Application of Infrared Spectroscopy in Catalysis: Impacts on Catalysts’ Selectivity

Catalysis plays an important role in sustainable chemistry, enabling the development of more efficient processes by minimizing the consumption of energy and reducing the generation of by-products. The design of efficient catalysts is a key point in this respect, where spectroscopy confers fundamental knowledge at the molecular scale. Among the different spectroscopies, infrared (IR) spectroscopy is of great interest, enabling information about the nature of active species and the reaction mechanism, leading to precise structure-activity correlations, which are a key point in the design of new catalysts. Moreover, the dynamic behavior of the catalysts under working conditions can be also monitored by IR spectroscopy, where structural modifications of working catalysts have strong repercussion in catalysis. In this chapter, interesting examples will be discussed, related to industrial relevant processes, like Fischer-Tropsch synthesis, ethylene oligomerization, synthesis of aniline from nitrocompounds, and the dehydration of aldoximes to nitriles

Magnetocaloric Effect Caused by Paramagnetic Austenite–Ferromagnetic Martensite Phase Transformation

In the present work, the magnetization of Ni50Mn17.5Ga25Cu7.5 alloy undergoing the first-order phase transition from paramagnetic austenite to ferromagnetic martensite was measured to evaluate the magnetic-field-induced entropy change (MFIEC) and refrigerant capacity (RC) of the alloy. A standard method (SM) of evaluation of MFIEC is based on thermodynamic Maxwell relation. In view of the criticism of SM expressed by some scientists, the alternative method (AM), which is based on thermodynamic relationships for free energy, was proposed recently for the determination of MFIEC. We developed this method and computed MFIEC in two ways—by AM and SM. The values of MFIEC obtained for Ni50Mn17.5Ga25Cu7.5 alloy by these methods appeared to be large but very different from each other. Moreover, AM reveals the possibility of both normal and inverse magnetocaloric effects in the adjoining temperature ranges, while SM results only in the normal magnetocaloric effect.This research was funded by AEI/FEDER, UE (projects MAT2014-56116-C04-01-R and MAT2012- 37923-C02-01), NASU (project 0117U000433), MESU (project 0117U004340) and SFFR (President’s of Ukraine grant F75/156-2018)

Análisis del desarrollo de nuevos conceptos y teorías socio ambientales como estrategias para el logro del desarrollo sustentable regional en México

La causa de que actualmente nuestra especie se encuentre cada vez más interesada en los temas sobre medio ambiente y sustentabilidad es la concientización sobre la crisis ambiental. Tenemos muchos problemas ambientales que solucionar, mismos que han sido propiciados principalmente por la actividad económica del ser humano. Cada acción que realizamos para sobrevivir en éste planeta conlleva un impacto a nuestros ecosistemas, consumimos recursos y servicios ambientales y no es que seamos la única especie que los requiere pero si hemos abusado de ellos al considerarnos la única especie consiente y capaz de explotarlos a nuestro gusto y necesidad. Pero lo único que hemos conseguido a lo largo de nuestra existencia es ir agotando la calidad de la naturaleza y sus beneficios para con todos nosotros. Este análisis abordará a manera de ensayo de divulgación los diferentes conceptos para conseguir el desarrollo sustentable regional y algunas teorías socio ambientales que fomenten la utilización de esos conceptos en las diversas problemáticas ambientales, económicas y sociales que hay en México

Materias primas de elementos de molienda como marcadores de la ampliación de las áreas de captación durante el horizonte campaniforme. El ejemplo del yacimiento de Camino de las Yeseras

A través de los datos del yacimiento Calcolítico de Camino de las Yeseras se hace una revisión de las materias primas utilizadas en los elementos de molturacion donde, a partir del Horizonte campaniforme, las cuarcitas locales obtenidas de la base del propio yacimiento y de los aportes fluviales del entorno próximo van siendo sustituidas por otras piedras locales pero menos frecuentes y, sobre todo por el granito y, en menor proporción, por otras rocas metamórficas procedentes de la zona serrana, a unos 30-40 kilómetros del yacimiento, lugar donde también se benefician los minerales del cobre cuya transformación adquiere con los grupos campaniformes la definitiva introducción en la zona. Posiblemente este cambio se deba a dos circunstancias: la creciente especialización de los artefactos y la intensificación de las prospecciones de los minerales destinados a la metalurgia, todo ello en un contexto de importantes cambios socialesWithin the archaeological context of the Calcolithic Camino de las Yeseras settlement we propose a raw materials acquisition analysis of the milling elements, starting with the Bell Beaker Horizon. H e local quartzites present in the base of the deposit with a fl uvial origin, acquired in the next surroundings have being replaced by other local but less frequent stones and, mainly by the granite and other metamorphic rocks coming from the mountain area, about a 30-40 kilometers far from the site. H is mountainous region where also the location in which copper minerals were benefi t, whose transformation acquires with the Ball Beakers groups the defi nitive introduction in the zone. Possibly this changes are due to diff erent circumstances: the increasing specialization of the tools and the intensifi cation of the surveys destined to the metallurgy catchment, obviously in a context of important social change

