Structure-reactivity relationship in isolated Zr sites present in Zr-zeolite and ZrO2 for the Meerwein-Ponndorf-Verley reaction

[EN] The influence of the crystallographic phase of ZrO2 on its catalytic performance in the MPV reduction of cyclohexanone with propan-2-ol has been systematically investigated by combining accurate synthesis procedures, XRD and HRTEM characterization, kinetic measurements and DFT calculations, and compared to that of Zr-beta zeolite. The higher intrinsic activity of monoclinic zirconia as compared to other ZrO2 phases is not due to a lower activation energy for the rate-determining step, but to an adequate distribution of reactant fragments on the catalyst surface, indicating a structure-activity relationship for this reaction when catalyzed by ZrO2 and also by Zr-beta zeolite. Inexpensive and stable ZrO2 catalysts for the MPV reaction have been obtained by controlling the crystallographic phase of the synthesized material.This work has been supported by the Spanish Government through the "Severo Ochoa Program" (SEV 2012-0267). The Electron Microscopy Service of the UPV is acknowledged for their help in sample characterization. The Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia are gratefully acknowledged for computational facilities and technical assistance. F. Gonell is grateful to Ministerio de Educacion, Cultura y Deporte for a PhD grant (AP2010-2748).Gonell-Gómez, F.; Boronat Zaragoza, M.; Corma Canós, A. (2017). Structure-reactivity relationship in isolated Zr sites present in Zr-zeolite and ZrO2 for the Meerwein-Ponndorf-Verley reaction. Catalysis Science & Technology. 7(13):2865-2873. https://doi.org/10.1039/c7cy00567aS2865287371

From well-defined clusters to functional materials: molecular Engineering of amorphous molybdenum sulfides for hydrogen evolution Electrocatalysis

Developing precious-metal-free electrocatalysts for the hydrogen evolution reaction (HER) is crucial to establishing H2 produced from renewable energy sources as an alternative energy carrier to fossil fuels. Amorphous molybdenum sulfide-based materials are promising candidates that provide highly active HER electrocatalysts by introducing active sites at both the edge positions and the typically inactive basal planes. Herein, we report an innovative bottom-up synthesis of amorphous molybdenum sulfides using molecular complexes with Mo3S4 and Mo3S7 cluster cores as building entities. The ability to control the precursor of choice has made it viable to enhance the HER activity of these materials. Furthermore, the tunability of the atomic composition of the molecular cluster precursors allows the modification of the derived materials with atomic-scale precision, enabling us to track the synthesis mechanism and, in combination with Density Functional Theory (DFT) calculations, to decipher the nature of the HER active sites

Effect of the C-alpha substitution on the ketonic decarboxylation of carboxylic acids over m-ZrO2: the role of entropy

