Frutose e Ácido Glicônico são produtos importados empregados em diferentes setores nas áreas química, farmacêutica e alimentícia, representando um mercado de dois milhões de dólares (US$ 2,0 milhões) por ano. Por sua vez, a sacarose pode ser empregada como matéria-prima para a obtenção destes produtos através de conversão enzimátiva empregando invertase e glicose-oxidase. O uso de biorreatores com membrana (MBR) mostra-se interessante em processos enzimáticos, pois, ao serem empregados em processos contínuos permitem, simultaneamente, produção e separação dos produtos, reduzindo a formação de subprodutos e, eventual, inibição da enzima por excesso de substrato ou produtos. A sacarose é convertida em xarope de açúcar invertido (solução equimolar de frutose e glicose) pela invertase (Bioinvert®, enzima comercial), seguido pela oxidação da glicose em ácido glicônico pela ação da glicose oxidase (GO). O processo de conversão multi-enzimático da sacarose foi obtido através da alimentação de sacarose (50 mM) em reator com membrana (MBR) contendo invertase (24 U/mL), glicose-oxidase (0,5 U/mL) e catalase (470 U/mL) e operando com vazão específica de 6,0 h-1, 35ºC e pH 5,5. As condições operacionais otimizadas possibilitaram a conversão completa da sacarose (X = 100 %) e da glicose resultante (Y = 100%) com velocidades específicas de reação de 4,2 mmol/U.h, 0,60 mmol/U.h e 0,00062 mmol/U.h, respectivamente, para a invertase, glicose oxidase e catalase. A respeito da oxidação da glicose, a adição de catalase no meio reacional se fez necessária para minimizar os efeitos inibitórios sobre a GO através do peróxido de hidrogênio formado. / The fructose and gluconic acid are products of great application in chemical, pharmaceutical and food industry. The actual Brazilian market for these compounds is about US$ 2 millions, here as the sucrose, the raw-material used for their production, represents about 2.4% of the Brazil\'s GNP. This conversion increases the value added to the sugarcane, usually marketed as a commodity, because the fructose and gluconic acid are more valuable products than sucrose. The use of membrane bioreactor (MBR), which operates under mild conditions regarding internal pressure, temperature and pH, has been growing along the years for enzyme catalyzed processes. Moreover, in the MBR the reaction and separation of the products occur simultaneously, avoiding the formation of by-products and the eventual inhibition of the enzyme caused by excess of substrate or products. The sucrose is converted to the inverted syrup (an equimolar solution of fructose and glucose) by invertase (in this work was employed Bioinvert®, a commercial invertase) followed by the oxidation of glucose in gluconic acid by the glucose oxidase (GO). The multi-enzymatic conversion of sucrose was attained when carried out under initial substrate of 50mM and invertase, glucose oxidase and catalase concentrations, respectively, of 24.0 U/mL, 0.5 U/mL and 470 U/mL in a membrane reactor utilizing a dilution rate of 6.0 h-1, 35ºC and pH 5.5. The optimized operational conditions led to a conversion yield of 100% for sucrose hydrolysis and glucose oxidation steps resulting in enzyme productivity of 4.2 mmol/U.h, 0.60 mmol/U.h and 0.00062 mmol/U.h, respectively, to invertase, glucose oxidase and catalase. In regard to the glucose oxidation, the addition of catalase in the reaction medium was necessary, in order to minimize the inhibition of the GO by the hydrogen peroxide formed.

