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Article

Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH4 Catalytic Combustion

1
National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
2
NANOM-MEMS SRL, G. Cosbuc 9, 505400 Rasnov, Romania
*
Author to whom correspondence should be addressed.
These authors contributed equally.
Materials 2019, 12(11), 1771; https://doi.org/10.3390/ma12111771
Received: 22 April 2019 / Revised: 17 May 2019 / Accepted: 27 May 2019 / Published: 31 May 2019
(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)
This study presents the synthesis and characterization of lanthanum-modified alumina supported cerium–manganese mixed oxides, which were prepared by three different methods (coprecipitation, impregnation and citrate-based sol-gel method) followed by calcination at 500 °C. The physicochemical properties of the synthesized materials were investigated by various characterization techniques, namely: nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and H2–temperature programmed reduction (TPR). This experimental study demonstrated that the role of the catalytic surface is much more important than the bulk one. Indeed, the incipient impregnation of CeO2–MnOx catalyst, supported on an optimized amount of 4 wt.% La2O3–Al2O3, provided the best results of the catalytic combustion of methane on our catalytic micro-convertors. This is mainly due to: (i) the highest pore size dimensions according to the Brunauer-Emmett-Teller (BET) investigations, (ii) the highest amount of Mn4+ or/and Ce4+ on the surface as revealed by XPS, (iii) the presence of a mixed phase (Ce2MnO6) as shown by X-ray diffraction; and (iv) a higher reducibility of Mn4+ or/and Ce4+ species as displayed by H2–TPR and therefore more reactive oxygen species. View Full-Text
Keywords: surface vs bulk; mixed oxides; methane combustion surface vs bulk; mixed oxides; methane combustion
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MDPI and ACS Style

Neatu, S.; Trandafir, M.M.; Stănoiu, A.; Florea, O.G.; Simion, C.E.; Leonat, L.N.; Cobianu, C.; Gheorghe, M.; Florea, M.; Neatu, F. Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH4 Catalytic Combustion. Materials 2019, 12, 1771. https://doi.org/10.3390/ma12111771

AMA Style

Neatu S, Trandafir MM, Stănoiu A, Florea OG, Simion CE, Leonat LN, Cobianu C, Gheorghe M, Florea M, Neatu F. Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH4 Catalytic Combustion. Materials. 2019; 12(11):1771. https://doi.org/10.3390/ma12111771

Chicago/Turabian Style

Neatu, Stefan, Mihaela M. Trandafir, Adelina Stănoiu, Ovidiu G. Florea, Cristian E. Simion, Lucia N. Leonat, Cornel Cobianu, Marin Gheorghe, Mihaela Florea, and Florentina Neatu. 2019. "Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH4 Catalytic Combustion" Materials 12, no. 11: 1771. https://doi.org/10.3390/ma12111771

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