Methods for synthesizing diethyl carbonate from ethanol and supercritical carbon dioxide by one-pot or two-step reactions in the presence of potassium carbonate

Carbon dioxide sequestration was studied by synthesizing diethyl carbonate (DEC) from ethanol and CO2 under supercritical conditions in the presence of potassium carbonate as a base. The co-reagent was ethyl iodide or a concentrated strong acid. This sequestration reaction occurs in two steps, which were studied separately and in a one-pot reaction. An organic-inorganic carbonate hybrid, potassium ethyl carbonate (PEC) is generated at the end of the first step. This intermediate was characterized and was found to be a target molecule for CO2 capture. Different co-reactants, such as ethyl iodide and concentrated strong Brönsted acid, were compared in the second step and used to investigate the reactivity of the hybrid. With ethyl iodide as the co-reactant, one-pot DEC synthesis gave higher yields (46%) than two-step production. The supercritical CO2 acts as a swelling solvent and compatibilizing agent in the reaction medium, favoring interactions between ethanol and CO2 and between PEC and ethyl iodide. The use of a phase transfer catalyst (PTC) increased DEC production (yield 51%) without increasing the amount of diethyl ether (DEE) produced as a by-product (yield 2%)

Modelling the kinetics of transesterification reaction of sunflower oil with ethanol in microreactors

Transesterification reaction of vegetable oil with ethanol leads to ethyl esters, used to date for applications principally in food and cosmetic industry. To open the application field to biofuels (to substitute current fuels resulting from fossil resources), the process efficiency has to be developed to be economically profitable. In this work, the sunflower oil ethanolysis was performed in a micro-scaled continuous device, inducing better control for heat and mass transfer in comparison with batch processes. Moreover, this device ensures kinetic data acquisition at the first seconds of the reaction, which was not feasible in a conventional batch process. These data were used to model occurring phenomena and to determine kinetic constants and mass transfer coefficients. A single set of these parameters is able to represent the evolution of the reaction media composition function of time for five ethanol to oil molar ratios (6.0, 9.0, 16.2, 22.7 and 45.4). The model was validated in reaction and diffusion mode. Finally, it was subsequently used to simulate reactions with other operational conditions and to propose other process implementation

On-line monitoring of the transesterification reaction carried out in microreactors using near infrared spectroscopy

Biodiesel can be produced from vegetable oils, animal fats, and waste cooking oils by transesterification with ethanol (also called ethanolysis) in order to substitute fossil fuels. In this work, the batch ethanolysis of high oleic sunflower oil was transferred into a continuous microstructured device, which induces a better control of heat and mass transfers. Various parameters were studied, notably the initial ethanol to oil molar ratio. An innovative method using NIR spectroscopy was also developed to on-line monitor the transesterification reaction of high oleic sunflower oil with ethanol in microreactors (circular PFA tube 1/1600 OD, 0.0200 ID). The reactions were monitored directly in the microreactors through sequential scans of the reaction medium by the means of an adequate probe. The asset of the method is that no sample collection or preparation is necessary. Partial Least Squares regression was used to develop calibration and prediction models between NIR spectral data and analytical data obtained by a reference method (gas chromatography with flame ionization detection, GC–FID). This method is fast, safe, reliable, nondestructive and inexpensive contrary to conventional procedures, such as gas chromatography and high performance liquid chromatography generally used to determine the composition of crude transesterification medium

Creating an ecological and responsible manufacturing surfboard company: Marshall Handplanes

This master thesis presents an entrepreneurial project based on combining the intelligence of the human being with the wisdom of nature, focused on the search for natural and sustainable solutions applied to the world of surfing and skateboarding. The importance of this project lies in the consumer's awareness of the origin and process involved in the products acquired and the coherence of these concepts with the intrinsic values of a brand or company. Thanks to a ground study, we can see that today, especially in the world of surfing, there is a big paradox: for most of the people, surfing is closely linked to nature and its preservation, when in fact it is the opposite and every day is going to get worse, evolving in a throwaway industry. For this reason, it is necessary a change, innovations and radical actions are necessary to demonstrate that there are ways and alternative solutions for what we know today to be able to develop a sustainable future for this sport. The main reasons for the existence of this project is my particular interest in setting up and developing a project in the form of a company and my passion for innovation and surfing. I'm also friend with a good connoisseur of the surf industry, Alejandro Padro, who has professional experience in him and helped me through all the process. Therefore, I saw the need for the creation of a company that pursues ideals of respect, sustainability and logical development, using the greatest human capacity, intelligence, together with the wisdom of nature, which offers unsuspected alternatives, waiting for be discovered.Esta tese de mestrado apresenta um projeto empreendedor baseado na combinação da inteligência do ser humano com a sabedoria da natureza, focada na busca de soluções naturais e sustentáveis aplicadas ao mundo do surf e do skate. A importância deste projeto está na consciência do consumidor sobre a origem e o processo envolvido nos produtos adquiridos e a coerência desses conceitos com os valores intrínsecos de uma marca ou empresa. Graças a um estudo de campo, podemos ver que hoje, especialmente no mundo do surf, existe um grande paradoxo: para a maioria das pessoas, o surf está intimamente ligado à natureza e à sua preservação, quando na verdade é o oposto e tende a piorar, evoluindo para uma indústria descartável. Por esta razão, é necessário uma mudança, profunda para demonstrar que existem soluções alternativas para um futuro sustentável para este desporto As principais razões para a existência deste projeto são o meu interesse particular em montar e desenvolver um projeto na forma de uma empresa e a minha paixão por inovação e surf. Também sou amigo de um bom conhecedor da indústria do surf, Alejandro Padro, que tem experiência profissional no sector e contribuiu em todo o processo. Por isso, vi a necessidade da criação de uma empresa que busca ideais de respeito, sustentabilidade e desenvolvimento lógico, utilizando a maior capacidade humana, a inteligência, junto com a sabedoria da natureza, que oferece alternativas insuspeitas, aguardando serem descobertas

