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[ES] La presente tesis doctoral ha mostrado la posibilidad de diseñar sitios activos de MOFs y materiales basados en grafeno para ser utilizados como catalizadores con actividad mejorada para reacciones de oxidación y condensación. Específicamente, el desarrollo de una combinación de metales MIL-101(Cr,Fe) ha dado como resultado un catalizador con actividad catalítica mejorada para la reacción de Prins entre ß-pineno y formaldehído con respecto al MIL-101(Cr) o el inestable MIL-101(Fe) en las condiciones de reacción estudiadas. La presencia de iones Fe3+ en los nodos metálicos del MIL-101(Cr, Fe) aumenta la densidad y la fuerza de los sitios ácidos de Lewis del material, mientras que la presencia de Cr+3 en los nodos metálicos proporciona estabilidad al catalizador. Además, esta Tesis ha demostrado que la presencia de grupos NO2 en el ligando orgánico tereftalato de MIL-101(Cr) aumenta la densidad y la fuerza de los sitios ácidos de Lewis del material. Por lo tanto, MIL-101(Cr)-NO2 exhibe una actividad catalítica superior para la síntesis de bencimidazoles a partir de o-fenilendiaminas y derivados de benzaldehído, así como para la oxidación aeróbica del tiofenol y la desulfuración oxidativa aeróbica de dibenzotiofenos. Esta Tesis también ha demostrado que la selección de un agente reductor apropiado como la hidroquinona para la preparación de rGO a partir de GO aumenta la densidad de los sitios activos para promover las oxidaciones aeróbicas de tiofenol e indano., [CA] La present Tesi doctoral ha mostrat la possibilitat de dissenyar llocs actius de MOFs i materials basats en grafè per ser utilitzats com a catalitzadors amb activitat millorada per a reaccions d'oxidació i condensació. Específicament, el desenvolupament d'una combinació de metalls MIL-101(Cr,Fe) ha donat com a resultat un catalitzador amb activitat catalítica millorada per a la reacció de Prins entre ß-pinè i formaldehíd pel que fa a MIL-101(Cr) o l'inestable MIL-101(Fe) en les condicions de reacció estudiades. La presència de ions Fe3+ en els nodes metàl·lics de MIL-101(Cr,Fe) augmenta la densitat i la força dels llocs àcids de Lewis del material, mentre que la presència de Cr3+ en els nodes metàl·lics proporciona estabilitat al catalitzador. A més a més, aquesta Tesi ha demostrat que la presència de grups NO2 al lligam orgànic tereftalat de MIL-101(Cr) augmenta la densitat i la força dels llocs àcids de Lewis del material. Per tant, MIL 101(Cr)-NO2 exhibeix una activitat catalítica superior per a la síntesis de bencimidazols a partir de o-fenilendiamines i derivats de benzaldehid, així com per a l'oxidació aeròbica del tiofenol i la desulfuració oxidativa aeròbica de dibenzotiofens. Aquesta Tesi també ha demostrat que la sel·lecció d'un agent reductor apropiat com la hidroquinona per a la preparació de rGO a partir de GO augmenta la densitat dels llocs actius per a promoure les oxidacions aeròbiques de tiofenol i indano., [EN] The present doctoral thesis has shown the possibility of engineering the active sites of MOFs and graphene-based materials as catalysts with enhanced activity for oxidation and condensation reactions. Specifically, the development of a mixed-metal MIL-101(Cr, Fe) has resulted in a catalyst with enhanced catalytic activity for the Prins reaction between ß-pinene and formaldehyde with respect to the use of MIL-101(Cr) or the unstable MIL 101(Fe) under the studied reaction conditions. The presence of Fe3+ ions in the metal nodes of the MIL-101(Cr, Fe) increases the density and strength of the Lewis acid sites of the material and the presence of Cr3+ in the metal nodes provides catalyst stability. Furthermore, this thesis has demonstrated that the presence of NO2 groups in the terephthalate organic ligand of MIL 101(Cr) increases the density and strength of Lewis acid sites of the material. Thus, MIL-101(Cr)-NO2 exhibits a superior catalytic activity for the synthesis of benzimidazoles from o-phenylenediamines and benzaldehyde derivatives, as well as for the aerobic oxidation of thiophenol and the aerobic oxidative desulfuration of dibenzothiophenes. This thesis has also shown that the selection of an appropriate reducing agent (such as hydroquinone) for the preparation of rGO from GO increases the density of active sites and promotes the aerobic oxidations of thiophenol and indane., Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, CTQ2018-890237-CO2-R1 and Maria de Maeztu, CEX2019-000919-M), is gratefully acknowledged. Generalidad Valenciana is also thanked for funding (Prometeo 2017/083). S.N. thanks financial support by the Ministerio de Ciencia, Innovación y Universidades (RTI 2018-099482-A-100 project), Fundación Ramón Areces (XVIII Concurso Nacional para la Adjudicación de Ayudas a la Investigación en Ciencias de la Vida y de la Materia, 2016), and Generalitat Valenciana grupos de investigación consolidables 2019 (ref: AICO/2019/214) Project. E. G. thanks the ANR-11-LABEX-0039 (LabEx CHARM3AT) for financial support. M.G.-M thanks support from “la Caixa” Fundation (LCF/BQ/PI19/11690022) and Generalitat Valenciana (SEJI/2020/036). Financial support by the Spanish Ministry of Science and Innovation (Severo Ochoa and RTI2018-098237-CO21) and Generalitat Valenciana (Prometeo 2017/083) is gratefully acknowledged.

