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3. Promotion of Different Active Phases in MnOX-CeO2 Catalysts for Simultaneous NO Reduction and o-DCB Oxidation.

Author

Martín-Martín, J. A., González-Marcos, M. P., Aranzabal, A., González-Velasco, J. R., and Finocchio, E.

Subjects
PHYSICAL & theoretical chemistry, CATALYTIC activity, OXIDATION states, MANGANESE oxides, X-ray diffraction
Abstract

MnOX-CeO2 catalysts with different Mn and Ce content were prepared to evaluate the effect of metal content on catalytic properties and activity in the simultaneous NO reduction and o-DCB oxidation, in order to elucidate the most active species for the process. Catalytic properties were evaluated by ICP-AES, XRD, skeletal FTIR, STEM-HAADF, XPS, N2-physisorption, H2-TPR, NH3-TPD and pyridine-FTIR. Catalysts with 85%Mn and 15%Ce molar content have been found to be the most active. Their excellent catalytic performance is related to the coexistence of Mn in different phases, i.e., Mn species strongly interacting with Ce and segregated Mn species. The effect of the preparation methods has also been deeply investigated: Co-precipitation method (CP) leads to Mn segregation as Mn2O3, whereas sol-gel preparation method (SG) promotes the formation of an amorphous powder. The synergy between segregated Mn2O3 species and Mn species in high interaction with Ce (resulting in a mixed oxide phase) leads to the presence of Mn with different oxidation states. This effect, together with the high oxygen mobility caused by structural defects, enhances redox, acidic and oxidative properties. The improvement of catalytic properties with Mn content also favors NO reduction side-reactions, with N2O and NO2 being the most important by-products, whereas it limits the production of chlorinated organic by-products in o-DCB oxidation. Highlights: High Mn content, 85%Mn-15%Ce (molar), leads to the best catalytic activity. At low Mn content, Mn incorporates into cerium oxide structure (mixed oxide phase). At high Mn content, Mn gradually segregates as manganese oxide. Co-precipitation enhances morphological properties compared to sol-gel synthesis. The synergy between Mn in high interaction with Ce and segregated Mn is key for catalytic activity. [ABSTRACT FROM AUTHOR]

Published
2025
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11. Potencialidades del hidrógeno como vector de energía en Iberoamérica

Author

Laborde, Miguel Ángel, Lombardo, E. A., Bellot Noronha, F., Soares Boaventura, Filoho, J, García Fierro, José Luis, and González Marcos, M. P.

Subjects
Ingeniería Química, Otras Ingeniería Química, Energía limpia, Purificación, INGENIERÍAS Y TECNOLOGÍAS, Hidrógeno
Abstract

La Red de Hidrógeno CYTED reúne a más de 200 investigadores iberoamericanos, con el objetivo de brindar un espacio donde analizar y discutir los avances relacionados con las tecnologías actuales y futuras de producción de hidrógeno, como así también analizar los avances vinculados al almacenamiento, transporte y seguridad, además de vincular a estos grupos con el sector productivo y con los organismos estatales y realizar acciones de capacitación y formación de recursos humanos. Dentro de este marco, surgió la idea de escribir este documento destinado fundamentalmente a los administradores y gstores de I+D en Ibero América. Se trata aquí de suministrar en forma concisa y precisa información de carácter universal analizada críticamente con el fin de asistir a los planificadores del área de energía en la gestación de programas de I+D. Fil: Laborde, Miguel Ángel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lombardo, E. A.. No especifíca; Fil: Bellot Noronha, F.. No especifíca; Fil: Soares Boaventura, Filoho, J. No especifíca; Fil: García Fierro, José Luis. No especifíca; Fil: González Marcos, M. P.. No especifíca

Published
2010

13. Comparative study of CuO-CeO2 catalysts prepared by wet impregnation and deposition-precipitation

Author

Ministerio de Educación y Ciencia (España), Gurbani, A., Ayastuy, J. L., González-Marcos, M. P., Herrero García, Josefa E., Guil, J. M., Gutiérrez-Ortiz, M. A., Ministerio de Educación y Ciencia (España), Gurbani, A., Ayastuy, J. L., González-Marcos, M. P., Herrero García, Josefa E., Guil, J. M., and Gutiérrez-Ortiz, M. A.

