Letteratura scientifica selezionata sul tema "Y-valerolactone"

Abstract Ru supported on mesoporous carbon Sibunit and microporous zeolites (HZSM-5, SiO2/Al2O3 = 250; H-Beta, SiO2/Al2O3 = 30; H-Y, SiO2/Al2O3 = 5; H-USY, SiO2/Al2O3 = 30) synthesized by the sol-gel method (CSIR-National Chemical Laboratory, Pune India) were prepared by impregnation of the corresponding supports with RuCl3∙nH2O (0.1 M) followed by reduction in H2. Catalyst screening in levulinic acid (LA) (15 mL, 6.9 mmol) hydrogenation into g-valerolactone (GVL) with 1,4-dioxane (165°C, hydrogen pressure ca. 16 bar) as a solvent showed higher activity and selectivity to GVL of Ru/zeolites compared to carbon supported catalysts. Among Ru/zeolites LA conversion increased as follows Ru/HZSM-5 < Ru/H-Y < Ru/H-USY < Ru/H-Beta demonstrating a clear advantage of H-Beta preparation method. Optimization of the support microstructure and acidity opens a reliable way for selective catalytic LA hydrogenation to GVL. The catalysts were analyzed by TEM, XRD, H2-TPR and N2 physisorption to compare their physical chemical properties.

Abstract The introduction of a biomass-derived ionic liquid into the Hiyama coupling reactions, which has been considered as a powerful tool for the synthesis of symmetrically and non-symmetrically substituted biaryl structures, could further control or even reduce the environmental impact of this transformation. It was shown that tetrabutylphosphonium 4-ethoxyvalerate, a γ-valerolactone-based ionic liquid, can be utilized as an alternative solvent to create carbon–carbon bonds between aryl iodides and functionalized organosilanes in the presence of 1 mol% Pd under typical Hiyama conditions (130 °C, 24 h, tetrabutylammonium fluoride activator). A comparison of different ionic liquids was performed, and the effects of the catalyst precursor and the moisture content of the reaction mixture on the activity of the catalyst system were investigated. The functional group tolerance was also studied, resulting in 15 cross-coupling products (3a–o) with isolated yields of 45–72% and excellent purity (> 98%).

Introduction: Biodegradable cardiac patches need to be mechanically matching with native heart muscle, in order to provide appropriate mechanical support to rapidly restore heart functions and promote tissue remodeling for myocardial infarction (MI) management. Here, we utilized chemical molecular design to develop biodegradable elastomers with low initial modulus and then process them into porous scaffolds mechanically matching with native heart muscle. Methods and Results: We synthesized various amorphous copolymers including poly (δ-valerolactone-co-ε-caprolactone) (PVCL) and poly (ether ester) triblock copolymers with various molecular weights and poly(ethylene glycol) (PEG) molecular weights (PVCL-PEG-PVCL). The polyurethanes were then synthesized from PVCL or PVCL-PEG-PVCL as a soft segment, hexamethylene diisocyanate (HDI) as a hard segment and putrescine as a chain extender. The polyurethane products were presented as PU-PEGx-VCLy, where x and y refer to molecular weights of PEG and PVCL, respectively. Five polymers including PU-VCL 2k , PU-VCL 6K , PU-PEG 1K -VCL 1K , PU-PEG 1K -VCL 6K and PU-PEG 2K -VCL 6K were obtained. All polymers gradually degraded in phosphate buffer solution and enzyme solution. The 3T3 fibroblasts can grow and proliferate on all polymer film surface within 5 day culture, indicating the polymers have good cellular compatibility. PU-VCL 6K , PU-PEG 1K -VCL 6K and PU-PEG 2K -VCL 6K were further processed into porous scaffolds using thermally induced phase separation (TIPS). The PU-PEG 2K -VCL 6K scaffold at wet state had 0.19 ± 0.08 MPa initial modulus, which has no significant difference from initial modulus (0.19 ± 0.04 MPa) of the native porcine heart muscle. But the tensile strength of this scaffold is lower than that of heart muscle, which requies to be improved in the future. Conclusions: A new family of biodegradable elastic polyurethanes was synthesized and processed into porous scaffolds. The scaffolds showed promising mechanical match with heart muscle. These biodegradable polyurethane scaffolds would find opportunities to be used as a cardiac patch for heart infarction treatment.

