Lithium ion batteries (LIBs) are widely used for storing and converting chemical energy into electrical energy. During battery operation, lithium ions move between electrode materials, enabling energy storage. However, aging mechanisms like lithium plating can negatively impact battery performance and lifetime. Lithium plating occurs when lithium ions are reduced to metallic lithium on the graphite electrode. The undesired Li plating in LIBs leads to dendrite formation that may puncture the separator, causing internal short-circuit and ultimately thermal runaway. This study aims to investigate the internal processes of LIBs during charge and discharge. Two analysis methods are employed: online electrochemical mass spectrometry (OEMS) and acoustic emission monitoring (AEM). OEMS is a gas analysis technique that combines electrochemical measurements with mass spectrometry to provide real-time testing of cells. OEMS allows identifying and quantifying gas evolution/consumption of chemical species. AE is a diagnostic tool, offering monitoring the health of LIBs through detection and characterisation of stress waves produced by parasitic mechano-electrochemical events. The results indicates that the formation of SEI thin film layer, generated gases like hydrogen and ethylene, while consuming carbon dioxide. During induced lithium plating, hydrogen and carbon dioxide were consumed, and ethylene gas was produced, due to new SEI film formation process. The acoustic emission analysis indicated that lithium plating was an active process, whereas SEI formation was less AE active. Further research is needed to understand the relationships and significance of these processes for battery performance and safety. Overall, this study highlighted the importance of investigating aging mechanisms in LIBs to enhance their performance and longevity. By combining OEMS and AE, it was possible to analyse the batteries behaviour during cycling. The evolution of gas and acoustic signals provided insights into the reactions and processes occurring inside the battery during cycling.

京都大学 / 新制・課程博士 / 博士(人間・環境学) / 甲第24711号 / 人博第1084号 / 新制||人||254(附属図書館) / 2022||人博||1084(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 吉田 寿雄, 教授 田部 勢津久, 教授 中村 敏浩, 教授 田中 庸裕 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

La presente tesis doctoral emplea herramientas de síntesis y caracterización de catalizadores metálicos nanoparticulados modelo, con el objetivo de elucidar la influencia de varias características estructurales y físico-químicas relevantes y sentar las bases para el diseño de nuevas generaciones de catalizadores avanzados para las rutas catalíticas de conversión de gas de síntesis. Por un lado, el diseño y la síntesis de catalizadores de Co monodispersos, empleando coloides metálicos y soportes nanométricos, en combinación con espectroscopias in situ y operando, ha permitido relacionar la sensibilidad a la estructura no clásica de la síntesis de Fischer-Tropsch (SFT) con modificaciones morfológicas y electrónicas de las nanopartículas de Co durante la catálisis, en función del tamaño de nanopartícula. Por otro lado, este trabajo esclarece la influencia de la historia térmica de los catalizadores de Co, desde los tratamientos más tempranos, en la topología metálica superficial del catalizador activado final y sus consecuencias en la actividad catalítica intrínseca. Adicionalmente, en base al conocimiento adquirido, se ha optimizado la estructura porosa de los catalizadores de Co para la SFT mediante un diseño racional de los soportes catalíticos. De este modo, se ha demostrado que estructuras porosas bimodales macro-mesoporosas así como soportes mesoestructurados con poros uniformes y de longitud reducida dan lugar a catalizadores de actividad mejorada y elevada selectividad a destilados medios. Finalmente, el empleo de soportes sintetizados mediante técnicas de deposición de óxidos capa-por-capa ha permitido sintetizar una serie de catalizadores de Rh promovidos y estudiar su comportamiento en la síntesis selectiva de compuestos oxigenados. Esta tesis presenta, por primera vez, una interpretación general para el papel de los promotores en este sistema. / Prieto González, G. (2010). Requerimientos físico-químicos y estructurales en catalizadores avanzados para la conversión de gas de síntesis [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/7026