[EN] The kinetics of the ketonic decarboxylation of linear and branched carboxylic acids over m-ZrO2 as a catalyst has been investigated. The same apparent activation energy is experimentally determined for the ketonic decarboxylation of both linear pentanoic and branched 2-methyl butanoic acids, while the change in entropy for the rate-determining step differs by nearly 50 kJ mol(-1). These results show that the difference in reactivity between linear and branched acids is due to entropic effects, and is related to the probability of finding the reactant molecules adsorbed and activated in a suitable way on the catalyst surface.The authors thank MINECO (Consolider Ingenio 2010-MULTICAT, CSD2009-00050 and Severo Ochoa program, SEV-2012-0267), Generalitat Valenciana (PROMETEOII/2013/011 Project), and the Spanish National Research Council (CSIC, Es 2010RU0108) for financial support. Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia are gratefully acknowledged for computational facilities and technical assistance. A. P., F. G. and B. O.-T. thank MINECO (Juan de la Cierva and FPU Programme) and CSIC (JAE Programme) for their fellowships, respectively. M. R. is grateful to the Generalitat Valenciana for a BEST 2015 fellowship.Oliver-Tomás, B.; Gonell-Gómez, F.; Pulido, A.; Renz, M.; Boronat Zaragoza, M. (2016). Effect of the C-alpha substitution on the ketonic decarboxylation of carboxylic acids over m-ZrO2: the role of entropy. Catalysis Science and Technology. 6(14):5561-5566. https://doi.org/10.1039/c6cy00395hS55615566614Friedel, C. (1858). Ueber s. g. gemischte Acetone. Annalen der Chemie und Pharmacie, 108(1), 122-125. doi:10.1002/jlac.18581080124W. L. Howard , in Encyclopedia of Chemical Technology (Kirk-Othmer), Wiley-Interscience, New York, 4th edn, 1998, vol. 1, pp. 176–194H. Siegel and M.Eggersdorfer, Ullmann's Encyclopedia of Industrial Chemistry, VCH, Weinheim, 1990Huber, G. W., Iborra, S., & Corma, A. (2006). Synthesis of Transportation Fuels from Biomass:  Chemistry, Catalysts, and Engineering. Chemical Reviews, 106(9), 4044-4098. doi:10.1021/cr068360dCorma, A., Iborra, S., & Velty, A. (2007). Chemical Routes for the Transformation of Biomass into Chemicals. Chemical Reviews, 107(6), 2411-2502. doi:10.1021/cr050989dChheda, J. N., Huber, G. W., & Dumesic, J. A. (2007). Liquid-Phase Catalytic Processing of Biomass-Derived Oxygenated Hydrocarbons to Fuels and Chemicals. Angewandte Chemie International Edition, 46(38), 7164-7183. doi:10.1002/anie.200604274Renz, M. (2005). Ketonization of Carboxylic Acids by Decarboxylation: Mechanism and Scope. European Journal of Organic Chemistry, 2005(6), 979-988. doi:10.1002/ejoc.200400546Corma, A., Renz, M., & Schaverien, C. (2008). Coupling Fatty Acids by Ketonic Decarboxylation Using Solid Catalysts for the Direct Production of Diesel, Lubricants, and Chemicals. ChemSusChem, 1(8-9), 739-741. doi:10.1002/cssc.200800103Pham, T. N., Sooknoi, T., Crossley, S. P., & Resasco, D. E. (2013). Ketonization of Carboxylic Acids: Mechanisms, Catalysts, and Implications for Biomass Conversion. ACS Catalysis, 3(11), 2456-2473. doi:10.1021/cs400501hSerrano-Ruiz, J. C., Wang, D., & Dumesic, J. A. (2010). Catalytic upgrading of levulinic acid to 5-nonanone. Green Chemistry, 12(4), 574. doi:10.1039/b923907cAlonso, D. M., Bond, J. Q., & Dumesic, J. A. (2010). Catalytic conversion of biomass to biofuels. Green Chemistry, 12(9), 1493. doi:10.1039/c004654jCorma, A., Oliver-Tomas, B., Renz, M., & Simakova, I. L. (2014). Conversion of levulinic acid derived valeric acid into a liquid transportation fuel of the kerosene type. Journal of Molecular Catalysis A: Chemical, 388-389, 116-122. doi:10.1016/j.molcata.2013.11.015Rajadurai, S. (1994). Pathways for Carboxylic Acid Decomposition on Transition Metal Oxides. Catalysis Reviews, 36(3), 385-403. doi:10.1080/01614949408009466Gliński, M., Kijeński, J., & Jakubowski, A. (1995). Ketones from monocarboxylic acids: Catalytic ketonization over oxide systems. Applied Catalysis A: General, 128(2), 209-217. doi:10.1016/0926-860x(95)00082-8Pestman, R., Koster, R. M., van Duijne, A., Pieterse, J. A. Z., & Ponec, V. (1997). Reactions of Carboxylic Acids on Oxides. Journal of Catalysis, 168(2), 265-272. doi:10.1006/jcat.1997.1624Parida, K., & Mishra, H. K. (1999). Catalytic ketonisation of acetic acid over modified zirconia. Journal of Molecular Catalysis A: Chemical, 139(1), 73-80. doi:10.1016/s1381-1169(98)00184-8Hendren, T. S., & Dooley, K. M. (2003). Kinetics of catalyzed acid/acid and acid/aldehyde condensation reactions to non-symmetric ketones. Catalysis Today, 85(2-4), 333-351. doi:10.1016/s0920-5861(03)00399-7Martinez, R. (2004). Ketonization of acetic acid on titania-functionalized silica monoliths. Journal of Catalysis, 222(2), 404-409. doi:10.1016/j.jcat.2003.12.002Pulido, A., Oliver-Tomas, B., Renz, M., Boronat, M., & Corma, A. (2012). Ketonic Decarboxylation Reaction Mechanism: A Combined Experimental and DFT Study. ChemSusChem, 6(1), 141-151. doi:10.1002/cssc.201200419Ignatchenko, A. V., DeRaddo, J. S., Marino, V. J., & Mercado, A. (2015). Cross-selectivity in the catalytic ketonization of carboxylic acids. Applied Catalysis A: General, 498, 10-24. doi:10.1016/j.apcata.2015.03.017Ignatchenko, A. V., & Kozliak, E. I. (2012). Distinguishing Enolic and Carbonyl Components in the Mechanism of Carboxylic Acid Ketonization on Monoclinic Zirconia. ACS Catalysis, 2(8), 1555-1562. doi:10.1021/cs3002989Ignatchenko, A. V. (2011). Density Functional Theory Study of Carboxylic Acids Adsorption and Enolization on Monoclinic Zirconia Surfaces. The Journal of Physical Chemistry C, 115(32), 16012-16018. doi:10.1021/jp203381hJackson, M. A., & Cermak, S. C. (2012). Cross ketonization of Cuphea sp. oil with acetic acid over a composite oxide of Fe, Ce, and Al. Applied Catalysis A: General, 431-432, 157-163. doi:10.1016/j.apcata.2012.04.034Plint, N. ., Coville, N. ., Lack, D., Nattrass, G. ., & Vallay, T. (2001). The catalysed synthesis of symmetrical ketones from alcohols. Journal of Molecular Catalysis A: Chemical, 165(1-2), 275-281. doi:10.1016/s1381-1169(00)00445-3Randery, S. (2002). Cerium oxide-based catalysts for production of ketones by acid condensation. Applied Catalysis A: General, 226(1-2), 265-280. doi:10.1016/s0926-860x(01)00912-