Abstract The energy consumption around the globe is on the rise due to the exponential population growth and urbanization. There is a need for alternative and non-conventional energy sources, which are CO2-neutral, and a need to produce less or no environmental pollutants and to have high energy efficiency. One of the alternative approaches is hydrogen economy with the fuel cell (FC) technology which is forecasted to lead to a sustainable society. Hydrogen (H2) is recognized as a potential fuel and clean energy carrier being at the same time a carbon-free element. Moreover, H2 is utilized in many processes in chemical, food, metallurgical, and pharmaceutical industry and it is also a valuable chemical in many reactions (e.g. refineries). Non-renewable resources have been the major feedstock for H2 production for many years. At present, ~50% of H2 is produced via catalytic steam reforming of natural gas followed by various down-stream purification steps to produce ~99.99% H2, the process being highly energy intensive. Henceforth, bio-fuels like biomass derived alcohols (e.g. bio-ethanol and bio-glycerol), can be viable raw materials for the H2 production. In a membrane based reactor, the reaction and selective separation of H2 occur simultaneously in one unit, thus improving the overall reactor efficiency. The main motivation of this work is to produce H2 more efficiently and in an environmentally friendly way from bio-alcohols with a high H2 selectivity, purity and yield. In this thesis, the work was divided into two research areas, the first being the catalytic studies using metal decorated carbon nanotube (CNT) based catalysts in steam reforming of ethanol (SRE) at low temperatures (<450 °C). The second part was the study of steam reforming (SR) and the water-gas-shift (WGS) reactions in a membrane reactor (MR) using dense and composite Pd-based membranes to produce high purity H2. CNTs were found to be promising support materials for the low temperature reforming compared to conventional catalyst supports, e.g. Al2O3. The metal/metal oxide decorated CNTs presented active particles with narrow size distribution and small size (~2–5 nm). The ZnO promoted Ni/CNT based catalysts showed the highest H2 selectivity of ~76% with very low CO selectivity <1%. Ethanol was shown to be a more suitable and viable source for H2 than glycerol. The dense Pd-Ag membrane had higher selectivity but a lower permeating flux than the composite membrane. The MR performance is also dependent on the active catalyst materials and thus, both the catalyst and membrane play an important role. Overall, the membrane–assisted reformer outperforms the conventional reformer and it is a potential technology in pure H2 production. The high purity of H2 gas with a CO-free reformate for fuel cell applications can be gained using the MR system. / Tiivistelmä Maailman energiankulutus on kasvussa räjähdysmäisen väestönkasvun ja voimakkaan kaupungistumisen myötä. Tällä hetkellä energian tuottamisen aiheuttamat ympäristöongelmat ja taloudellinen epävarmuus ovat seikkoja, joiden ratkaisemiseksi tarvitaan vaihtoehtoisia ja ei-perinteisiä energialähteitä, joilla on korkea energiasisältö ja jotka tuottavat vähän hiilidioksidipäästöjä. Eräs vaihtoehtoisista lähestymistavoista on vetytalous yhdistettynä polttokennotekniikkaan, minkä on esitetty helpottavan siirtymistä kestävään yhteiskuntaan. Vety on puhdas ja hiilivapaa polttoaine ja energian kantaja. Lisäksi vetyä käytetään monissa prosesseissa kemian-, elintarvike-, metalli- ja lääketeollisuudessa ja se on arvokas kemikaali monissa prosesseissa (mm. öljynjalostamoissa). Uusiutumattomat luonnonvarat ovat olleet tähän saakka merkittävin vedyn tuotannon raaka-aine. Tällä hetkellä noin 50 % vedystä tuotetaan maakaasun katalyyttisellä höyryreformoinilla. Puhtaan (yli 99,99 %) vedyn tuotanto vaatii kuitenkin useita puhdistusvaiheita, jotka ovat erittäin energiaintensiivisiä. Integroimalla reaktio- ja puhdistusvaihe samaan yksikköön (membraanireaktori) saavutetaan huomattavia kustannussäästöjä. Biopolttoaineet, kuten biomassapohjaiset alkoholit (bioetanoli ja bioglyseroli), ovat vaihtoehtoisia lähtöaineita vedyn valmistuksessa. Tämän työn tavoitteena on tuottaa vetyä bioalkoholeista tehokkaasti (korkea selektiivisyys ja saanto) ja ympäristöystävällisesti. Tutkimus on jaettu kahteen osaan, joista ensimmäisessä tutkittiin etanolin katalyyttistä höyryreformointia matalissa lämpötiloissa (<450 °C) hyödyntämällä metallipinnoitettuja hiilinanoputkia. Työn toisessa osassa höyryreformointia ja vesikaasun siirtoreaktioa tutkittiin membraanireaktorissa käyttämällä vedyn tuotantoon tiheitä palladiumpohjaisia kalvoja sekä huokoisia palladiumkomposiittikalvoja. Hiilinanoputket (CNT) havaittiin lupaaviksi katalyyttien tukimateriaaleiksi verrattuna tavanomaisesti valmistettuihin tukiaineisiin, kuten Al2O3. CNT-tukiaineelle pinnoitetuilla aktiivisilla aineilla (metalli-/metallioksidit) todettiin olevan pieni partikkelikoko (~2–5 nm) ja kapea partikkelikokojakauma. Sinkkioksidin (ZnO) lisäyksellä Ni/CNT-katalyytteihin saavutettiin korkea vetyselektiivisyys (~76 %) ja erittäin alhainen hiilimoksidiselektiivisyys (<1 %). Etanolin todettiin olevan parempi vedyn raaka-aine kuin glyserolin. Tiheillä Pd-Ag-kalvoilla havaittiin olevan vedyn suhteen korkeampi selektiivisyys mutta matalampi vuo verrattuna palladiumkomposiittikalvoihin. Membraanireaktorin suorituskyky oli riippuvainen myös katalyytin aktiivisuudesta, joten sekä kalvolla että katalyyttimateriaalilla oli merkittävä rooli kyseisessä reaktorirakenteessa. Yhteenvetona voidaan todeta, että membraanierotukseen perustuva reformointiyksikkö on huomattavasti perinteistä reformeriyksikköä suorituskykyisempi mahdollistaen tehokkaan teknologian puhtaan vedyn tuottamiseksi. Membraanitekniikalla tuotettua puhdasta vetyä voidaan hyödyntää mm. polttokennojen polttoaineena.

