Dynamic Structure and Subsurface Oxygen Formation of a Working Copper Catalyst under Methanol Steam Reforming Conditions: An in Situ Time-Resolved Spectroscopic Study

"This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acscatal.8b05042."[EN] The dynamic behavior of a CuO/ZnO/Ga2O3 catalyst under methanol steam reforming (MSR) reaction conditions promoted by a high dispersion of the copper nanoparticles and defect sites of a nonstoichiometric ZnGa2O4 spinel phase has been observed, where structural changes taking place in the initial state of the reaction determine the final state of the catalyst in stationary reaction conditions. Mass spectrometry (MS) studies under transient conditions coupled to X-ray photoelectron spectroscopy (XPS) have shown copper oxidation to Cu+ in the initial state of the reaction (TOS = 4 min), followed by a fast reduction of the outer shell to Cu-0, while keeping dissolved oxygen species in the inner layers of the nanoparticle. The presence of this subsurface oxygen impairs a positive charge to the uppermost surface copper species, that is, Cu delta+, which undoubtedly plays an important role on the MSR catalytic activity. The detection of these features, unperceived by conventional spectroscopic and catalytic studies, has only been possible by combining synchrotron NAP-XPS studies with transient studies performed in a low volume catalytic reactor connected to MS and linked with Raman and laboratory scale XPS studies.The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under Grant Agreement No. [303476]. Part of this work was financially supported by the following projects: (i) Project POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy UID/EQU/00511/2013) funded by the European Regional Development Fund (ERDF), through COMPETE2020 - Programa Operacional Competitividade e Internacionalizacao (POCI) and by national funds, through FCT - Fundacao para a Ciencia e a Tecnologia; (ii) NORTE-01-0145-FEDER-000005 - LEPABE-2-ECO-INNOVATION, supported by North Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); and (iii) the Spanish Government-MINECO through "Severo Ochoa" Excellence Programme (SEV-2016-0683). D.R. thanks European Research Council project SYNCATMATCH (671093). J.C. thanks the Spanish Government (MINECO) for a "Severo Ochoa" grant (BES-2015-075748). The NAP-XPS experiments were performed at the NAPP branch of the CIRCE beamline at the ALBA Synchrotron with the collaboration of ALBA staff.Ruano-Sánchez, D.; Cored-Bandrés, J.; Azenha, C.; Pérez-Dieste, V.; Mendes, A.; Mateos-Pedrero, C.; Concepción Heydorn, P. (2019). Dynamic Structure and Subsurface Oxygen Formation of a Working Copper Catalyst under Methanol Steam Reforming Conditions: An in Situ Time-Resolved Spectroscopic Study. ACS Catalysis. 9(4):2922-2930. https://doi.org/10.1021/acscatal.8b05042S292229309

Water Formation Reaction under Interfacial Confinement: Al0.25Si0.75O2 on O-Ru(0001)

Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can change the reaction pathway of the water formation reaction (WFR) near room temperature when compared to the bare metal. In this work, we looked at the effect of doping the silicate with Al, resulting in a stoichiometry of AlSiO . We investigated the kinetics of WFR at elevated H pressures and various temperatures under interfacial confinement using ambient pressure X-ray photoelectron spectroscopy. The apparent activation energy was lower than that on bare Ru(0001) but higher than that on the BL-silica/Ru(0001). The apparent reaction order with respect to H was also determined. The increased residence time of water at the surface, resulting from the presence of the BL-aluminosilicate (and its subsequent electrostatic stabilization), favors the so-called disproportionation reaction pathway (*HO + *O ↔ 2 *OH), but with a higher energy barrier than for pure BL-silica.Research was carried out in part at the 23-ID-2 (IOS) beamline of the National Synchrotron Light Source II and the Center for Functional Nanomaterials, which are U.S. DOE Office of Science Facilities, and the Scientific Data and Computing Center, a component of the Computational Science Initiative, at Brookhaven National Laboratory under Contract No. DE-SC0012704. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. J.C. thanks the Spanish Ministry of Science, Innovation and Universities for a “Severo Ochoa” grant (BES-2015-075748) through “Severo Ochoa” Excellence Programme (SEV-2016-0683). Z.D. is supported by ACS PRF grant #61059-ND5