Key insights on the structural characterization of textured Er2O3–ZrO2 nano-oxides prepared by a surfactant-free solvothermal route

Zirconia-mixed oxides can exhibit cubic fluorite and pyrochlore structure. Their discrimination is not easy in nanooxides with a crystal size close to that of a few unit cells. In this work, high resolution transmission electron microscopy (HRTEM) has been employed to provide key insights on the structural characterization of a nanometric and porous mixed Er2O3–ZrO2 oxide. The material was prepared by a simple template-free solvothermal route that provided nanocrystalline powders at low temperature (170 °C) with spherical morphology, and high surface area (∼280 m2 g−1). The porosity was mainly originated from the assembling of organic complexing agents used in the synthesis to limit the crystal growth and to control hydrolysis and condensation reaction rates. The samples were characterized by thermal analysis, X-ray diffraction, scanning electron microscopy and N2 adsorption measurements. A detailed study by HRTEM was conducted on microtomed samples. It was observed that the material was made of nanocrystals packed into spherical agglomerates. HRTEM simulations indicated that it is not possible to identify the pyrochlore phase in nanoparticles with diameter below 2 nm. In our samples, the analysis of the HRTEM lattice images by means of fast Fourier transform (FFT) techniques revealed well defined spots that can be assigned to different planes of a cubic fluorite-type phase, even in the raw material. Raman spectroscopy was also a powerful technique to elucidate the crystalline phase of the materials with the smallest nanoparticles. HREM and Raman results evidenced that the material is constituted, irrespective of the temperature of the final calcination step, by an ensemble of randomly oriented nanocrystals with fluorite structure. This study opens new perspectives for the design of synthetic approaches to prepare nanooxides (fluorites and pyrochlores) and the analysis of their crystalline structure

Isolated Fe(III)-O Sites Catalyze the Hydrogenation of Acetylene in Ethylene Flows under Front-End Industrial Conditions