This work aims at modelling and evaluating a new type of photocatalytic reactors, named fixed-bed photocatalytic membrane reactor (FPMR). Such reactors are based on the deposition of a thin layer of photocatalysts on a permeable substrate by filtration. This layer serves as a photocatalytic membrane, named fixed-bed photocatalytic mem-brane (FPM), which is perpendicularly passed by the reactant solution and illuminated by a suitable light source. One advantage of FPMs is their renewability. The model, which was developed for this reactor, relates the overall reaction rate in the FPM with the intrinsic reaction kinetic at the catalyst surface and accounts for light intensity, structural and optical layer properties as well as the mass transfer in the pores. The concept of FPMR was realised by using a flat sheet membrane cell. It facilitated principal investigations into the reactor performance and the validity of the model. For this purpose, the photocatalytic degradation of organic compounds, such as meth-ylene blue and diclofenac sodium, was conducted at varying conditions. Pyrogenic ti-tania was used as a photocatalyst. The experimental data support the developed mod-el. They also indicate a significant impact of the flow conditions on the overall photo-catalytic activity, even though the Reynolds number in the FPM was very small; the to-tal mass transfer rate in the FPM amounted to more than 1.0 s−1. The experiments also showed a sufficient structural strength of the FPM and photocatalytic stability. In addi-tion, the renewal and regeneration of FPMs was successfully demonstrated. Furthermore, another FPMR was designed by means of submerged ceramic mem-branes. This reactor was mainly used to assess the effectiveness and efficiency of FPMRs at the example of the photocatalytic degradation of oxalic acid. The correspond-ing reactor was run closed loop and in continuous mode. The effectiveness of the reac-tor was evaluated based on common descriptors, such as apparent quantum yield, photocatalytic space-time yield and light energy consumption. The results showed that the FPMR based on submerged ceramic membrane had a higher efficiency than other reported photocatalytic reactors. The comparison of the different modes of operation revealed that the closed loop FPMR is most efficient with regard to light energy con-sumption. Finally, this work discusses the up-scaling of FPMRs for industrial applications and proposes a solution, which can e.g. be employed for wastewater treatment or CO2 conversion.:Abstract iii Kurzfassung v Acknowledgment vii Contents ix Nomenclature xiii 1 Introduction 1 1.1 Motivation 1 1.2 Aim and objectives of the work 3 1.3 Thesis outline 3 2 Heterogeneous photocatalytic reactors 5 2.1 Introduction to photocatalysis 5 2.2 Processes in heterogeneous photocatalysis 6 2.2.1 Optical phenomena 7 2.2.2 Mass transfer 8 2.2.3 Adsorption and desorption 9 2.2.4 Photocatalytic reactions 10 2.2.5 Factors affecting heterogeneous photocatalysis 12 2.3 Photocatalytic reactor systems towards water treatment 16 2.3.1 Introduction to photocatalytic reactors 16 2.3.2 Development of photocatalytic reactor designs 17 2.3.3 Quantitative criteria for evaluating photocatalytic reactor designs 21 2.4 Cake layer formation in membrane microfiltration 22 2.4.1 Suspension preparation 22 2.4.2 Cake layer formation 23 2.5 Fluid flow through a fixed bed of particles 25 2.5.1 Pressure drop through a fixed-bed 25 2.5.2 Liquid-solid mass transfer correlation in fixed-bed 25 3 Concept and mathematical modelling of FPMRs 29 3.1 Concept of fixed-bed photocatalytic membrane reactors 29 3.2 Modelling of fixed-bed photocatalytic membrane reactors 31 3.3 Model sensitivity analysis 37 3.4 Chapter summary 39 4 FPMR realised with flat sheet polymeric membrane 41 4.1 Introduction 41 4.2 Materials and set-up 41 4.2.1 Materials 41 4.2.2 Experimental set-up 43 4.3 Experiments and methods 48 4.3.1 Formation of fixed-bed photocatalytic membrane 48 4.3.2 Reactor performance 50 4.3.3 Parameters study and model verification 53 4.3.4 Catalyst layer characterisation 56 4.3.5 Measurement and evaluation of photocatalytic activity of FPM 59 4.4 Results and model verification 60 4.4.1 Reactor performance 60 4.4.2 Influence parameters 71 4.4.3 Model verification 79 5 FPMR realised with submerged ceramic membrane 92 5.1 Introduction 92 5.2 Materials and reactor set-up 93 5.2.1 Reactor set-up 93 5.2.2 Chemicals 97 5.3 Experiments and methods 97 5.3.1 Formation of fixed-bed photocatalytic membranes 97 5.3.2 