This thesis work was carried out entirely in the laboratories of the Centre for Nature Inspired Engineering (CNIE) directed by Prof. Marc-Olivier Coppens and located in the Department of Chemical Engineering at University College London (UCL). The topic of interest was the catalytic selective oxidation of propene to propene oxide with molecular O2 and H2, studied through several experimental tests. The study was carried out over a heterogeneous, gold-based catalyst supported on four different titanosilicates, corresponding to TS-1, m-TS1, Ti-SBA-15 and Ti-MCM-41. The catalysts were prepared according to two different methodologies: by deposition-precipitation, which represents the traditional method discussed in the literature, and by immobilisation of colloidal nanoparticles, which represents the main interest of this thesis. The result is, in both cases, an active phase dispersed onto the surface of the chosen support. All catalysts were prepared in the laboratory and characterised by nitrogen physisorption, X-ray diffraction, thermogravimetric analysis, diffuse reflectance UV-visible spectroscopy, scanning electron microscopy, transmission electron microscopy and atomic emission spectroscopy. The objective of the work was to assess the performance of the catalyst prepared by colloidal immobilisation and to compare it with the catalyst prepared according to the traditional methodology. The experimental part analysed the new catalyst under various operating conditions, comparing the different supports, preparation methods, and calcination or pre-treatment methods. The reaction experiments were carried out at two different temperatures, 200 [°C] and 225 [°C], depending on the supports under test. The chosen reactor configuration was that of a tubular, packed bed reactor on a laboratory scale. At the end of each catalytic test, the collected data were analysed to obtain a comparison between the different catalysts tested and understand their differences in terms of activity, selectivity and stability. The results show, regarding the immobilisation of colloidal nanoparticles methodology, quite a good performance in terms of catalyst yield, but lower than the catalyst prepared by deposition-precipitation. Positive results were also observed concerning the catalyst stability and the total absence of propane in the reaction products for all tests.
Il presente lavoro di tesi è stato interamente svolto presso i laboratori del “Centre for Nature Inspired Engineering” (CNIE) diretto dal Prof. Marc-Olivier Coppens e situato nel Dipartimento di Ingegneria Chimica dell’ateneo University College London (UCL). L’argomento di interesse è stata la reazione di ossidazione catalitica selettiva di propilene ad ossido di propilene con ossigeno ed idrogeno molecolari, studiata attraverso diverse prove sperimentali. L’analisi è stata effettuata su un catalizzatore eterogeneo a base di oro, supportato su quattro diversi titanosilicati corrispondenti a TS-1, m-TS1, Ti-SBA-15 e Ti-MCM-41. Il catalizzatore è stato preparato secondo due diverse metodologie: per deposizione-precipitazione, che rapprensenta il metodo di preparazione di riferimento in letteratura, e per immobilizzazione di nanoparticelle colloidali, che rappresenta l’oggetto principale di studio. Il risultato è costituito, in entrambi i casi, da una fase attiva dispersa sulla superficie del supporto scelto. Tutti i catalizzatori sono stati sintetizzati in laboratorio e caratterizzati tramite adsorbimento fisico di azoto, diffrazione a raggi X, analisi termogravimetrica, spettroscopia ultravioletta-visibile a riflettanza diffusa, microscopia elettronica a scansione, microscopia elettronica a trasmissione e spettroscopia di emissione atomica. L’obiettivo del lavoro è stato quello di valutare le prestazioni del catalizzatore preparato per immobilizzazione colloidale, e confrontarlo con il catalizzatore preparato secondo la metodologia di riferimento. La parte sperimentale ha analizzato il nuovo catalizzatore sottoposto a determinate condizioni operative, confrontando fra loro i diversi supporti, metodi di preparazione, e metodi calcinazione o pretrattamento. Gli esperimenti sono stati condotti a due diverse temperature, 200 [°C] e 225 [°C], in funzione dei supporti testati. La configurazione reattoristica utilizzata è stata quella di reattore tubolare a letto fisso impaccato su scala di laboratorio. Terminata la campagna di raccolta dati si è proceduto quindi all’analisi degli stessi al fine di ottenere un confronto tra i diversi catalizzatori testati, al fine di capirne le differenze in termini di attività, selettività e stabilità. I risultati delle prove evidenziano, per quanto riguarda la metodologia di immobilizzazione di nanoparticelle colloidali, delle prestazioni abbastanza buone in termini di resa del catalizzatore, ma ancora non soddisfacenti rispetto ai requisiti di un processo su scala commerciale, e comunque inferiori rispetto al catalizzatore preparato per deposizione-precipitazione. Riscontri positivi si sono osservati anche per quanto riguarda la stabilità del catalizzatore e per la totale assenza di propano nei prodotti di reazione in tutti i test effettuati.
Catalytic gas phase epoxidation of propene over gold supported on different titanosilicates
CARDINALE, FABIO
2018/2019
Abstract
This thesis work was carried out entirely in the laboratories of the Centre for Nature Inspired Engineering (CNIE) directed by Prof. Marc-Olivier Coppens and located in the Department of Chemical Engineering at University College London (UCL). The topic of interest was the catalytic selective oxidation of propene to propene oxide with molecular O2 and H2, studied through several experimental tests. The study was carried out over a heterogeneous, gold-based catalyst supported on four different titanosilicates, corresponding to TS-1, m-TS1, Ti-SBA-15 and Ti-MCM-41. The catalysts were prepared according to two different methodologies: by deposition-precipitation, which represents the traditional method discussed in the literature, and by immobilisation of colloidal nanoparticles, which represents the main interest of this thesis. The result is, in both cases, an active phase dispersed onto the surface of the chosen support. All catalysts were prepared in the laboratory and characterised by nitrogen physisorption, X-ray diffraction, thermogravimetric analysis, diffuse reflectance UV-visible spectroscopy, scanning electron microscopy, transmission electron microscopy and atomic emission spectroscopy. The objective of the work was to assess the performance of the catalyst prepared by colloidal immobilisation and to compare it with the catalyst prepared according to the traditional methodology. The experimental part analysed the new catalyst under various operating conditions, comparing the different supports, preparation methods, and calcination or pre-treatment methods. The reaction experiments were carried out at two different temperatures, 200 [°C] and 225 [°C], depending on the supports under test. The chosen reactor configuration was that of a tubular, packed bed reactor on a laboratory scale. At the end of each catalytic test, the collected data were analysed to obtain a comparison between the different catalysts tested and understand their differences in terms of activity, selectivity and stability. The results show, regarding the immobilisation of colloidal nanoparticles methodology, quite a good performance in terms of catalyst yield, but lower than the catalyst prepared by deposition-precipitation. Positive results were also observed concerning the catalyst stability and the total absence of propane in the reaction products for all tests.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/153267