[EN] The search for simple, earth-abundant, cheap, and nontoxic metal catalysts able to perform industrial hydrogenations is a topic of interest, transversal to many catalytic processes. Here, we show that isolated FeIII¿O sites on solids are able to dissociate and chemoselectively transfer H2 to acetylene in an industrial process. For that, a novel, robust, and highly crystalline metal¿organic framework (MOF), embedding FeIII¿OH2 single sites within its pores, was prepared in multigram scale and used as an efficient catalyst for the hydrogenation of 1% acetylene in ethylene streams under front-end conditions. Cutting-edge X-ray crystallography allowed the resolution of the crystal structure and snapshotted the single-atom nature of the catalytic FeIII¿O site. Translation of the active site concept to even more robust and inexpensive titania and zirconia supports enabled the industrially relevant hydrogenation of acetylene with similar activity to the Pd-catalyzed process.This work was supported by the MINECO (Spain) (Projects CTQ2016-75671-P, CTQ2014-56312-P, CTQ2014-55178-R, and Excellence Units "Severo Ochoa" and "Maria de Maeztu" SEV-2016-0683 and MDM-2015-0538) and the Ministero dell'Istruzione, dell'Universita e della Ricerca (Italy) (FFABR 2017). M.M. thanks the mineco for a predoctoral contract. Thanks are also extended to the Ramon y Cajal Program (E.P.) and the "Suprograma atraccio de talent-contractes postdoctorals de la Universitat de Valencia" (J.F.-S.). A.L.-P. and J.F.S. also thank fBBVA for the concession of a young investigator grants.Tejeda-Serrano, M.; Mon, M.; Ross, B.; Gonell-Gómez, F.; Ferrando-Soria, J.; Corma Canós, A.; Leyva Perez, A.... (2018). Isolated Fe(III)-O Sites Catalyze the Hydrogenation of Acetylene in Ethylene Flows under Front-End Industrial Conditions. Journal of the American Chemical Society. 140(28):8827-8832. https://doi.org/10.1021/jacs.8b04669S882788321402

Copper-doped titania photocatalysts for simultaneous reduction of CO2 and production of H-2 from aqueous sulfide

Copper-doped titanium dioxide materials with anatase phase (Cu-TiO2, atomic Cu contents ranging from 0 to 3% relative to the sum of Cu and Ti), and particle sizes of 12-15 nm, were synthesised by a solvo-thermal method using ethanol as the solvent and small amounts of water to promote the hydrolysiscondensation processes. Diffuse reflectance UV-vis spectroscopy show that the edges of absorption of the titania materials are somewhat shifted to higher wavelengths due to the presence of Cu. X-ray photoelectron spectroscopy (XPS) indicate that Cu(II) is predominant. Photocatalytic CO2 reduction experiments were performed in aqueous Cu-TiO2 suspensions under UV-rich light and in the presence of different solutes. Sulfide was found to promote the efficient production of H-2 from water and formic acid from CO2. The effect of the Cu content on the photoactivity of Cu-TiO2 was also studied, showing that copper plays a role on the photocatalytic reduction of CO2.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2012-32315) is gratefully acknowledged. F.G. and B.J.-L. are thankful for financial support from Spanish Government (AP2010-2748 PhD grant and MAT2011-27008 project) and Jaume I University (P1 1B2014-21 project). SCIC from Jaume I University and Servicio de Microscopia Electronica at Universitat Politecnica de Valencia are also acknowledged for instrumental facilities. A.V.P. is grateful to both the Consejo Superior de Investigaciones Cientifficas (CSIC) and the European Social Fund (ESF) for a JAE-Doc postdoctoral grant. Lichen Liu is gratefully acknowledged for assistance in recording HRTEM images.Gonell-Gómez, F.; Puga Vaca, A.; Julián López, B.; García Gómez, H.; Corma Canós, A. (2016). Copper-doped titania photocatalysts for simultaneous reduction of CO2 and production of H-2 from aqueous sulfide. Applied Catalysis B: Environmental. 180:263-270. https://doi.org/10.1016/j.apcatb.2015.06.019S26327018

Structure–activity relationship in Ti phosphate-derived photocatalysts for H2 evolution