<p dir="ltr">Applications of Lithium-ion batteries (LIBs) are so widely spread from transportation like electric vehicles to portable storage devices. This is mainly due to their lighter weight and smaller size with higher energy density when compared to Lead-acid, Nickel Cadmium (Ni-Cd), and other batteries. One of the applications of LIB includes electric propulsion in-air like quadcopters. These electrically-propelled vehicles have diverse applications including risky jobs like wildlife management, search and rescue, and jobs that can be automated such as delivery of smaller packages, urban planning, and so on. These electrically-propelled vehicles produce heat around the LIB which leads to thermal abuse of the battery. Also, there are often cases where LIB undergoes different abuse conditions in-air when operating these vehicles. Present battery BMSs are highly accurate but require edge and cloud with a deep learning model to safely operate quadcopters in the air. In the work, we present a BMS capable of edge-cloud data transfer with a deep-learning model to predict the RUL of the battery. Benchmark differences between data collected on-ground and in-air are presented for comparison. It turns out that the temperature collected in the air is less than the temperature on the ground when different current profiles are experimented on different batteries used in quadcopters. This study helps in the improvement of BMS with edge-cloud and deep-learning models and helps in understanding the behavior of battery in-air.</p>

Les catalyseurs hétérogènes sont des matériaux complexes dont les structures peuvent être modifiées en cours de fonctionnement. Une meilleure compréhension des relations entre propriétés catalytiques et propriétés structurales est nécessaire pour répondre à de nouveaux enjeux environnementaux et économiques. Seules les caractérisations in situ résolues dans le temps i.e. dans des conditions réelles, permettent d'apporter ces informations. Dans ce travail, nous nous sommes intéressés à la caractérisation operando par spectroscopie d'absorption des rayons X (XAS) résolue dans le temps de deux types de catalyseurs hétérogènes : les catalyseurs Fischer-Tropsch et les catalyseurs d'hydrodésulfuration. Si ces catalyseurs sont connus depuis de nombreuses années, peu de caractérisations sont réalisées in situ ou operando au cours de la réaction.Etant données leurs conditions réactionnelles (haute température et haute pression), la mise en œuvre de ces caractérisations a nécessité tout d'abord la construction des outils nécessaires à la caractérisation in situ de catalyseurs hétérogènes sous haute pression de gaz. Ensuite, nous avons réuni un ensemble cohérent de techniques de caractérisation autour du catalyseur Fischer-Tropsch afin de permettre son étude structurale à différentes échelles : l'ordre local avec le Quick-EXAFS et l'ordre à grande distance avec la diffraction des rayons X. Afin d'observer l'effet de la forme cristalline de la phase active sur les propriétés catalytiques, nous avons pour un même catalyseur, activé selon deux voies d'activation, quantifié son activité au moyen de la spectroscopie Raman et la spectrométrie de masse. D'autre part, la caractérisation simultanée de deux centres métalliques, accessible par le dispositif QEXAFS installé sur la ligne de lumière SAMBA, a permis d'obtenir une description fine des processus d'activation des catalyseurs bimétalliques d'hydrodésulfuration. Notre étude s'est portée, sur la comparaison de catalyseurs de même formulation avec des prétraitements différents (séché/calciné) et de deux catalyseurs promus par des métaux différents : le cobalt et le nickel.