Le monde, et en particulier l'Europe, fait face aux effets du changement climatique dus à sa longue dépendance aux combustibles fossiles en reconnaissant la nécessité vitale de s'orienter vers des ressources énergétiques renouvelables. Parmi les énergies renouvelables, la biomasse alimente non seulement la production de bioénergie, mais constitue également une source vitale de biocarbone, utilisé pour créer des molécules à haute valeur ajoutée, en remplacement des produits d'origine fossile. Les lévulinates d'alkyle, dérivés de la biomasse, se distinguent particulièrement par leur potentiel en tant que bio-additifs et biocarburants. La solvolyse acide des sucres hexagonaux de la biomasse semble être une voie de production prometteuse et rentable. Le potentiel du lévulinate d'alkyle s'étend à sa conversion en γ-valérolactone (GVL), un biosolvant prometteur, généralement obtenu par hydrogénation avec hydrogène moléculaire. En plus d'être un réactif clé, l'hydrogène est également un vecteur énergétique prometteur, facilitant l'intégration des sources d'énergie renouvelables sur le marché. Les systèmes de stockage d'énergie à base d'hydrogène soutiennent cette intégration et favorisent la transformation industrielle "verte". Cette thèse porte sur l'étude technologique et l'évaluation de la durabilité d'un système de biotransformation, intégrant la valorisation de la biomasse lignocellulosique, la production d'énergie et la génération d'hydrogène. L'étude comprend des investigations expérimentales, optimisant les technologies pour la production de lévulinate de butyle et son hydrogénation en GVL, ainsi que la simulation et l'évaluation de la durabilité de l'ensemble du procédé. Afin de répondre à la question de la durabilité, la recherche présente une première section axée sur l'étude expérimentale de la technologie optimale pour la production de lévulinate de butyle. La solvolyse de l'hexose Fructose en lévulinate de butyle a été étudiée en termes de conditions optimales de procédé et de modélisation cinétique. Sélectionné le catalyseur hétérogène, l'effet du solvant a été étudié, montrant les avantages de l'utilisation du GVL comme co-solvant, avec le butanol, sur la cinétique de conversion et de dissolution du fructose. Dans ces conditions, la solvolyse en lévulinate de butyle a été étudiée d'un point de vue cinétique, d'abord en proposant un modèle pour la solvolyse du 5-HMF, un intermédiaire dans la voie du fructose, puis en étendant la modélisation à partir du fructose lui-même. Un modèle cinétique robuste, décrivant le mécanisme réactionnel de la solvolyse, a été défini et validé, en particulier dans des conditions de concentration élevée en fructose, et en incluant dans la modélisation la cinétique de dissolution et de dégradation du fructose. Dans la deuxième partie de la recherche, la perspective technologique a été étendue à l'hydrogénation du lévulinate de butyle en GVL. À partir d'une phase de conception, le schéma global du procédé de transformation du fructose en GVL a été défini, simulé et optimisé sur la base du concept d'intensification du procédé. Le procédé a ensuite été intégré dans une étude de cas réelle en Normandie, France, en adaptant l'analyse à la disponibilité locale de la biomasse lignocellulosique et de l'énergie éolienne. L'étude définit une méthodologie pour la conception et l'intégration du système d'approvisionnement en énergie, en évaluant différents scénarios. L'évaluation de la durabilité, basée sur des indicateurs de performance couvrant les dimensions économiques, environnementales et sociales, aboutit à un indice global de durabilité. Les résultats montrent que les scénarios intégrant le système de GVL, l'énergie éolienne et le stockage de l'énergie sous forme d'hydrogène sont prometteurs, car ils démontrent une rentabilité économique élevée et un impact environnemental réduit. Enfin, des analyses de sensibilité valident la robustesse et la fiabilité de la méthodologie
The world is facing the impacts of climate change due to its long dependence on fossil fuels, and specifically Europe, which is facing an energy crisis, has recognized the fragility of its fossil fuel-dependent energy system and has moved strongly towards renewable energy resources. Among renewables, biomass not only powers bio-energy production but also serves as a vital source of bio-carbon, used to create high-value molecules, replacing fossil-based products. Alkyl levulinates, derived from biomass, particularly stand out for their potential as bio-additives and bio-fuels. Acid solvolysis of hexose sugars from biomass appears to be a promising and cost-effective production route, which requires further investigation not yet found in the literature. The potential of alkyl levulinate extends to its conversion into γ-valerolactone (GVL), a promising bio-solvent, commonly obtained by hydrogenation through molecular-hydrogen. Besides being a key reagent, hydrogen is also a promising energy carrier, facilitating the integration of renewable energy sources into the market. Hydrogen energy storage systems support this integration, promoting 'green' industrial transformation. This thesis focuses on technological investigation and sustainability assessment of a potential biorefinery system, integrating lignocellulosic biomass valorization, energy production, and hydrogen generation. The study encompasses experimental investigations, optimizing technologies for the production of butyl levulinate and its subsequent hydrogenation to GVL. Sustainability considerations are fundamental to the process configuration, aligning with the global shift towards renewable and carbon bio-resources. In order to answer the question of sustainability, the research presents a first section focused on the experimental investigation of the optimal technology for the production of butyl levulinate. The solvolysis of the biomass-derived hexose Fructose to butyl levulinate was