[EN] Photocatalytic H2 production has emerged as one of the most clean and promising renewable energy sources. In spite of the efforts to obtain efficient photocatalysts able to produce H2 from Sun light and water, there is still the need to prepare cheaper and environmental friendlier photocatalysts. Phosphate-based materials could be good candidates to fulfill these requirements. In this manuscript we have prepared a set of mixed Ti3+/Ti4+ valence, open-framework titanium phosphates (of-TiPO4) and mixed titanium oxide/phosphate derivatives (cr-TiP), correlating their structure and composition with the photocatalytic activity for H2 production. We determined that mixed titanium oxide/phosphate crystalline phases produced enhanced H2 evolution under Sun simulated light irradiation than mixed Ti3+/Ti4+ valence, open-framework titanium phosphates and titanium oxide phases.Financial support by the Spanish Ministry of Economy and competitiveness (CIQ2015-69153-C2-1-R) is gratefully acknowledged.Mateo-Mateo, D.; Gonell-Gómez, F.; Albero-Sancho, J.; Corma Canós, A.; García Gómez, H. (2017). Structure–activity relationship in Ti phosphate-derived photocatalysts for H2 evolution. Journal of Energy Chemistry. 26(2):295-301. https://doi.org/10.1016/j.jechem.2016.09.016S29530126

Design of new nanomaterials for their use in catalysis and photochemistry

Durante el trabajo realizado en la presente tesis doctoral, se han diseñado y desarrollado nuevos nanomateriales para su uso en catálisis, fotocatálisis y fotoquímica. El capítulo 2, se ha centrado en la síntesis y caracterización de nanomateriales basados en ZrO2 y WOx-ZrO2 obtenidos mediante síntesis microondas. Además se han evaluado sus propiedades catalíticas en diferentes reacciones. El capítulo 3, trata sobre el diseño de nanocatalizadores para hidrogenaciones selectivas, cuyo contenido es confidencial. En el capítulo 4 se han desarrollado nanomateriales basado en Cu-TiO2 para la fotoreducción de CO2 y purificación de agua. Además se han introducido partículas de Er,Yb:Y2O3 conversoras de energía en fotoánodos para mejor aprovechamiento del espectro solar y producción de H2. Finalmente en el capítulo 4, se han introducido nanopartículas conversoras de energía basadas en Er,Yb:ZrO2 y ErTm,Yb:NaYF4 en nanocompuestos híbridos de diureasil y PDMS, respectivamente, y sus propiedades estructurales y ópticas fueron estudiadas en profundidad.The present PhD Thesis deals about the design and development of new nanomaterials for their use in catalysis, photocatalysis and photochemistry. Chapter 2 has devoted to the synthesis and characterization of ZrO2 and WOx-ZrO2 obtained by microwave synthesis. Moreover their catalytic properties have been tested in several reactions. Chapter 3 is focused on nanocatalysts design for selective hydrogenations, whose content is confidential. Chapter 4 deals about the synthesis of Cu-TiO2 for the simultaneous CO2 photoreduction and sulfide abatement. Moreover, upconverting particles based on Er,Yb:Y2O3 have been introduced in fotoanodes for a better solar spectrum profit. Finally, in chapter 4 Er,Yb:ZrO2 y ErTm,Yb:NaYF4 based upconversion nanoparticles were introduced in hybrid nanocomposites made of diureasil and PDMS, respectively, and their optical and structural properties were further studied.Programa de Doctorat en Cièncie

