Chemical-Loop Approach in Bio-Alcohols Reforming

Vozniuk, Olena (2017) Chemical-Loop Approach in Bio-Alcohols Reforming, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Chimica, 29 Ciclo. DOI 10.6092/unibo/amsdottorato/7775.
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The current research is focused on the study and evaluation of a new process for the hydrogen generation, named as Chemical-Loop Reforming (CLR) of Ethanol. The main principle of the CLR process is that an oxygen-storage material is first reduced by ethanol stream (T-450oC), and then re-oxidized by water (T-450oC), in order to produce hydrogen and restore the original oxidation state of a looping-material. Different M-modified spinel-type mixed oxides: TYPE I – MFe2O4 and TYPE II – M0.6Fe2.4Oy viz. modified ferrospinels (where M=Cu, Co, Mn, Mg, Ca and Cu/Co, Cu/Mn, Co/Mn), as potentially attractive ionic oxygen and electron carrier looping materials, were prepared via co-precipitation method and tested in terms of both redox properties and catalytic activity to generate hydrogen by oxidation with steam, after the reductive step carried out with ethanol. Particularly, the focus on the reactivity behavior of binary/ternary materials explained by their ability to form thermodynamically stable spinel oxides which allow us to re-obtain the initial spinel phase upon cycling and in turn increase a stability of the looping material itself. In addition, the research includes in-situ DRIFTS and in-situ XPS studies that allowed to extract information at molecular level and to follow surface changes within the reduction/re-oxidation processes during CLR process. Bulk characterizations have been done using XRD, TEM/SEM/EDX, TPR/O, Magnetic measurements and Raman/Mössbauer Spectroscopic techniques. Moreover, a modification of the conventional CLR process with an addition of the 3rd regeneration step (carried out with air) was done in order to increase the stability of the looping material and to overcome the deactivation problems, such as: a coke deposition/accumulation and an incomplete re-oxidation of M0 during the 2nd step.

Tipologia del documento
Tesi di dottorato
Vozniuk, Olena
Dottorato di ricerca
Settore disciplinare
Settore concorsuale
Parole chiave
Chemical-Loop Reforming Water Splitting Hydrogen production Spinel oxides Mössbauer spectroscopy Magnetic measurements TPR/O in-situ XPS in-situ DRIFTS
Data di discussione
19 Gennaio 2017

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