Records |
Author |
Benito, P.; Monti, M.; de Nolf, W.; Nuyts, G.; Janssens, K.; et al. |
Title |
Improvement in the coating homogeneity in electrosynthesized Rh structured catalysts for the partial oxidation of methane |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Catalysis today |
Abbreviated Journal |
Catal Today |
Volume |
246 |
Issue |
|
Pages |
154-164 |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
Abstract |
The precipitation of Rh/Mg/Al and Rh/Al hydroxides on the surface of FeCrAlloy foams by a base electrogeneration method was investigated to improve the properties of the deposited film (homogeneity and composition) and therefore the performances of the structured catalysts, obtained by calcination, in the Catalytic Partial Oxidation of CH4 to syngas. The work focussed on decreasing current gradients within open-cell foam cylinders by increasing the number of electrical contacts from 1 to 3 points to promote a more homogeneous precipitation of the hydroxides. Electrochemical and catalytic tests as well as SEM/EDS and mu-XRFIXRD analyses allowed to correlate the effect of the number of electrical contact points with materials properties. Lastly, syntheses were performed on Pt plates to study the effect of the electrical behaviour and shape of the support on the composition of the film. A more homogeneous coating of the foam surface was achieved by adopting a configuration with 3 contact points since the reduction of nitrates and water molecules that generates the basic media in the vicinity of the support was enhanced. Layer thicknesses up to 5-15 mu m were deposited; however, the sequential precipitation of a film with composition closer to the expected one and a layer enriched in Al and Rh (outer layer) was not avoided. The improvement in the coating gave rise to enhanced performances for a sample prepared at -1.1 V for 3000 s. Contrarily, the low adherence of the outer layer in a sample prepared at -1.2 V for 2000 s during both calcination and catalytic tests may be responsible of the unexpected decrease in catalytic performances. The same sequential precipitation was observed by performing the syntheses on Pt plates, showing that the electrical nature the support did not play a key role on this phenomenon. (C) 2014 Elsevier B.V. All rights reserved. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor ![sorted by Editor field, descending order (down)](img/sort_desc.gif) |
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Wos |
000349998300020 |
Publication Date |
2014-10-31 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0920-5861 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
4.636 |
Times cited |
14 |
Open Access |
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Notes |
; The financial support from the Ministero per l'Istruzione, l'Universita e la Ricerca (MIUR, Roma, I) is gratefully acknowledged. The authors thank D. Grolimund and C.N. Borca for assisting the mu XRF/XRD conducted experiments at MicroXAS Beamline of SLS Thanks are due to Porvair for supplying FeCrAlloy foams. ; |
Approved |
Most recent IF: 4.636; 2015 IF: 3.893 |
Call Number |
UA @ admin @ c:irua:124616 |
Serial |
5656 |
Permanent link to this record |
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Author |
Benito, P.; Nuyts, G.; Monti, M.; de Nolf, W.; Fornasari, G.; Janssens, K.; Scavetta, E.; Vaccari, A. |
Title |
Stable Rh particles in hydrotalcite-derived catalysts coated on FeCrAlloy foams by electrosynthesis |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Applied catalysis : B : environmental |
Abbreviated Journal |
Appl Catal B-Environ |
Volume |
179 |
Issue |
|
Pages |
321-332 |
Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
Abstract |
Rh-based structured catalysts for the Catalytic Partial Oxidation of CH4 to syngas were prepared by electrosynthesis of Rh/Mg/Al hydrotalcite-type compounds on FeCrAlloy foams and calcination. The effects of Rh content, total metal concentration, and partial replacement of Mg2+ by Ni2+ in the electrolytic solution on coating thickness, Rh speciation, metallic particle size, and catalytic activity were investigated by SEM/EDS, mu-XRF/XANES and tests under diluted and concentrated reaction conditions. The amount of Rh species, present as Mg (RhxAl1-x)(2)O-4, depended on the thickness of the electrosynthesised layer as well as the Rh particle size and dispersion. Smaller and more dispersed particles were obtained by decreasing the Rh concentration in the electrolytic solution from Rh/Mg/Al=11/70/19 to 5/70/25 and 2/70/28 atomic ratio% (a.r.%) and in thinner rather than thicker layers. Despite the improvement in metallic particles features, the CH4 conversion was negatively affected by the low amount of active sites in the coating, the high metal support interaction and possibly the oxidation of metallic particles and carbon formation. A larger amount of solid containing well dispersed Rh particles was deposited by increasing the total metal concentration from 0.03 M to 0.06 M with the Rh/Mg/Al=5/70/25 a.r.%, and the catalytic performances were enhanced. The partial replacement of Mg2+ by Ni2+ gave rise to a very active bimetallic Rh/Ni catalyst, CH4 conversion and selectivity to syngas were above 90%, however, it slightly deactivated with time-on-stream. (C) 2015 Elsevier B.V. All rights reserved. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor ![sorted by Editor field, descending order (down)](img/sort_desc.gif) |
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Language |
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Wos |
000359873800036 |
Publication Date |
2015-05-19 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0926-3373 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
9.446 |
Times cited |
14 |
Open Access |
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Notes |
; The Authors acknowledge M. Salome for helping during the mu XRF/XANES experiments at ID21 Beamline of the ESRF, the Department of Structural Characterisation of CNR-IMM of Bologna for the access to the FEG-SEM facility and Dr F. Ospitali for the scientific support. Thanks are due to Farrel Lytle database for providing the necessary Rh metal spectrum (rhfoil.a99 in http:// ixs.iit.edu/data/FarrelLytledata/). The financial support from the Ministero per l'Istruzione, l'Universita e la Ricerca (MIUR, Roma, Italy) and the University of Bologna (FARB program) is gratefully acknowledged. ; |
Approved |
Most recent IF: 9.446; 2015 IF: 7.435 |
Call Number |
UA @ admin @ c:irua:127777 |
Serial |
5846 |
Permanent link to this record |