investigated, in terms of optimal process conditions and kinetic modelling. Selected an effective heterogeneous catalyst, the effect of the solvent was investigated, showing the benefits of using GVL as co-solvent, together with butanol, on the conversion and dissolution kinetics of fructose. In these conditions, the solvolysis to butyl levulinate was studied in depth from a kinetic point of view, first by proposing a model for the solvolysis of 5-HMF, an intermediate in the fructose pathway, and then extending the modelling from fructose itself. A robust kinetic model, describing the reaction mechanism of solvolysis, was defined and validated, particularly under conditions of high initial fructose concentration (applying the concept of High-gravity), and including in the modelling the kinetics of dissolution, and degradation of fructose, under acidic conditions.In the second part of the research, the technological perspective was extended to the hydrogenation of butyl levulinate to GVL. Starting from a conceptual design phase, the overall fructose-to-GVL process scheme was defined, simulated, and optimized on the basis of the process intensification concept. In the third part, the process was then dropped into a real case study in Normandy, France, adapting the analysis to the local availability of lignocellulosic biomass and wind energy. The study defines a methodology for designing and integrating the energy-supply system, evaluating different scenarios. The sustainability assessment, based on key performance indicators spanning economic, environmental, and social dimensions, culminates in an aggregated overall sustainability index. The results highlight scenarios integrating the GVL biorefinery system with wind power and hydrogen energy storage as promising, demonstrating high economic profitability and reduced environmental impact. Finally, sensitivity analyses validate the robustness and reliability of the methodology, generally extendable also to other technological systems
Come previsto, il mondo sta affrontando gli effetti tangibili del cambiamento climatico come conseguenza di un'economia basata sui combustibili fossili per centinaia di anni. Oltre a dover affrontare e adottare misure correttive per limitare gli effetti del riscaldamento globale, l'Europa sta affrontando una grave crisi energetica, che rivela la fragilità del sistema energetico europeo, prevalentemente dipendente dalle importazioni di combustibili fossili. La geopolitica delle risorse fossili ha innescato la necessaria rimodulazione dell'economia energetica europea, che si sta spostando "forzatamente" verso le risorse energetiche rinnovabili per diventare un'economia fossile e a zero emissioni di carbonio. Nel panorama delle rinnovabili, le risorse più sfruttate sono l'energia solare, eolica e da biomassa. Oltre alla produzione di bioenergia, la biomassa è una fonte inestimabile di biocarbonio, che può essere sfruttata e valorizzata per la produzione di molecole ad alto valore aggiunto che possono essere utilizzate in vari settori industriali, per la produzione di carburanti, prodotti chimici, materiali e sostituendo i corrispondenti prodotti di origine fossile. In questo contesto, sono stati sviluppati sistemi innovativi di bioraffinazione della biomassa di seconda generazione per trasformare e decostruire la complessa struttura della biomassa in molecole piattaforma più semplici, che possono poi essere trasformate in molecole ad alto potenziale. Tra queste, gli alchil levulinati sono stati identificati per il loro notevole potenziale come bioadditivi e biocarburanti. Esteri dell'acido levulinico, questi composti possono essere ottenuti da derivati della biomassa, come i monosaccaridi dello zucchero, secondo diverse vie di reazione; tra queste, la solvolisi acida degli zuccheri esosi può essere una via di produzione promettente ed economicamente vantaggiosa, che richiede ulteriori indagini non ancora presenti in letteratura. Il potenziale degli alchil levulinati risiede anche nella possibilità di un ulteriore trasformazione mediante idrogenazione per produrre γ-valerolattone (GVL), una molecola con un mercato promettente come bio-solvente, grazie alle sue proprietà di stabilità, ecotossicità e biodegradabilità. L'uso dell'idrogeno gassoso è la via più comune per l'idrogenazione del GVL, ma, oltre a essere un reagente chimico fondamentale, l'idrogeno è anche uno dei principali protagonisti della transizione energetica. Infatti, come vettore energetico, l'idrogeno può portare alla piena penetrazione delle fonti energetiche rinnovabili nel mercato dell'energia, costituendo un complemento-tampone per lo stoccaggio delle energie rinnovabili intermittenti, attraverso la progettazione di sistemi di stoccaggio dell'energia dell'idrogeno (HydESS). L'accumulo di energia a idrogeno a lungo termine può consentire l'autosufficienza dei sistemi di energia rinnovabile, in quanto agisce da ponte tra le funzionalità dei sistemi Power-to-Hydrogen, in grado di assorbire i surplus energetici delle energie rinnovabili e di immagazzinarli, e quelle dei sistemi Hydrogen-to-Power, che restituiscono energia rinnovabile quando le fonti di energia primaria non sono disponibili. In quest'ottica, lo sviluppo di tali sistemi può portare all'integrazione completa e stabile delle fonti di energia rinnovabile in asset industriali già esistenti, così come in nuovi mercati industriali, come le bioraffinerie di biomassa lignocellulosica, promuovendo lo sviluppo di realtà industriali "verdi" in termini di trasformazione di materiali ed energia. Il mercato industriale globale si sta evolvendo verso la decarbonizzazione e la riqualificazione di diversi asset, attraverso investimenti in efficienza energetica e l'introduzione di processi green per la valorizzazione delle fonti rinnovabili, ma l'implementazione su larga scala di queste iniziative richiede un'analisi completa e approfondita della loro sostenibilità