Photocatalytic performance 97 5.3.3 Parameter study 98 5.3.4 Reactor model for calculating reaction rate constant of FPM 99 5.3.5 Comparison of different reactor schemes 102 5.4 Results and discussions 105 5.4.1 Reactor performance 105 5.4.2 Consistency of CPMR and LPMR data 107 5.4.3 Influence of catalyst loading 108 5.4.4 Influence of permeate flux and light intensity 109 5.4.5 Reactor efficiency 111 5.4.6 Comparison of different reactor schemes 113 5.5 Proposed up-scaled FPMR systems 113 5.6 Concluding remarks 116 6 Conclusion and outlook 118 6.1 Summary of thesis contributions 118 6.2 Discussion and outlook 120 References 122 List of Figures 134 List of Tables 138 Appendix A Calibration 139 A.1 Distribution of light intensity on the surface of catalyst layer 139 A.2 Concentration and absorbance of diclofenac 141 A.3 TOC concentration and electrical conductivity of oxalic acid 141 A.4 Concentration and absorbance of methylene blue 142 Appendix B Mathematical modelling 143 B.1 Influence of axial dispersion on the reaction rate 143 B.2 Special case 146 Appendix C Comparison the photocatalytic activity of TiO2 and ZnO 147 Appendix D Mathematical validation of model for LPMR and CPMR 148 D.1 Model for LPMR (cf. Eq. (5 12)):148 D.2 Model for CPMR (cf. Eq. (5 17)) 149 Appendix E Particle size distribution 151

À la lumière du changement climatique et de l'épuisement des réserves de combustibles fossiles, l'innovation dans les technologies énergétiques vertes et durables devient un défi crucial. La fabrication de produits chimiques consomme de grandes quantités d'énergie et est responsable d'une part importante des émissions mondiales de carbone. Dans ce contexte, l'électrosynthèse, alimentée par de l'électricité renouvelable, peut remplacer de nombreux procédés thermochimiques industriels pour générer des carburants, des produits chimiques et des engrais. Plutôt que de nous concentrer sur des domaines qui ont reçu beaucoup d'attention ces dernières années (par exemple, l'électrolyse de l'eau et la réduction du CO2), nous avons exploré les domaines émergents de l'électrosynthèse hétérogène pour lesquels il existe un besoin substantiel. Dans le chapitre 3, nous soulignons l'importance de concevoir des électrocatalyseurs avec des sites actifs bien définis. Nous rapportons l'utilisation de la chimie réticulaire pour concevoir un système de modèle électrocatalytique à base d'organo-métallique conducteur avec des sites actifs moléculaires M-O4 pour l'oxydation électrochimique du 5-hydroxyméthylfurfural (HMFOR). L'activité des MOF portant des sites actifs Ni-O4 (Ni-CAT) et Co-O4 (Co-CAT) a été analysée avec des techniques spectroscopiques électrochimiques et operando pour élucider le mécanisme de réaction se produisant à la surface. Les expériences électrochimiques révèlent que le Co-CAT a un potentiel d'apparition plus précoce pour activer le HMFOR, par rapport à la plupart des catalyseurs établis, tandis que le Ni-CAT présente une cinétique plus rapide pour la conversion du 5-hydroxyméthylfurfural (HMF) en acide 2,5-furandicarboxylique (FDCA) . Nous avons déterminé que Ni-CAT atteignait des rendements de FDCA (notre molécule cible) de 98,7 %. L'efficacité faradique peut atteindre 86,8% d'efficacité faradique. La spectroscopie infrarouge indique le HMF avec un groupe aldéhyde lié à la surface comme intermédiaire clé dans le cycle catalytique, qui se forme une fois que l'oxydation M (II \ III) se produit. Ce travail illustre l'avantage d'utiliser des sites actifs moléculairement définis couplés à la spectroscopie operando pour fournir des informations fondamentales sur une variété de réactions électrosynthétiques et ouvrir la voie à la conception future de catalyseurs. Suite à ce projet, nous nous sommes tournés vers l'utilisation d'un réacteur à membrane sélective pour l'hydrogène afin d'explorer de nouveaux concepts de réaction et de catalyseurs. La clé ici était d'utiliser une feuille de Pd comme matériau qui réduisait les protons en *H dans un compartiment aqueux et transférait l'hydrogène dans un compartiment organique où il hydrogénait le réactif de choix. À l'aide d'un réacteur à membrane, nous avons pu séparer physiquement la réduction électrochimique de l'hydrogène et la chimie de l'hydrogénation d'une manière qui contournait l'utilisation du gaz H2 qui serait autrement nécessaire. Nous choisissons comme point de départ un produit chimique produit industriellement en excès, l'acétonitrile. Le réacteur à membrane Pd est appliqué pour hydrogéner complètement la liaison C≡N de