Artículos SCI
2022
2022
Materiales y Procesos Catalíticos de Interés Ambiental y Energético
Research on properties and catalytic behaviour in CO hydrogenation at atmospheric and high pressure of bimetallic systems (10%Co+0.5%Pd)/TiO2 (Al2O3)
Shopska, M; Caballero, A; Platero, F; Todorova, S; Tenchev, K; Fabian, M; Aleksieva, K;Kolev, H; Kadinov, GReaction Kinetics Mechanisms and Catalysis, 135 (2022) 589-618
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The properties of prereduced (10%Co + 0.5%Pd)/Al2O3 (TiO2) systems in the CO hydrogenation reaction at atmospheric and high pressure were studied. At atmospheric pressure, alumina-supported catalysts were more selective toward methane but those using titania were more active. Alumina containing samples demonstrated high temperature H-2 desorption, firmly held surface carbonate species, high tendency to agglomeration. During the reaction metal surface reconstruction and increased formation of CH2 groups occurred being more pronounced with titania-supported catalysts. Stability tests at 250 degrees C showed opposite behaviour of both systems. Monodentate carbonate intermediates adsorbed on sites of moderate strength prevailed on titania samples, while formate species predominated on high strength sites of alumina-supported catalysts. High pressure catalytic tests revealed dependence of activity on T-red, synthesis of C2+ hydrocarbons, decreased CO2 production, a higher CH4/CO2 ratio for alumina containing system. Due to SMSI, increased CO2 production on titania samples was preserved. Titania-supported catalysts revealed a stronger decrease of CO conversion rising T-red while alumina catalysts had almost unchanged activity. CO conversion decreased with time due to difficulties in surface diffusion of reagents/intermediates/products and metal particle agglomeration. Concerning T-red comparison of product distribution showed a steady trend. Because of stable CO and CHx surface species, titania containing catalysts produced lower content of C5+ compounds. Alumina-supported samples showed a higher selectivity to C5+ compounds at the expense of methane. A higher selectivity ratio for CH4 and CO2 determined in catalytic CO hydrogenation over a certain catalyst at atmospheric pressure could indicate that a given sample is predisposed to form C2+ hydrocarbons at a higher pressure.
Marzo, 2022 | DOI: 10.1007/s11144-022-02194-x
Nanotecnología en Superficies y Plasma - Materiales Nanoestructurados y Microestructura
Highly Anisotropic Organometal Halide Perovskite Nanowalls Grown by Glancing-Angle Deposition
Castillo-Seoane, J; Contreras-Bernal, L; Obrero-Perez, JM; Garcia-Casas, X; Lorenzo-Lazaro, F; Aparicio, FJ; Lopez-Santos, C; Rojas, TC; Anta, JA; Borras, A; Barranco, A; Sanchez-Valencia, JRAdvanced Materials (2022) 2107739
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Polarizers are ubiquitous components in current optoelectronic devices as displays or photographic cameras. Yet, control over light polarization is an unsolved challenge, since the main drawback of the existing display technologies is the significant optical losses. In such a context, organometal halide perovskites (OMHP) can play a decisive role given their flexible synthesis with tunable optical properties such as bandgap and photoluminescence, and excellent light emission with a low non-radiative recombination rate. Therefore, along with their outstanding electrical properties have elevated hybrid perovskites as the material of choice in photovoltaics and optoelectronics. Among the different OMHP nanostructures, nanowires and nanorods have lately arisen as key players in the control of light polarization for lighting or detector applications. Herein, the fabrication of highly aligned and anisotropic methylammonium lead iodide perovskite nanowalls by glancing-angle deposition, which is compatible with most substrates, is presented. Their high alignment degree provides the samples with anisotropic optical properties such as light absorption and photoluminescence. Furthermore, their implementation in photovoltaic devices provides them with a polarization-sensitive response. This facile vacuum-based approach embodies a milestone in the development of last-generation polarization-sensitive perovskite-based optoelectronic devices such as lighting appliances or self-powered photodetectors.