Single-atom and cluster catalysts have been receiving significant interest due to not only their capability to approach the limit of atom efficiency but also to explore fundamentally unique properties. Supported Pt-group single atoms and clusters catalysts in the subnanometer size regime maximize the metal utilization and were reported to have extraordinary activities and/or selectivities compared with nanoparticles for various reactions including hydrogenation reactions. However, the relationship between metal nuclearity, electronic and their unique catalytic properties are still unclear. Thus, it is crucial to establish their relations for better future catalyst design. Ethylene hydrogenation and acetylene hydrogenation are two important probe reactions with the simplest alkene and alkyne, and they have been broadly studied as the benchmark reactions on the various catalyst systems. However, the catalytic properties and reaction mechanism of those hydrogenation reactions for metal nuclearitiy in the subnanometer regime is still not well understood. In this study, we applied different characterization techniques including x-ray absorption fine structure (XAFS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS), diffuse reflectance infrared spectroscopy (DRIFTS), calorimetry and high-resolution scanning transmission electron microscopy (STEM) to investigate the structure of Pt/TiO2 and Pd/COF single-atom catalysts and tested their catalytic properties for hydrogenation reactions. In order to develop such relations, we varied the nuclearity of Pt supported on TiO2 from single atoms to subnanometer clusters to larger nanoparticles. For acetylene hydrogenation, Pt in the subnanometer size regime exhibits remarkably high selectivity to ethylene compared to its nanoparticle counterparts. The high selectivity is resulted from the decreased electron density on Pt and destabilization of C2H4, which were rationalized by X-ray photoelectron spectroscopy and calorimetry results. On the other hand, the activity of H2 activation and acetylene hydrogenation decreased as Pt nuclearity decreased. Therefore, our results show there's a trade-off between activity and selectivity for acetylene hydrogenation. Additionally, the kinetics measurements of ethylene hydrogenation and acetylene hydrogenation were performed on Pt/TiO2 catalysts, and they found to be structure sensitive for both reactions, which the reaction orders and activation energy changes as particles size change. The activity of ethylene hydrogenation decreases, and activation energy increase from 43 to 86 kJ/mol, as Pt nuclearity decreased from an average size of 2.1 nm to 0.7 nm and single atoms. The reaction orders in hydrocarbons (ethylene and acetylene) were less negative on subnanometer clusters and single atoms in contract to nanoparticles. The results imply that hydrocarbons, ethylene and acetylene species, do not poison the catalyst on Pt in the subnanometer size regime, and hydrogen activation turn to competitive adsorption path with surface hydrocarbons species. Moreover, single atom Pd supported on imine-linked covalent organic framework was synthesized, characterized by a various of techniques including X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of adsorbed CO, and evaluated its catalytic properties for ethylene hydrogenation. The XAS results show that Pd atoms are isolated and stabilized by two covalent Pd–N and Pd-Cl bonds. DRIFTS of CO adsorption shows a sharp symmetrical peak at 2130 cm−1. The Pd single atoms are active for hydrogenation of ethylene to ethane at room temperature. The reaction orders in C2H4 and H2 were 0.0 and 0.5 suggesting that ethylene adsorption is not limiting while hydrogen forms on Pd through dissociative adsorption. / Doctor of Philosophy / More than 90% of chemicals come from petroleum and natural gas, and most of these chemicals are composed of alkene and alkyne, hydrocarbons containing at least one double bonds or triple bonds, such as ethylene, propylene, butenes, butadiene. These small hydrocarbon molecules with carbon-carbon bonds (double or triple) are in great interest of fundamental study and serve as probe units for understanding more complex reactions. Catalysts are materials that can be added to a chemical reaction to accelerate the specific rate of reactions. Most catalysts are supported noble metals thus increase the utilization of metal atoms are important. Decreasing the particle size to increase the metal dispersion is the simple approach to maximize the atom efficiency. However, it is not well understood how do the electronic property and catalytic performance change as particle size decrease. In this work, we focus on the structure sensitivity on catalysts in sub-nanometer region. Supported Pt and Pd catalysts, known to be highly active for hydrogenation reactions, are studied on hydrogenation reactions of acetylene and ethylene, the simplest alkene and alkyne. The Pd and Pt catalysts with particle sizes ranging from single atoms, sub-nanometer clusters and nanoparticles were prepared, characterized and tested for hydrogenation reactions mentioned above. The results show that significantly change in electronic property, catalytic performance (activity and/or selectivity) and reaction kinetics of the catalysts as the particle size changing from nanometer to sub-nanometer region. The fundamental understanding of structure sensitivity on catalysts and their relations between surface structure, electronic property and catalytic performance presented in this work can help the researchers design better catalysts for future work.

