used as support (Co/SiO2). Each catalyst from the first class is prepared by precipitation of a mixed Co/Mg oxalate in acetone. This coprecipitation is followed by a thermal decomposition under reductive atmosphere leading to a mixed Co/MgO catalyst. On the other hand, Co/SiO2 catalysts are prepared by impregnation of a commercial silica support with a chloroform solution containing Co nanoparticles. This impregnation is then followed by a thermal activation under reductive atmosphere.
The mixed Co/Mg oxalates and the resulting Co/MgO catalysts have been extensively characterized in order to gain a better understanding of the composition, the structure and the morphology of these materials: thermal treatments under reductive and inert atmospheres (followed by MS, DRIFTS, TGA and DTA), BET surface area measurements, XRD and electron microscopy studies have been performed. Moreover, an original in situ technique for measuring the H2 chemisorption surface area of catalysts has been developed and used over our catalysts.
The performances of the Co/MgO and Co/SiO2 catalysts have then been evaluated in the CO+H2 reaction at atmospheric pressure. Chemical Transient Kinetics (CTK) experiments have been carried out in order to obtain information about the reaction kinetics and mechanism and the nature of the catalyst active surface under reaction conditions. The influence of several experimental parameters (temperature, H2 and CO partial pressures, total volumetric flow rate) and the effect of passivation are also discussed with regard to the catalyst behavior.
Our results indicate that the FT active surface of Co/MgO 10/1 (molar ratio) is entirely covered by carbon, oxygen and hydrogen atoms, most probably associated as surface complexes (possibly formate species). Thus, this active surface does not present the properties of a metallic Co surface (this has been proved by performing original experiments consisting in switching from the CO+H2 reaction to the propane hydrogenolysis reaction (C3H8+H2) which is sensitive to the metallic nature of the catalyst). CTK experiments have also shown that gaseous CO is the monomer responsible for chain lengthening in the FT reaction (and not any CHx surface intermediates as commonly believed). Moreover, CO chemisorption has been found to be irreversible under reaction conditions.
The CTK results obtained over Co/SiO2 are quite different and do not permit to draw sharp conclusions concerning the FT reaction mechanism. More detailed studies would have to be carried out over these samples.
Finally, Co/MgO catalysts have also been studied on a combined DRIFTS/MS experimental set-up in Belfast. CTK and Steady-State Isotopic Transient Kinetic Analysis (SSITKA) experiments have been carried out. While formate and methylene (CH2) groups have been detected by DRIFTS during the FT reaction, the results indicate that these species play no role as active intermediates. These formates are most probably located on MgO or at the Co/MgO interface, while methylene groups stand for skeleton CH2 in either hydrocarbon or carboxylate. Unfortunately, formate/methylene species have not been detected by DRIFTS over pure Co catalyst without MgO, because of the full signal absorption.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Huve, Joffrey. "Highly selective, active and stable Fischer-Tropsch catalyst using entrapped iron nanoparticles in silicalite-1". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1042/document.
Fischer-Tropsch synthesis (FTS) is gaining renewed interests as it allows converting alternative feedstocks (biomass) into liquid fuels. Compared to Co-based catalysts, state of the art Fe catalysts show lower activity, faster deactivation and lower selectivity as it produces an undesirable amount of CO2. Despite decades of studies, the origins of low activity and selectivity and fast deactivation are still unclear. Typical Fe based catalysts are highly metal loaded (>70 wt.%) and composed of many different phases, which strongly impedes the establishment of structure-activity relationships. There is a need to develop more active, more selective and more stable iron FTS catalysts by rational approaches.The synthesis of well-controlled 3.5 nm iron nanoparticles encapsulated in the walls of a hollow-silicalite-1 zeolite (Fe@hollow-silicalite-1) is presented. The encapsulation prevents particle sintering under FTS conditions leading to a high and stable Fe dispersion. The catalyst Fe@hollow-silicalite-1 is active and highly selective in FTS. Most importantly, Fe@hollow-silicalite-1 does not produce CO2 in contrast to all other Fe-based catalysts. The strong hydrophobicity of the silicalite-1 is likely the origin of the lack of CO2 production by inhibition of the forward WGS reaction. We demonstrated that Fe@hollow-silicalite-1converts CO2 into CO by the reverse WGS reaction. In order to establish a structure-activity relationship, a series of Fe-based catalysts with well-controlled particle sizes were synthesized and characterized (TEM, in-situ XANES, in-situ Mössbauer, XRD). We observed two distinct categories of TOFs depending on the particle size, ~10-2 s-1 for larger (>20 nm) and ~10-3 s-1 for smaller ones
Dembélé, Kassiogé. "Etude des catalyseurs hétérogènes à base de Co en conditions réactives "réalistes" par microscopie électronique in-situ et opérando". Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE008/document.