l'acétonitrile. Avec succès, nous avons obtenu de l'ammoniac et de l'acétaldéhyde comme produits de réaction à un potentiel de début record de 0,4 V vs Ag/AgCl. Enfin, en concevant soigneusement une cellule spectroélectrochimique unique, nous avons pu effectuer des mesures spectroscopiques infrarouges pour visualiser le processus de réaction dans la membrane Pd et par conséquent proposé un mécanisme unique de réaction d'hydrolyse de l'imine (Chapitre 4). Dans le chapitre 5, nous choisissons d'innover dans un domaine émergent : la formation de liaisons électrochimiques C-N à partir de réactifs de petites molécules (par exemple CO2, NH3). Le mécanisme conventionnel de formation de liaisons électrochimiques C-N est basé sur le CO2RR électrochimique. Dans ce chapitre, nous proposons une stratégie orthogonale pour activer simultanément le CO2 et les N-réactifs en appliquant respectivement des impulsions de potentiel négatives et positives. Les nanoparticules de Cu sont utilisées comme catalyseur modèle, le CO2 agit comme réactif C et le NH3 agit comme réactif N pour le couplage C-N. Dans des conditions optimisées dans lesquelles la couverture *NH2 est maintenue à l'état stable tandis que Cu reste métallique, l'électrolyse pulsée augmente à la fois le taux de formation et la sélectivité des produits C-N urée, formamide et acétamide de 3 à 20 fois. En étendant le champ d'application à des réactifs C et N supplémentaires, ainsi qu'au couplage C-S, cette nouvelle approche démontre davantage sa valeur générale en électrosynthèse. / In light of climate change and depleting fossil fuel reserves, innovating green and sustainable energy technologies becomes a critical challenge. Chemical manufacturing consumes large amounts of energy and is responsible for a substantial portion of global carbon emissions. Against this backdrop, electrosynthesis, powered by renewable electricity, can replace many industrial thermochemical processes to generate fuels, chemicals, and fertilizers. Rather than focusing on areas that have received much attention in recent years (e.g. water electrolysis and CO2 reduction), we explored emerging areas within heterogeneous electrosynthesis for which there is a substantial need. In chapter 3, we highlight the importance of designing electrocatalysts with well defined active sites. We report the use of reticular chemistry to design a conductive metal organic framework-based electrocatalytic model system with molecular M-O4 active sites for electrochemical oxidation of 5-hydroxymethylfurfural (HMFOR). The activity of MOFs bearing Ni-O4 (Ni-CAT) and Co-O4 (Co-CAT) active sites were analyzed with electrochemical and operando spectroscopic techniques to elucidate the reaction mechanism occurring on the surface. Electrochemical experiments reveal that Co-CAT has an earlier onset potential for enabling HMFOR, relative to most established catalysts, while the Ni-CAT shows faster kinetics for the conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). We determined that Ni-CAT achieved FDCA (our target molecule) yields of 98.7% yield. The faradic efficiency can reach out to 86.8% faradic efficiency. Infrared spectroscopy points to HMF with a surface-bound aldehyde group as the key intermediate in the catalytic cycle, which forms once the M(II\III) oxidation occurs. This work illustrates the advantage of utilizing molecularly defined active sites coupled with operando spectroscopy to provide fundamental insights into a variety of electrosynthetic reactions and pave the way for future catalyst design. Following this project, we turned to the use of a hydrogen-selective membrane reactor to explore more new reaction and catalysts concepts. The key here was using a Pd foil as a material that reduced protons to *H at an aqueous compartment and transferred the hydrogen through to an organic compartment where it hydrogenated the reactant of choice. Using a membrane reactor, we could physically separate electrochemical hydrogen reduction and hydrogenation chemistry in a manner that circumvented the use of H2 gas as would otherwise be necessary. We choose a chemical that is industrially produced in excess, acetonitrile, as a starting point. The Pd membrane reactor is applied to fully hydrogenate the C≡N bond of acetonitrile. Successfully, we obtained ammonia and acetaldehyde as reaction products at a record onset potential of 0.4 V vs Ag/AgCl. Finally, by carefully designing a unique spectroelectrochemical cell, we were able to carry out infrared spectroscopic measurements to