Supported noble metal catalysts make the best utilization of noble metal atoms. Recent advances in nanotechnology have brought many attentions into the rational design of catalysts in the nanometer and subnanometer region. Recent studies showed that catalysts in the subnanometer regime could have extraordinary activity and selectivity. However, the structural performance relationships behind their unique catalytic performances are still unclear. To understand the effect of particle size and shape of noble metals, it is essential to understand the fundamental reaction mechanism. Single atoms catalysts and subnanometer clusters provide a unique opportunity for designing heterogeneous catalysts because of their unique geometric and electronic properties. CO oxidation is one of the important probe reactions. However, the reaction mechanism of noble single atoms is still unclear. Additionally, there is no agreement on whether the activity of supported single atoms is higher or lower than supported nanoparticles. In this study, we applied different operando techniques including x-ray absorption fine structure (XAFS), diffuse reflectance infrared spectroscopy (DRIFTS), with other characterization techniques including calorimetry and high-resolution scanning transmission electron microscopy (STEM) to investigate the active and stable structure of Ir/MgAl2O4 and Pt/CeO2 single-atom catalysts during CO oxidation. With all these characterization techniques, we also performed a kinetic study and first principle calculations to understand the reaction mechanism of single atoms for CO oxidation. For Ir single atoms catalysts, our results indicate that instead of poisoning by CO on Ir nanoparticles, Ir single atoms could adsorb more than one ligand, and the Ir(CO)(O) structure was identified as the most stable structure under reaction condition. Though one CO was strongly adsorbed during the entire reaction cycle, another CO could react with the surface adsorbed O* through an Eley-Rideal reaction mechanism. Ir single atoms also provide an interfacial site for the facile O2 activation between Ir and Al with a low barrier, and therefore O2 activation step is feasible even at room temperature. For Pt single-atom catalysts, our results showed that Pt(O)3(CO) structure is stable in O2 and N2 at 150 °C. However, when dosing CO at 150 °C, one surface O* in Pt(O)3(CO) could react with CO to form CO2, and the reacted O* can be refilled when flowing O2 again at 150 °C. This suggests that an adsorbed CO is present in the entire reaction cycle as a ligand, and another gas phase CO could react with surface O* to form CO2 during low-temperature CO oxidation. Supported single atoms synthesized with conventional methods usually consist of a mixture of single atoms and nanoparticles. It is important to quantify the surface site fraction of single atoms and nanoparticles when studying catalytic performances. Because of the unique reaction mechanism of Ir single atoms and Ir nanoparticles, we showed that kinetic measurements could be applied as a simple and direct method of quantifying surface site fractions. Our kinetic methods could also potentially be applied to quantifying other surface species when their kinetic behaviors are significantly different. We also benchmarked other in-situ and ex-situ methods of quantifying surface site fraction of single atoms and nanoparticles. To bridge the gap between single atoms and nanoparticles and have a better understanding of the effect of nuclearity on CO oxidation, we also studied supported Ir subnanometer clusters with the average size less than 0.7 nm (< 13 atoms) prepared by both inorganic precursor and organometallic complex Ir4(CO)12. Low-temperature CO adsorption indicates that CO and O2/O could co-adsorb on Ir subnanometer clusters, however on larger nanoparticle the particle surface is covered by CO only. Additional co-adsorption of CO and O2 was studied by CO and O2 calorimetry at room temperature. CO oxidation results showed that Ir subnanometer clusters are more active than Ir single atoms and Ir nanoparticles at all conditions, and this could be explained by the competitive adsorption of CO and O2 on subnanometer clusters. / Doctor of Philosophy / CO oxidation is one of the important reactions in catalytic converters. Three-way catalysts, typically supported noble metals, are very efficient at high temperature but could be poisoned by CO at cold start. Better designed catalysts are required to improve the performance of the catalytic converter to lower the emissions of gasoline engines. To reach this goal, more efficient use of the noble metal is required. Single-atom catalysts consist of isolated noble metal atoms supported on different supports, which provide the best utilization of noble metal atoms and provides a new opportunity for a better design of heterogeneous catalysts. The unique electronic and geometric properties of metal single atoms catalysts could lead to a better activity and selectivity. Subnanometer clusters have also been shown to have unique electronic properties. With a better understanding of the structure of supported single atoms and subnanometer clusters, their catalytic performance can be optimized for better catalysts