Sicignano, Luca (2017) Development of continuous flow microreactor for Buchwald-Hartwig amination. Analysis of reaction kinetics and microreactor clogging. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Lingua: English
Title: Development of continuous flow microreactor for Buchwald-Hartwig amination. Analysis of reaction kinetics and microreactor clogging
Date: 7 December 2017
Number of Pages: 75
Institution: Università degli Studi di Napoli Federico II
Department: dep08
Dottorato: phd038
Ciclo di dottorato: 30
Coordinatore del Corso di dottorato:
Tomaiuolo, GiovannaUNSPECIFIED
Date: 7 December 2017
Number of Pages: 75
Uncontrolled Keywords: microfluidic; reactor; microreactor; clogging; fouling; amination; Buchwald-Hartwig; cross-coupling; Particle clustering; Solid handling
Settori scientifico-disciplinari del MIUR: Area 09 - Ingegneria industriale e dell'informazione > ING-IND/06 - Fluidodinamica
Area 09 - Ingegneria industriale e dell'informazione > ING-IND/24 - Principi di ingegneria chimica
Area 09 - Ingegneria industriale e dell'informazione > ING-IND/25 - Impianti chimici
Area 09 - Ingegneria industriale e dell'informazione > ING-IND/27 - Chimica industriale e tecnologica
Date Deposited: 08 Jan 2018 00:57
Last Modified: 10 Apr 2019 10:43


Several applications, ranging from petrochemical industry to pharmaceutical processes, involve the use of microfluidics devices in order to manipulate and study heterogeneous systems under flow in view of process intensification. These devices present many advantages, including lower flow rate compared to traditional batches, higher speed of heat and mass transfer, lower waste production and lower costs and operational safety. Otherwise, they show some drawbacks such as a lower degree of mixing, due to the laminar flow conditions typical of microfluidics, and solid formation, which may lead to the clogging of the device. For this reason, many studies are conducted to develop novel microsystems to combine the flexibility of batch reactors with all of the advantages of conventional flow systems and to understand the mechanisms basis to the solid handling, i.e. fouling problems. Here, an innovative methodology to investigate the reaction kinetics of the Buchwald-Hartwig (B-H) cross-coupling reaction, chosen as key study, and the problem of solid handling in a continuous flow microreactor is presented. In particular, the first is investigated by developing a home-made microfluidic system to study the effects of process parameters, such as temperature and reagent concentration, on kinetic reaction, in order to optimize the microreactor set-up and the reactive process. Regarding the study of solid aggregation inside the device, it is examined by coupling microfluidic and microscopy and analyzing the effect of shear flow on surface fouling onto microchannel walls when running B-H reaction. To make this, a microfluidic apparatus has been created to process the reaction and to observe online aggregates growth and the subsequent clogging of the channels. The present work is organized as follows: in Chapter 1, a general background about microreactors and solids handling, which causes the clogging problems, is presented by describing in detail the mechanisms at the base of surface fouling. In addition, the organic reaction of Buchwald-Hartwig run in the microreactor is described. Motivations of the study are also discussed. In Chapter 2, an innovative home-made flow microreactor to process and to study B-H amination is presented. In particular, the efficiency of the microdevice is compared to the one of traditional batch reactors and a detailed study on the effect of the operating parameters is showed. In Chapter 3, the experimental set-up based on the microreactor is used as a novel approach to make the system more flexible in terms of number of feeds and imposed flow rates. Initially the results are compared to the previous ones to validate the new set-up. Subsequently, the effect of the operating parameters on the reaction kinetics are investigated to elaborate a kinetic law. In Chapter 4, the direct visualization of particles adhesion to the wall, cluster growth and reactor clogging is investigated in detail by using a home-made flow continuous device linked to a microfluidic system, in order to visualize the processes by microscopy techniques. In particular, the effect of the flow rate on cluster morphology and on channel clogging is analyzed, proposing an experimental alternative to study and understand the mechanism to the base of the surface fouling. Cluster formation and growth are studied by both qualitative and quantitative approach also using a mathematical model shown in the literature. Conclusions and future works are described in Chapter 5. Lastly in Appendix A shows the preparation protocol of the aryl bromide (i.e. the limiting reagent of B-H reaction), and in Appendix B reports in detail the home-made macro used to measure the cluster parameters, such as cluster area and cluster optical intensity of each image at different times.

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