Ruthenium-based homogenous catalysis is a broad and extremely useful branch of transition metal catalysis. Surely, the most famous example is olefin metathesis, for which Yves Chauvin, Robert Grubbs and Richard Schrock were awarded the 2005 Chemistry Nobel Prize. Although some of the most well-known catalysts are widely used and considered benchmark catalysts, the research around this topic has not stopped. The modification of known systems to achieve better performance and better understanding of the catalytic mechanism is very important and an example of such modification is reported in this thesis. The newly synthesised catalysts were compared to the parent commercially available catalyst showing better reactivity. Ruthenium catalysis, though, is not limited to olefin metathesis and C-H activation, for example, it has become a useful approach to the functionalisation of organic molecules. In this field, the deuteration of C-H bonds is an interesting transformation, which has many applications. The synthesis of new hydridosilylruthenium complexes and their application in the deuteration of a variety of substrates is reported in this manuscript. The unprecedented synthesis of tetradeuterated Ketoprofene is also reported. Recently, ruthenium-based catalysts have found application in the dehydrogenation of suitable compounds, such as formic acid, ammonia-borane and other hydrogen-rich substances. The driving force behind these discoveries is the use of H2 as an energy vector in place of fossil fuels. A hydrido-ruthenium catalyst was shown to catalyse the decomposition of formic acid in CO2 and H2 and to catalyse the reduction of olefinic substrates. The released CO2 from the reaction did not interfere with the fuel cell due to its inertness. This property makes its employment as C1 source very challenging, although its use would also be extremely attractive because of the abundance of this gas. In these regards, both frustrated Lewis pairs (FLPs) and gold catalysts have shown interesting reactivity in the activation of CO2. A new FLP and a silica supported gold catalyst were synthesised to test them in CO2 activation and the results are reported in this manuscript.

Magnetic separation has received a lot of attention as a robust, highly efficient and rapid catalyst separation technology. Many studies have focused on developing methodologies for the immobilization of catalytic active species, but the development of magnetic supports has been mainly limited to silica, polymer or carbon-coated magnetic nanoparticles (NPs). The design of magnetic nanocomposites and the incorporation of other oxides are highly welcome to broaden the application of this separation technology in the field of catalysis. In this context, studies of the thermal stability of silica-coated magnetite (Fe3O4@SiO2) were performed to evaluate the possibility of calcining it without losing the magnetic properties of the support. The calcination would permit the deposition of different oxides on the silica surface, such as ceria and titania. The calcined Fe3O4@SiO2 material preserved the core-shell morphology and magnetic properties, but increased its surface area six times. New magnetic supports were developed by using post-coating process for the deposition of ceria and titania onto silica-coated magnetite. Magnetically recoverable Rh, Pd and Ru nanocatalysts were prepared. The catalysts were employed in hydrogenation of cyclohexene, benzene or phenol and the study of the influence of each support on the catalytic activity was a main objective of this thesis. The catalysts were prepared by two different approaches: the impregnation and the sol-immobilization of pre-formed metal NPs. The colloidal metal NPs were prepared by reduction of metal salts and also by decomposition of organometallic complexes. Rhodium catalysts prepared by impregnation of rhodium(III) chloride and reduction with H2 showed some reproducibility issues that were surpassed by using NaBH4 or hydrazine as reducing agents. The preparation of catalysts by the immobilization of colloidal NPs is an interesting alternative to obtain reproducible and very active catalysts. Nanoparticles of Pd, Rh and Ru were prepared by an organometallic approach and immobilized on calcined Fe3O4@SiO2, Fe3O4@SiO2CeO2 and Fe3O4@SiO2TiO2. The elimination of the stabilizing agent leads to more active catalysts upon recycling. Rhodium catalysts supported on ceria support was the most active catalyst in the hydrogenation of cyclohexene (TOF 125,000 h-1). Palladium catalysts were the most selective catalyst for the hydrogenation of phenol to cyclohexanone, no matter the support used. The formation of cyclohexanol is enhanced with titania and the hydrodeoxygenation to