in the catalytic converter and other applications. In this work, we applied in-situ and operando characterization, kinetic studies and first principle calculations aiming to understand the active and stable structure of noble metal single atoms and vi subnanometer clusters under reaction condition, and their reaction mechanisms during CO oxidations. For MgAl₂O₄ supported Ir single atoms, our results suggest that CO could be co-adsorbed with O₂/O under reaction conditions. These multiple ligands adsorption leads to a unique reaction mechanism during CO oxidation. Though one CO was adsorbed during the whole reaction cycle, another gas phase CO could react with the O* species co-adsorbed with CO through an Eley-Rideal mechanism. This suggests that Ir single atoms are no longer poisoned by CO, and on the other hand the O₂ can be activated on an interfacial site with a low reaction barrier. Ir subnanometer clusters showed higher activities than Ir single atoms and nanoparticles. In-situ IR and high energy resolution fluorescence detected – X-ray absorption near edge spectroscopy (HERFD-XANES) showed that CO could co-adsorb with O₂ at room temperature, and this competitive adsorption could explain the high activity during CO oxidation. Supported Ir single atoms and subnanometer clusters are not poisoned by CO and O₂ could be co-adsorbed, this could be potentially applied to solve the poisoning of catalyst in the catalytic converter at cold start temperature. We also performed kinetic study on CeO₂ supported Pt single atoms. Similar behavior was observed, and we showed that the CO and O co-adsorbed complex is stable in O₂ and N₂, but could react in CO. With the understanding of the active structure of noble metal single atoms and the origin of activities, better-designed catalysts can be synthesized to improve the activity and selectivity of low-temperature oxidation reactions.

Printed circuit board manufacturing involves subtractive copper (Cu) etching where fine features are developed with a specific spatial resolution and etch profile of the Cu interconnects. A UV-Vis ATR metrology, to characterize the chemical transitions, has been developed to monitor the state of the bath by an in-situ measurement. This method provides a direct correlation of the Cu etch bath and was able to predict a 35% lower etch rate that was not predicted by the three current monitoring methods (ORP, specific gravity, and conductivity). Application of this UV-Vis ATR probe confirmed that two industrial etch baths, in identical working conditions, confirmed a difference in Cu2+ concentration by the difference of the near IR 860nm peak. The scope of this probe allowed chemically specific monitoring of the Cu etch bath to achieve a successful regeneration for repeated use. Interlayer dielectrics (ILDs) provide mechanical and electrical stability to the 3D electrical interconnects found in IC devices. It is particularly important that the structural support is created properly in the multilayered architecture to prevent the electrical cross signaling in short range distances. A combined multiple internal reflection and transmission FTIR has been employed for the characterization of silicon oxycarbonitride (SiOCN) films. These dielectric low-k films incorporate various functional groups bonded to silicon and require chemical bonding insight in the transformation and curing process. Distinct SiOx bonding patterns were differentiated, and the structure of the films can be predicted based on the amount of Si network and caged species. Further optimization of the FTIR analysis must minimize interference from moisture that can impact the judgement of peak heights. To accommodate this, a high-quality glove box was designed for dry air feedthrough to achieve a 95% moisture reduction during analysis, where less than 0.1 mAbs of moisture is detected in the spectra (without additional correction). The glove box allows for the rapid analysis of multiple sample throughput to outpace alternative characterization methods while retaining low spectral noise and a dry environment for 24/7 analysis. There is a great need to identify new catalysts that are suitable for tackling current economic demands, one of which is the nitrogen reduction reaction (NRR). The development of the surface enhanced infrared absorption spectroscopy (SEIRAS) has been applied to characterize the NRR mechanisms on the vanadium oxynitride electrocatalyst. Electrochemical measurements demonstrate NRR activity that is up to three times greater in the presence of N2 than the control Ar. FTIR operando suggests that a considerable number of intermediates were formed and continued to increase in absorbing value under an applied potential of -0.8 V vs Ag/AgCl. XPS results of the post-NRR film suggest a restricting of the film where vanadium oxynitride films are prone to instabilities under the possible MvK mechanism. After 90 minutes of NRR, the NH3 generated was approximately 0.01 ppm was calculated for through the salicylate colorimetric method. On-going efforts are focusing on optimizing the vanadium oxynitride film by the tuning of the oxynitride ratios and crystalline properties to promote the formation of V≡N: during the nitrogen reduction reaction.