TiO2 polymorph dependent SMSI effect in Co-Ru/TiO2 catalysts and its relevance to Fischer-Tropsch synthesis

[EN] Pure anatase and rutile TiO2 samples were synthesized by thermal treatment of reverse microemulsions and applied as supports for preparing Ru-promoted Co catalysts (0.5 wt% Ru, 10 wt% Co). The catalysts were characterized by ICP-OES,XRD,Raman spectroscopy, N2 physisorption, H2-TPR, electronmicroscopy (FESEM, HAADF-STEM), H2 chemisorption,XPS, and in situ IR-CO after H2 reduction and reaction with syngas, and their catalytic performance for Fischer-Tropsch synthesis (FTS) studied at industrial conditions (220 ¿C, 2.0 MPa, H2/CO = 2). The two catalysts exhibited comparable mean Co particle sizes (5¿6 nm) as well as high and alike degrees of cobalt reduction (ca. 90%). The SMSI decoration effect arising during H2 reduction was much more pronounced for the anatase-supported catalyst resulting in lower cobalt-timeyield (CTY) compared to that supported on TiO2-rutile. In situ IR-CO under syngas conversion conditions showed equivalent cobalt surface reconstruction and nature of the surface Co0 sites for both catalysts in their working state, and revealed a partial reversibility of the SMSI effect during FTS by which a significant fraction of the decorated Co0 centers in the anatase-based catalyst was uncovered and became available for reaction. The implication of this effect on TOFs is discussed. The C5+ selectivity was higher for the rutile-based catalyst, although a clear impact of the SMSI effect on selectivities was not inferred from our results.Financial support by the MINECO of Spain through the Severo Ochoa project (SEV 2012-0267) is gratefully ackonowledged. The authors also thank the Microscopy Service of the Universitat Politecnica de Valencia for its assistance in microscopy characterization. F. Bertella (Science without Frontiers - Process no. 13705/13-0) thanks CAPES for a predoctoral fellowship.Bertella, F.; Concepción Heydorn, P.; Martinez Feliu, A. (2017). TiO2 polymorph dependent SMSI effect in Co-Ru/TiO2 catalysts and its relevance to Fischer-Tropsch synthesis. Catalysis Today. 289:181-191. https://doi.org/10.1016/j.cattod.2016.08.008S18119128

Modulating the catalytic behavior of non-noble metal nanoparticles by inter-particle interaction for chemoselective hydrogenation of nitroarenes into corresponding azoxy or azo compounds

[EN] Aromatic azoxy compounds have wide applications and they can be prepared by stoichiometric or catalytic reactions with H2O2 or N2H4 starting from anilines or nitroarenes. In this work, we will present the direct chemoselective hydrogenation of nitroarenes with H-2 to give aromatic azoxy compounds under base-free mild conditions, with a bifunctional catalytic system formed by Ni nanoparticles covered by a few layers of carbon (Ni@C NPs) and CeO2 nanoparticles. The catalytic performance of Ni@C-CeO2 catalyst surpasses the state-of-art Au/CeO2 catalyst for the direct production of azoxybenzene from nitrobenzene. By means of kinetic and spectroscopic results, a bifunctional mechanism is proposed in which, the hydrogenation of nitrobenzene can be stopped at the formation of azoxybenzene with >95% conversion and >93% selectivity, or can be further driven to the formation of azobenzene with >85% selectivity. By making a bifunctional catalyst with a non-noble metal, one can achieve chemoselective hydrogenation of nitroarenes not only to anilines, but also to corresponding azoxy and azo compounds. (C) 2018 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).This work has been supported by the European Union through the SynCatMatch project (ERC-AdG-2014-671093). Financial supports by the Spanish Government-MINECO through the program "Severo Ochoa" (SEV-2016-0683) are gratefully acknowledged. The authors also thank the Microscopy Service of UPV for kind help with TEM and STEM measurements.Liu, L.; Concepción Heydorn, P.; Corma Canós, A. (2019). Modulating the catalytic behavior of non-noble metal nanoparticles by inter-particle interaction for chemoselective hydrogenation of nitroarenes into corresponding azoxy or azo compounds. Journal of Catalysis. 369:312-323. https://doi.org/10.1016/j.jcat.2018.11.011S31232336

The impact of support surface area on the SMSI decoration effect and catalytic performance for Fischer-Tropsch synthesis of Co-Ru/TiO2-anatase catalysts