In this work, we studied cobalt catalysts used in producing hydrocarbons through the Fischer-Trospch synthesis process, in which their activation, operation and deactivation mechanisms are recorded using in-situ and environmental transmission electron microscopy. An operando methodology was developed by combining electron microscopy-based structural studies in an environmental cell and mass spectrometry analysis of the reacting gases. Using controlled-morphology nanocatalysts we have demonstrated that deactivation occurs through particles sintering, re-oxidation, encapsulation and carburization. The activation of supported catalysts arises due to particles densification. It was clearly established that the reduction of the nanoparticles is better enhanced on a silica support than on an alumina one. Also, Pt doping of the catalysts greatly increases their reduction. By analysing the hydrocarbons formed during the Fischer-Tropsch reactions of a series of cobalt catalysts, we could obtain a comprehensive physico-chemical characterization, thus opening the way to in-depth studies of heterogeneous catalysts by operando microscopy
Bento, Carvalho Alexandre Antônio. "Investigation of intrinsic activity of cobalt and iron based Fischer-Tropsch catalysts using transient kinetic methods". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10116/document.
The work exposed in this manuscript concerns the study of the intrinsic activity and localization of active sites in cobalt and iron based catalysts using a combination of transient kinetic methods such as SSITKA, extended physicochemical characterization and catalytic tests under quasi steady state conditions. Promotion of iron catalysts with metals used for soldering (Bi and Pb) results a remarkable increase in the light olefin production rate with the possibility to conduct Fischer-Tropsch synthesis at very mild reaction conditions (low pressure) and even at atmospheric pressure. Transient kinetic experiments showed facilitation of CO dissociation in the presence of promoters by scavenging O atoms from iron carbide. Cobalt catalyst supported by mordenite zeolite presented higher value of SSITKA rate constant. Localization of cobalt active sites in bifunctional cobalt-zeolite catalysts has a major impact on the reaction rate and in particular on the hydrocarbon selectivity. A proximity between the cobalt active site and Bronsted active sites was found to be a key parameter to obtain higher selectivity and yield of isomerized hydrocarbons. SSITKA combined with catalyst characterization revealed that carbon deposition and cobalt nanoparticle agglomeration were responsible for the deactivation of silica supported cobalt catalysts. Catalyst rejuvenation in hydrogen lessened the amounts of deposited carbon species and partially released the most active sites of carbon monoxide dissociative adsorption and stronger sites of carbon monoxide reversible adsorption
Béliard, Pierre-Emmanuel. "Mesure et caractérisation du transfert de chaleur dans les colonnes à bulles type slurry". Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00846650.
Girardon, Jean-Sébastien. "Influence des précurseurs et du prétraitement des catalyseurs sur la genèse des particules de cobalt pour la synthèse Fischer-Tropsch". Lille 1, 2005. https://ori-nuxeo.univ-lille1.fr/nuxeo/site/esupversions/cf83b23f-5e3a-4ce5-bd77-1483924564a0.
Connord, Vincent. "Echauffement de nanoparticules par un champ magnétique haute fréquence : Applications en cancérologie et catalyse de réaction Fischer-Tropsch". Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0016/document.