Aplicación de rúbricas para la evaluación de los alumnos del laboratorio químico

El present treball de millora educativa constitueix un exemple de millora en les pràctiques de laboratori de l’assignatura QU0924 Química Inorgànica III mitjançant la introducció de rúbriques com a instrument d’avaluació. Clàssicament, l’avaluació en el laboratori químic es feia de manera subjectiva, és a dir, el professor tenia la intuïció de qui estava seguint i fent correctament les pràctiques. A més a més, la distribució dels grups de treball de laboratori per parelles feia més dificultosa l’avaluació individual dels estudiants, que en molts casos no sabien molt bé amb quins criteris se’ls avaluava.La introducció d’una rúbrica per a avaluar les distintes competències dels estudiants al laboratori químic ha permès sistematitzar l’avaluació d’aquesta assignatura desglossant-la en les parts més importants que s’han de tenir en compte a l’hora d’avaluar i aportant-li una major objectivitat. Aquest fet es reflecteix en una major confiança del professor a l’hora de realitzar l’avaluació. A més, els alumnes tenen molt més clars quins són els criteris que utilitzarà el professor quan avalua, donant-los la oportunitat de centrar-se en les coses importants.The current work is an example of improvement in the laboratory practices of the subject QU0924 Química Inorgànica III through the introduction of rubrics as an evaluation tool. Classically, the evaluation of the chemical laboratory used to be carried out in a subjective way, in other words, the teacher had an intuition about who was following and developing correctly the practices. Moreover, the students distribution in work groups (in pairs) produced that the individual evaluation was more difficult, thus in several cases the students did not know which one was the evaluation criteria. The introduction of a rubric for the evaluation of the different student’s competences in the chemical laboratory has allowed a systematization of the evaluation of this subject dividing it in the most important parts that have to be taken into account when evaluating. This fact is translated into an increase in the confidence and objectivity of the teacher in the evaluation part. Moreover, the students have much more clear which is the criteria that the teacher is going to use when evaluating, giving them the chance of focusing in the important things.El presente trabajo de mejora educativa constituye un ejemplo de mejora en las prácticas de laboratorio de la asignatura QU0924 Química Inorgánica III mediante la introducción de rúbricas como instrumento de evaluación. Clásicamente, la evaluación del laboratorio químico se solía hacer de manera subjetiva, es decir, el profesor tenía la intuición de quien estaba siguiendo y haciendo correctamente las prácticas. Además, la distribución de grupos de trabajo por parejas hacía aún más dificultosa la evaluación individual de los estudiantes, que en muchos casos no sabían muy bien con qué criterios se los iba a evaluar. La introducción de una rúbrica para evaluar las distintas competencias de los estudiantes de laboratorio químico ha permitido sistematizar la evaluación de esta asignatura dividiéndola en las partes más importantes que tienen que tenerse en cuenta a la hora de evaluar y aportándole mayor objetividad. Este hecho se refleja en una mayor confianza del profesor a la hora de realizar la evaluación. Además, los alumnos tienen mucho más claro cuáles son los criterios que el profesor utilizará cuando evalúa, dándoles la oportunidad de centrarse en las cosas importantes

Aplicació de rúbriques per a l'avaluació d'estudiants en grups de treball de laboratori químic

El present treball de millora educativa constitueix un exemple de millora en les pràctiques de laboratori de l’assignatura QU0924 Química Inorgànica III mitjançant la introducció de rúbriques com a instrument d’avaluació. Clàssicament, l’avaluació en el laboratori químic es feia de manera subjectiva, és a dir, el professor tenia la intuïció de qui estava seguint i fent correctament les pràctiques. A més a més, la distribució dels grups de treball de laboratori per parelles feia més dificultosa l’avaluació individual dels estudiants, que en molts casos no sabien molt bé amb quins criteris se’ls avaluava. La introducció d’una rúbrica per a avaluar les distintes competències dels estudiants al laboratori químic ha permès sistematitzar l’avaluació d’aquesta assignatura desglossant-la en les parts més importants que s’han de tenir en compte a l’hora d’avaluar i aportant-li una major objectivitat. Aquest fet es reflecteix en una major confiança del professor a l’hora de realitzar l’avaluació. A més, els alumnes tenen molt més clars quins són els criteris que utilitzarà el professor quan avalua, donant-los la oportunitat de centrar-se en les coses importants.El presente trabajo de mejora educativa constituye un ejemplo de mejora en las prácticas de laboratorio de la asignatura QU0924 Química Inorgánica III mediante la introducción de rúbricas como instrumento de evaluación. Clásicamente, la evaluación en el laboratorio químico se hacía de manera subjetiva, es decir, el profesor tenía la intuición de quien estaba siguiendo y haciendo correctamente las prácticas. Además, la distribución de los grupos de trabajo de laboratorio por parejas hacía más dificultosa la evaluación individual de los estudiantes, que en muchos casos no sabían muy bien con qué criterios se les evaluaba. La introducción de una rúbrica para evaluar las distintas competencias de los estudiantes en el laboratorio químico ha permitido sistematizar la evaluación de esta asignatura desglosándola en las partes más importantes que se deben tener en cuenta a la hora de evaluar y aportándole una mayor objetividad. Este hecho se refleja en una mayor confianza del profesor a la hora de realizar la evaluación. Además, los alumnos tienen mucho más claros cuáles son los criterios que utilizará el profesor cuando evalúa, dándoles la oportunidad de centrarse en las cosas importantes