visualize the reaction process in Pd-membrane and consequently proposed a unique imine-hydrolysis reaction mechanism (Chapter 4). In Chapter 5, we choose to innovate in an emerging area: electrochemical C-N bond formation from small molecule reactants (e.g. CO2, NH3). The conventional electrochemical C-N bond formation mechanism is based on electrochemical CO2RR. In this chapter, we propose an orthogonal strategy to simultaneously activate CO2 and N-reactants by applying negative and positive potential pulses, respectively. Cu nanoparticles are used as a model catalyst, CO2 acts as the C-reactant, and NH3 acts as the N-reactant for C-N coupling. Under optimized conditions in which *NH2 coverage is maintained at steady state while Cu remains metallic, pulsed electrolysis increases both the rate of formation and the selectivity of the C-N products urea, formamide and acetamide by 3-20 times. By extending the scope to additional C- and N-reactants, as well as C-S coupling, this new approach further demonstrates its general value in electrosynthesis.

Dans ce travail, la production in-situ d'hydrogène (pur) à partir de vapo-reformage d’éthanol (ESR) dans un réacteur catalytique à membrane (MR) a été étudiée. Un mélange d'éthanol pur et distillé a été utilisé comme combustible. Le réacteur est constitué d’un catalyseur Pd-Rh/CeO2 et d’une membrane Pd-Ag: l’ensemble est désigné par « reformeur ». Les expériences sur ce reformeur ont été effectuées dans diverses conditions de fonctionnement: température, pression, débit de combustible et rapport molaire de l'eau-éthanol (rapportSC). La performance du réacteur catalytique à membrane (CMR) a été étudiée en termes de facteur de production d'hydrogène théorique, d’efficacité de production de l’hydrogène et de la part d’hydrogène récupérée. L’évaluation thermodynamique du reformeur a été présentée. L'analyse exergétique a été réalisée sur la base des résultats expérimentaux visant non seulement à comprendre la performance thermodynamique du reformeur, mais aussi d'introduire l'application de l'analyse exergétique dans les études CMRs. L'analyse exergétique a fourni des informations importantes sur l'effet des conditions d'exploitation et les pertes thermodynamiques, et a donné lieu à la compréhension des meilleures conditions de fonctionnement. Outre les évaluations expérimentales et thermodynamiques du reformeur, la simulation de la dynamique de la production d'hydrogène (perméation) a été effectuée comme la dernière étape pour étudier l'applicabilité d'un tel système dans le cadre d'une utilisation finale réelle, qui peut être l’alimentation d’une pile à combustible. La simulation présentée dans ce travail est semblable aux ajustements de débit d'hydrogène nécessaires pour régler la charge électrique d'une pile à combustible répondant à des besoins variables. / In this work, in-situ production of fuel cell grade hydrogen (pure hydrogen) via catalytic ethanol steam reforming (ESR) in a membrane reactor (MR) was investigated. A mixture of pure ethanol and distilled was used as the fuel. ESR experiments were carried out over a Pd-Rh/CeO2 catalyst in a Pd-Ag membrane reactor – named as the fuel reformer – at variety of operating conditions regarding the operating temperature, pressure, fuel flow rate, and the molar ratio of water-ethanol (S/C ratio). The performance of the catalytic membrane reactor (CMR) was studied in terms of pure hydrogen production, hydrogen yield, andhydrogen recovery.Thermodynamic evaluation of the CMR was presented as a supplement to the comprehensive investigation of the overall performance of the mentioned pure hydrogen generating system. Exergy analysis was performed based on the experimental results aiming not only to understand the thermodynamic performance of the fuel reformer, but also to introduce the application of the exergy analysis in CMRs studies. Exergy analysis provided important information on the effect of operating conditions and thermodynamic losses, resulting in understanding of the best operating conditions.In addition to the experimental and thermodynamic evaluation of the reforming system, the simulation of the dynamics of hydrogen production (permeation) was performed as the last step to study the applicability of such a system in connection with a real end user, which can be a fuel cell. The simulation presented in this work is similar to the hydrogen flow rate adjustments needed to set the electrical load of a fuel cell, if fed on line by the studied pure hydrogen generating system.