As partners of Multifun by which this thesis was funded, we have worked with European groups of chemists to provide iron oxide nanoparticles dedicated to the detection and treatment of cancer by magnetic hyperthermia. Usually, the nanoparticles efficiency is determined by the SAR value (Specific Absoption Rate, in W / g), measured by a calorimetric method. We have developed a device for measuring hysteresis loops at the same amplitude and frequency range of magnetic fields than those usually used in magnetic hyperthermia. Hysteresis loops provide more information about the samples and allows for example to assess the importance of inter-particle interactions. Multifun project also included the study of in vivo treatments. LPCNO has developed an inductor suitable for experiments on small animals (mice, rats). The electromagnet is air-cooled, displays a gap of 3 cm and operates at a field of 23 mT during one hour. We also worked with the Laboratoire de Réceptologie et Ciblage Thérapeutique en Cancérologie, Toulouse, to perform in vitro magnetic hyperthermia experiments using functionalized nanoparticles specifically internalized into lysosomes. The application of a high frequency magnetic field to the cells containing these nanoparticles induces a significant cell death (mainly apoptotic pathways). In these studies, the nanoparticles have low SAR, and are present in small quantities in the cells. Thus no temperature rise is measured during the experiments. The efficacy of treatment in these conditions poses many questions about the actual mechanisms at the origin of cell death. To try to answer these questions, we have designed a setup permitting to apply high frequency magnetic fields under a confocal fluorescence microscope; the latter is commonly used to monitor intracellular mechanisms with fluorochromes. We introduce a miniaturized solenoid (gap width ≈ 400 µm) directly into a cell culture box. This generates a field of approximately 60 mT at 300 kHz. This method allows us to observe the cells and their organelles during the time of treatment. Infected cell death levels here are equivalent to the previous experiments, which thus validates the use of this reduced gap inductor. For now, we quantified the appearance of ROS (Reactive Oxygen Species) in real time in the cell during the application of the field. We also evidenced the lysosomal permeabilization, which can cause the release of cellular death agents. Finally this tool will serve to continue research on intracellular mechanisms in cells inside an external high-frequency magnetic field. Nanoparticles subjected to an alternating magnetic field can also be used as catalysts of chemical reactions. We used the nanoparticles synthesized LPCNO as catalysts for the Fischer-Tropsch reaction. This process allows the industrial production of hydrocarbons from carbon monoxide and hydrogen gas. Extensive characterizations of structural, magnetic, heating and catalysis properties were carried out on nanoparticles with an iron core coated with a catalytic metal (ruthenium or cobalt). Evidence that these nanoparticles catalyze the Fischer-Tropsch synthesis when subjected to a high-frequency magnetic field has been established, and a good correlation between their heating power and their catalytic activity has been shown
Cheng, Kang. "Novel Fischer-Tropsch catalysts based on mesoporous zeolites and carbon materials for the production of gasoline-range hydrocarbons and lower olefins". Electronic Thesis or Diss., Lille 1, 2015. http://www.theses.fr/2015LIL10001.
Novel bifunctional Fischer-Tropsch (FT) catalysts were developed for the selective production of gasoline-range (C5−C11) hydrocarbons from syngas. These catalysts are constituted by ruthenium or cobalt nanoparticles and mesoporous zeolites. Our results reveal that heavier hydrocarbons form on metal nanoparticles, while hydrocarbon hydrocracking/isomerization occurs on the Brønsted acid sites of the catalysts. The zeolite mesoporosity contributes to suppressing the formation of lighter (C1−C4) hydrocarbons. The selectivity of C5−C11 hydrocarbons could reach 65-70% with a high ratio of isoparaffins to n-paraffins, markedly higher than the maximum value (~45%) expected from the theory. The effects of pore size, support, chemical composition and sodium addition on the performance of iron catalysts in high temperature FT synthesis were also investigated in this thesis. It was found that larger iron oxide crystallites in large pore silicas were much easier to transform to iron carbides than smaller Fe2O3 crystallites in smaller pore supports. Higher FT reaction rates, better olefin selectivities were observed over iron catalysts supported by large pore silicas with higher concentration of iron carbide active phase. Iron catalysts supported on carbon nanotubes (CNT) and activated carbon showed very high activity in FT synthesis. This phenomenon was attributed to the formation of stable nanocomposites of iron carbide and magnetite. The interaction of Na with the catalysts strongly depends on the amount of added Na and type of the support. The strong interaction of Fe and Na promoter leads to higher olefin selectivity
Harmel, Justine. "Synthèse de nano-catalyseurs hybrides à base de cobalt pour la catalyse Fischer-Tropsch". Thesis, Toulouse, INSA, 2016. http://www.theses.fr/2016ISAT0035/document.