[ES] El etileno representa uno de los pilares de la industria química actual como parte de los denominados "productos químicos básicos". Los procesos de recuperación y valorización de etileno actuales están basados en fuentes de carbono de origen fósil y son operados a gran escala, por lo que tienen asociado un elevado coste energético y contribuyen significativamente a la emisión de gases de efecto invernadero. La preocupación actual por avanzar hacia la descarbonización de la industria química ha impulsado el diseño de procesos químicos más sostenibles. En este contexto, el diseño de nuevos procesos catalíticos (tándem), con alta economía atómica y operando a condiciones de operación más suaves, supone una alternativa de gran interés. La presente tesis doctoral se centra en el desarrollo de procesos catalíticos alternativos para la conversión de (bio-)etileno en productos de alto valor añadido, como el propileno o los compuestos oxigenados C3. En primer lugar, se ha estudiado el efecto de emplear diferentes soportes basados en óxidos metálicos en catalizadores de Rh de dispersión atómica para la hidroformilación de etileno en fase gas para producir propanal. Entre los materiales estudiados con diferente grado de reducibilidad superficial, el catalizador Rh1/SnO2 mostró el mejor rendimiento, con altos valores de actividad y con una selectividad a hidroformilación prácticamente total, a unas condiciones de operación muy suaves (P=20 bar, T=383 K). El comportamiento extraordinario de este material se ha atribuido a la capacidad de formar vacantes de oxígeno superficiales, lo que facilita la formación de especies de Rh de alta flexibilidad de coordinación y con propiedades electrónicas que se asemejan a de los catalizadores moleculares en disolución empleados industrialmente. A continuación, se estudió el uso de catalizadores bimetálicos Ag-Pt para la hidrogenación selectiva de aldehídos en presencia de olefinas. Para la composición óptima del catalizador (<4 at% Pt), se descubrió que las especies de Pt estaban altamente dispersas sobre la matriz de Ag, posiblemente en forma de las denominadas "aleaciones de átomos aislados". Dicho catalizador se combinó junto al catalizador de hidroformilación altamente selectivo Rh1/SnO2 en un proceso de hidroformilación reductiva, que permitió la conversión directa de etileno a 1-propanol con selectividad prácticamente total (98%) a conversiones de etileno >50%. Por último, se estudió la conversión de etileno a propileno mediante procesos tándem de dimerización-metátesis. Para ello, se estudiaron métodos de calentamiento específico y termometría selectiva combinando técnicas de calentamiento por inducción y termometría por luminiscencia. Dichos métodos resultaron adecuados para solventar las incompatibilidades de temperatura inherentes a los procesos de catálisis tándem del estado del arte y desbloquear, de esta manera, rendimientos inaccesibles para procesos operados mediante calentamiento convencional. / [CA] L'etilè representa un dels pilars de la indústria química actual com a part dels denominats "productes químics bàsics". Els processos de recuperació i valorització d'etilé actuals estan basats en fonts de carboni d'origen fòssil i són operats a gran escala, per la qual cosa tenen associat un elevat cost energètic i contribueixen significativament a l'emissió de gasos d'efecte d'hivernacle. La preocupació actual per avançar cap a la descarbonització de la indústria química requereix el disseny de processos químics més sostenibles. En este context, el disseny de nous processos catalítics (tàndem), amb alta economia atòmica i operant a condicions d'operació més suaus, suposa una alternativa de gran interés. La present tesi doctoral se centra en el desenvolupament de processos catalítics alternatius per a la conversió de (bio-)etilè en productes d'alt valor afegit, com el propilé o els