produce cyclohexane occurred mainly with silica. / A separação magnética tem recebido muita atenção como uma tecnologia robusta, altamente eficiente e rápida para recuperar catalisadores sólidos após uso em reações em fase líquida. Muitos estudos têm focado nas metodologias para a imobilização de espécies cataliticamente ativas, mas o desenvolvimento de suportes magnéticos tem se limitado a nanopartículas magnéticas revestidas com sílica, polímeros ou carbono. O desenvolvimento de nanocompósitos magnéticos com a incorporação de outros óxidos é muito desejável para ampliar a aplicação dessa tecnologia de separação em catálise. Nesse contexto, estudos da estabilidade térmica de magnetita revestida com sílica (Fe3O4@SiO2) foram realizados para avaliar a possibilidade de calcina-la sem perder as propriedades magnéticas do suporte. Uma etapa de calcinação é necessária para a deposição de diferentes óxidos na superfície da sílica, tais como céria e titânia. O Fe3O4@SiO2 calcinado preservou a morfologia \"core-shell\" e as propriedades magnéticas, porém apresentou um aumentou de seis vezes na área superficial. Novos suportes magnéticos foram desenvolvidos pela deposição de céria e titânia sobre magnetita previamente revestida com sílica. Nanocatalisadores magneticamente recuperáveis de Rh, Pd e Ru foram preparados. Os catalisadores foram utilizados na hidrogenação de ciclo-hexano, benzeno ou fenol e o principal objetivo dessa tese foi o estudo da influência de cada suporte na atividade catalítica. Os catalisadores foram preparados de duas formas diferentes: impregnação-redução e imobilização de nanopartículas (NPs) metálicas pré-formadas. As NPs coloidais foram preparadas pela redução de sais metálicos e, também, pela decomposição de complexos organometálicos. Catalisadores de ródio preparados pela impregnação de cloreto de ródio(III) e redução com H2 mostraram alguns problemas de reprodutibilidade, que foram superados utilizando NaBH4 ou hidrazina como agentes redutores. A preparação de catalisadores pela imobilização de NPs coloidais é uma alternativa interessante para obter catalisadores reprodutíveis e muito ativos. Nanopartículas de Pd, Rh e Ru foram preparadas a partir de organometálicos e imobilizadas em Fe3O4@SiO2 calcinada, Fe3O4@SiO2CeO2 e Fe3O4@SiO2TiO2. A eliminação do agente estabilizante torna os catalisadores mais ativos durante os reusos. O catalisador de Rh sobre o suporte de céria foi o catalisador mais ativo na hidrogenação de ciclohexeno (TOF 125000 h-1). O catalisador de Pd foi o catalisador mais seletivo para a hidrogenação de fenol em ciclo-hexanona, independente do suporte usado. A formação de ciclo-hexanol é favorecida pelo suporte de titânia e a hidrodesoxigenação para produzir ciclo-hexano ocorreu principalmente no suporte de sílica.

Magnetic separation has received a lot of attention as a robust, highly efficient and rapid catalyst separation technology. Many studies have focused on developing methodologies for the immobilization of catalytic active species, but the development of magnetic supports has been mainly limited to silica, polymer or carbon-coated magnetic nanoparticles (NPs). The design of magnetic nanocomposites and the incorporation of other oxides are highly welcome to broaden the application of this separation technology in the field of catalysis. In this context, studies of the thermal stability of silica-coated magnetite (Fe3O4@SiO2) were performed to evaluate the possibility of calcining it without losing the magnetic properties of the support. The calcination would permit the deposition of different oxides on the silica surface, such as ceria and titania. The calcined Fe3O4@SiO2 material preserved the core-shell morphology and magnetic properties, but increased its surface area six times. New magnetic supports were developed by using post-coating process for the deposition of ceria and titania onto silica-coated magnetite. Magnetically recoverable Rh, Pd and Ru nanocatalysts were prepared. The catalysts were employed in hydrogenation of cyclohexene, benzene or phenol and the study of the influence of each support on the catalytic activity was a main objective of this thesis. The catalysts were prepared by two different approaches: the impregnation and the sol-immobilization of pre-formed metal NPs. The colloidal metal NPs were prepared by reduction of metal salts and also by decomposition of organometallic complexes. Rhodium catalysts prepared by impregnation of rhodium(III) chloride and reduction with H2 showed some reproducibility issues that were surpassed by using NaBH4 or hydrazine as reducing agents. The preparation of catalysts by the immobilization of colloidal NPs is an interesting alternative to obtain reproducible and very