Marzo, 2022 | DOI: 10.1002/adma.202107739
Química de Superficies y Catálisis
Understanding the promotional effect of Pt/CeO2 in cobalt-catalyzed Fischer-Tropsch synthesis using operando infrared spectroscopy at moderated pressures
Bobadilla, LF; Egana, A; Castillo, R.; Romero-Sarria, F.; Centeno, M.A.; Sanz, O.; Montes, M.; Odriozola, J.A.FUEL, 312 (2022) 122964
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![](https://icms.us-csic.es/sites/icms.us-csic.es/files/1-s2_341.png)
Fischer-Tropsch (FTS) reaction is a well-known catalytic process for the conversion of synthesis gas into liquid fuels. The addition of a water gas shift (WGS) catalyst to the FTS one has been postulate to notably increase the efficiency of the process. In order to investigate this issue, we conducted the FTS reaction over a Co-Re/Al2O3 catalyst combined with an optimal WGS Pt/CeO2 catalyst. We observed a notable increase of CO conversion in presence of the Pt/CeO2 catalyst that a priori could be attributed to the WGS reaction. However, the WGS reaction is unfavourable at pressures higher than 1 bar and CO/CO2 hydrogenation over Pt/CeO2 could be more favoured under FTS reaction conditions. In order to gain insights on this fact and elucidate the role of Pt/CeO2 in the FTS reaction we have performed an operando DRIFTS-MS study under close FTS reaction conditions at 4 bar over the Pt/CeO2 catalyst.
Marzo, 2022 | DOI: 10.1016/j.fuel.2021.122964
Fotocatálisis Heterogénea: Aplicaciones
Exploring the photocatalytic activities of a highly {0 0 1} faceted TiO2 sensitized by coupling with AgBr or Ag3PO4
F.Puga; J.A.Navío; M.A.Paulete-Romero; J.M.Córdoba; M.C.HidalgoMaterials Science and Engineering: B, 276 (2022) 115555
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![](https://icms.us-csic.es/sites/icms.us-csic.es/files/1-s2_327.png)
TiO2 with high {0 0 1} facet exposure was coupled with AgBr or Ag3PO4. Catalysts were widely characterized and tested with rhodamine B (RhB) or caffeic acid under UV and visible light. Combination of the used sensitizer (AgBr or Ag3PO4) with TiO2, not only enhances the high photocatalytic activity shown in the UV for TiO2, but it also largely increases the degradation activity under visible illumination. A synergistic effect toward photocatalytic degradation in the visible light was observed when coupling AgBr and TiO2, with the photocatalytic degradation profiles being strongly related to the molar percentages of the coupled materials and to the nature of the contaminant. The recycling of the coupled materials allows us to conclude that the AgBr(50%)/TiO2 sample presents better results in the consecutive reuse cycles and percentages of RhB dye mineralization, in contrast to those observed for the Ag3PO4(50%)/TiO2 composite.
Febrero, 2022 | DOI: 10.1016/j.mseb.2021.115555
Reactividad de Sólidos
Predictions of polymer thermal degradation: relevance of selecting the proper kinetic model
Sanchez-Jimenez, PE; Perejon, A; Arcenegui-Troya, J; Perez-Maqueda, LAJournal of Thermal Analysis and Calorimetry, 147 (2022) 2335-2341
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Making predictions, such as lifetime estimations, is one of the main objectives of kinetic studies. Thus, from conventional thermal analysis experiments, the behavior of polymeric materials under processing or application conditions, usually far away from those used in the laboratory experiments, could be estimated. Conventional prediction procedures usually make use of oversimplified equations based on simple approaches. One of the most common approaches is the assumption of a first, or n-order, kinetic model for the process. However, recent studies have shown, for a number of polymers, that random scission kinetic models are not only physically sound, but more reliable in terms of describing the degradation kinetics. In this paper, the consequences of selecting an erroneous kinetic model on lifetime predictions is discussed. It is demonstrated, using both simulated and experimental data, that any kinetic analysis of a chain scission driven reaction performed assuming a first-order model entails enormous deviations in predictions. This occurs despite the fact that the first-order kinetic model can fit experimental data from chain scission driven reactions with significant correlation coefficients, and even lead to a reasonably good reconstruction of the original experimental curves.
Febrero, 2022 | DOI: 10.1007/s10973-021-10649-x
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