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green engineering --- process intensification --- green chemistry --- nanomaterials --- biomass & bioenergy --- bioprocessing

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The main objective of the present work is to contribute to the transition from semi-batch production to continuous production of the sodium dithionite process. The project is focused on the first reaction of the mentioned process. The challenge of changing the operational mode is to redefine all the parameters. In this study, the global heat transfer coefficient of the reactor cooling jacket is calculated, and an analysis of the flow exiting the continuous reactor is carried out using a spectrophotometer. Additionally, the process has been simulated using Matlab codes to conduct sensitivity studies of specific parameters. These studies aim to understand how these parameters affect the outputs, including temperature and conversion, and to determine which parameters need to be defined accurately. This master thesis is part of Jean-Luc Hoxha’s PhD, which investigates the implementation of continuous operation for sodium dithionite process at SILOX S.A. Currently, the entire process is carried out in batches. However, there is the desire to change the operational mode to avoid, mainly, the problem of product’s degradation that can occur inside the batch reactor due to the long operational time. As a consequence, all the parameters must be redefined. One of the most relevant parameters is the temperature, which must be maintained below 60°C for the first reaction of the process, as it is highly exothermic. Therefore, the reactor is equipped with a cooling jacket surrounds it. The first objective, then, is to study the characteristic coefficient of
the heat exchanger; the overall heat transfer coefficient (U). Experiments were conducted at the laboratory from ULiège, determining, in this way, an average value of 1036 J/(s·m2·K). The second objective is to examine the output from the lab-scale continuous reactor during the reaction between the zinc powder and liquid dioxide sulphur; the first reaction. This analysis is conducting using a spectrophotometer. The equipment calibration was performed in R&D SILOX laboratory and the experiments themselves at ULiége. The calibration was not satisfactory because of the high uncertainty obtained. In addition, the results from the continuous reactor were limited, due to the fact that, only, a few experimental points were obtained. This was attributed to the pump damage caused by zinc accumulation. Nevertheless, the observed trend suggests that the reactor lengths does not significantly affect the reactor yield but rather helps in cooling the reaction medium. The amount of reagents added is what, truly, impacts on the conversion of reactants to product.
Additionally, as the final part of this project, sensitivity studies have been conducted through a simulation model designed with MATLAB and provided by Jean-Luc Hoxha. These studies show that the parameters that need to be defined with greater precision are the global heat transfer and the reaction enthalpy. In the appendix of this work, also, you can find some work plans that can be used as a guide to replicate the experimental part related to the heat exchanger and the spectrophotometer. Cette thèse de master fait partie du doctorat de Jean-Luc Hoxha, qui étudie la mise en œuvre du fonctionnement continu pour le processus de dithionite de sodium chez SILOX S.A. Actuellement, l'ensemble du processus est réalisé par lots. Cependant, il y a le désir de changer le mode opératoire pour éviter, principalement, le problème de la dégradation du produit qui peut se produire à l'intérieur du réacteur en lot en raison du temps de fonctionnement prolongé. En conséquence, tous les paramètres doivent être redéfinis. Un des paramètres les plus pertinents est la température, qui doit être maintenue en dessous de 60°C pour la première réaction du processus, car elle est très exothermique. Par conséquent, le réacteur est équipé d'une veste de refroidissement l'entourant. Le premier objectif est donc d'étudier le coefficient caractéristique de l'échangeur de chaleur ; le coefficient global de transfert de chaleur
(U). Des expériences ont été menées au laboratoire de l'ULiège, déterminant ainsi une valeur moyenne de 1036 J/(s·m2·K).
Le deuxième objectif est d'examiner la sortie du réacteur continu à l'échelle du laboratoire pendant la réaction entre la poudre de zinc et le dioxyde de soufre liquide ; la première réaction. Cette analyse est réalisée à l'aide d'un spectrophotomètre. L'étalonnage de l'équipement a été effectué au laboratoire de R&D de SILOX et les expériences elles-mêmes à l'ULiège. L'étalonnage n'était pas satisfaisant en raison de l'incertitude élevée obtenue. De plus, les résultats du réacteur continu étaient limités, en raison du fait que seuls quelques points expérimentaux ont été obtenus. Cela a été attribué aux dommages causés par l'accumulation de zinc à la pompe. Néanmoins, la tendance observée suggère que la longueur du réacteur n'affecte pas significativement le rendement du réacteur mais aide plutôt à refroidir le milieu réactionnel. La quantité de réactifs ajoutés est ce qui impacte vraiment sur la conversion des réactifs en produit.
De plus, comme dernière partie de ce projet, des études de sensibilité ont été menées à travers un modèle de simulation conçu avec MATLAB et fourni par Jean-Luc Hoxha. Ces études montrent que les paramètres qui doivent être définis avec une plus grande précision sont le transfert de chaleur global et l'enthalpie de réaction. Dans l'annexe de ce travail, vous trouverez également des plans de travail pouvant servir de guide pour reproduire la partie expérimentale liée à l'échangeur de chaleur et au spectrophotomètre.

