Growing energy demand and ecological transition make it necessary to study new low-emission energy resources. Among them, one of the most promising is hydrogen, but its transportation and storage turn out to be energy and economically expensive. Ammonia is considered as an excellent carrier of hydrogen, because of its high H2 content and the well-developed technologies and infrastructures for its synthesis, storage and transport. For NH3 cracking, the key point is to develop highly active and stable catalysts. Therefore, the catalytic decomposition of ammonia to produce hydrogen needs further study. Among the various catalysts used, ruthenium-based ones seem to be most promising, and therefore, to further refine their performance, both their properties and reaction kinetics, which is still under discussion, need to be studied. In this study, a series of ruthenium catalysts, with Ru(NO)(NO3)3 as precursor, using three different supports (Ru/Al2O3, Ru/MgO and Ru/MgAl2O4) were produced by incipient wet impregnation (IWI), and characterized by BET tests, ICP-MS and H2 pulses chemisorption. Then kinetic investigation of NH3 decomposition over these home-made catalysts was carried out by experiments and modelling work. In following, the potential of H2-removal from the catalyst surface was studied by co-feeding O2 with NH3 decomposition and the effect of an oxidative pretreatment over the catalysts were tested.
La crescente domanda di energia e la transizione ecologica rendono necessario lo studio di nuove risorse energetiche a bassa emissione. Tra di esse, uno delle più promettenti è l’idrogeno, ma il suo trasporto e stoccaggio risultano essere energeticamente ed economicamente dispendiosi. L’ammoniaca viene considerata un eccellente vettore di idrogeno per il suo alto contenuto di H2 e le sviluppate tecnologie e infrastrutture per la sua sintesi e il trasporto. Per la sua decomposizione catalitica, è fondamentale sviluppare catalizzatori estremamente attivi e stabili, e pertanto è necessario approfondirne lo studio. Tra i vari catalizzatori utilizzati, i più promettenti sembrano essere quelli a base di rutenio, di conseguenza occorre investigarne le proprietà e la cinetica di reazione, per migliorarne ulteriormente le prestazioni. In questo studio, una sere di catalizzatori al rutenio è stata prodotta attraverso il metodo di Incipient Wet Impregnation (IWI), utilizzando Ru(NO)(NO3)3 come precursore e tre differenti supporti (Ru/Al2O3, Ru/MgO and Ru/MgAl2O4), e sono stati poi caratterizzati mediante le tecniche di BET, ICP-MS e chemisorbimento di pulsi di H2. Successivamente, l’investigazione cinetica della decomposizione di NH3 su questi catalizzatori artigianali è stata svolta attraverso una campagna sperimentale e di modellizzazione. È anche stato studiato il potenziale della rimozione di idrogeno dalla superficie del catalizzatore attraverso il co-feed di ossigeno, e sono stati testati gli effetti di un pretrattamento ossidativo.
NH3 decomposition over Ru catalysts: experimental and modelling analysis of the kinetics with focus on H-inhibition
ABATE, FEDERICO
2023/2024
Abstract
Growing energy demand and ecological transition make it necessary to study new low-emission energy resources. Among them, one of the most promising is hydrogen, but its transportation and storage turn out to be energy and economically expensive. Ammonia is considered as an excellent carrier of hydrogen, because of its high H2 content and the well-developed technologies and infrastructures for its synthesis, storage and transport. For NH3 cracking, the key point is to develop highly active and stable catalysts. Therefore, the catalytic decomposition of ammonia to produce hydrogen needs further study. Among the various catalysts used, ruthenium-based ones seem to be most promising, and therefore, to further refine their performance, both their properties and reaction kinetics, which is still under discussion, need to be studied. In this study, a series of ruthenium catalysts, with Ru(NO)(NO3)3 as precursor, using three different supports (Ru/Al2O3, Ru/MgO and Ru/MgAl2O4) were produced by incipient wet impregnation (IWI), and characterized by BET tests, ICP-MS and H2 pulses chemisorption. Then kinetic investigation of NH3 decomposition over these home-made catalysts was carried out by experiments and modelling work. In following, the potential of H2-removal from the catalyst surface was studied by co-feeding O2 with NH3 decomposition and the effect of an oxidative pretreatment over the catalysts were tested.| File | Dimensione | Formato | |
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2024_07_Abate_ExecutiveSummary.pdf
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Descrizione: Executive Summary
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2024_07_Abate_Thesis.pdf
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Descrizione: Thesis
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https://hdl.handle.net/10589/222192