compostos oxigenats C3. En primer lloc, s'ha estudiat l'efecte d'utilitzar diferents suports basats en òxids metàllics en catalitzadors de Rh de dispersió atòmica per a la *hidroformilación d'etilè en fase gas per a produir probresca. Entre els materials estudiats amb diferent grau de reducibilidad superficial, el catalitzador Rh1/SnO2 va mostrar el millor rendiment, amb alts valors d'activitat i amb una selectivitat a hidroformilació pràcticament total, a unes condicions d'operació molt suaus (P=20 bar, T=383 K). El comportament extraordinari d'este material s'ha atribuït a la capacitat de formar vacants d'oxigen superficials, la qual cosa facilita la formació d'espècies de Rh d'alta flexibilitat de coordinació i amb propietats electròniques que s'assemblen a dels catalitzadors moleculars en dissolució utilitzats industrialment. A continuació, es va a estudiar l'ús de catalitzadors bimetàl·lics Ag-Pt per a la hidrogenació selectiva d'aldehids en presència d'olefines. Per a la composició òptima del catalitzador (<4 at% Pt), es va descobrir que les espècies de Pt estaven altament disperses sobre la matriu de Ag, possiblement en forma dels denominats "aliatges d'àtoms aïllats". Aquest catalitzador es va a combinar al costat del catalitzador de hidroformilació altament selectiu Rh1/SnO2 en un procés de hidroformilació reductiva, que va permetre la conversió directa d'etilè a 1-propanol amb selectivitat pràcticament total (98%) a conversions d'etilé >50%. Finalment, es va a estudiar la conversió d'etilè a propilè mitjançant processos tàndem de dimerització-metàtesi. Per a això, es van a estudiar mètodes de calfament específic i termometria selectiva combinant tècniques de calfament per inducció i termometria per luminescència. Aquests mètodes van a resultar adequats per a solucionar les incompatibilitats de temperatura inherents als processos de catàlisis tàndem de l'estat de l'art i desbloquejar, d'esta manera, rendiments inaccessibles per a processos operats mitjançant calfament convencional. / [EN] Ethylene constitutes one of the pillars of the current chemical industry as part of the so-called "commodity chemicals". Current ethylene recovery and valorization technologies are based on fossil-based carbon feedstocks operated at the large scale, which are very energy-intense and contribute to important greenhouse gas emissions. The current concern on progressing towards a defossilized chemical industry calls for the design of more sustainable chemical processes. In this regard, the design of novel (tandem-) catalytic processes, with high atom economy at milder operation conditions, is desired. In this thesis, the conversion of (bio-)ethylene into high-added value chemicals such as propylene and C3 oxygenates via alternative catalytic processes is addressed. Firstly, metal oxide support effects have been explored in Rh single-atom catalysts for gas-phase ethylene hydroformylation to propanal. By exploring a series of materials with different surface reducibility, a Rh1/SnO2 catalyst showed to deliver the best performance, with high Rh-specific activity and essentially full selectivity to hydroformylation under very mild operation conditions (P=20 bar, T=383 K). The unconventional performance of this material has been ascribed to the capacity of forming surface oxygen vacancies on the SnO2 support, which triggers the formation of Rh species that resemble the electronic and coordination flexibility properties of Rh centers in benchmark molecular complexes operating in solution. Next, bimetallic Ag-Pt catalysts were explored, computationally and experimentally, for the selective hydrogenation of aldehydes in the presence of olefins under the same set of mild operation conditions. For the optimal catalyst formulation (<4 at% Pt), Pt species were highly dispersed within the Ag matrix, possibly forming a so-called "single-atom alloy". This