Sodium dithionite process --- Continuous production --- process intensification --- Reactor cooling jacket --- Spectrophotometer analysis --- Sensitivity studies --- MATLAB --- Ingénierie, informatique & technologie > Ingénierie chimique

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Biomass has received significant attention as a sustainable feedstock that can replace diminishing fossil fuels in the production of value-added chemicals and energy. Many new catalytic technologies have been developed for the conversion of biomass feedstocks into valuable biofuels and bioproducts. However, many of these still suffer from several disadvantages, such as weak catalytic performance, harsh reaction conditions, a high processing cost, and questionable sustainability, which limit their further applicability/development in the immediate future. In this context, the esterification of carboxylic acids represents a very valuable solution to these problems, requiring mild reaction conditions and being advantageously integrable with many existing processes of biomass conversion. An emblematic example is the acid-catalyzed hydrothermal route for levulinic acid production, already upgraded to that of higher value alkyl levulinates, obtained by esterification or directly by biomass alcoholysis. Many other chemical processes benefit from esterification, such as the synthesis of biodiesel, which includes monoalkyl esters of long-chain fatty acids prepared from renewable vegetable oils and animal fats, or that of cellulose esters, mainly acetates, for textile uses. Even pyrolysis bio-oil should be stabilized by esterification to neutralize the acidity of carboxylic acids and moderate the reactivity of other typical biomass-derived compounds, such as sugars, furans, aldehydes, and phenolics. This Special Issue reports on the recent main advances in the homogeneous/heterogeneous catalytic conversion of model/real biomass components into ester derivatives that are extremely attractive for both the academic and industrial fields. Dr. Domenico Licursi Guest Editor

Research & information: general --- Chemistry --- eugenol --- acetylation --- flint kaolin --- mesoporous aluminosilicate --- functionalization --- heterogeneous catalysis --- n-butyl levulinate --- alcoholysis --- butanolysis --- Eucalyptus nitens --- microwaves --- biorefinery --- diesel blends --- process intensification --- hydrolysis --- solvothermal process --- alkyl levulinate --- levulinic acid --- 5-hydroxymethylfurfural --- furfural --- humins --- biomass ester derivatives --- solvothermal processing --- γ-valerolactone --- Ni-Fe bimetallic catalysts --- ABE fermentation --- Ni-MgO-Al2O3 catalyst --- biofuel --- catalytic performance --- sewage scum --- methyl (R)-10-hydroxystearate --- FAMEs --- biodiesel --- estolides --- cardoon --- waste biomass --- bio-fuels --- heterogeneous catalysts --- combustion --- PEG --- transesterification --- eugenol --- acetylation --- flint kaolin --- mesoporous aluminosilicate --- functionalization --- heterogeneous catalysis --- n-butyl levulinate --- alcoholysis --- butanolysis --- Eucalyptus nitens --- microwaves --- biorefinery --- diesel blends --- process intensification --- hydrolysis --- solvothermal process --- alkyl levulinate --- levulinic acid --- 5-hydroxymethylfurfural --- furfural --- humins --- biomass ester derivatives --- solvothermal processing --- γ-valerolactone --- Ni-Fe bimetallic catalysts --- ABE fermentation --- Ni-MgO-Al2O3 catalyst --- biofuel --- catalytic performance --- sewage scum --- methyl (R)-10-hydroxystearate --- FAMEs --- biodiesel --- estolides --- cardoon --- waste biomass --- bio-fuels --- heterogeneous catalysts --- combustion --- PEG --- transesterification