Due to the decreasing the oil resources, and because of the the fluctuations of the price as a result of the geopolitical context, the Fischer-Tropsch synthesis, that enables the production of hydrocarbons form the syngas mixture (CO and H2) in the presence of a catalyst based on cobalt or iron, has recently gained a renewed interest from industrial as well as form the academic communities. Although this reaction was discovered in 1923 by the Germans Franz Fischer and Hans Tropsch, the mechanisms that come into play during this reaction and the crucial properties of the catalyst properties remain uncertain. In this context, the work presented in this thesis, aims to investigate the impact of parameters such as the crystallographic structure and the shape of the cobalt nano-objects, which is the active phase of the catalyst for this reaction. For this purpose, model cobalt nano-objects were synthetized and their catalytic properties were studied. As a first step, a cobalt based catalyst exhibiting an hcp crystallographic structure and an anisotropic shape was prepared via a synthetic route involving the decomposition of an organometallic precursor of cobalt and leading to the formation of anisotropic cobalt nano-objects. Catalytic tests were then conducted in a slurry reactor, in collaboration with an industrial partner, IFP-EN. This collaboration allowed performing catalytic studies under conditions that are very close to the actual industrial conditions. These studies revealed an increased stability of these catalysts compared to reference catalysts that deactivate with time. Finally, several cobalt-based catalysts, supported on innovative supports, such as macrostuctured supports, allowing a better control of the exothermicity, were prepared and their catalytic properties studied on a fixed-bed reactor that was set up during the course of this thesis work
Hong, Jingping. "Novel preparation techniques and reactivity of cobalt metal nanoparticles for synthesis of clean fuels using Fischer-Tropsch reaction". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10018/document.
Fischer-Tropsch synthesis produces clean hydrocarbon fuels from natural gas, biomass or coal. These synthetic fuels are totally free of sulfur and aromatics. This thesis addresses novel approaches to the design of cobalt Fischer-Tropsch catalysts supported by mesoporous silicas. These approaches involve catalyst promotion with ruthenium and zirconium oxide, use of plasma technology for the decomposition of cobalt precursors and kinetic studies of the elementary steps of the Fischer-Tropsch by transient kinetic methods including TAP. The structure of catalysts was characterized at each stage of their synthesis and their activation by physico-chemical techniques including in-situ methods. It was shown that the promotion of catalysts with ruthenium and zirconium oxide strongly depended on the texture of the support. The promotion improved the catalytic performance more importantly for the catalysts supported by narrow pore silicas. Use of plasma technology for the decomposition of cobalt precursors allowed efficient control of the size of cobalt nanoparticles and thus resulted in the enhanced catalytic performance. Transient kinetic studies and modeling of the elementary reaction steps have provided fundamental information on the nature of active sites in the supported cobalt catalysts for Fischer-Tropsch reaction
Cheng, Kang. "Novel Fischer-Tropsch catalysts based on mesoporous zeolites and carbon materials for the production of gasoline-range hydrocarbons and lower olefins". Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10001/document.
