Readily available Ti-beta as an efficient catalyst for greener and sustainable production of campholenic aldehyde

[EN] Different Ti-beta zeolite samples were prepared following a convenient and optimized post-synthetic route and starting from commercial Al-beta zeolite. Lewis acid sites have been successfully incorporated into vacant tetrahedral (T)-sites of a dealuminated beta-framework by ball-milling solid-state ion-exchange. A tribology-ball milling process was used in order to increase the interaction between dealuminated-beta zeolite and the Ti-precursor. Thermal treatments with water and aqueous solution of NaNO or Li NO allowed optimization of the catalytic properties of the Ti-Lewis active sites which exhibited excellent catalytic activity and stability for the isomerization of ¿-pinene oxide into campholenic aldehyde in both batch and fixed bed reactor systems. Additionally, the catalytic performance of the post-synthesised Ti-beta zeolite was compared to a Ti-beta zeolite prepared in fluoride media. From different points of view such as preparation of readily, highly active, selective and stable catalysts, throughput, sustainability and cost, herein we report the selective solid catalysed ¿-PO isomerization with excellent results, 88% selectivity and yield, a CA production of 225 g g h and new opportunities.The authors are grateful for financial support from the Spanish Government by MAT2017-82288-C2-1-P and Severo Ochoa Excellence Program SEV-2016-0683. The contribution of Mr. Pablo Ramos to the experimental work is also gratefully acknowledged.Puche Panadero, M.; Velty, A. (2019). Readily available Ti-beta as an efficient catalyst for greener and sustainable production of campholenic aldehyde. Catalysis Science & Technology. 9(16):4293-4303. https://doi.org/10.1039/c9cy00957dS42934303916Stekrova, M., Kumar, N., Aho, A., Sinev, I., Grünert, W., Dahl, J., … Murzin, D. Y. (2014). Isomerization of α-pinene oxide using Fe-supported catalysts: Selective synthesis of campholenic aldehyde. Applied Catalysis A: General, 470, 162-176. doi:10.1016/j.apcata.2013.10.044Kunkeler, P. J., van der Waal, J. C., Bremmer, J., Zuurdeeg, B. J., Downing, R. S., & van Bekkum, H. (1998). Catalysis Letters, 53(1/2), 135-138. doi:10.1023/a:1019049704709Pitínová-Štekrová, M., Eliášová, P., Weissenberger, T., Shamzhy, M., Musilová, Z., & Čejka, J. (2018). Highly selective synthesis of campholenic aldehyde over Ti-MWW catalysts by α-pinene oxide isomerization. Catalysis Science & Technology, 8(18), 4690-4701. doi:10.1039/c8cy01231hArbusow, B. (1935). Studium der Isomerisation von Terpen-oxyden, I. Mitteil.: Isomerisation des α-Pinen-oxydes bei der Reaktion von Reformatsky. Berichte der deutschen chemischen Gesellschaft (A and B Series), 68(8), 1430-1435. doi:10.1002/cber.19350680803Arata, K., & Tanabe, K. (1979). ISOMERIZATION OF α-PlNENE OXIDE OVER SOLID ACIDS AND BASES. Chemistry Letters, 8(8), 1017-1018. doi:10.1246/cl.1979.1017Kaminska, J., Schwegler, M. A., Hoefnagel, A. J., & van Bekkum, H. (1992). The isomerization of α-pinene oxide with Brønsted and Lewis acids. Recueil des Travaux Chimiques des Pays-Bas, 111(10), 432-437. doi:10.1002/recl.19921111004Huybrechts, D. R. C., Bruycker, L. D., & Jacobs, P. A. (1990). Oxyfunctionalization of alkanes with hydrogen peroxide on titanium silicalite. Nature, 345(6272), 240-242. doi:10.1038/345240a0C. Ferrini and H. W.Kouwenhoven , New Developments in Selective Oxidation , ed. G. Centi and F. Trifiro , Elsevier , Amsterdam , 1990 , p. 53Camblor, M. A., Costantini, M., Corma, A., Gilbert, L., Esteve, P., Martínez, A., & Valencia, S. (1996). Synthesis and catalytic activity of aluminium-free zeolite Ti-β oxidation