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Biomass has received significant attention as a sustainable feedstock that can replace diminishing fossil fuels in the production of value-added chemicals and energy. Many new catalytic technologies have been developed for the conversion of biomass feedstocks into valuable biofuels and bioproducts. However, many of these still suffer from several disadvantages, such as weak catalytic performance, harsh reaction conditions, a high processing cost, and questionable sustainability, which limit their further applicability/development in the immediate future. In this context, the esterification of carboxylic acids represents a very valuable solution to these problems, requiring mild reaction conditions and being advantageously integrable with many existing processes of biomass conversion. An emblematic example is the acid-catalyzed hydrothermal route for levulinic acid production, already upgraded to that of higher value alkyl levulinates, obtained by esterification or directly by biomass alcoholysis. Many other chemical processes benefit from esterification, such as the synthesis of biodiesel, which includes monoalkyl esters of long-chain fatty acids prepared from renewable vegetable oils and animal fats, or that of cellulose esters, mainly acetates, for textile uses. Even pyrolysis bio-oil should be stabilized by esterification to neutralize the acidity of carboxylic acids and moderate the reactivity of other typical biomass-derived compounds, such as sugars, furans, aldehydes, and phenolics. This Special Issue reports on the recent main advances in the homogeneous/heterogeneous catalytic conversion of model/real biomass components into ester derivatives that are extremely attractive for both the academic and industrial fields. Dr. Domenico Licursi Guest Editor

Research & information: general --- Chemistry --- eugenol --- acetylation --- flint kaolin --- mesoporous aluminosilicate --- functionalization --- heterogeneous catalysis --- n-butyl levulinate --- alcoholysis --- butanolysis --- Eucalyptus nitens --- microwaves --- biorefinery --- diesel blends --- process intensification --- hydrolysis --- solvothermal process --- alkyl levulinate --- levulinic acid --- 5-hydroxymethylfurfural --- furfural --- humins --- biomass ester derivatives --- solvothermal processing --- γ-valerolactone --- Ni-Fe bimetallic catalysts --- ABE fermentation --- Ni-MgO-Al2O3 catalyst --- biofuel --- catalytic performance --- sewage scum --- methyl (R)-10-hydroxystearate --- FAMEs --- biodiesel --- estolides --- cardoon --- waste biomass --- bio-fuels --- heterogeneous catalysts --- combustion --- PEG --- transesterification --- n/a

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In this book, we propose a collection of scientific and review articles on the production of hydrogen. The articles focus on the controlled storage and release of hydrogen; on the production of hydrogen from reforming from renewable sources, water splitting, and biological and photonic methods; on the intensification of the water gas shift process; and on the integration with purification methods such as pressure swing adsorption.

Technology: general issues --- Chemical engineering --- CO-PROX --- CO-SMET --- CO2 methanation --- hydrogen purification --- process integration --- microalgae --- acetic acid --- steam reforming --- hydrogen --- cobalt --- mesostructured materials --- biomass conversion --- hydrogen production --- kinetic models --- lignocellulosic residue --- thermal degradation --- water–gas shift --- process intensification --- structured catalysts --- kinetics --- aluminum alloy foam --- ceria --- platinum --- rhenium --- bioalcohol --- reforming --- coke --- catalyst stability --- active phase --- support --- promoter --- ammonia borane --- noble metal catalysts --- chemical hydrogen --- sulfurization --- NiS-NiS2 --- stainless steel 304 --- hydrogen evolution --- hydrogen energy and fuel cells --- impurity --- gasification --- water splitting --- dark-fermentation --- photo-fermentation --- CO gas-fermentation --- bio-photolysis --- electrolysis --- n/a --- water-gas shift