>Magister Scientiae - MSc / Supercapacitors are one of the important subjects concerning energy storage which has proven to be a challenge in this country. Currently, the electrodes of most commercial supercapacitor are made of carbon which is known to be inexpensive and has high resistance to corrosion. These carbon based supercapacitors operate under EDLC. They offer fast charging/discharging rates and have the ability to sustain millions of cycles without degrading. With their high power densities, they bridge the gap between batteries which offer high energy densities but are slow in charging/discharging and conventional dielectric capacitors which are very fast but having very low energy densities. The objective of this work was to develop a high performance supercapacitor using polyanilino-graphene oxide intercalated with platinum group metal nanocomposites. Specific capacitance of each material was investigated with the objective of ascertaining the material that has the best capacitance. In this work, GO was functionalized with aniline and intercalated with Pt, Pd and Pd-Pt nanocomposites. The nanomaterials were characterized with FTIR, Ultravioletvisible (UV-visible) spectroscopy, high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscopy (HRTEM), energy dispersive x-ray microanalysis (EDS) and X-ray diffraction (XRD) analysis. The composites were tested for possible application as supercapacitor materials using potentiostatic-galvanostatic constant current charge/discharge. The synthesized materials had good electronic, mechanical, optical, physical etc. properties as proven by the various characterization techniques but they proved not to be ideal for application as supercapacitor materials. The materials tested negative when tested for both anodic and cathodic materials therefore we can conclude that the materials are not good supercapacitor materials and therefore cannot be used in application as novel as supercapacitors.

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Orientador: Fernando Galembeck / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-16T14:11:34Z (GMT). No. of bitstreams: 1 MirandaeBritto_AndreiaGoncalves_M.pdf: 3688378 bytes, checksum: 62a326372d2a0139c22b57dd76dbc498 (MD5) Previous issue date: 2009 / Resumo: Dois catalisadores, denominados nesta dissertação por A e B, contendo 9% de paládio suportados em carvão ativado foram produzidos pelo mesmo método em escala industrial, porém em anos diferentes. O catalisador A apresentou uma atividade catalítica de hidrogenação do ácido cinâmico 40% inferior ao catalisador B e a hidrogenação de nitrato para formação de hidroxilamina, conhecido como teste Hyam, 31% inferior. Testes adicionais para caracterização dos dois catalisadores foram realizados, como determinação quantitativa do teor metálico via ICP-OES, área superficial e volume de poros calculados pelas técnicas propostas por Brunauer-Emmett-Teller (BET) e Barrett-Joyner-Halenda (BJH) através da isoterma de N2 e quimissorção de CO. Porém esses resultados foram insuficientes para justificar a diferença de atividade na hidrogenação do ácido cinâmico. Microscopia eletrônica de transmissão foi utilizada para investigar essa diferença catalítica. Com as imagens de campo claro e campo escuro obtidas, foi observado que o catalisador A continha aglomerados de cristalitos de paládio que se correlacionavam com as regiões de oxigênio presentes no carvão obtidas pelas imagens de mapeamento elementar. Porém um maior contraste no mapeamento de oxigênio do catalisador A foi observado confirmando a relação existente entre os grupos oxigenados e a dispersão dos nanocristais de paládio. Com as análises de Temperatura Programada de Dessorção (TPD) e Ponto Isoeletrônico (PI) foi constatado que o carvão A¿ continha grupos oxigenados mais ácidos que o carvão B¿. Estes resultados mostraram que o grau e padrão de oxidação do carvão usado como suporte têm grande importância na morfologia e propriedades finais dos catalisadores. / Abstract: Two catalysts, named in this dissertation A and B, containing 9% of palladium supported on active carbon were produced by the same method in an industrial scale, but in different years. Catalyst A had a catalytic activity of cinnamic acid hydrogenation 40% lower than catalyst B and nitrate hydrogenation to hydroxylamine formation, known as Hyam test, 31% lower. Additional tests for the characterization of the two catalysts were performed, such as metal content by ICP-OES, surface area and pore volume obtained from N2 isotherm and Barrett-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) techniques and CO chemisorption. However, these results were insufficient to justify the difference in activity of cinnamic acid hydrogenation. Transmission electron microscopy was used in order