catalysts. Chem. Commun., (11), 1339-1340. doi:10.1039/cc9960001339Blasco, T., Camblor, M. A., Corma, A., Esteve, P., Martínez, A., Prieto, C., & Valencia, S. (1996). Unseeded synthesis of Al-free Ti-β zeolite in fluoride medium: a hydrophobic selective oxidation catalyst. Chem. Commun., (20), 2367-2368. doi:10.1039/cc9960002367Li, P., Liu, G., Wu, H., Liu, Y., Jiang, J., & Wu, P. (2011). Postsynthesis and Selective Oxidation Properties of Nanosized Sn-Beta Zeolite. The Journal of Physical Chemistry C, 115(9), 3663-3670. doi:10.1021/jp1076966Dijkmans, J., Gabriëls, D., Dusselier, M., de Clippel, F., Vanelderen, P., Houthoofd, K., … Sels, B. F. (2013). Productive sugar isomerization with highly active Sn in dealuminated β zeolites. Green Chemistry, 15(10), 2777. doi:10.1039/c3gc41239cHammond, C., Conrad, S., & Hermans, I. (2012). Simple and Scalable Preparation of Highly Active Lewis Acidic Sn-β. Angewandte Chemie International Edition, 51(47), 11736-11739. doi:10.1002/anie.201206193Wolf, P., Hammond, C., Conrad, S., & Hermans, I. (2014). Post-synthetic preparation of Sn-, Ti- and Zr-beta: a facile route to water tolerant, highly active Lewis acidic zeolites. Dalton Transactions, 43(11), 4514. doi:10.1039/c3dt52972jTolborg, S., Sádaba, I., Osmundsen, C. M., Fristrup, P., Holm, M. S., & Taarning, E. (2015). Tin-containing Silicates: Alkali Salts Improve Methyl Lactate Yield from Sugars. ChemSusChem, 8(4), 613-617. doi:10.1002/cssc.201403057Camblor, M. A., Corma, A., & Pérez-Pariente, J. (1993). Synthesis of titanoaluminosilicates isomorphous to zeolite Beta, active as oxidation catalysts. Zeolites, 13(2), 82-87. doi:10.1016/0144-2449(93)90064-aGarcia Vargas, N., Stevenson, S., & Shantz, D. F. (2012). Synthesis and characterization of tin(IV) MFI: Sodium inhibits the synthesis of phase pure materials. Microporous and Mesoporous Materials, 152, 37-49. doi:10.1016/j.micromeso.2011.11.036Tatsumi, T., Koyano, K. A., & Shimizu, Y. (2000). Effect of potassium on the catalytic activity of TS-1. Applied Catalysis A: General, 200(1-2), 125-134. doi:10.1016/s0926-860x(00)00630-xKhouw, C. B., & Davis, M. E. (1995). Catalytic Activity of Titanium Silicates Synthesized in the Presence of Alkali-Metal and Alkaline-Earth Ions. Journal of Catalysis, 151(1), 77-86. doi:10.1006/jcat.1995.1010Kuwahara, Y., Nishizawa, K., Nakajima, T., Kamegawa, T., Mori, K., & Yamashita, H. (2011). Enhanced Catalytic Activity on Titanosilicate Molecular Sieves Controlled by Cation−π Interactions. Journal of the American Chemical Society, 133(32), 12462-12465. doi:10.1021/ja205699dTaarning, E., Saravanamurugan, S., Spangsberg Holm, M., Xiong, J., West, R. M., & Christensen, C. H. (2009). Zeolite-Catalyzed Isomerization of Triose Sugars. ChemSusChem, 2(7), 625-627. doi:10.1002/cssc.200900099Bermejo-Deval, R., Orazov, M., Gounder, R., Hwang, S.-J., & Davis, M. E. (2014). Active Sites in Sn-Beta for Glucose Isomerization to Fructose and Epimerization to Mannose. ACS Catalysis, 4(7), 2288-2297. doi:10.1021/cs500466jBlasco, T., Camblor, M. A., Corma, A., Esteve, P., Guil, J. M., Martínez, A., … Valencia, S. (1998). Direct Synthesis and Characterization of Hydrophobic Aluminum-Free Ti−Beta Zeolite. The Journal of Physical Chemistry B, 102(1), 75-88. doi:10.1021/jp973288wR. K. Iler , The Chemistry of Silica , Wiley , New York , 1979Cordon, M. J., Harris, J. W., Vega-Vila, J. C., Bates, J. S., Kaur, S., Gupta, M., … Gounder, R. (2018). Dominant Role of Entropy in Stabilizing Sugar Isomerization Transition States within Hydrophobic Zeolite Pores. Journal of the American Chemical Society, 140(43), 14244-14266. doi:10.1021/jacs.8b08336BORONAT, M., CONCEPCION, P., CORMA, A., RENZ, M., & VALENCIA, S. (2005). Determination of the catalytically active oxidation Lewis acid sites in Sn-beta zeolites, and their optimisation by the combination of theoretical and experimental studies. 