Water Formation Reaction under Interfacial Confinement: Al0.25Si0.75O2 on O-Ru(0001)

Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can change the reaction pathway of the water formation reaction (WFR) near room temperature when compared to the bare metal. In this work, we looked at the effect of doping the silicate with Al, resulting in a stoichiometry of Al0.25Si0.75O2. We investigated the kinetics of WFR at elevated H2 pressures and various temperatures under interfacial confinement using ambient pressure X-ray photoelectron spectroscopy. The apparent activation energy was lower than that on bare Ru(0001) but higher than that on the BL-silica/Ru(0001). The apparent reaction order with respect to H2 was also determined. The increased residence time of water at the surface, resulting from the presence of the BL-aluminosilicate (and its subsequent electrostatic stabilization), favors the so-called disproportionation reaction pathway (*H2O + *O ↔ 2 *OH), but with a higher energy barrier than for pure BL-silica

Innovative Design of Heterogeneous Catalysts with Improved CO2 Hydrogenation Performance

Tesis por compendio[ES] El cambio climático es una de las amenazas de nuestro tiempo. Los gases de efecto invernadero, como el CO2, son los principales causantes de este fenómeno, siendo necesario disminuir urgentemente sus emisiones. En 2019, la Comisión Europa presentó el "Pacto Verde Europeo", que será clave para alcanzar un objetivo tremendamente ambicioso para nuestra región: la neutralidad climática de aquí a 2050. Las estrategias de descarbonización incluidas en su hoja de ruta van a implicar necesariamente la transición energética de los combustibles fósiles a las energías renovables, reduciendo de forma masiva la liberación de CO2. En este sentido, el desarrollo de tecnologías efectivas de Captura, Almacenamiento y Uso del Carbono (CAUC) permitirá la valorización del CO2, evolucionando hacia una economía de carbono circular. La presente Tesis Doctoral se enmarca en el diseño, síntesis y caracterización de sistemas catalíticos heterogéneos innovadores basados en metales capaces de transformar el CO2 en otros productos de valor añadido. Entre un amplio catálogo de reacciones que "conectan" el CO2 con diversos compuestos basados en carbono, esta Tesis se centrará principalmente en la síntesis de dos moléculas C1 plataforma de interés industrial: el metanol y el metano. Los Capítulos 3 y 4 están dedicados a la síntesis de metanol, un proceso exotérmico limitado termodinámicamente debido a la estabilidad inherente de la molécula de CO2, así como a la presencia de la reacción competitiva RWGS. Por un lado, el Capítulo 3 se centra en el efecto promotor del galio sobre las propiedades estructurales, electrónicas y catalíticas de materiales basados en Cu/ZnO (sistemas CZG). Mediante un enfoque espectroscópico-catalítico multidisciplinar se ha comparado el efecto promotor del Ga3+ dopado en la red de un ZnO tipo wurtzita presente en un catalizador Cu/ZnO/Ga2O3 con el de una fase de galato de zinc (ZnGa2O4). Por otro lado, en el Capítulo 4 se muestra un catalizador bifuncional que contiene nanopartículas de Cu de 2 nm y especies Cu+, con el objetivo de enfrentarse a la inherente baja actividad de estas pequeñas partículas, hecho que impide mejorar la eficiencia atómica de los catalizadores, dificultando así la obtención de resultados catalíticos competitivos en la hidrogenación de CO2. La realización de un estudio espectroscópico detallado (combinado con cálculo teórico y ensayos catalíticos) sobre un catalizador óxido mixto de Cu-Mg-Al derivado de un precursor de hidrotalcita tras calcinación y posterior reducción (CuHT-230) pone de manifiesto el papel clave de los iones Cu+ dopados en estructura en la producción de metanol. El éxito de las tecnologías CAUC a medio-largo plazo dependerá no solo del desarrollo de catalizadores competitivos, sino también de su capacidad para operar en condiciones de reacción más suaves, permitiendo que estos procesos sean viables económicamente. Por ello, el concepto de eficiencia energética se abordará en el Capítulo 5, a través de un innovador diseño de catalizador tipo "shell/core" formado por un núcleo de rutenio metálico y una envoltura de carburo de rutenio, sintetizado via