Novel bifunctional Fischer-Tropsch (FT) catalysts were developed for the selective production of gasoline-range (C5−C11) hydrocarbons from syngas. These catalysts are constituted by ruthenium or cobalt nanoparticles and mesoporous zeolites. Our results reveal that heavier hydrocarbons form on metal nanoparticles, while hydrocarbon hydrocracking/isomerization occurs on the Brønsted acid sites of the catalysts. The zeolite mesoporosity contributes to suppressing the formation of lighter (C1−C4) hydrocarbons. The selectivity of C5−C11 hydrocarbons could reach 65-70% with a high ratio of isoparaffins to n-paraffins, markedly higher than the maximum value (~45%) expected from the theory. The effects of pore size, support, chemical composition and sodium addition on the performance of iron catalysts in high temperature FT synthesis were also investigated in this thesis. It was found that larger iron oxide crystallites in large pore silicas were much easier to transform to iron carbides than smaller Fe2O3 crystallites in smaller pore supports. Higher FT reaction rates, better olefin selectivities were observed over iron catalysts supported by large pore silicas with higher concentration of iron carbide active phase. Iron catalysts supported on carbon nanotubes (CNT) and activated carbon showed very high activity in FT synthesis. This phenomenon was attributed to the formation of stable nanocomposites of iron carbide and magnetite. The interaction of Na with the catalysts strongly depends on the amount of added Na and type of the support. The strong interaction of Fe and Na promoter leads to higher olefin selectivity
Bridoux, Alexandre. "Conception, synthèse et évaluation pharmacologique de γ-carbolines, inhibiteurs potentiels de 5-lipoxygénase et de cyclooxygénases". Lille 2, 2005. http://www.theses.fr/2005LIL2S022.
Two key enzymatic systems in the inflammation process revealed being implicated in many cancers (colon, pancreas, breast, lng) and more particularly in prostate cancer (Pca). The 5-lipoxygenase (5-LO) monitors leucotrienes’ formation which are inflammation of allergy mediators. There are two isoforms of the cyclooxygenase enzyme : COX1 and COX2. COX1 is constitutively expressed and COX2 is the inducible isoform. The cyclooxygenases monitor the formation of the prostaglandins, responsive inflammation mediators. Facing the similarities of the overexpressions of those enzymes in human cancer, a new treatment based on the disregulation of the arachidonic acid metabolism can be considered. The purpose of this study is to participate to the Pca therapeutical research particularly in its hormono-independant sate by the rational design, the organic synthesis and then the pharmacological valuation of some N-benzoyltetrahydro--carbolines, a new class f potential 5-LO/COX dual inhibitors. With this intention, a convergent synthetic strategy was developed starting from para substituted phenylhydrazine chlorides and 4-piperidone derivatives which further cyclise in tetrahydro--carbolines by an acid catalysis (the Fischer method). In parallel, a 5-LO inhibitor, the methoxytetrahydropyran (MTHP) part of ZD-2138, is alkylated by a polymethylenic scheme composed of three carbon atoms. The condensation reaction between the tetrahydro--carboline and the alkylated MTHP in alkaline medium results in a compound which is subsequently benzoylated or benzylated. 5-LO and COX1/COX2 activities were obtained ex vivo on human whole blood. The tests measuring the inhibition of the cellular proliferation were achieved on different cellular issues (L-1210, MCF7, PC-3) in order to display the cytotoxic potential of the compounds
Lacroix, Maxime. "Optimisation et caractérisation d’un nouveau support catalytique à base de mousses alvéolaires de β-SiC : Application à la synthèse de Fischer-Tropsch". Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/restreint/theses_doctorat/2009/LACROIX_Maxime_2009.pdf.