to investigate this catalytic difference. Through the images of bright field and dark field obtained it was observed that the catalyst A contained clusters of palladium crystallites, which are correlated with the oxygen map present in the carbon obtained by energy-loss spectroscopy imaging (ESI). However, a marked contrast in oxygen map for the catalyst A was observed confirming the existing relationship among the oxygen groups and palladium nanocrystals dispersion. Analysis Temperature Programmed Desorption (TPD) and Isoeletric Point (IEP) measurements were performed on the carbon support and it was verified that carbon A¿ contained oxygen groups which are more acid than those in carbon B¿. These results demonstrated that the degree and oxidation pattern in the carbon used as support has great influence in the morphology and final proprieties of the catalyst. / Mestrado / Físico-Química / Mestre em Química

Abstract: A brief overview of this PhD thesis, The emergence of nanotechnology has stimulated both fundamental and industrially relevant studies of the catalytic activity of noble metal nanoparticles. Palladium, ruthenium and gold are well known catalysts when used in nanoparticle- based systems. This body of work endeavoured to investigate the catalytic activity of these noble metal nanoparticles through three studies as a briefly overviewed below. Study 1: Palladium is a well-known catalyst, even in bulk phases, but its high cost had driven industry towards its use in nanoparticle- based systems well before nanotechnology had attracted the attention of the media. Palladium nanoparticles often show remarkable catalytic activity and selectivity, particularly for the hydrogenation of some unsaturated hydrocarbons, such as alkenes, alkynes and unsaturated carbonyl compounds. The nature of supports can affect the catalytic activity and selectivity of metal-support interaction. Natural polymeric supports, such as wool, can be suitable for new generation of composite materials incorporating nanosized metal nanoparticles and have the added advantage of being “environmentally friendly”. Catalytic hydrogenation of cyclohexene to cyclohexane by palladium nanoparticles immobilized on wool was demonstrated by using a Parr high pressure hydrogenation set-up. The efficiency of the process was explored over loading rates from 1.6% to 2.6% of palladium nanoparticles (by weight) with a variety of particle sizes. Optimization of the reaction conditions including, stirring rate, amounts of reactants, gas pressure and target temperature, led to series of catalytic activity tests carried out for 5 or 24 hours (each) at 400psi H2 and 40 oC using a stirring rate 750 rpm. Product mixtures were analysed using gas chromatography (GC-FID) to determine conversions. Samples S1 and S2 proved to be the most active catalysts because the average Pd particle size was around ~5 nm and the particles were more accessible for the reactant (i.e., Pd particles were on the surface of wool). However, under the catalytic testing conditions studied, wool (Pd/wool) did not show advantages over commercially used palladium nanoparticles on activated carbon (Pd/C). Study 2: Ruthenium fabricated as noble metal nanoparticles can be catalytically active for hydrogenation of organic compounds. However, a challenging issue for researchers is that Ru nanocatalysts can be spontaneously deactivated due to effects, such as sintering or leaching of active components, oxidation of noble metal nanoparticles, inactive metal or metal oxide deposition and impurities in solvents and reagents. Calcination of noble metal nanoparticles is one option for reactivation of Ru nanoparticles immobilized on SiO2 (Ru/SiO2) utilized as nanocatalysts in chemical reactions. In fact, the catalytic activity of noble metal nanoparticles is known to be proportional to the active part of the surface area. The effects of calcinations on catalytic activity of “shape- specific” 0.1 wt% Ru/SiO2 for hydrogenation of cyclohexene to cyclohexane were investigated. Optimization of calcinations by varying temperature and time proved to be effective on the activity of nanocatalysts retaining the Ru nanocatalysts shapes for the hydrogenation of cyclohexene. Product mixtures were analysed using gas chromatography (GC-FID) to determine conversions. The Ru catalysts showed the highest activity (100%) when they were activated by calcination following protocol No.1 in a furnace under the mildest reductive conditions studied (temperature = 200 oC for 1 hour, which was the shortest calcination time). HRTEM study showed only minor deformation of the Ru nanoparticles and minimal aggregation for this type of activation. Study 3: Supported gold nanoparticles have excited much interest owing to their unusual and somewhat unexpected