active catalysts. Nanoparticles of Pd, Rh and Ru were prepared by an organometallic approach and immobilized on calcined Fe3O4@SiO2, Fe3O4@SiO2CeO2 and Fe3O4@SiO2TiO2. The elimination of the stabilizing agent leads to more active catalysts upon recycling. Rhodium catalysts supported on ceria support was the most active catalyst in the hydrogenation of cyclohexene (TOF 125,000 h-1). Palladium catalysts were the most selective catalyst for the hydrogenation of phenol to cyclohexanone, no matter the support used. The formation of cyclohexanol is enhanced with titania and the hydrodeoxygenation to produce cyclohexane occurred mainly with silica. / A separação magnética tem recebido muita atenção como uma tecnologia robusta, altamente eficiente e rápida para recuperar catalisadores sólidos após uso em reações em fase líquida. Muitos estudos têm focado nas metodologias para a imobilização de espécies cataliticamente ativas, mas o desenvolvimento de suportes magnéticos tem se limitado a nanopartículas magnéticas revestidas com sílica, polímeros ou carbono. O desenvolvimento de nanocompósitos magnéticos com a incorporação de outros óxidos é muito desejável para ampliar a aplicação dessa tecnologia de separação em catálise. Nesse contexto, estudos da estabilidade térmica de magnetita revestida com sílica (Fe3O4@SiO2) foram realizados para avaliar a possibilidade de calcina-la sem perder as propriedades magnéticas do suporte. Uma etapa de calcinação é necessária para a deposição de diferentes óxidos na superfície da sílica, tais como céria e titânia. O Fe3O4@SiO2 calcinado preservou a morfologia \"core-shell\" e as propriedades magnéticas, porém apresentou um aumentou de seis vezes na área superficial. Novos suportes magnéticos foram desenvolvidos pela deposição de céria e titânia sobre magnetita previamente revestida com sílica. Nanocatalisadores magneticamente recuperáveis de Rh, Pd e Ru foram preparados. Os catalisadores foram utilizados na hidrogenação de ciclo-hexano, benzeno ou fenol e o principal objetivo dessa tese foi o estudo da influência de cada suporte na atividade catalítica. Os catalisadores foram preparados de duas formas diferentes: impregnação-redução e imobilização de nanopartículas (NPs) metálicas pré-formadas. As NPs coloidais foram preparadas pela redução de sais metálicos e, também, pela decomposição de complexos organometálicos. Catalisadores de ródio preparados pela impregnação de cloreto de ródio(III) e redução com H2 mostraram alguns problemas de reprodutibilidade, que foram superados utilizando NaBH4 ou hidrazina como agentes redutores. A preparação de catalisadores pela imobilização de NPs coloidais é uma alternativa interessante para obter catalisadores reprodutíveis e muito ativos. Nanopartículas de Pd, Rh e Ru foram preparadas a partir de organometálicos e imobilizadas em Fe3O4@SiO2 calcinada, Fe3O4@SiO2CeO2 e Fe3O4@SiO2TiO2. A eliminação do agente estabilizante torna os catalisadores mais ativos durante os reusos. O catalisador de Rh sobre o suporte de céria foi o catalisador mais ativo na hidrogenação de ciclohexeno (TOF 125000 h-1). O catalisador de Pd foi o catalisador mais seletivo para a hidrogenação de fenol em ciclo-hexanona, independente do suporte usado. A formação de ciclo-hexanol é favorecida pelo suporte de titânia e a hidrodesoxigenação para produzir ciclo-hexano ocorreu principalmente no suporte de sílica.

La séparation magnétique a reçu beaucoup d'attention en tant que technologie de séparation de catalyseurs solides, très efficace et rapide. De nombreuses études ont porté sur l'immobilisation de systèmes catalytiques actifs sur un support magnétique afin de les séparer par la simple application d'un aimant. Cependant, le développement de supports magnétiques s'avère limité à des nanoparticules (NPs) magnétiques encapsulées dans une silice, un polymère ou du carbone. La conception de nanocomposites magnétiques incorporant d'autres oxydes est donc intéressante afin d'élargir l'application de cette technologie de séparation dans le domaine de la catalyse. Dans ce contexte, des études de stabilité thermique ont été menées sur magnétite revêtue de silice (Fe3O4@SiO2) pour évaluer la possibilité de la calciner sans perdre les propriétés magnétiques du support. La calcination permettrait le dépôt de différents oxydes sur la surface de la silice, tels que l'oxyde de cérium et l'oxyde de titane. Il a été observé que le matériau Fe3O4@SiO2 calciné a conservé sa morphologie core-shell et ses propriétés magnétiques, tandis que sa surface spécifique at a augmenté de 6 odres de grandeur. Un processus a pu être développé pour le dépôt d'oxyde de cérium et d'oxyde de titane sur Fe3O4@SiO2. Des nanocatalyseurs aisément récupérables par séparation magnétique