[EN] A series of Co-Ru/TiO2 catalysts (10 wt% Co, 0.5 wt% Ru, nominal loadings) were prepared by impregnation of TiO2-anatase supports synthesized with different specific surface areas (Ti-L: 53 m2 /g, Ti-M: 117 m2 /g, and Ti-H: 148 m2 /g) by tuning the conditions of the hydrothermal synthesis and/or the calcination treatments. The most relevant physicochemical properties of supports and catalysts were determined by a set of techniques including ICP-OES, XRD, N2 physisorption, electron microscopy (FESEM, HAADF-STEM, HR-TEM), H2-TPR, H2 chemisorption, and IR-CO. Oxidized precursors were reduced in-reactor under flowing pure H2 at 400 °C for 10 h and evaluated for Fischer-Tropsch synthesis (FTS) in a fixed bed reactor at 220 °C, 2.0 MPa, and H2/CO molar ratio of 2. These catalysts exhibited the well-known strong metal-support interaction (SMSI) effect reported for TiO2 materials by which partially reduced TiOx species formed during the catalyst reduction step migrate and decorate the surface of the supported metal phases. The extent to which the SMSI effect occurred was found to increase with the surface area of the TiO2-anatase carrier, as supported by H2 chemisorption, TEM, and IR-CO surface titration experiments. As a consequence, the activity per total mass of cobalt or cobalt-time-yield (CTY) of the Co-Ru/TiO2 catalysts gradually declined with the increase in support surface area: Co-Ru/Ti-L > Co-Ru/ Ti-M > Co-Ru/Ti-H. The catalysts, however, displayed similar initial TOFs, implying a negligible influence of the SMSI effect on the initial intrinsic activity of the surface Co0 sites. The high surface area Co-Ru/Ti-H catalyst exhibiting the most pronounced SMSI also presented the lowest C5+ selectivity. This behavior was explained by considering the contribution of two effects: the lower resistance to the intraparticle diffusion of ¿-olefins when increasing the support surface area, as inferred from the olefin-to-paraffin ratios and the values of the diffusionrelated parameter ¿, and the reduction in size of the cobalt ensembles on the terraces of Co0 nanoparticles, connected to the extent of SMSI, on which chain growth events are favored.Financial support by the MINECO of Spain through the Severo Ochoa (SEV 2012-0267) and ENE2014-5761-R projects is gratefully acknowledged. The authors also thank the Microscopy Service of the Universitat Politecnica de Valencia for its assistance in microscopy characterization. F. Bertella (Science without Frontiers - Process no. 13705/13-0) thanks CAPES for a predoctoral fellowship.Bertella, F.; Concepción Heydorn, P.; Martinez Feliu, A. (2017). The impact of support surface area on the SMSI decoration effect and catalytic performance for Fischer-Tropsch synthesis of Co-Ru/TiO2-anatase catalysts. Catalysis Today. 296:170-180. https://doi.org/10.1016/j.cattod.2017.05.001S17018029

Economía verde vs. economía azul: un análisis de viabilidad

La economía verde se caracteriza porque sus acciones a largo plazo dividen a la sociedad, son costosas, y necesitan para funcionar subsidios para sobrevivir con sus programas y los gobiernos quebrados necesitan poner más impuestos; la economía azul es innovadora, competitiva y genera empleo. La Economía verde propone la protección, el cumplimiento de la ley; sin embargo si analizamos la economía sostenible utiliza y necesita la creatividad del ser humano que es lo que propone la economía azul, el poder contar con gente capaz de emprender asumiendo riesgos haciendo lo mejor posible, con base a un conocimiento local y ético. El presente trabajo tiene el objetivo de mostrar lo que se entiende por economía verde y lo que se entiende por economía azul, realizando un estudio comparativo y llegando a conclusiones preliminares como son: la economía verde al asumirse como respuesta a un sistema económico perdió legitimidad y fue absorbida por este sistema y sus propuestas son vistas ahora como grandes negocios de empresas trasnacionales que intentan adueñarse de los recursos de los países en desarrollo, intentan vender una filosofía más que soluciones de verdad sustentables, la economía verde ha pasado a formar parte del sistema y ha perdido toda credibilidad, sin embargo aún es utilizada y enseñada como una solución ética para los problemas ambientales, siendo que solo está pintando las manos de verde de los grandes capitales mediante la producción de algo que no es verde; surge una propuesta que retoma que lo sostenible se logra con el conocimiento local y la aplicación de los conocimientos a determinada sociedad, plantea un estudio de las necesidades y recursos locales en lugar de aplicaciones globalizadas. Si bien la economía azul tiene ventajas también existen desventajas, sin embargo es una alternativa más que vale la pena conocer a todos los interesados en el desarrollo sostenible

La función del metal entre los grupos campaniformes. Oro versus cobre. El ejemplo de la Región de Madrid

This paper offers an overview of the Bell Beaker metallurgy in Madrid. This is a renewed vision thanks to data provided by the recent excavations in Camino de las Yeseras, a big settlement whose funerary contexts do not match the known conventions in these graves, for example, weapons – absent in the grave goods – are replaced with gold ornaments and other items made in exotic raw materials.El trabajo ofrece una visión renovada de la metalurgia del Horizonte campaniforme en Madrid a partir de los datos que aportan las recientes intervenciones en el yacimiento de Camino de las Yeseras. Sus contextos funerarios no se ajustan a los convencionalismos conocidos para estas tumbas pues las armas ausentes en los ajuares singulares son sustituidas por ornatos de oro y otras piezas realizadas en materias exóticas