Abstract

Two different preparation methods are used to synthesize wt. 7% CuO–CeO2 catalysts: a conventional wet impregnation method, and a deposition–precipitation (DP) method using Na2CO3 as precipitating agent. Both samples are characterized by a series of techniques. CuO–CeO2 (Cu–Ce) prepared by DP shows a lower capacity to release the lattice oxygen to form CO2. From CO-TPR results, it is demonstrated that this catalyst is not able to reduce copper clusters at low temperatures. Also, CO-TPD shows no CO2 formation. The activity results confirm the worse performance of Cu–Ce prepared by DP especially when oxygen is not in excess (PROX reaction with stoichometric oxygen). A copper particle size which is too small could create a stronger metal-support interaction, with lower Cu–Ce interface to react.

Published
2009

14. Kinetics and simulation of CO oxidation over CO/CeO 2 catalysts

Author

Avastuy, J. L., Gurbani, A., González-Marcos, M. P., Gutiérrez-Ortiz, M. A., Herrero García, Josefa E., Guil, J. M., Avastuy, J. L., Gurbani, A., González-Marcos, M. P., Gutiérrez-Ortiz, M. A., Herrero García, Josefa E., and Guil, J. M.

Abstract

A CuO-ceria catalyst prepared by incipient wetness impregnation was characterized and the kinetics of CO oxidation was studied. The power law rate equation, as well as mechanistic derived ones, was analyzed by fitting the experimental data obtained in plug flow reactor assuming differential reactor. The genetic algorithm was used, and the modified LH-based mechanism, as well as MVK mechanism was the best fitting. This is an abstract of a paper presented at the 8th World Congress of Chemical Engineering (Montreal, Quebec, Canada 8/23-27/2009).

Published
2009

19. Control of the product distribution in the hydrogenation of vegetable oils over nickel on silica catalysts

Author

González‐Marcos, M. Pilar, Gutiérrez‐Ortiz, José I., De Elguea, Cristina González‐Ortiz, Alvarez, Jon I., and González‐Velasco, Juan R.

Abstract

Several nickel on silica catalysts, prepared by impregnation or precipitation/deposition, and a commercial catalyst were tested for activity and selectivity in the sunflower seed oil hydrogenation. An average turn‐over frequency of 2.57 s−1was found for the catalysts, assuming inaccessibility of nickel in pores smaller than 2 nm and a constant nickel surface concentration poisoned by the reaction mixture. After studying the mass‐transfer steps, the effect of temperature (373‐453 K) and pressure (101‐608 kPa) on reaction rates in the kinetic regime was analyzed, and the corresponding apparent activation energies and reaction orders were obtained. Conclusions on the effect of temperature and pressure on the selectivity to the preferential hydrogenation of polyunsaturates (So) and to the formation of trans‐isomers ((Strans)0)in the kinetic regime were derived from the results. Finally, a similar analysis was carried out when diffusion limitations were known to be present.

Published
1998
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20. Reactivation of aged model Pd/Ce<SUB>0.68</SUB>Zr<SUB>0.32</SUB>O<SUB>2</SUB> three-way catalyst by high temperature oxidising treatment

Author

Hickey, N., Fornasiero, P., Monte, R. Di, Kašpar, J., González-Velasco, J. R., Gutiérrez-Ortiz, M. A., González-Marcos, M. P., Gatica, J. M., and Bernal, S.

Abstract

A deactivated (aged under redox-cycled model TWC feed-stream) Pd/Ce0.68Zr0.32O2 catalyst is remarkably reactivated when subjected to a high temperature oxidising treatment whereas this effect is only marginal for Pd/Al2O3, which indicates the key role of such treatment in restoring the Pd–Ce0.68Zr0.32O2 interactions leading to highly active catalysts.

Published
2004

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