Tuning the Integration Rate of Ce(Ln)O2 Nanoclusters into Nanoparticulated ZrO2 Supports: When the Cation Size Matters

Three nanostructured catalysts with low total rare earth elements (REEs) content (i.e., 15 mol.%) were prepared by depositing CeO(2)or Ln(3+)-doped CeO2(Ln(3+)= Y(3+)or La3+; Ln/Ce = 0.15) on the surface of ZrO(2)nanoparticles, as nanometre-thick, fluorite-type clusters. These samples were subjected to successive reduction treatments at increasing temperatures, from 500 to 900 degrees C. A characterisation study by XPS was performed to clarify the diffusion process of cerium into the bulk of ZrO(2)crystallites upon reduction to yield Ce(x)Zr(1-x)O(2-delta)surface phases, and the influence of the incorporation of non-reducible trivalent REE cations, with sizes smaller (Y3+) and larger (La3+) than Ce(4+)and Ce3+. For all nanocatalysts, a reduction treatment at a minimum temperature of 900 degrees C was required to accomplish a significant cerium diffusion. Notwithstanding, the size of the dopant noticeably affected the extent of this diffusion process. As compared to the undoped ZrO2-CeO(2)sample, Y(3+)incorporation slightly hindered the cerium diffusion, while the opposite effect was found for the La3+-doped nanocatalyst. Furthermore, such differences in cerium diffusion led to changes in the surface and nanostructural features of the oxides, which were tentatively correlated with the redox response of the thermally aged samples

Thermocatalytic CO2 Conversion over a Nickel-Loaded Ceria Nanostructured Catalyst: A NAP-XPS Study

Despite the increasing economic incentives and environmental advantages associated to their substitution, carbon-rich fossil fuels are expected to remain as the dominant worldwide source of energy through at least the next two decades and perhaps later. Therefore, both the control and reduction of CO2 emissions have become environmental issues of major concern and big challenges for the international scientific community. Among the proposed strategies to achieve these goals, conversion of CO2 by its reduction into high added value products, such as methane or syngas, has been widely agreed to be the most attractive from the environmental and economic points of view. In the present work, thermocatalytic reduction of CO2 with H-2 was studied over a nanostructured ceria-supported nickel catalyst. Ceria nanocubes were employed as support, while the nickel phase was supported by means a surfactant-free controlled chemical precipitation method. The resulting nanocatalyst was characterized in terms of its physicochemical properties, with special attention paid to both surface basicity and reducibility. The nanocatalyst was studied during CO2 reduction by means of Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS). Two different catalytic behaviors were observed depending on the reaction temperature. At low temperature, with both Ce and Ni in an oxidized state, CH4 formation was observed, whereas at high temperature above 500 degrees C, the reverse water gas shift reaction became dominant, with CO and H2O being the main products. NAP-XPS was revealed as a powerful tool to study the behavior of this nanostructured catalyst under reaction conditions

Enhanced Artificial Enzyme Activities on the Reconstructed Sawtoothlike Nanofacets of Pure and Pr-Doped Ceria Nanocubes

In this work, a simple one-step thermal oxidation process was established to achieve a significant surface increase in {110} and {111} nanofacets on well-defined, pure and Pr-doped, ceria nanocubes. More importantly, without changing most of the bulk properties, this treatment leads to a remarkable boost of their enzymatic activities: from the oxidant (oxidase-like) to antioxidant (hydroxyl radical scavenging) as well as the paraoxon degradation (phosphatase-like) activities. Such performance improvement might be due to the thermally generated sawtoothlike {111} nanofacets and defects, which facilitate the oxygen mobility and the formation of oxygen vacancies on the surface. Finally, possible mechanisms of nanoceria as artificial enzymes have been proposed in this manuscript. Considering the potential application of ceria as artificial enzymes, this thermal treatment may enable the future design of highly efficient nanozymes without changing the bulk composition.This work has been supported by the Ministry of Science, Innovation and Universities of Spain with Reference Numbers of ENE2017-82451-C3-2-R, MAT2016-81118-P and MAT2017-87579-R. The research projects funded by the Natural Science Foundation of Shandong Province (Grant ZR2017LB028), Key R&D Program of Shandong Province (Grant 2018GSF118032), and Fundamental Research Funds for the Central Universities (Grant 18CX02125A) in China are also acknowledged. TEM/STEM data were obtained at DMEUCA node of the Spanish Unique Scientific and Technological Infrastructure (ICTS) of Electron Microscopy of Materials ELECMIM. M. Tinoco thanks the FPU Scholarship Program (Grant AP2010-3737) from Ministry of Education of Spain. H. Pan is grateful for financial support (Grant 201406140130) from the Chinese Scholarship Council to accomplish her Ph.D. study at the University of Cadiz (Spain). J. M. Gonzalez, G. Blanco, and X. Chen are also grateful for the financial support from the joint project (Proyectos Integradores, Grant PI20201) in IMEYMAT of the University of Cadiz