à base de Rh, Pd et Ru ont pu être préparés en utilisant ces supports de silice modifiés par dépôt de CeO2 et TiO2. Ces nanocatalyseurs obtenus ont été évalués en catalyse d'hydrogénation du cyclohexène, du benzène ou du phénol. L'étude de l'influence de chaque support sur l'activité catalytique des nanocatalyseurs a consitué l'objectif principal de cette thèse. Le dépôt des nanoparticules métalliques sur les supports pour l'obtention des catalyseurs actifs a été réalisé par deux approches différentes: l'imprégnation et l'immobilisation de sols contenant des NP métalliques préformées. Quant aux NPs métalliques colloïdales, elles ont été préparées par réduction de sels métalliques et par la décomposition de complexes organométalliques précurseurs. Des catalyseurs de rhodium préparés par imprégnation de rhodium (III) chlorure et réduction avec H2 ont montré des problèmes de reproductibilité qui ont été contournés en utilisant NaBH4 ou l'hydrazine comme agents réducteurs. La préparation des catalyseurs par l'immobilisation des NP colloïdales s'est avérée une alternative intéressante pour obtenir des catalyseurs très actifs de façon reproductible. Des nanoparticules de Pd, Rh et Ru ont été préparées par l'approche organométallique et immobilisées sur les supports Fe3O4@SiO2 calciné, Fe3O4@SiO2CeO2 et Fe3O4@SiO2TiO2. L'élimination de l'agent stabilisant pour les NPs de Rh déposées sur Fe3O4@SiO2CeO2 semble conduire à un état de surface différent comparativement aux autres supports car ce catalyseur s'est montré le plus actif vis-à-vis de l'hydrogénation du cyclohexène (TOF 125 000 h-1). Les catalyseurs à base de Rh, Pd et Ru ont été utilisées pour l'hydrogénation de phénol. Le palladium s'est avéré le catalyseur le plus sélectif envers la cyclohexanone, quel que soit le support utilisé. La formation de cyclohexanol a été renforcée avec le support fonctionnalisé par l'oxyde de titane et la production de cyclohexane par hydrodéoxygénation a eu lieu principalement avec le support de silice. / Magnetic separation has received a lot of attention as a robust, highly efficient and rapid catalyst separation technology. Many studies have focused on the immobilization of catalytic active species, but the development of magnetic supports has been limited to silica, polymer or carbon-coated magnetic nanoparticles (NPs). The design of magnetic nanocomposites and the incorporation of other oxides are thus highly welcome to broaden the application of this separation technology in the field of catalysis. In this context, studies of the thermal stability of silica coated magnetite (Fe3O4@SiO2) were performed to evaluate the possibility of calcining it without losing the magnetic properties of the support. The calcination would permit the deposition of different oxides on the silica surface, such as ceria and titania. The calcined Fe3O4@SiO2 material preserved its core-shell morphology and magnetic properties, and increased its surface area six times. A post-coating process was developed for the deposition of ceria and titania on Fe3O4@SiO2. Magnetically recoverable Rh, Pd and Ru nanocatalysts were prepared on the surface of the magnetic supports. The obtained catalysts were employed in hydrogenation of cyclohexene, benzene or phenol and the study of the influence of each support on the catalytic activity was the main objective of this thesis. For the deposition of the metallic nanoparticles on the supports in order to obtain the active catalysts two different approaches were followed: the impregnation and the sol immobilization of pre-formed metal NPs. Concerning the synthesis of the colloidal metal NPs, they were prepared either by reduction of metal salts or by decomposition of organometallic complexes. Rhodium catalysts prepared by impregnation of rhodium(III) chloride and reduction with H2 showed some reproducibility issues that were surpassed by using NaBH4 or hydrazine as reducing agents. The preparation of catalysts by the immobilization of colloidal NPs is an interesting alternative to obtain reproducible and very active catalysts. Nanoparticles of Pd, Rh and Ru were prepared by an organometallic approach and immobilized on calcined Fe3O4@SiO2, Fe3O4@SiO2CeO2 and Fe3O4@SiO2TiO2. The elimination of Rh stabilizing agent over ceria support appears to be different than in other supports and was the most active catalyst in the hydrogenation of cyclohexene (TOF 125,000 h-1). The Rh, Pd and Ru catalysts were employed in the hydrogenation of phenol. Palladium was the most selective catalyst to cyclohexanone, no matter the support used. The formation of cyclohexanol is enhanced in the support with titania and the hydrodeoxygenation to produce cyclohexane occurred mainly in the support with silica.