catalytic activity particularly with the selective oxidation of organic compounds. Gold nanoparticles immobilized on Norit activated carbon (Au101/C) via colloidal deposition gave high selectivity of benzyl alcohol oxidation. The presence of a base (K2CO3) increased the catalytic activity of gold nanocatalysts (which was negligible in the absence of base) through dehydrogenation of the alcohol via deprotonation of a primary OH groups, and helped overcome the rate-limitation step of the oxidation process. The interaction between the gold species and the support was investigated by measuring change in catalytic activity with different activation methods (i.e., washing with a solvent at elevated temperature, and/or followed by calcinations). A mixture of benzyl alcohol as a reactant, methanol as a solvent, K2CO3 as a base and oxygen gas was studied by the activated gold nanocatalysts using a mini reactor set-up. The efficiency of the process was explored by varying the amounts of benzyl alcohol and the base, target temperature, metal loading of the gold catalysts rate and the solvent, between 3 and 24 hours at 73 psi O2 and a stirring rate (750 rpm). The samples of the reaction mixture were centrifuged and analysed by highperformance liquid chromatography (HPLC) to determine conversions. The effect of size on the catalytic activity was studied for different types of gold particles (Au101, Aunaked and Aucitrate) and clusters (Au8 and Au9) immobilized on powder Norit activated carbon. The highest activity of benzyl alcohol oxidation was observed for activated 1.0 wt% Au101/C catalysts (washed with toluene and followed by calcination under vacuum at 100 oC for 3 h) for ~3.5 nm gold particles. Additionally, the support effect was studied for gold particles immobilized on different types of carbons, such as Norit activated carbon (powder, granular and powdered) and mesoporous carbons (CMK-3, CMK-8 and NCCR-41), granular modified carbon (–SH and –SO3H groups) and Vulcan carbon. The highest activity was observed by activated 1.0 wt% Au101/C8 catalysts (washed with toluene and followed by calcination under vacuum at 100 oC for 3 h). Activated 1% Au101/C41 (washed with toluene followed by calcination under vacuum at 100 oC for 3 hours) with 2.6 ± 0.1 nm gold particle size showed the highest selectivity towards methyl benzoate as a main product (S%: 88%) after 3 hours reaction time. However, activated 1% Au101/C (calcination in O2 -H2 at 100 oC for 3 hours) with 6.6 ± 0.3 nm gold particle size exhibited the highest selectivity towards benzoic acid as a main product (S: 86%) after 24 hours reaction time.Therefore, particle size and type of carbon support can be considered as playing crucial roles in defining the catalytic activity of gold nanocatalysts which were used for benzyl alcohol oxidation.

abstract: Palladium metal in its various forms has been heavily studied for many catalytic, hydrogen storage and sensing applications and as an electrocatalyst in fuel cells. A short review on various applications of palladium and the mechanism of Pd nanoparticles synthesis will be discussed in chapter 1. Size dependent properties of various metal nanoparticles and a thermodynamic theory proposed by Plieth to predict size dependent redox properties of metal nanoparticles will also be discussed in chapter 1. To evaluate size dependent stability of metal nanoparticles using electrochemical techniques in aqueous media, a synthetic route was designed to produce water soluble Pd nanoparticles. Also, a purification technique was developed to obtain monodisperse metal nanoparticles to study size dependent stability using electrochemical methods. Chapter 2 will describe in detail the synthesis, characterization and size dependent anodic dissolution studies of water soluble palladium nanoparticles. The cost associated with using expensive metal catalysts can further decreased by using the underpotential deposition (UPD) technique, in which one metal is electrodeposited in monolayer or submonolayer form on a different metal substrate. Electrochemically, this process can be detected by the presence of a deposition peak positive to the bulk deposition potential in a cyclic voltammetry (CV) experiment. The difference between the bulk deposition potential and underpotential deposition peak (i.e. the UPD shift), which is a measure of the energetics of the monolayer deposition step, depends on the work function difference between the metal pairs. Chapter 3 will explore how metal nanoparticles of different sizes will change the energetics of the UPD phenomenon, using the UPD of Cu on palladium nanoparticles as an example. It will be shown that the UPD shift depends on the size of the nanoparticle substrate in a way that is understandable based on the Plieth model. High electrocatalytic activity of palladium towards ethanol oxidation in an alkaline medium makes it an ideal candidate for the anode electrocatalyst in direct ethanol based fuel cells (DEFCs). Chapter 4 will explore the poisoning of the catalytic activity of palladium in the presence of halide impurities, often used in synthesis of palladium nanoparticles as precursors or shape directing agents. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2016

