This work focuses on a preliminary study to perform a passage from a batch reactor to a continuous one. In particular, a research about the main differences between the two configurations is reported. After the description of some procedures that allow to understand how to switch a general reactor from batch to continuous configuration, the free-radical polymerization is explained. In fact, the case-study involves the polymerization in aqueous solution of acrylic (AA) and methacrylic (MAA) acids. In order to define the feasibility of a continuous configuration, the determination of the microkinetics is performed. After the identification of some issues related to AA polymerization, it is necessary to develop a kinetic scheme related to the polymerization of non-ionized MAA using ammonium persulfate (APS) as initiator. The equations of the model are then implemented in a numerical software (MATLAB®) to obtain a predictive model. Therefore, an experimental kinetic study is performed to obtain the conversion profiles and to describe the behavior of the system by varying the operating conditions. From the analysis of the data, the validity of the model is verified. Similar experimental investigations are performed for the polymerization of ionized MAA with sodium hydroxide (NaOH) and ammonia (NH3) to evaluate their effect on the kinetics of the system. Other parameters, such as the effects of the degree of ionization and mixing on the conversion profile, are taken into account. In addition, an attempt of scale-up is tested in order to overcome some limitations related to the magnetic stirring, using one-liter reactor with mechanical impellers. The characterization techniques used to obtain the experimental results are the gravimetric analysis and the 11H-NMR. In particular, a study related to the dependence of the conversion obtained via these two techniques is considered to properly evaluate the reliability of the experimental results. The uniqueness of the results is investigated by using distilled water and deuterium oxide (D2O) as solvents for the reaction.
Il presente lavoro rappresenta uno studio preliminare per valutare un passaggio da un reattore batch a uno continuo, nel quale vengono affrontate le principali differenze tra le due configurazioni. Dopo la descrizione di alcune procedure che consentono di capire come trasformare un generico reattore batch in uno continuo, la polimerizzazione free-radical è presa in considerazione. In questo caso, l’argomento di studio riguarda una polimerizzazione in soluzione acquosa di acido acrilico (AA) e metacrilico (MAA). Per definire la fattibilità di un passaggio da batch a continuo, viene realizzato lo studio microcinetico delle reazioni. Dopo aver identificato alcune complicazioni legate alla polimerizzazione di AA, viene analizzato lo sviluppo di uno schema cinetico riguardante la polimerizzazione di MAA non ionizzato in soluzione acquosa, utilizzando persolfato di ammonio (APS) come iniziatore. Le equazioni del modello vengono poi implementate in un programma numerico (MATLAB®) per ottenere un modello predittivo. Dunque, variando le condizioni operative, gli andamenti sperimentali delle conversioni vengono raccolti tramite uno studio cinetico e confrontati con l’andamento del modello realizzato. Vengono poi sviluppati degli studi successivi per la polimerizzazione di MAA ionizzato tramite idrossido di sodio (NaOH) e ammoniaca (NH3), in modo da valutare il loro effetto sulla cinetica. Altri parametri, quali i gradi di ionizzazione e agitazione vengono fatti variare per determinarne gli effetti sulle conversioni. Inoltre, per superare alcune limitazioni legate all’agitazione magnetica e per realizzare una prova di scale-up, viene utilizzato un reattore da un litro dotato di agitazione meccanica. Per valutare la riproducibilità dei risultati, i metodi di caratterizzazione utilizzati sono l’analisi gravimetrica ed il 11H-NMR e le reazioni vengono svolte in soluzione di acqua distillata e acqua deuterata (D2O).
From batch to continuous : study of methacrylic acid polymerization
CERRA, LUCA MARIA
2016/2017
Abstract
This work focuses on a preliminary study to perform a passage from a batch reactor to a continuous one. In particular, a research about the main differences between the two configurations is reported. After the description of some procedures that allow to understand how to switch a general reactor from batch to continuous configuration, the free-radical polymerization is explained. In fact, the case-study involves the polymerization in aqueous solution of acrylic (AA) and methacrylic (MAA) acids. In order to define the feasibility of a continuous configuration, the determination of the microkinetics is performed. After the identification of some issues related to AA polymerization, it is necessary to develop a kinetic scheme related to the polymerization of non-ionized MAA using ammonium persulfate (APS) as initiator. The equations of the model are then implemented in a numerical software (MATLAB®) to obtain a predictive model. Therefore, an experimental kinetic study is performed to obtain the conversion profiles and to describe the behavior of the system by varying the operating conditions. From the analysis of the data, the validity of the model is verified. Similar experimental investigations are performed for the polymerization of ionized MAA with sodium hydroxide (NaOH) and ammonia (NH3) to evaluate their effect on the kinetics of the system. Other parameters, such as the effects of the degree of ionization and mixing on the conversion profile, are taken into account. In addition, an attempt of scale-up is tested in order to overcome some limitations related to the magnetic stirring, using one-liter reactor with mechanical impellers. The characterization techniques used to obtain the experimental results are the gravimetric analysis and the 11H-NMR. In particular, a study related to the dependence of the conversion obtained via these two techniques is considered to properly evaluate the reliability of the experimental results. The uniqueness of the results is investigated by using distilled water and deuterium oxide (D2O) as solvents for the reaction.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/134987