hidrotermal. Este sistema (Ru@EDTA-20) exhibe una actividad excepcionalmente alta para la hidrogenación de CO2 a metano a bajas temperaturas (160-200 °C) con una selectividad a CH4 del 100%, superando a catalizadores de bibliografía que normalmente operan a mayores temperaturas (400-500 °C). Por último, en el Capítulo 6 se estudia un catalizador modelo compuesto por un alumino-silicato bidimensional sintetizado sobre una superficie de Ru(0001), investigación realizada durante mi estancia internacional en el Laboratorio Nacional de Brookhaven (Nueva York, EE.UU.). La combinación de estos materiales en el mismo composite permite la creación de un nanoespacio confinado que puede emplearse como nanorreactor. En este proyecto, se seleccionó la reacción de formación de agua como modelo, que se exploró a nivel fundamental en el sincrotrón NSLS-II.[CA] El canvi climàtic és una de les amenaces del nostre temps. Els gasos d'efecte d'hivernacle, com el diòxid de carboni, són els principals causants d'aquest fenomen, sent necessari reduir urgentment les seues emissions. En 2019, la Comissió Europea va presentar el "Pacte Verd Europeu", que serà clau per a aconseguir un objectiu tremendament ambiciós per a la nostra regió: la neutralitat climàtica d'ací a 2050. Les estratègies de descarbonització incloses en el seu full de ruta implicaran necessàriament la transició energètica dels combustibles fòssils a les energies renovables, reduint de manera massiva l'alliberament de CO2. En aquest sentit, el desenvolupament de tecnologies efectives de Captura, Emmagatzematge i Ús del Carboni (CEUC) permetrà la valorització del CO2, evolucionant cap a una economia de carboni circular. La present Tesi Doctoral s'emmarca en el disseny, síntesi i caracterització de sistemes catalítics heterogenis innovadors basats en metalls capaços de transformar el CO2 en altres productes de valor afegit. Entre un ampli catàleg de reaccions que "connecten" el CO2 amb diversos compostos basats en carboni, aquesta Tesi se centrarà principalment en la síntesi de dues molècules C1 plataforma d'interés industrial: el metanol i el metà. Els Capítols 3 i 4 estan dedicats a la síntesi de metanol, un procés exotèrmic limitat degut tant a l'estabilitat inherent de la molècula de CO2 com a la presència de la reacció competitiva RWGS. D'una banda, el Capítol 3 se centra en l'efecte promotor del gal·li sobre les propietats estructurals, electròniques i catalítiques de materials basats en Cu/ZnO (sistemes CZG). Mitjançant un enfocament espectroscòpic-catalític multidisciplinari s'ha comparat l'efecte promotor del Ga3+ dopat en la xarxa d'un ZnO (wurtzita) present en un catalitzador Cu/ZnO/Ga2O3 amb el d'una fase de ZnGa2O4. D'altra banda, en el Capítol 4 es mostra un catalitzador bifuncional que conté nanopartícules de Cu de 2 nm i espècies Cu+, amb l'objectiu d'enfrontar-se a la inherent baixa activitat d'aquestes petites partícules, fet que impedeix millorar l'eficiència atòmica dels catalitzadors, dificultant així l'obtenció de resultats catalítics competitius en la hidrogenació de CO2. La realització d'un estudi espectroscòpic detallat (combinat amb càlcul teòric i assajos catalítics) sobre un catalitzador òxid mixt de Cu-Mg-Al derivat d'un precursor de hidrotalcita després de calcinació i posterior reducció (CuHT-230) posa de manifest el paper clau dels ions Cu+ dopats en estructura en la producció de metanol. L'èxit de les tecnologies CEUC a mig-llarg termini dependrà no solament del desenvolupament de catalitzadors competitius, sinó també de la seua capacitat per a operar en condicions de reacció més suaus, permetent que aquests processos siguen viables econòmicament. Per això, el concepte d'eficiència energètica s'abordarà en el Capítol 5, a través un innovador disseny de catalitzador tipus "shell/core" format per un nucli de ruteni metàl·lic i un embolcall de carbur de ruteni, sintetitzat mitjançant tractament hidrotermal. Aquest sistema (Ru@EDTA-20) exhibeix una activitat excepcionalment alta per a la hidrogenació de CO2 a metà a baixes temperatures (160-200 °C) amb una selectivitat a CH4 del 100%, superant a catalitzadors de bibliografia que normalment operen a majors temperatures (400-500 °C). Finalment, en el Capítol 6 s'estudia un catalitzador model compost per un alumino-silicat bidimensional sintetitzat sobre una superfície de Ru(0001), investigació realitzada durant la meua estada internacional en el Laboratori Nacional de Brookhaven (Nova York, els Estats Units). La combinació d'aquests dos materials en el mateix "composite" permet la creació d'un nano-espai confinat que pot emprar-se com nano-reactor. En aquest projecte, es va seleccionar la reacció de formació d'aigua com a model, que es va explorar a nivell fonamental en el sincrotró NSLS-II.