Diffusive Molecular Dynamics (DMD) is a class of recently developed computational methods for the simulation of long-term mass transport with a full atomic fidelity. Its basic idea is to couple a discrete kinetic model for the evolution of mass transport process with a non-equilibrium thermodynamics model that governs lattice deformation and supplies the requisite driving forces for kinetics. Compared to previous atomistic models, e.g., accelerated Molecular Dynamics and on-the-fly kinetic Monte Carlo, DMD allows the use of larger time-step sizes and hence has a larger simulation time window for mass transport problems. This dissertation focuses on the development, assessment and application of a DMD computational framework for the long-term, three-dimensional, deformation-diffusion coupled analysis of solute mass transport in nanomaterials. First, a computational framework is presented, which consists mainly of: (1) a computational model for interstitial solute diffusion, which couples a nonlinear optimization problem with a first-order nonlinear ordinary differential equation; (2) two numerical methods, i.e., mean field approximation and subcycling time integration, for accelerating DMD simulations; and (3) a high-performance computational solver, which is parallelized based on Message Passing Interface (MPI) and the PETSc/TAO library for large-scale simulations. Next, the computational framework is validated and assessed in two groups of numerical experiments that simulate hydrogen mass transport in palladium. Specifically, the framework is validated against a classical lattice random walk model. Its capability to capture the atomic details in nanomaterials over a long diffusive time scale is also demonstrated. In these experiments, the effects of the proposed numerical methods on solution accuracy and computation time are assessed quantitatively. Finally, the computational framework is employed to investigate the long-term hydrogen absorption into palladium nanoparticles with different sizes and shapes. Several significant findings are shown, including the propagation of an atomistically sharp phase boundary, the dynamics of solute-induced lattice deformation and stacking faults, and the effect of lattice crystallinity on absorption rate. Specifically, the two-way interaction between phase boundary propagation and stacking fault dynamics is noteworthy. The effects of particle size and shape on both hydrogen absorption and lattice deformation are also discussed in detail. / Ph. D. / Interstitial diffusion in crystalline solids describes a phenomenon in which the solute constituents (e.g., atoms) move from an interstitial space of the host lattice to a neighboring one that is empty. It is a dominating feature in many important engineering applications, such as metal hydrides, lithium-ion batteries and hydrogen-induced material failures. These applications involve some key problems that might take place over long time periods (e.g., longer than 1 s), while the nanoscale behaviors and mechanisms become significant. The time scale of these problems is beyond the capability of established atomistic models, e.g., accelerated Molecular Dynamics and on-the-fly kinetic Monte Carlo. To this end, this dissertation presents the development and application of a new computational framework, referred to as Diffusive Molecular Dynamics (DMD), for the simulation of long-term interstitial solute diffusion in advanced nanomaterials. The framework includes three key components. Firstly, a DMD computational model is proposed, which accounts for three-dimensional, deformation-diffusion coupled analysis of interstitial solute mass transport. Secondly, nu- merical methods are employed to accelerate the DMD simulations while maintaining a high solution accuracy. Thirdly, a high-performance computational solver is developed to implement the DMD model and the numerical methods. Moreover, regarding its application, the DMD framework is first validated and assessed in the numerical experiments pertaining to hydrogen mass transport in palladium crystals. Then, it is employed to investigate the atomic behaviors and mechanisms involved in the long-term hydrogen absorption by palladium nanoparticles with different sizes and shapes. The two-way interaction between hydrogen absorption and lattice deformation is studied in detail.

