Academic literature on the topic 'Consecutive reaction'

Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(工学)<br>甲第11597号<br>工博第2543号<br>新制||工||1346(附属図書館)<br>23240<br>UT51-2005-D346<br>京都大学大学院工学研究科合成･生物化学専攻<br>(主査)教授 吉田 潤一, 教授 杉野 目道紀, 教授 前 一廣<br>学位規則第4条第1項該当

La distillation réactive est l’un des procédés chimiques intensifiés les plus reconnus, qui intègre la séparation et la réaction au sein d’un même appareil. Les principaux avantages de la distillation réactive concerne l’amélioration de la conversion de la réaction, la diminution significative des investissements, des coûts de fonctionnement, de la consommation énergétique, et de la production de sous produits. Une méthodologie de conception systématique, générale et hiérarchisée de la distillation réactive discontinue avec des réactions consécutives est présentée dans ce manuscrit. La méthode élaborée est présentée sur la transestérification du carbonate de diméthyle par le procédé de distillation réactive discontinue dans une colonne avec un bac intermédiaire. Après l’acquisition de données phisicochimiques de base nécessaire à notre méthode, une nouvelle méthode de l’analyse de faisabilité pour les systèmes multiréactifs et multiconstituant a été développée. L’étape suivante est l’analyse de sensibilité afin d’explorer les effets des paramètres du procédé. Une configuration faisable, qui est entièrement réactive avec une alimentation dans la partie supérieure et inférieure de la colonne et avec un bac intermédiaire a été choisie et étudiée au cours de l’analyse de sensibilité par des simulations rigoureuses effectuées en utilisant le logiciel ProSIM Batch<br>Reactive distillation, a process integrating separation and reaction in a single unit, is one of the best known intensified chemical processes. Major advantages of reactive distillation include higher conversion, reduced investment, operating costs, energy consumption, and quantity of secondary products. A systematic and hierarchic general methodology for conceptual design of multireactive batch reactive distillation (BRD) is presented in this manuscript. The elaborated method is presented on the transesterification of dimethyl carbonate by the process of batch reactive distillation in a middle vessel column.After collecting the physico-chemical basic data necessary for our method, the new method of feasibility analysis for multicomponent and multireactive systems has been developed. The next step is the sensibility analysis, when the effects of the process parameters are analysed. As a configuration feasible a fully reactive configuration of middle vessel column with entrainer feeding to the upper and lower column sections is studied by simulations using ProSIM Batch

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-10-19T12:15:24Z No. of bitstreams: 1 ARIANNE DE FREITAS BARROS SOARES - DISSERTAÇÃO (PPGEQ) 2017.pdf: 1645096 bytes, checksum: d2c070ce1e85b955e552b026e872343c (MD5)<br>Made available in DSpace on 2018-10-19T12:15:24Z (GMT). No. of bitstreams: 1 ARIANNE DE FREITAS BARROS SOARES - DISSERTAÇÃO (PPGEQ) 2017.pdf: 1645096 bytes, checksum: d2c070ce1e85b955e552b026e872343c (MD5) Previous issue date: 2017-01-27<br>O presente trabalho estende a metodologia de análise e otimização de processos químicos via minimização da taxa de produção de entropia a um sistema considerado complexo e pouco explorado pela metodologia adotada. Com o intuito de determinar as condições ótimas operacionais do processo, um sistema de reações múltiplas, genéricas e consecutivas conduzidas em um reator de mistura perfeita foi analisado. Tendo em vista que o produto intermediário é o de interesse comercial, o desenvolvimento da metodologia foi baseado nos balanços de massa e energia associados ao balanço entrópico objetivando a minimização da taxa de produção de entropia da reação de interesse. Em conformidade com estudos antecedentes, o procedimento de otimização revelou que a obtenção de uma relação entre a temperatura de alimentação e a temperatura de operação é fundamental para que a condição de mínima produção de entropia seja alcançada. Se tratando da temperatura de reação, uma única condição operacional foi considerada ótima do ponto de vista da mínima produção de entropia, maximizando o rendimento do produto desejado; enquanto que a metodologia clássica de análise e otimização sugeriu diversos pontos operacionais, incluindo um que direciona o sistema para a maximização do produto indesejado em detrimento do produto de interesse. Por se tratar de reações consecutivas, um parâmetro construtivo do reator também foi analisado para alcançar a condição de mínima entropia. A otimização entrópica do tempo de residência revelou que quanto maior for seu valor menor será a taxa de produção de entropia. Uma análise econômica de modo simplificado foi aplicada ao sistema com o intuito de se configurar um critério de seleção de tal parâmetro. Os resultados obtidos revelaram uma nova condição operacional capaz de reduzir os custos energéticos do processo e melhorar o desempenho reacional do sistema.<br>The present study extends the methodology of analysis and optimization of chemical process by minimizing the entropy rate production to a system considered complex and still not explored by the adopted methodology. In order to determinate the optimal operational conditions of the process, a system of multiple generic and consecutive reactions conducted in a perfect mixing reactor was analyzed. Since the intermediate product is of commercial interest, the development of the methodology was based on the mass and energy balances associated with the entropic balance aiming to minimize the entropy rate production of the reaction of interest. In accordance with previous studies, the optimization procedure revealed that obtaining a relation between inlet and operating temperatures is essential to reach the minimum entropy production condition. If treating of reaction temperature, a single operational condition was considered optimal from the point of view of minimum entropy production, while the classical analysis methodology suggested several operating points. Because it is a consecutive reaction, a constructive parameter of the reactor was also analyzed to reach the minimum entropy condition. The entropic optimization of the residence time revealed that the higher its value the lower is the entropy rate production. A simplified economic analysis was applied in order to configure a selection criterion for such parameter. The results reveals a new operating condition capable of reducing the energy costs of the process and improving the reactive performance of the system.