A non-reactive model system comprising a highly concentrated and unstable oil-in-water emulsion was used to investigate the retention of oil by the membrane in producing biodiesel with a membrane reactor. Critical flux was identified using the relationship between the permeate flux and transmembrane pressure along with the separation efficiency of the membrane. It was shown that separation efficiencies above 99.5% could be obtained at all operating conditions up to the critical flux. It was observed that the concentration of oil in all collected permeate samples using the oil-water system was below 0.2 wt% when operating at a flux below the critical flux. Studies to date have been limited to the characterization of low concentrated emulsions below 15 vol.%. The average oil droplet size in highly concentrated emulsions was measured as 3200 nm employing direct light scattering (DLS) measurement methods. It was observed that the estimated cake layer thickness of 20 to 80 mm was larger than external diameter of the membrane tube i.e. 6 mm based on a large particle size. Settling of the concentrated emulsion permitted the detection of a smaller particle size distribution (30-100 nm) within the larger particles averaging 3200 nm. It was identified that DLS methods could not efficiently give the droplet size distribution of the oil in the emulsion since large particles interfered with the detection of smaller particles. The content of the smaller particles represented 1% of the total weight of oil at 30°C and 5% at 70°C. This was too low to be detected using DLS measurements but was sufficient to affect ultrafiltration. In order to study the critical flux in the presence of transesterification reaction and the effect of cross flow velocity on separation, various oils were transesterified in another membrane reactor providing higher cross flow velocity. higher cross flow velocity provides better separation by reducing materials deposition on the surface of the membrane due to higher shearing. The oils tested were canola, corn, sunflower and unrefined soy oils (Free Fatty Acids (FFA< 1%)), and waste cooking oil (FFA= 9%). The quality of all biodiesel samples was studied in terms of glycerine, mono-glyceride, di-glyceride and tri-glyceride concentrations. The composition of all biodiesel samples were in the range required by ASTM D6751 and EN 14214 standards. A critical flux based on operating pressure in the reactor was reached for waste cooking and pre-treated corn oils. It was identified that the reaction residence time in the reactor was an extremely important design parameter affecting the operating pressure in the reactor. / Natural Sciences and Engineering Research Council of Canada (NSERC)

A non-reactive model system comprising a highly concentrated and unstable oil-in-water emulsion was used to investigate the retention of oil by the membrane in producing biodiesel with a membrane reactor. Critical flux was identified using the relationship between the permeate flux and transmembrane pressure along with the separation efficiency of the membrane. It was shown that separation efficiencies above 99.5% could be obtained at all operating conditions up to the critical flux. It was observed that the concentration of oil in all collected permeate samples using the oil-water system was below 0.2 wt% when operating at a flux below the critical flux. Studies to date have been limited to the characterization of low concentrated emulsions below 15 vol.%. The average oil droplet size in highly concentrated emulsions was measured as 3200 nm employing direct light scattering (DLS) measurement methods. It was observed that the estimated cake layer thickness of 20 to 80 mm was larger than external diameter of the membrane tube i.e. 6 mm based on a large particle size. Settling of the concentrated emulsion permitted the detection of a smaller particle size distribution (30-100 nm) within the larger particles averaging 3200 nm. It was identified that DLS methods could not efficiently give the droplet size distribution of the oil in the emulsion since large particles interfered with the detection of smaller particles. The content of the smaller particles represented 1% of the total weight of oil at 30°C and 5% at 70°C. This was too low to be detected using DLS measurements but was sufficient to affect ultrafiltration. In order to study the critical flux in the presence of transesterification reaction and the effect of cross flow velocity on separation, various oils were transesterified in another membrane reactor providing higher cross flow velocity. higher cross flow velocity provides better separation by reducing materials deposition on the surface of the membrane due to higher shearing. The oils tested were canola, corn, sunflower and unrefined soy oils (Free Fatty Acids (FFA< 1%)), and waste cooking oil (FFA= 9%). The quality of all biodiesel samples was studied in terms of glycerine, mono-glyceride, di-glyceride and tri-glyceride concentrations. The composition of all biodiesel samples were in the range required by ASTM D6751 and EN 14214 standards. A critical flux based on operating pressure in the reactor was reached for waste cooking and pre-treated corn oils. It was identified that the reaction residence time in the reactor was an extremely important design parameter affecting the operating pressure in the reactor. / Natural Sciences and Engineering Research Council of Canada (NSERC)