Dendrimers are hyperbranched macromolecules, with branches-upon-branches architectures, precise constitutions and molecular weights of several kiloDaltons (Figure 1). The dendritic structure remains to be an influential feature in the developments of dendrimer chemistry at large. Organometallic catalysis forms an active area, wherein the dendrimers find a defined importance. A number of dendrimer types have been utilized to study organometallic catalysis that combine the dendritic architectural principles. Chapter 1 of the Thesis summarizes the advances in the dendrimer-mediated catalyses, apart from an overview of the methods adopted to synthesize dendrimers. Chapter 2 describes the synthesis of newer types of larger generation poly(propyl ether imine) (PETIM) dendrimers. The molecular structure of a sixth generation PETIM dendrimer is shown in Figure 2. The PETIM series of dendrimers are synthesized by iterative synthetic cycles of two reductions and two Michael addition reactions. Modifications of the synthetic methods were identified, so as to facilitate the synthesis and purification of the higher generation dendrimers. Formation of the PETIM dendrimers, possessing a tertiary amine as the branch juncture and ether as the linker component, is assessed systematically by routine analytical techniques. The peripheries of these dendrimers possess either alcohols or amines or carboxylic acids or esters or nitriles, thereby opening up possibilities for varied studies. Architecturally-driven effects are searched constantly while integrating dendrimers in wide ranging studies. With knowledge that un-functionalized PAMAM and PPI dendrimers show fluorescence properties, we tested the PETIM dendrimers for their luminescence property. The photophysical properties of PETIM dendrimers presenting esters, alcohols, acid salts, nitriles and amines at their peripheries were studied. The anomalous fluorescence arising from alcohol terminated PETIM dendrimers (Figure 3) was established through a series of experiments. Various experimental parameters including pH, viscosity of the solvents, aging, temperature and concentration were used to assess the photochemical properties of the PETIM dendrimers. It was observed that generations 1 to 5 absorbed in the region of 260-340 nm, in MeOH and in aqueous solutions. Excitation of the OH-terminated dendrimer solutions at 330 nm led to an emission at ~390 nm (Figure 4). Dendrimers presenting esters, acid salts and amines at their peripheries also exhibited a similar excitation and emission wavelengths. An increase in the fluorescence intensity was observed at low pH and with more viscous solvents. Lifetime measurements showed at least two species (~2.5 and ~7.0 ns) were responsible for the emission. The quenching of the fluorescence originating from the PETIM dendrimers by inorganic anions was also established in the present study. The periodate, persulfate, perchlorate and nitrite anions quenched the fluorescence efficiently among several anions tested. An ‘oxygen-interacted moiety’, in addition to altered hydrogen bonding properties of the dendrimers, was presumed contribute to the anomalous fluorescence behavior. Chapter 3 of the Thesis elaborates photophysical studies of several PETIM dendrimers. Incorporation of catalytically active moieties at the peripheries of dendrimers was identified as an important avenue, in order to explore the effect of the dendritic architectures on the catalytic activities of chosen catalytic moieties. In order to assess the effect of the dendritic scaffold, in relation to both numbers and locations of the catalytic units, an effort was undertaken to study the catalytic activities of catalytic units, that are present in varying numbers within one generation. Partial and full phosphine-metal complex substituted three generations of dendritic catalysts were synthesized, by using a selective alkylation as a key step. The number of the primary amine groups led to define the number of phosphine groups at the peripheries. The primary amine groups were, in turn, prepared by a Michael addition of acrylonitrile and hydroxyl groups, followed by a reduction of the nitrile moieties to the corresponding amines. The first and the second generation PETIM dendrimers utilized in this study present up to four and eight hydroxyl groups at their peripheries. A partial etherification was exercised in order to mask