Carbon integral honeycomb monoliths as support of copper catalysts in the Kharasch–Sosnovsky oxidation of cyclohexene

Carbon integral honeycomb monoliths prepared from a natural coal were employed as support of copper catalysts for organic synthetic purposes. In particular good to excellent yields (60–100% as function of the carboxylic acid employed) were obtained in the preparation of allylic esters by the Kharasch–Sosnovsky oxidation of cyclohexene. Different characterization techniques such as chemical analysis by Inductively Coupled Plasma Spectroscopy, nitrogen physisorption, X-ray Diffraction with Rietveld analysis, X-ray Photoelectron and Raman Spectroscopies, Temperature-Programmed Reduction and Scanning Electron Microscopy allowed finding that key parameters such as textural properties, degree of copper precursor decomposition and active phase homogeneity and dispersion can be modulated as function of a simple synthetic variable: the method used to dry the monoliths after impregnation with the metal precursor, either conventional or using microwaves. The results obtained allow understanding the key role of the nature and chemical surrounding (O2 anions or OH groups) of Cu2+ ions in the catalytic activity in the reaction investigated as well as the operating deactivation mechanisms. The use of the structured catalysts here proposed also opens up an interesting alternative to homogeneous catalysis in the field of organic synthesis

Proyecto de Innovación AAA_14_059. Cuestionarios de Evaluación sobre Diseño, Realización, Resultados y Satisfacción con las Prácticas de Laboratorio y Taller

EVALUACIÓN Y MEJORA DE LAS PRÁCTICAS DE TALLER Y LABORATORIO DE LAS ÁREAS DE CONOCIMIENTO DE CIENCIA DE LOS MATERIALES E INGENIERÍA METALÚRGICA Y DE QUÍMICA INORGÁNICA. Proyecto de Innovación Docente. Acción avalada: AAA_14_059 Una vez que los estudios de Grado están implantados y que se ha elegido un conjunto de prácticas para ilustrar los conceptos teóricos, transcurridos cuatro años se considera necesario evaluar lo hecho y plantear propuestas de revisión y mejora. La revisión se plantea desde la participación de una mayoría de profesores del Departamento C128 que voluntariamente se han sumado al proyecto. Partiendo de los materiales docentes actuales, de los resultados alcanzados, de las opiniones de los profesores, alumnos y personal técnico de laboratorio, y apoyándose en bibliografía actualizada sobre prácticas de laboratorio, se analizará en qué medida se están alcanzando los objetivos de aprendizaje, se redefinirán en los casos que sea necesario, y se identificarán propuestas de mejora con los medios disponibles, y otras que puedan requerir inversión para su implementación futura. En el marco del anterior proyecto se han elaborado cuestionarios dirigidos a estudiantes y a profesores. En cada caso se contemplan las distintas dimensiones del proceso de enseñanza aprendizaje: A.- SELECCIÓN, DISEÑO Y PREPARACIÓN DE LAS PRÁCTICAS POR EL PROFESORADO. B. REALIZACIÓN DE LAS PRÁCTICAS. C. RESULTADOS Y EVALUACIÓN. D. NIVELES DE APRENDIZAJE Y SATISFACCIÓN. E. DESARROLLO DE COMPETENCIAS TRANSVERSALES. A partir de los más de 40 aspectos sobre los que se pide la opinión de estudiantes y profesores se pueden valorar el proceso formativo, la convergencia o divergencia de opinión entre profesores y alumnos, y recoger opiniones y propuestas personales de puntos fuertes y débiles y propuestas de mejora.Se presentan los cuestionarios elaborados para la valoración de las prácticas de taller y laboratorio que se han realizado durante la implantación de los grados en el Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica. Hay cuestionarios dirigidos a alumnos de una parte y a profesores por otra. El trabajo se ha realizado en el marco del proyecto de innovación AAA_14_059.Unidad de Innovación DocenteIncluye un total de 5 archivos. Cuestionarios por asignatura para alumnos en versión texto para realizar en papel. El mismo cuestionario en forma de fichero para hacerlo llegar mediante campus virtual; se incluye otro fichero de instrucciones. Un cuestionario para profesores por cada asignatura. Un cuestionario para profesores para valorar las prácticas de las asignaturas de un título en su conjunto