The catalytic Fischer Tropsch Synthesis (FTS) enables the transformation of synthetic gas, i. E. Mixture of H2 and CO, into a distribution of hydrocarbons (CnH2n+2 with 1 < n < 60-100), more or less saturated and more or less oxygenated. The Gas to Liquids way, including FTS, is consequently an opportunity allowing the transformation of the flared and/or stranded gas into liquid hydrocarbons for car or plane fuelling. This could first reduce the CO2 release in the atmosphere and secondly increase the oil resources by the transformation of natural gas. The classical catalysts used in Fischer-Tropsch processes are composed of cobalt or iron supported on alumina or silica, and, although they present good performances, they are highly constricted by the high exothermicity of the reaction inducing high temperature on the catalyst surface, leading to low selectivity towards desired products (i. E. Long chained parafins). In this context, silicon carbide (β-SiC) has been proposed as replacement support to alumina and silica in order to better evacuate the heat released by the reaction and thus keeping higher selectivity even at high conversion levels. Moreover, always in order to optimize the process, the impact of the catalytic support morphology (extrudates, cellular foams) on the Fischer-Tropsch reaction has been studied. It appeared that the intrinsic properties of the cellular supports (high effective thermal conductivity, low pressure drops) could let foresee new perspectives in the fixed bed FT reaction. In this work, silicon carbide as catalyst support revealed to be far more attractive than alumina both in the form of extrudates or cellular foams. Indeed, thermal runaway have been observed on alumina whereas the use of β-SiC allowed better control of the temperature and thus better selectivity towards C5+ products. A study on the influence of the active phase charge on the catalytic performances of the catalyst supported on β-SiC foams has been performed. A simple geometric model of the foam as been developed in order to estimate the pressure drop induced by the cellular supports. A correlation with classical packed beds was showed to be able to model the pressure loss induced by a gaseous flow in the cellular material. Finally, a study on the biphasic behaviour of β-SiC foams has evidenced higher liquid hold-ups compared to classical packed beds. The influence of this property on the FT reaction has here not been made and will be the subject of a next study
Barrios, Medina Alan Josue. "Synthèse Directe d'Oléfines Légères par des Réactions d'Hydrogénation du CO et du CO2". Electronic Thesis or Diss., Centrale Lille Institut, 2021. http://www.theses.fr/2021CLIL0030.
CO and CO2 Hydrogenation are an attractive way to convert non-petroleum and renewable feedstocks such as biomass, plastic and organic waste into fuels and chemicals. Activity, selectivity to light olefins and stability are major challenges of these reactions over Fe catalysts. In this thesis, we synthesized different iron-based catalysts for both CO and CO2 hydrogenation in order to get highly selective, active and stable catalysts. For CO hydrogenation SiO2 was used as support while for CO2 hydrogenation reaction ZrO2 supported catalysts presented the most encouraging results. We relied on High Throughput Experimentation (HTE) to identify among 27 promoters the most efficient ones for FT synthesis at the same time that different selectivity trends were evaluated. HTE tests allowed us to clearly identify Sn, Sb, Bi and Pb as the most promising promoters in order to obtain Fe catalysts with higher activity in FT synthesis. Then, we focused on studying the strong promoting effects of Sb and Sn on the catalytic performance of SiO2 supported iron Fischer Tropsch catalysts using a combination of advanced and in-situ techniques. TEM in the activated FeSn/SiO2 catalyst showed highly dispersed Sn nanoparticles on the silica support. On the other hand, activated FeSb/SiO2 catalyst showed a core-shell morphology. Additionally, smaller amount of carbon deposition detected is crucial for better stability of the Sn- and Sb-promoted catalysts in FT reaction. Finally, we focused on the identification of efficient promoters for ZrO2 supported iron catalysts in CO2 hydrogenation reaction. We observed the most pronounced increase in the reaction rate for the K and Cs promoted catalysts. HTE clearly showed that the presence of K was essential to achieve higher light olefin selectivity. Additionally, Mo, Cu, Cs, Ce and Ga were identified as possible promoters to further increase the selectivity of CO2 hydrogenation to this fraction. The work performed during this thesis allowed to design new catalysts for CO and CO2 hydrogenation reaction that could be easily implemented at industrial level. Catalysts studied for both reactions showed improvement three key aspects: activity, selectivity, and stability