A non-reactive model system comprising a highly concentrated and unstable oil-in-water emulsion was used to investigate the retention of oil by the membrane in producing biodiesel with a membrane reactor. Critical flux was identified using the relationship between the permeate flux and transmembrane pressure along with the separation efficiency of the membrane. It was shown that separation efficiencies above 99.5% could be obtained at all operating conditions up to the critical flux. It was observed that the concentration of oil in all collected permeate samples using the oil-water system was below 0.2 wt% when operating at a flux below the critical flux. Studies to date have been limited to the characterization of low concentrated emulsions below 15 vol.%. The average oil droplet size in highly concentrated emulsions was measured as 3200 nm employing direct light scattering (DLS) measurement methods. It was observed that the estimated cake layer thickness of 20 to 80 mm was larger than external diameter of the membrane tube i.e. 6 mm based on a large particle size. Settling of the concentrated emulsion permitted the detection of a smaller particle size distribution (30-100 nm) within the larger particles averaging 3200 nm. It was identified that DLS methods could not efficiently give the droplet size distribution of the oil in the emulsion since large particles interfered with the detection of smaller particles. The content of the smaller particles represented 1% of the total weight of oil at 30°C and 5% at 70°C. This was too low to be detected using DLS measurements but was sufficient to affect ultrafiltration. In order to study the critical flux in the presence of transesterification reaction and the effect of cross flow velocity on separation, various oils were transesterified in another membrane reactor providing higher cross flow velocity. higher cross flow velocity provides better separation by reducing materials deposition on the surface of the membrane due to higher shearing. The oils tested were canola, corn, sunflower and unrefined soy oils (Free Fatty Acids (FFA< 1%)), and waste cooking oil (FFA= 9%). The quality of all biodiesel samples was studied in terms of glycerine, mono-glyceride, di-glyceride and tri-glyceride concentrations. The composition of all biodiesel samples were in the range required by ASTM D6751 and EN 14214 standards. A critical flux based on operating pressure in the reactor was reached for waste cooking and pre-treated corn oils. It was identified that the reaction residence time in the reactor was an extremely important design parameter affecting the operating pressure in the reactor. / Natural Sciences and Engineering Research Council of Canada (NSERC)

A non-reactive model system comprising a highly concentrated and unstable oil-in-water emulsion was used to investigate the retention of oil by the membrane in producing biodiesel with a membrane reactor. Critical flux was identified using the relationship between the permeate flux and transmembrane pressure along with the separation efficiency of the membrane. It was shown that separation efficiencies above 99.5% could be obtained at all operating conditions up to the critical flux. It was observed that the concentration of oil in all collected permeate samples using the oil-water system was below 0.2 wt% when operating at a flux below the critical flux. Studies to date have been limited to the characterization of low concentrated emulsions below 15 vol.%. The average oil droplet size in highly concentrated emulsions was measured as 3200 nm employing direct light scattering (DLS) measurement methods. It was observed that the estimated cake layer thickness of 20 to 80 mm was larger than external diameter of the membrane tube i.e. 6 mm based on a large particle size. Settling of the concentrated emulsion permitted the detection of a smaller particle size distribution (30-100 nm) within the larger particles averaging 3200 nm. It was identified that DLS methods could not efficiently give the droplet size distribution of the oil in the emulsion since large particles interfered with the detection of smaller particles. The content of the smaller particles represented 1% of the total weight of oil at 30°C and 5% at 70°C. This was too low to be detected using DLS measurements but was sufficient to affect ultrafiltration. In order to study the critical flux in the presence of transesterification reaction and the effect of cross flow velocity on separation, various oils were transesterified in another membrane reactor providing higher cross flow velocity. higher cross flow velocity provides better separation by reducing materials deposition on the surface of the membrane due to higher shearing. The oils tested were canola, corn, sunflower and unrefined soy oils (Free Fatty Acids (FFA< 1%)), and waste cooking oil (FFA= 9%). The quality of all biodiesel samples was studied in terms of glycerine, mono-glyceride, di-glyceride and tri-glyceride concentrations. The composition of all biodiesel samples were in the range required by ASTM D6751 and EN 14214 standards. A critical flux based on operating pressure in the reactor was reached for waste cooking and pre-treated corn oils. It was identified that the reaction residence time in the reactor was an extremely important design parameter affecting the operating pressure in the reactor. / Natural Sciences and Engineering Research Council of Canada (NSERC)