On-line monitoring of the transesterification reaction between triglycerides and ethanol using near infrared spectroscopy combined with gas chromatography

Many analytical procedures have been developed to determine the composition of reaction mixtures during transesterification of vegetable oils with alcohols. However, despite their accuracy, these methods are time consuming and cannot be easily used for on-line monitoring. In this work, a fast analytical method was developed to on-line monitor the transesterification reaction of high oleic sunflower oil with ethanol using Near InfraRed spectroscopy and a multivariate approach. The reactions were monitored through sequential scans of the reaction medium with a probe in a one-liter batch reactor without collecting and preparing samples. To calibrate the NIR analytical method, gas chromatography-flame ionization detection was used as a reference method. The method was validated by studying the kinetics of the EtONa-catalyzed transesterification reaction. Activation energy (51.0 kJ/mol) was also determined by considering a pseudo second order kinetics model

Central nervous system regulation of diffuse glioma growth and invasion: from single unit physiology to circuit remodeling

PurposeUnderstanding the complex bidirectional interactions between neurons and glioma cells could help to identify new therapeutic targets. Herein, the techniques and application of novel neuroscience tools implemented to study the complex interactions between brain and malignant gliomas, their results, and the potential therapeutic opportunities were reviewed.MethodsLiterature search was performed on PubMed between 2001 and 2023 using the keywords "glioma", "glioblastoma", "circuit remodeling", "plasticity", "neuron networks" and "cortical networks". Studies including grade 2 to 4 gliomas, diffuse midline gliomas, and diffuse intrinsic pontine gliomas were considered.ResultsGlioma cells are connected through tumour microtubes and form a highly connected network within which pacemaker cells drive tumorigenesis. Unconnected cells have increased invasion capabilities. Glioma cells are also synaptically integrated within neural circuitry. Neurons promote tumour growth via paracrine and direct electrochemical mechanisms, including glutamatergic AMPA-receptors. Increased glutamate release in the tumor microenvironment and loss of peritumoral GABAergic inhibitory interneurons result in network hyperexcitability and secondary epilepsy. Functional imaging, local field potentials and subcortical mapping, performed in awake patients, have defined patterns of malignant circuit remodeling. Glioma-induced remodeling is frequent in language and even motor cortical networks, depending on tumour biological parameters, and influences functional outcomes.ConclusionThese data offer new insights into glioma tumorigenesis. Future work will be needed to understand how tumor intrinsic molecular drivers influence neuron-glioma interactions but also to integrate these results to design new therapeutic options for patients

Caractérisation et analyse de tubes composites carbone / époxyde = Characterization and Analysis of Carbon Fibre / Epoxy Composite Tubes

National audienceLes propriétés mécaniques d'un matériau composite de type résine époxyde renforcée par des fibres de carbone sont déterminées par des essais sur des éprouvettes tubulaires. Trois empilements - [±15°], [±45°], et [±75°] - sont utilisés pour caractériser le comportement dans la direction des fibres, dans la direction transverse, et en cisaillement. Des essais quasi-statiques et en fluage sont effectués. Les résultats sont comparés aux approches analytiques

Développement de nouveaux procédés de transestérification de triglycérides en microréacteurs - Applications : biocarburants, biodétergents, biosolvants

L’objectif de la thèse est d’étudier de nouveaux types de réacteurs permettant de dépasser les limites des technologies actuelles pour la transestérification de triglycérides avec de l’éthanol (ou bioéthanol). La réaction de transestérification est équilibrée et peut s’écrire globalement de la manière suivante : Triglycéride + 3EtOH ---> 3 RCO2Et + Glycérol. Cette réaction se décompose en trois réactions successives. La première étape est la conversion des triglycérides en diglycérides ; elle est suivie de la conversion des diglycérides en monoglycérides, qui sont finalement transformés en glycérol, en formant une molécule d’ester éthylique à chaque étape