few hydroxyl groups, useful to prepare the partially substituted phosphine groups. Subsequent Michael addition of acrylonitrile with remaining hydroxyl groups, to afford the nitrile terminated dendrimers, and a metal-mediated reduction of the nitrile to amine led to the required number of amine functionalized dendrimers. Functionalization of the peripheries with alkyldiphenyl phosphine moieties was conducted through a Mannich reaction of the amines with formaldehyde and diphenyl phosphine. The subsequent metal complexation with Pd(COD)Cl2 afforded a series of phosphine-Pd(II) complexes, for the zero, first and second generation PETIM dendrimers. Figure 5 shows the molecular structures of a partially and a fully substituted second generation dendrimer. Catalytic activities of the dendrimer-Pd(II) complexes were assessed in both Heck and Suzuki coupling reactions. A C-C bond forming reactions were studied, with the series of dendritic-Pd(II) catalysts, using Cs2CO3 as a base and at 40 oC. In an overall observation, it was found that an individual catalytic site showed a considerable increase in the catalytic activity when it was present in multiple numbers than as a single unit within the same generation (Figure 6). Figure 6. Bar diagrams of (a) Heck reaction and (b) Suzuki reaction, employing the dendritic catalysts 1 - 11. The Heck coupling reaction involved tert-butyl acrylate and iodobenzene, and the Suzuki coupling reaction involved phenyl boronic acid and iodobenzene. The observations revealed that: (i) the higher generation dendritic catalysts exhibited higher catalytic activities per catalytic site and (ii) the dendritic scaffold has a role in enhancing the activities of the individual catalytic sites. The catalysis study identified the catalytic activities that occurred when a series of catalysts within a given dendrimer generation was used. Such a study is hitherto unknown and the observations of this study address some of the pertinent queries relating to the efficiencies of multivalent dendritic catalysts. Chapter 4 of the Thesis describes the synthesis and characterization of series of organometallic PETIM dendrimer and studies of their catalytic activities. Studies on solid-supported catalysis present a significant importance in heterogeneous organometallic catalysis. Silica is a prominently utilized heterogeneous metal catalyst support. Functionalization of the solid supports with suitable chelating ligands is emerging as a viable strategy to circumvent not only the pertinent metal catalyst deterioration and leaching limitations, but also to stabilize the metal particles and to adjust their catalytic efficiencies. In exploring heterogeneous organometallic catalysis, functionalization of silica with a first generation phosphinated dendritic amine was undertaken. The synthetic scheme adopted to synthesize dendrimer functionalized silica is shown in Scheme 1. The reaction of the chloropropylated silica 4 with amine 3 was conducted in CHCl3. Complexation of the functionalized silica 5 with Pd(COD)Cl2 led to isolation of Pd(II)- impregnated silica. Scheme 1. Preparation of Pd nanoparticles stabilized by functionalized silica. It was anticipated that the ratio of phosphine to Pd(II) would be 1:0.5, resulting from a bidendate binding of the phosphine ligand to Pd metal. The observed ICP-OES result indicated that all phosphine ligands did not chelate the metal. With the desire to obtain the metal nanoparticles, the metal complex was subjected to a reduction, which was performed by conditioning 5-Pd(II) complex in EtOH. The Pd metal nanoparticle thus formed was characterized by physical methods, and the spherical nanoparticles were found to have >85 % size distribution between 2-4 nm (Figure 7). Analyses of the Pd(0) impregnated in dendrimer functionalized silica were performed using NMR, XPS spectroscopies, elemental analysis and microscopies. Figure 7. Transmission electron micrograph and histogram of 6, obtained after treatment with EtOH. The Pd-nanoparticle stabilized silica was used in the hydrogenation of several α, β-unsaturated olefins. The catalyst recycling experiments were conducted more than 10 times, and no loss in the catalytic activities were observed. Chapter 5 describes the functionalization of the silica support with diphenylphosphinomethyl-derivatized dendritic amine, palladium nanoparticle formation and the catalysis studies. Overall, the Thesis establishes the synthesis of larger generation PETIM dendrimers, studies of their anomalous fluorescence behavior, organometallic catalysis in solution, as well as, in heterogeneous conditions, pertaining to the C-C bond forming reactions and hydrogenation reactions. (For figure, graph and structural formula pl see the pdf file)