catalyst was integrated with the fully selective hydroformylation Rh1/SnO2 catalyst in a reductive hydroformylation process, which unlocked the direct conversion of ethylene to 1-propanol with almost full selectivity (98%) at ethylene conversion >50%. Finally, the direct conversion of ethylene into propylene via tandem dimerization-metathesis has been explored. Catalyst-specific heating and thermometry methods, combining induction heating and remote luminescence thermometry, proved suitable to alleviate temperature incompatibilities inherent to state-of-the-art tandem catalytic processes and unlock catalytic performances inaccessible to conventionally heated conversion processes. / I would like to thank the Spanish Ministry of Science, Innovation and Universities (MCIU) for my FPU grant (FPU17/04701) and the European Research Council (ERC) under the Horizon 2020 research and innovation program (ERC-CoG-TANDEng; grant agreement 864195), which have made possible the realization of this thesis. I would like to thank the Institute of Chemical Technology (ITQ) and the Spanish Research Council (CSIC) for giving me access to the infrastructure I have used for my PhD work. I would like also to thank the Institute of Materials Science of Madrid (ICMM) and the Massachusetts Institute of Technology (MIT) for giving me access to their facilities during my short stays. Thanks also to the ALBA synchrotron and, particularly, to the CLÆSS beamline for making possible the access to synchrotron experiments granting us with several beamtimes. Finally I would like to thank the Chemical and Nuclear Engineering department (DIQN) of the Polytechnic University of Valencia (UPV), for hosting me as a teaching assistant during these years / García Farpón, M. (2024). Tandem Catalytic Processes for Selective Ethylene Valorization into C3 Chemicals [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203261

Dans ce travail de thèse, deux objectifs ont été fixés. Le premier a été de mieux comprendre le mécanisme très complexe qui est en jeu dans les accumulateurs Li/S. Pour cela, les modifications structurales du matériau actif ont été observées in operando et ont permis de valider un modèle clair concernant les réactions de transformations de phases qui contrôlent le lithium/soufre. La cristallisation d’une forme métastable du soufre (bêta-S8 monoclinique) en fin de recharge a ainsi été observée pour la première fois lors d’expériences au synchrotron de l’ESRF. La technique d’impédance électrochimique a également donné d’importantes informations sur les cinétiques deces réactions. Le deuxième objectif visait l’amélioration du système Li/S par l’optimisation des électrodes de soufre afin d’augmenter leurs performances mais également par la fabrication d’électrodes de Li2S efficaces permettant la transition vers le Li-ion/S, plus sécuritaire. / In this work two main aspects has been conducted in parallel. The first one was focused on betterunderstanding the very complex working mechanism of Li/S cell. Structural changes evolution ofactive material upon real time battery operation was explored, giving a clear answer on thesolid/liquid reaction evolution, which govern the electrochemistry of Li/S technology. Formationof another allotropic form of sulfur (monoclinic beta-S8) during recharging the battery have beenreported for the first time ever in Li/S community. Impedance technique applied to such systemprovided additional information concerning the kinetics of these reactions. Apart from that,another aspect targeted rather on improvements of already existing solutions (making better sulfurelectrodes, with significantly improved specific capacities) as well as development the alternativesolutions, i.e. fabrication and test of new Li2S-based positive electrodes, which could be apromising transition from classical Li/S cells into safer Li-ion/S batteries.