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica Submitted by Isabel Melo (imelo@sa.isel.pt) on 2022-01-25T11:08:26Z No. of bitstreams: 1 Dissertacao.pdf: 2918184 bytes, checksum: b68572f0ff492e4d83286f624fbc0337 (MD5) Made available in DSpace on 2022-01-25T11:08:26Z (GMT). No. of bitstreams: 1 Dissertacao.pdf: 2918184 bytes, checksum: b68572f0ff492e4d83286f624fbc0337 (MD5) Previous issue date: 2021-07 info:eu-repo/semantics/publishedVersion

My PhD dealt with the preparation and characterization of effective and efficient heterogenization of polymeric perfluorosulphonic acid (PFSA) Aquivion resin into a silica network. The material proved to be an active organocatalyst for redox processes, allowing selective oxidation of toluene to benzaldehyde with hydrogen peroxide under solvent- and metal-free conditions. Remarkably, the oxidation of benzylic C-H bonds with an organocatalyst was not previously reported. Preliminary results with the perfluorinated resin delivered good selectivity but low conversions. Therefore, we decided to heterogeneize Aquivion on silica. The Aquivion-silica composites (10wt% of Aquivion) were prepared by Sol-Gel method with the aid of different types of surfactants, obtaining materials with either mesoporous structure or as nanoparticles. Under optimized conditions, the hybrid materials Aquivion-silica showed good catalytic activity and excellent selectivity. The nanoparticle catalyst is fully reusable, maintaining stable performances for up several consecutive cycles without any intermediate treatment. The complex catalytic cycle likely involves -SO3H groups and the morphology of the support can influence the activity and selectivity of this radical reaction. Anilines could be selectively oxidized too, enabling one to access diphenyldiazenes via oxidative dimerization. Also in this case it was investigated the reaction mechanism, proving that the complex catalytic cycle likely involves –SO3H groups and the morphology of the support can influence the activity and selectivity of these radical reactions. My studies was focused on the scope of these novel catalytic methods and under respectively optimized conditions the hybrid material Aquivion-silica showed good catalytic activity and excellent selectivity, which occurs under mild conditions on gram scale and allows broad functional group tolerance. Another topic dealt during my PhD was the oxidation of naphthalene with hydrogen peroxide to 1,4-naphthoquinone. The best results was obtained with Aquivion powder as catalyst and I optimized this reaction for 2 mmol of naphthalene (92% of conversion and 95% of selectivity). Later I monitored the reaction and I observed that the reaction time was 7 hours. Then I studied the mechanism of reaction through some tests thanks to which I can affirm that the reaction mechanism is radical. Finally I supposed that 1,4-dihidroxynaphthalene is an intermedium. Once the oxidation reaction of naphthalene was optimized, I then studied the scope of this reaction, trying to oxidize different kinds of substituted naphthalenes and polycyclic aromatic compounds. Last topic of my PhD thesis was the effective and efficient synthesis of a titanium oxide-based catalyst on a commercial silica network. The material proved to be an active catalyst for batch organosulfur oxidation processes of liquid fuels, allowing the selective oxidation of dibenzothiophene to the corresponding sulphone using diluted hydrogen peroxide solution as oxidant, in acetonitrile under metal-free conditions. Preliminary tests led to a very good conversion of the substrate. However, we noticed a rapid deactivation of the catalyst probably due to the adsorption of the polar product on the catalyst surface or for strong interactions between catalyst and water molecules. Replacing hydrogen peroxide with TBHP, we finally reached complete conversion and demonstrated that in these conditions the catalyst could be reused for several times in batch without any intermediate treatment. More studies are focused on inorganic support modification and on the upscale of this catalytic method, screening a real fuel containing different organosulfur groups as substrates.