[EN] Climate change is one of the existential threats of our times. Greenhouse gases (GHG), such as carbon dioxide, are primary drivers of this phenomenon, and their emissions need to be urgently reduced. In 2019, the European Commission presented the European Green Deal, which will help the EU to attain an ambitious goal for our region: to become carbon-neutral by 2050. The decarbonization strategies included in the roadmap towards net-zero emissions will imply the energy transition from fossil fuels to renewable energies, with a massive reduction of CO2 deliverance. In this sense, the development of effective Carbon Capture and Storage (CCS) and Carbon Capture and Utilization (CCU) technologies will allow the valorization of CO2, evolving into a circular carbon economy. The present Doctoral Thesis focuses on the design, synthesis and characterization of innovative heterogeneous metal-based systems, which are able to transform CO2 into value-added products. Among a wide catalogue of reactions that "connects" CO2 with various carbon-based compounds, this thesis will be devoted to the synthesis of two C1 platform chemicals of industrial interest: methanol and methane. Chapters 3 and 4 are dedicated to methanol synthesis, a highly hampered exothermic process due to the inherent stability of the CO2 molecule and the presence of the competitive reverse water-gas shift reaction (RWSG). On the one hand, Chapter 3 is focused on the promoting effect of gallium on the structural, electronic, and catalytic properties of Cu/ZnO based materials (CZG systems). In particular, the promoting effect of Ga3+-doped in the wurtzite ZnO lattice of a Cu/ZnO/Ga2O3 catalyst is compared to that of a zinc gallate (ZnGa2O4) phase following a multimodal spectroscopic-catalytic approach. In Chapter 4, a bifunctional catalyst containing 2 nm Cu nanoparticles and Cu+ species is presented, to overcome the "assumed" low activity of small copper particles that prevents obtaining high atom efficiency and competitive catalytic results in the CO2 hydrogenation to methanol. A detailed spectroscopic study (combined with theoretical calculations and catalytic tests) performed on a Cu-Mg-Al mixed oxide catalyst derived from a hydrotalcite precursor by calcination and further reduction (CuHT-230) highlights the key role of doped Cu+ ions in methanol production. The success of CCU technologies in the medium-long term will depend not only on the development of competitive catalysts but also on their ability to operate under milder reaction conditions, which will make these processes economically viable. Consequently, the energy efficiency issue will be addressed in Chapter 5 with the innovative design of a core-shell structure formed by a core of metallic ruthenium and a shell of ruthenium carbide, synthesized via hydrothermal treatment. This catalyst (Ru@EDTA-20) exhibits exceptional high activity for CO2 hydrogenation to methane (Sabatier reaction) at low temperatures (160-200 °C) with 100% selectivity to CH4, outperforming the state of the art catalysts operating at 400-500 °C. Finally, Chapter 6 covers the investigation carried out on a model ruthenium-based catalyst composed of a 2D-bilayered aluminosilicate grown over a Ru(0001) surface during my international short-term stay at Brookhaven National Laboratory (New York, USA). The combination of these materials in a composite allows the creation of a confined nano-space that can be exploited as a nano-reactor. In this project, water formation reaction (WFR) was selected as model reaction, which was fundamentally explored at NSLS-II synchrotron.Cored Bandrés, J. (2022). Innovative Design of Heterogeneous Catalysts with Improved CO2 Hydrogenation Performance [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/182403Compendi