Des membranes polymères catalytiques ont été préparées via la polymérisation photo-amorcée de monomères acryliques à la surface de membranes support MicroPES(r). Des nanoparticules de palladium (PdNP) avec diamètre moyen compris entre 4 et 10 nm sont ensuite synthétisés et immobilisées dans ces gels polymères greffés. Cette thèse se focalise sur le greffage d'un gel de polymère neutre : (2-hydroxyethyl acrylate) (PHEA), pour négliger les contributions ioniques du réseau polymère sur la synthèse in-situ des PdNP. La stabilisation de PdNP dans le gel de PHEA greffé est possible par des moyens stériques étant donné que la distance entre des chaînes de polymère réticules (entre 0.3 à 2.5 nm) est plus petite que le diamètre moyen de PdNP. Une approche à la fois théorique et expérimentale, sur la base des mecanismes de nucléation et de croissance, permet la conception de PdNP de taille spécifique. La performance catalytique des membranes a été évaluée avec une configuration en filtration traversée. Sur la réaction de couplage de Suzuki-Miyaura, des conversions et sélectivités de 100 % ont été obtenues pour des temps de séjour de 10 secondes avec des membranes planes. Les réactions d'hydrogénation de plusieurs composés aromatiques ont également été testées. Des taux de conversion élevés ont été obtenus en quelques secondes avec des membranes planes en filtration avec des solutions saturés d'H2. Des taux de conversion élevés sont obtenus en seulement quelques minutes avec des membranes fibres creuses catalytiques en mode contacteur permettant une importante intensification du procédé. / Catalytic polymeric membranes are prepared via photo-grafting polymerization of neutral acrylic monomers onto the surface of a MicroPES(r) membrane support. Palladium nanoparticles (PdNP) of mean diameter of 4-10 nm are synthetized and immobilized within the grafted polymer gels. The research is focused on grafting a neutral polymer gel: poly (2-hydroxyethyl acrylate) (PHEA), to avoid any ionic contribution of the polymer network on the in-situ synthesis of PdNP. The stabilization of PdNP within the grafted PHEA is achieved by steric means as the distance between polymeric crosslinked chains (ca. 0.3 to 2.5 nm) is smaller than the mean diameter of PdNP. Both theoretical and experimental approaches are presented on the PdNP synthesis as an approach to conceive PdNP of specific sizes using nucleation and growth theories. Catalytic performance of the membranes is evaluated in flow-through configuration. Catalytic tests are performed on Suzuki-Miyaura cross-coupling reactions. Full conversion and selectivity within 10 seconds of residence time using flat sheet membrane are obtained. Hydrogenation of several aromatic compounds are also tested and high conversions were achieved within seconds of residence time using flat sheet membranes in flow-through configuration with H2-saturated solutions and within minutes using catalytic hollow fibers in contactor mode.

[pt] A reação de acoplamento C-C de Suzuki, desde a sua descoberta, sempre atraiu o interesse de diversos pesquisadores e encontrou aplicação em diversos campos tanto na academia como na indústria. Movidos pelos problemas ambientais que tanto preocupam nossa sociedade e pelos princípios da química verde, criados para guiar os químicos na direção de uma ciência sustentável, pesquisadores tem buscado criar catalisadores eficientes para essa reação, que consigam uma alta seletividade em condições reacionais brandas. O desenvolvimento de catalisadores heterogêneos é motivado pela sua fácil remoção do meio reacional e seu possível reuso para um elevado número de reações. Uma abordagem para criação desses catalisadores é a ancoragem de íons metálicos ou de nanopartículas (Nps) metálicas em suportes que facilitem seu manuseio, remoção e reuso. Neste trabalho foram sintetizadas nanopartículas de paládio (Nps Pd) estabilizadas por carboximetilcelulose (CMC), em cuja síntese foi utilizado o ácido L-ascórbico (AA) como agente redutor. Essas Nps foram caracterizadas por UV-VIS, FT-IR-ATR, DLS, potencial