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Effect of Mg, Ca, and Sr on CeO2 based catalysts for the oxidative coupling of methane / Victor J. Ferreira in Industrial & engineering chemistry research, Vol. 51 N° 32 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 32 (Août 2012) . - pp. 10535-10541 Titre : Effect of Mg, Ca, and Sr on CeO2 based catalysts for the oxidative coupling of methane : Investigation on the oxygen species responsible for catalytic performance Type de document : texte imprimé Auteurs : Victor J. Ferreira, Auteur ; Pedro Tavares, Auteur ; José L. Figueiredo, Auteur Année de publication : 2012 Article en page(s) : pp. 10535-10541 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalytic  reaction  Oxidative  coupling  Catalyst Résumé : CeO2 catalysts modified with earth alkaline metals (M = Mg, Ca, and Sr) were prepared by the citrate method in a M:Ce molar ratio of 1:1. Different analytical techniques including diffuse reflectance Ultraviolet―Visible (DR UV―vis) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and temperature programmed desorption of CO2 (TPD-CO2) were used for the characterization of the catalysts. The materials were tested in the oxidative coupling of methane (OCM). The results of calcined samples revealed that the charge transfer from cerium to oxygen ions is shifted when CeO2 is doped, indicating defects on the catalyst surface. A linear correlation was found between the amount of surface basic sites and the ratio of the oxygen species O2― and O22― to lattice oxygen. This behavior is crucial for the CH4 conversion and selectivity to C2H6 and C2H4 at 700 °C. Ca-doped CeO2 catalyst revealed the best performance in the OCM, which can be attributed to the similar ionic radii of Ca2+ and Ce4+. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26259756 [article] Effect of Mg, Ca, and Sr on CeO2 based catalysts for the oxidative coupling of methane : Investigation on the oxygen species responsible for catalytic performance [texte imprimé] / Victor J. Ferreira, Auteur ; Pedro Tavares, Auteur ; José L. Figueiredo, Auteur . - 2012 . - pp. 10535-10541. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 32 (Août 2012) . - pp. 10535-10541 Mots-clés : Catalytic  reaction  Oxidative  coupling  Catalyst Résumé : CeO2 catalysts modified with earth alkaline metals (M = Mg, Ca, and Sr) were prepared by the citrate method in a M:Ce molar ratio of 1:1. Different analytical techniques including diffuse reflectance Ultraviolet―Visible (DR UV―vis) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and temperature programmed desorption of CO2 (TPD-CO2) were used for the characterization of the catalysts. The materials were tested in the oxidative coupling of methane (OCM). The results of calcined samples revealed that the charge transfer from cerium to oxygen ions is shifted when CeO2 is doped, indicating defects on the catalyst surface. A linear correlation was found between the amount of surface basic sites and the ratio of the oxygen species O2― and O22― to lattice oxygen. This behavior is crucial for the CH4 conversion and selectivity to C2H6 and C2H4 at 700 °C. Ca-doped CeO2 catalyst revealed the best performance in the OCM, which can be attributed to the similar ionic radii of Ca2+ and Ce4+. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26259756