This work presents the recovery of biosorption supports as an alternative source of benign production of heterogeneous catalysts for oxidation reactions in mild conditions. Cr-containing FAU zeolite, in sodium form (NaY) and in proton form (HY), was recovered from biosorption studies and reused as support for the preparation of heterogeneous catalysts by the flexible ligand method, using 1,3-diphenyltriazene derivatives. Results showed that the ligand play an important role in the coordination of Cr inside the zeolite. The catalysts showed good activity for the oxidation of cyclohexanol, reaching a maximum of 63.5% conversion. Cr leaching was evaluated and it was found that the Cr–FAU supports lost some of the Cr into the reaction medium, whereas immobilization of Cr-complexes reduced the referred leaching. For the cyclohexene oxidation, a maximum 72.9% conversion was achieved with a HY zeolite-based catalyst., This work was partially funded by the Centre of Biological Engineering and the Centre of Chemistry (University of Minho, Portugal) through FCT strategic projects PEst-OE/EQB/LA0023/2013 and PEst-C/QUI/UI0686/2011 (nF-COMP-01-0124-FEDER-022716), the Project “BioEnv - Biotechnology and Bioengineering for a sustainable world”, REF. NORTE-07-0124-FEDER-000048, co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN and FEDER, and by the Spanish Ministry of Science and Innovation (CTQ2008-04261/PPQ).

The products of the fine chemical industry have become a fundamental need to maintain current social life. Fine chemicals include pharmaceuticals, flavorings, fragrances, etc. It should be noted that many of the processes of preparation of these products generate high amounts of by-products and / or pollutant residues. One of the alternatives for the development of sustainable and less polluting processes is the use of heterogeneous catalysts. In this context, the hybrid metal-organic materials called MOFs that emerged in 2006, characterized by being crystalline and highly porous, have high potential for their use as heterogeneous liquid phase catalysts for reactions of interest to the fine chemical industry. In the present Master Final Work the catalytic activity of materials type MOF based on the family UiO-67 (Zr) (UiO: Universitetet i Oslo) has been studied. In particular, the influence of the presence of metal complexes based on bipyridines coordinated with metals (Cu2+, Co2+ and Fe3+) has been studied, acting as organic ligands of the MOF in the catalytic activity. The reaction studied has been the oxidation of indane in the absence of solvent and exclusively using molecular oxygen as an oxidizing agent. In general, the results indicate that the presence of the metal complexes in the MOF structure improves the catalytic activity. Among all the materials prepared, by pre- or post-synthetic methods, the material prepared by the pre-synthesis method using cobalt has proved to be the most active. The higher activity of this catalyst has been attributed to the high crystallinity, pore volume and surface area with respect to the other catalysts prepared. In addition, the material can be reused without appreciable loss of its catalytic activity., Los productos de la industria química fina se han convertido en una necesidad fundamental para mantener la vida social actual. Los productos de química fina incluye a productos farmaceúticos, aromizantes y saborizantes, fragancias, etc. Cabe comentar que muchos de los procesos de preparación de estos productos generan cantidades elevadas de subproductos y/o residuos contaminantes. Una de las alternativas para el desarrollo de procesos sostenibles y menos contaminantes es el empleo de catalizadores heterogéneos. En este contexto, los materiales híbridos metal-orgánico llamados MOFs surgidos en 2006, caracterizados por ser cristalinos y altamentes porosos, tienen elevado potencial para su empleo como catalizadores heterogéneos en fase líquida para reacciones de interes para la industria de química fina. En el presente Trabajo Final de Master se ha estudiado la actividad catalítica de materiales tipo MOF basados en la familia UiO-67(Zr) (UiO: Universitetet i Oslo). En particular, se ha estudiado la influencia de la presencia de complejos metálicos basados en bipiridinas coordinadas con metales (Cu2+, Co2+ y Fe3+) actuando como ligandos orgánicos del MOF en la actividad catalítica. Las reacción estudiada ha sido la oxidación de indano en ausencia de disolvente y empleando exclusivamente oxígeno molecular como agente oxidante. En general, los resultados indican que la presencia de los complejos metálicos en la estructura del MOF mejora la actividad catalítica. Entre todos los materiales preparados, por métodos pre- o post-sintéticos, el material preparado por el método pre-síntesis empleando cobalto ha resultado ser el más activo. La mayor actividad de este catalizador ha sido atribuida a la elevada cristalinidad, volumen de poro y área superficial respecto al resto de catalizadores preparados. Además, el material puede ser reusado sin pérdida apreciable de su actividad catalítica.