Catalyst for the hydrogenation of CO2 to methane at low temperatures

[EN] The present invention describes a method for preparing a ruthenium catalyst with a carbon matrix, consisting of the following steps: (a) mixing a ruthenium compound with an organic compound in the presence of a solvent; (b) subjecting the mixture to hydrothermal conditions; and (c) washing and drying. The invention also relates to the catalyst obtained according to the method and to the use thereof in reactions to hydrogenate CO2 to methane at low temperatures[ES] La presente invención describe un procedimiento de preparación de un catalizador de rutenio con una matriz de carbón que consiste en las siguientes etapas: a) Mezcla de un compuesto de rutenio con un compuesto orgánico en presencia de un disolvente. b) Someterse a condiciones hidrotermales. c) Lavado y secado. el catalizador obtenido según dicho procedimiento y su uso en reacciones de hidrogenación de CO2 a metano a bajas temperaturas[FR] La présente invention décrit un procédé de préparation d'un catalyseur de ruthénium avec une matrice de carbone, ledit procédé comprenant les étapes suivantes consistant à: a) mélanger un composé de ruthénium avec un composé organique en présence d'un dissolvant, b) soumettre à des conditions hydrothermiques, c) laver et sécher. Ladite invention concerne aussi le catalyseur obtenu selon ledit procédé et son utilisation dans des réactions d'hydrogéntation de CO2 en méthane à basses températeuresPeer reviewedConsejo Superior de Investigaciones Científicas (España), Universitat Politècnica de ValènciaA1 Solicitud de patente con informe sobre el estado de la técnic

Catalizador para la hidrogenación de C02 a metano a bajas temperaturas

[ES] La presente invención describe un procedimiento de preparación de un catalizador de rutenio con una matriz de carbón que comprende, al menos, las siguientes etapas: a) Mezcla de un compuesto de rutenio con un compuesto orgánico en presencia de un disolvente. b) Someterse a condiciones hidrotermal. c) Lavado y secado. el material obtenido según dicho procedimiento y su uso en reacciones de hidrogenación de CO2 a metano a bajas temperaturas.[EN] The present invention describes a process for the preparation of a ruthenium catalyst with a carbon matrix that comprises, at least, the following steps: a) Mixing a ruthenium compound with an organic compound in the presence of a solvent. b) Submit to hydrothermal conditions. c) Washing and drying. the material obtained according to said procedure and its use in hydrogenation reactions of CO2 to methane at low temperatures.NoConsejo Superior de Investigaciones Científicas, Universitat Politècnica de Valènci

Catalizador para la hidrogenación de C02 a metano a bajas temperaturas

La presente invención describe un procedimiento de preparación de un catalizador de rutenio con una matriz de carbón que comprende, al menos, las siguientes etapas: a) Mezcla de un compuesto de rutenio con un compuesto orgánico en presencia de un disolvente. b) Someterse a condiciones hidrotermal. c) Lavado y secado. el material obtenido según dicho procedimiento y su uso en reacciones de hidrogenación de CO2 a metano a bajas temperaturas.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Universitat Politècnica de ValènciaA1 Solicitud de patente con informe sobre el estado de la técnic

