Catalysts and processes for next-generation H2 production

Mafessanti, Rodolfo (2014) Catalysts and processes for next-generation H2 production, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Chimica, 26 Ciclo. DOI 10.6092/unibo/amsdottorato/6485.
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The present study is focused on the development of new VIII group metal on CeO2 – ZrO2 (CZO) catalyst to be used in reforming reaction for syngas production. The catalyst are tested in the oxyreforming process, extensively studied by Barbera [44] in a new multistep process configuration, with intermediate H2 membrane separation, that can be carried out at lower temperature (750°C) with respect the reforming processes (900 – 1000°C). In spite of the milder temperatures, the oxy-reforming conditions (S/C = 0.7; O2/C = 0.21) remain critical regarding the deactivation problems mainly deriving from thermal sintering and carbon formation phenomena. The combination of the high thermal stability characterizing the ZrO2, with the CeO2 redox properties, allows the formation of stable mixed oxide system with high oxygen mobility. This feature can be exploited in order to contrast the carbon deposition on the active metal surface through the oxidation of the carbon by means of the mobile oxygen atoms available at the surface of the CZO support. Ce0.5Zr0.5O2 is the phase claimed to have the highest oxygen mobility but its formation is difficult through classical synthesis (co-precipitation), hence a water-in-oil microemulsion method is, widely studied and characterized. Two methods (IWI and bulk) for the insertion of the active metal (Rh, Ru, Ni) are followed and their effects, mainly related to the metal stability and dispersion on the support, are discussed, correlating the characterization with the catalytic activity. Different parameters (calcination and reduction temperatures) are tuned to obtain the best catalytic system both in terms of activity and stability. Interesting results are obtained with impregnated and bulk catalysts, the latter representing a new class of catalysts. The best catalysts are also tested in a low temperature (350 – 500°C) steam reforming process and preliminary tests with H2 membrane separation have been also carried out.

Tipologia del documento
Tesi di dottorato
Mafessanti, Rodolfo
Dottorato di ricerca
Scuola di dottorato
Scienze chimiche
Settore disciplinare
Settore concorsuale
Parole chiave
Methane steam Reforming Catalytic partial oxidation oxyreforming H2 production Membrane separation CeO2 –ZrO2 support Rh, Ru catalyst Ni catalyst Ce0.5Zr0.5O2 phase Oxygen mobility Strong metal support interaction
Data di discussione
11 Aprile 2014

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