In recent years, several research groups have focused their attention on the development of synthetic and functional models of biological systems based on copper. Here we report the synthesis strategy, characterization, and catalytic activity for new copper-based porphyrins (CuP2 and CuP3) isolated by metallation of the corresponding free base derivatives, H2P2 and H2P3. The solid CuP2S was obtained from the reaction of H2P2 with copper(II) acetate (10 equiv.). These complexes have been used in homogeneous (CuP2 and CuP3) and heterogeneous (CuP2S) oxidative catalysis of 3,5-di-tert-butylcatechol and catechol, in the presence of air, with or without hydrogen peroxide. The obtained results show that the new copper porphyrins CuP2 and CuP3 and the CuP2S material are able to efficiently mimic the activity of catechol oxidase, the latter being easily reused and maintaining its activity for more than three catalytic cycles.

Wastewater pollution with heavy metals is an issue of great environmental concern. The future development of clean technologies for the treatment of wastewater loaded with heavy metals entails environment friendly and sustainable processes that may allow simultaneously the recovery of the metals and their reutilization as value-added catalysts to be used in environmental applications. This is the first review regarding the biorecovery of metals and their further reutilization as heterogeneous catalysts. In this regard, metallic residues that generally would be considered as a waste at the end of the treatment process can be reutilized and transformed into value-added catalysts to be used in environmental applications. This review is focused in two broad areas: the biorecovery of chromium by a combined biosorption system consisting of bacteria supported on zeolites, and the catalytic reutilization of the metal-loaded zeolites in the oxidation of organic compounds, both in gaseous and liquid phase. After an overview describing the main subjects in the field of heavy metals recovery, biosorption, zeolites and catalytic oxidation, in the following sections special emphasis will be given to the main results and findings regarding these clean technologies of biorecovery and reuse of metals in catalytic reactions of environmental concern., B. Silva is thankful for the Project “BioEnv—Biotechnology and Bioengineering for a sustainable world,” REF. NORTE-07-0124-FEDER-000048, cofunded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER. The authors are grateful to FCT and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support to the Research Centres, PEst-OE/EQB/LA0023/2013, and PEst-C/QUI/UI0686/2013 (F-COMP-01-0124-FEDER-037302).

