Spectroscopic characterization of Ni/Al2O3 catalytic materials for the steam reforming of renewables

Ni/alumina catalytic materials (with 0, 5, 16, 39, 125 and a % wtNi/Wsupport, using a 5% silica-containing alumina with 170 m2/g surface area) have been characterized by XRD, IR, MicroRaman, UVavisaNIR techniques. Three types of nickel oxide species have been identified: i) isolated Ni2+ species dis...

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Published in:	Applied catalysis. A, General Vol. 452; pp. 163 - 173
Main Authors:	GARBARINO, Gabriella, CAMPODONICOB, Serena, ROMERO PEREZ, Alvaro, CARNASCIALIB, Maria M, RIANIB, Paola, FINOCCHIO, Elisabetta, BUSCA, Guido
Format:	Journal Article
Language:	English
Published:	Kidlington Elsevier 15-02-2013
Subjects:	Aluminum oxide Carbon monoxide Catalysis Catalysts Chemistry Ethyl alcohol Exact sciences and technology General and physical chemistry Nickel Reduction Spectra Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry Nickel oxides Tar Ni/Al Hydrogen Ethanol steam reforming Alcohol Biomass Supported catalyst O Characterization Catalyst deactivation catalysts Alkanol Steam reforming of tars Raman spectrometry MicroRaman Spectroscopy Biomass tar Electronic properties Catalytic reaction Deactivation Ethanol Transition element compounds Transition metal Raman spectroscopy IR spectroscopy Infrared spectrometry Heterogeneous catalysis Nickel Steam reforming Alumina Catalyst Nickel oxide Hydrogen production
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Summary:	Ni/alumina catalytic materials (with 0, 5, 16, 39, 125 and a % wtNi/Wsupport, using a 5% silica-containing alumina with 170 m2/g surface area) have been characterized by XRD, IR, MicroRaman, UVavisaNIR techniques. Three types of nickel oxide species have been identified: i) isolated Ni2+ species dispersed and strongly interacting with the support surface, predominant when the NiO coverage is well below that of the atheoretical monolayera. (ii) Ni oxide-like particles having a vibrational environment similar to that of NiO nanoparticles, but with different Raman and UV spectra, predominant near or well above the atheoretical monolayera. (iii) normal NiO particles at even higher Ni oxide contents, characterized by (2 M) magnonic and several phononic peaks in the Raman spectrum and normal position for the optical gap (absorption edge at ca. 300 nm). IR spectra of adsorbed CO recorded after reduction in hydrogen suggest that species i) predominantly gives rise to isolated Nio atoms, producing Nio polycarbonyls, while species ii) gives rise by reduction to Ni metal particles, over which unusually CO adsorbs producing only terminal species, without any formation of bridging CO species. This may be due to an unusual structure or morphology of these particles. The catalysts have been tested in the steam reforming of ethanolaphenol mixture as well as of pure ethanol. XRD, UVavisaNIR and Raman studies show that the spent catalysts are largely reduced to metal with the appearance of hexagonal nickel, although unreduced or easily oxidixable centers are also detected.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0926-860X 1873-3875
DOI:	10.1016/j.apcata.2012.10.039