Catalyseur pour l'hydrogénation de coen méthane à basses températures

The present invention describes a method for preparing a ruthenium catalyst with a carbon matrix, consisting of the following steps: (a) mixing a ruthenium compound with an organic compound in the presence of a solvent; (b) subjecting the mixture to hydrothermal conditions; and (c) washing and drying. The invention also relates to the catalyst obtained according to the method and to the use thereof in reactions to hydrogenate CO2 to methane at low temperatures.NoConsejo Superior de Investigaciones Científicas, Universitat Politècnica de ValènciaA1 Solicitud de patente con informe sobre el estado de la técnic

Decisive influence of the metal in multifunctional gold, silver, and copper metallacycles: High quantum yield phosphorescence, color switching, and liquid crystalline behavior

Three cyclic trinuclear pyrazolate complexes with Au(I), Ag(I), or Cu(I) have been studied. These complexes have interesting and distinct optical and thermal properties depending on the metal, namely, liquid crystalline behavior, red or deep-red phosphorescence at room temperature, thermoluminochromism, and response to silver ions. The selected ligand, 4-hexyl-3,5-dimethylpyrazolate, maximizes the effect that the nature of the metals has on the properties of the complexes, thus allowing the intermolecular metallophilic interactions to be responsible for the optical properties. Moreover, the gold and silver complexes show columnar liquid crystal phases at high temperature. All of the complexes have good solubility properties for processing as poly(methyl methacrylate) (PMMA) doped films. Films of the gold, silver, and copper complexes show interesting optical behavior such as wide-range color switching or phosphorescence turn-on upon cooling. In addition, films of the gold complex show a bright color switching (red to blue) in the presence of silver ions. The gold and copper complexes are bright phosphors with phosphorescent quantum yields of 90% in PMMA films, the highest values reported for this class of compounds at room temperature.This work was supported by MINECO-FEDER, UE (projects MAT2015-66208-C3-1-P, CTQ2015-70174-P, CTQ2014-53033-P, CTQ2016-75816C2-1-P), Gobierno de Aragón FSE, UE, and Catedra IQE (Industrias Quimicas del Ebro) for a postgraduate grant (J.C.).Peer reviewe

Gold, silver and copper luminescent molecular materials with mesomorphic properties

Resumen del trabajo presentado a la 20th International Conference on Solid Compounds of Transition Elements, celebrada del 11 al 15 de abril de 2016 en Zaragoza (España).Cyclic trinuclear complexes of the gold group are unique molecular materials that contain a planar or nearly planar nine-membered metallacycle. Increasing interest has been taken in them owing to their chemical and luminescent properties. Their emission spectra depends on the arrangement of the molecules in the solid state, which can involve intermolecular metallophilic interactions, and these can be easily influenced by external factors such as temperature, ions, solvents, and so forth. All these studies have opened new perspectives for the development of new stimuli responsive luminescent materials for sensors, organic electronics or biomedicine. We report herein the synthesis and characterization of novel gold, silver and copper cyclic trinuclear pyrazolate complexes able to self-assemble in columnar phases. In particular, gold and silver complexes display thermotropic columnar liquid crystal phases at high temperatures which have been characterized by POM, DSC and XRD. The luminescent properties have been studied by luminescence spectroscopy. Gold and copper compounds show phosphorescence in the visible-near IR region at room temperature. It has been observed that luminescent behavior is temperature sensitive with unique color changes (thermochromism), and chemically sensitive, leading to new stimuli-responsive materials.The authors thank the Gobierno de Aragón - Fondo Social Europeo (FSE) (research group E04), the Spanish Ministerio de Economia y Competitividad (MINECO) - Fondo Europeo para el Desarrollo Regional (FEDER) (projects CTQ2012-35692, CTQ2011-22516, and MAT2012-38538-CO3-01) and Cátedra IQE for financial support.Peer Reviewe