Au cours de ce travail, nous avons tente de determiner le role du monoxyde d'azote (no) dans la reaction cerebrovasculaire et les dommages neuronaux consecutifs a la crise d'epilepsie induite par l'acide kainique et de preciser son origine cellulaire. Au niveau cerebral, le no est synthetise de facon constitutive par la no synthase (nos) dite endotheliale localisee dans l'endothelium des vaisseaux sanguins cerebraux et par la nos dite neuronale localisee dans des neurones centraux, des fibres nerveuses perivasculaires et des astrocytes. Nous avons montre chez le rat eveille que le 7-nitro indazole (7-ni), inhibiteur relativement selectif de la nos neuronale reduit l'activite de la nos cerebrale, l'apport sanguin et l'oxygenation tissulaire au niveau du cortex parietal et de l'hippocampe et qu'il protege les neurones pyramidaux des regions ca1 et ca3 de l'hippocampe consecutifs a l'epilepsie. Nous avons egalement mis en evidence que le no synthetise par la nos neuronale joue un role deletere lors d'une ischemie globale transitoire. L'analyse de nos resultats, a la lumiere des donnees bibliographiques, nous a amene a proposer l'hypothese suivante. Le no produit par la nos neuronale est deletere non seulement en participant a la toxicite du glutamate, mais egalement en induisant une perfusion sanguine et une oxygenation tissulaire excessives, conduisant a la formation de l'oxydant cytotoxique, le peroxynitrite ( -oono). Le monoxyde de carbone (co) etant une molecule vasodilatatrice aux proprietes semblables a celles du no, nous avons egalement etudie son role dans la reponse cerebrovasculaire a l'hypercapnie et a l'epilepsie. Nous avons montre que l'inhibition de l'heme oxygenase 2, enzyme constitutive qui synthetise le co, ne modifie ni le debit sanguin cerebral basal, ni la reponse cerebrovasculaire a l'hypercapnie mais, reduit significativement l'augmentation du debit sanguin du neocortex lors de la crise d'epilepsie. Nos resultats suggerent que le co participe a la regulation du debit sanguin cerebral dans des conditions specifiques, notamment celles associees a une liberation accrue de glutamate. Cette etude suggere que le no n'est pas le seul gaz diatomique endogene jouant un role dans l'hyperemie concomitante a l'epilepsie mais que le co serait egalement un mediateur de cette reaction cerebrovasculaire.

The kinetics of drugs photodegradation have traditionally been treated using thermal kinetic analysis methods consisting most commonly in zero and first order kinetics. These treatment strategies were shown to lack specificity and present a number of limitations when applied to photoreactions kinetics. Nevertheless, these methods have widely been used due to a lack of integrated rate-laws for the majority of photoreactions types, in turn, due to the presence of a variable time-dependent factor in most photoreactions rate-laws that prevents their mathematical integration. To address these limitations, a new methodology for the development and validation of semi-empirical integrated rate-laws that faithfully describe photoreactions kinetics and photoreactions simulated cases generated by numerical integration methods (NIMs), is hereby presented. Using this methodology, a new kinetic order was ascribed to photoreactions namely the Φ-order kinetics. Semi-empirical integrated rate-laws were, thus, developed for three photoreaction types namely, unimolecular, AB(1Φ), photoreversible ,AB(2Φ), and consecutive, AB4(4Φ), photoreactions. The proposed models were further tested experimentally on drugs following these photodegradation mechanisms using; nifedipine and nisoldipine for unimolecular photoreactions; montelukast and fluvoxamine for photoreversible reactions; and riboflavin for consecutive photoreactions. The developed models not only accurately described the photoreaction kinetics of these drugs but also allowed the determination of all the kinetic parameters that characterise them. Furthermore, the above studied drugs were shown to act as precise and simple actinometers when analytically treated with the Φ-order kinetic methods, hereby presented. A universal standard method for the precise and worldwide reproducible study of drugs stability and compounds photoreactions, based on monochromatic irradiation and Φ-kinetics data analysis, is also detailed and adopted throughout the thesis. Finally, two new kinetic parameters namely, the pseudo-rate-constant and pseudo-initial velocity have been identified and shown to be more reliable and accurate in the description and universal comparison of photoreactions kinetics.

Competitive-Consecutive and Competitive-Parallel reactions are both mixing sensitive reactions; the yield of desired product from these reactions depends on how fast the reactants are brought together. Recent experimental results have suggested that the mixing effect may depend strongly on the stoichiometry of the reactions. To investigate this, a 1-D, non-dimensional, reaction-diffusion model at the micro-mixing scale has been developed. Assuming constant mass concentration and diffusivities, systems of PDEs have been derived on a mass fraction basis for both types of reactions. A single general Damkhler number and specific dimensionless reaction rate ratios were derived for both reaction schemes. The resulting dimensionless equations were simulated to investigate the effects of mixing, reaction rate ratio and stoichiometry of the reactions. It was found that decreasing the striation thickness and the dimensionless rate ratio maximizes yield for both types of reactions and that the stoichiometry has a considerable effect on yield. All three variables were found to interact strongly. Phase plots showing the interactions between the three variables were developed.