zeta, MEV e EDS. A reação de redução do 4-nitrofenol foi utilizada como teste preliminar para verificar a atividade catalítica dessas Nps e, em diferentes condições, a reação ocorreu com tempos que variaram de 3 a 10 minutos. Depois, foram empregadas três diferentes metodologias para a síntese de Nps Pd que utilizaram a CMC como agente redutor e estabilizador a fim de eliminar o uso do AA. As três Nps sintetizadas foram usadas para catalisar uma reação de acoplamento entre o ácido fenilborônico e o 4-iodofenol com rendimentos de 68-76 por cento em duas horas. As Nps que obtiveram maior rendimento foram escolhidas para dar prosseguimento ao projeto. Foram caracterizadas por UV-VIS, FT-IR-ATR, DLS, potencial zeta, MEV e EDS e foram utilizadas para catalisar mais três acoplamentos de Suzuki com rendimentos de 74 por cento a 86 por cento. Um suporte lignocelulósico, mecanicamente e termicamente resistente, feito a partir da biomassa de bambu foi funcionalizado com 1-oxil-2,2,6,6-tetrametilpiperidina (TEMPO) e caracterizado por FT-IR-ATR. Foi, então, impregnado para a imobilização de Na2PdCl4 (T_PdCl2) e das Nps Pd reduzidas e estabilizadas com CMC escolhidas (T_PdCMC_R). Os catalisadores desenvolvidos foram caracterizados por FT-IR-ATR, MEV e EDS. O catalisador T_PdCl2 foi utilizado em 4 reações seguidas com perdas de rendimento a cada reação (de 92,2 por cento até 18,4 por cento). Por ICP OES foi determinado que a quantidade de paládio lixiviada foi de 0,20 ppm na primeira reação e de 0,10 ppm nas reações seguintes. O catalisador T_PdCMC_R foi usado para a reação acoplamento entre ácido fenilborônico e 4-iodofenol e, em diferentes condições, obteve rendimentos de 35 por cento e 43 por cento. / [en] Suzuki C-C coupling reaction, since its discovery, has always attracted the interest of researchers and has found application in several fields both in academia and industry. Driven by environmental problems that concern our society so much and by the principles of green chemistry, created to guide chemists towards a sustainable science, researchers have sought to create efficient catalysts for this reaction, which achieve high selectivity in mild reaction conditions. The development of heterogeneous catalysts is motivated by its easy removal from the reaction medium and its possible reuse for a high number of reactions. One approach for creating these catalysts is to anchor metallic ions or metallic nanoparticles (Nps) in supports that facilitate their handling, removal and reuse. In this work, palladium nanoparticles (Nps Pd) reduced by ascorbic acid (AA) and stabilized by carboxymethylcellulose (CMC) were synthesized. These Nps were characterized by UV-VIS, FT-IR-ATR, DLS, zeta potential, SEM and EDS. The 4-nitrophenol reduction reaction was used as a preliminary test to verify the catalytic activity of these Nps and, under different conditions, the reaction occurred with times ranging from 3 to 10 minutes. Then, three different methodologies for the synthesis of Nps Pd using CMC as reducing and stabilizing agent were proposed in order to eliminate the use of AA. The three synthesized Nps were used to catalyze the coupling reaction between phenylboronic acid and 4-iodophenol with yields of 68-76 percent in two hours. The Nps that obtained the highest yield were chosen to be used in the next steps of the project. These Nps were characterized by UV-VIS, FT-IR-ATR, DLS, zeta potential, SEM and EDS and were used to catalyze three more Suzuki couplings with yields of 74-86 percent. A mechanically and thermally resistant lignocellulosic support, made of bamboo biomass, was functionalized with 1-oxyl-2,2,6,6-tetramethylpiperidine (TEMPO) and characterized by FT-IR-ATR. It was then impregnated for the immobilization of Na2PdCl4 (T_PdCl2) and the chosen Nps Pd reduced and stabilized by CMC (T_PdCMC_R). The developed catalysts were characterized by FT-IR-ATR, MEV and EDS. The catalyst T_PdCl2 was used in 4 reactions in a row with yield losses for each reaction (from 92.2 percent to 18.4 percent). By ICP OES it was determined that the amount of palladium leached was 0.20 ppm in the first reaction and 0.10 ppm in the following reactions. The catalyst T_PdCMC_R was used for the coupling reaction between phenylboronic acid and 4-iodophenol and, under different conditions, obtained yields of 35 percent and 43 percent.

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