Esta tesis doctoral trata sobre la síntesis, y el estudio de la actividad catalítica de partículas de oro de tamaño inferior a 2 nm, nanoclústers de oro. El interés proviene de la actividad catalítica a temperatura ambiente que tiene el oro cuando las dimensiones son inferiores a aproximadamente los 5 nm. En esta tesis se desarrollan dos métodos de síntesis que permiten obtener clústeres de oro estables con un tamaño de partícula bien definido. En un método se sintetizan nanoclústeres de oro de tamaño inferior a 2 nm, los cuales son posteriormente depositados sobre un soporte. En cambio, el otro método consiste en sintetizar los nanoclústeres de oro directamente sobre el soporte seleccionado. Con este ultimo método, se puede modificar el tamaño de los clústeres de oro alterando la cantidad de precursor de oro durante el proceso de síntesis. De esta manera se puede obtener desde una dispersión uniforme de átomos de oro aislados, clústeres de Au de 2 nm o nanopartículas de más de 10 nm en la superficie del material de soporte. Los catalizadores sintetizados han sido caracterizados mediante distintas técnicas físico químicas: HRTEM, SEM, AFM, XPS and XAS. Además también se ha estudiado la actividad catalítica para la oxidación de CO y materiales carbonosos. Finalmente, se ha relacionado el tamaño de partícula con la actividad catalítica del material., This doctoral thesis is about the synthesis and the catalytic activity study of gold particles with a diameter lower than 2 nm, gold nanoclusters. The interest is due to the catalytic activity that gold has at room temperature when its size is less than approximately 5 nm. In this thesis, two distinct synthesis’ methods that allow stable gold clusters with a well defined particle size to be obtained have been developed. In one method, gold clusters with a narrow size distribution and a particle diameter less than 2 nm are firstly synthesised and then deposited on a support. In the other method, gold clusters are directly synthesised on the selected support. In the latter method, the size of gold can be easily varied by simply altering the gold precursor quantity during the synthesis process. Thus, uniformly dispersed isolated gold atoms, 2 nm Au clusters or nanoparticles larger than 10 nm can be obtained on the material support surface. The synthesised catalysts were characterised using distinct physico-chemical techniques: HRTEM, SEM, AFM, XPS and XAS. Additionally, their catalytic activity was investigated for the oxidation of CO and carbonaceous materials. Finally, the particle size was related with the catalytic activity of the material.

The immobilization of Fe(III) picolinate and Fe(III) dipicolinate complexes on kaolinite furnished heterogeneous catalysts, whose catalytic activity was evaluated. The precursor materials were kaolinite grafted with picolinic (Ka-pa) and dipicolinic (Ka-dpa) acids obtained by melting of the pyridine carboxylic acids. To obtain the catalysts Fe(Ka-pa)-n and Fe(Ka-dpa)-n (n = 1, 2, or 3 is the ligand/Fe ratio), the precursors were suspended in Fe3+ solutions with cation/ligand ratios of 1:1, 1:2, or 1:3. The resulting materials were characterized by thermal analyses (simultaneous TG/DTA), X-ray diffraction, UV/vis and infrared spectroscopies, and transmission electron microscopy. The grafted complexes were employed as heterogeneous catalysts in the epoxidation of cis-cyclooctene to cis-cyclooctenoxide and in the oxidation of cyclohexane to cyclohexanol and cyclohexanone at ambient temperature and pressure. Hydrogen peroxide was used as oxygen donor at a catalyst/oxidant/substrate molar ratio of 1:300:100. Fe(Ka-pa)-n catalysts were very efficient for cis-cyclooctene epoxidation (38% conversion). For cyclohexane oxidation, Fe(Ka-dpa)-n was 100% selective for cyclohexanone formation, with substrate conversion of 14%. This last series of catalysts was also very effective in the Baeyer–Villiger reaction, with 60% substrate conversion and 100% selectivity for ξ-caprolactone. After reuse (5 times), the catalysts still led to high substrate conversion.

[EN] Three MIL-100 (Fe) samples differing in average crystal size (from 60-70 to >400 nm) have been synthesized by microwave heating using three HF/Fe 3+ ratios. Oxidation of diphenylmethane with tert-butylhydroperoxide (TBHP) and thiophenol with oxygen are catalyzed by three MIL-100 (Fe) samples with similar reaction rates regardless of its average particle size. In contrast, the activity of the three MIL-100 (Fe) samples for the oxidation of bulky triphenylmethane by TBHP largely depends on the average crystal size of the sample: the smaller the average particle size, the larger the initial reaction rate of triphenylmethane oxidation. These results show that diffusion limitation takes place on MOF catalysis depending on the substrate size and provides indirect evidence that these reactions take place inside the intracrystalline space of the porous catalysts. © 2011 The Royal Society of Chemistry., Financial support by the Spanish DGI (CTQ2009-11587 and CTQ2010-18671 and Consolider MULTICAT) is gratefully acknowledged. Prof. Jong-San Chang and his group are thanked for providing us with sufficient quantities of the three MIL-100 (Fe) samples. Korean researchers acknowledge the financial support of KICOS and KRICT for the international collaboration program.