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Scientific Reports, 7(1). doi:10.1038/s41598-017-16409-yAlaerts, L., Séguin, E., Poelman, H., Thibault-Starzyk, F., Jacobs, P. A., & De Vos, D. E. (2006). Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu3(btc)2] (BTC=Benzene-1,3,5-tricarboxylate). Chemistry - A European Journal, 12(28), 7353-7363. doi:10.1002/chem.20060022

Nanomateriales híbridos basados en complejos de metales de transición anclados sobre óxido de grafeno. Aplicaciones catalíticas

Graphene-based hybrid materials and transition metal complexes play an important role in the science of materials and catalysis, as well as in other technological fields, as highlighted in the literature. In this doctoral thesis new hybrid nanomaterials based on different transition metal complexes (mono- and multimetallic) anchored on the surface of graphene oxide or graphene oxide modified with organic groups have been developed. This doctoral memory constitutes a "classic" work from the point of view of content structure, which are distributed over seven chapters. In the first chapter, the general considerations and applications of graphene and associated hybrid materials are presented together with a classification of strategies of synthesis and chemical structure of graphene oxides under study. Next, the second chapter addresses the objectives of this research work focused on the study of hybrid nanomaterials based on transition metals and graphene. The third and fourth chapter focuses on the synthesis of delaminated graphene oxide by modifying the conventional Hummers method, which provides the laminar support on which donor oxygen and nitrogen groups are covalently anchored. These groups allow the coordinating or axial immobilization of a chiral Mn (III) -salen complex, to provide hybrid nanocatalysts directed to the enantioselective epoxidation of prochiral alkenes. In the fifth chapter of this specification, the chemical modification of graphene oxide is described by amidation and acylation reactions of the carboxylic groups and by the covalent anchoring of a ruthenium (II) organometallic complex. Hybrid nanomaterials are studied in the catalytic racemization of (S) -1-phenylethanol, and the multifunctional enzyme catalyst (CALB)-Ru-OG in the kinetic resolution of 1- phenylethanol. The sixth chapter focuses on the coordinating immobilization of hexanuclear molybdenum (II) nanoclusters with halogens in graphene oxide to provide nanohybrids that have been investigated in the field of photocatalysis and whose activity has been compared with that obtained under homogeneous conditions. Specifically, photoreduction of H2O to H2 and photooxidation of certain organic substrates has been approached, taking advantage of the photoluminescent properties of the molybdenum (II) clusters and the electronic properties of the graphite materials. The characterization of the molecular complexes and nanomaterials synthesized throughout chapters 3-6 of the present thesis is carried out using chemical and structural analysis techniques and spectroscopic, chromatographic, surface and image techniques. The last chapter, and not the least important, highlights the conclusions obtained in this research.Los materiales híbridos basados en grafeno y complejos de metales de transición juegan un papel importante en la ciencia de materiales y catálisis, así como en otros campos tecnológicos, según se destaca en la literatura. En esta tesis doctoral se han desarrollado nuevos nanomateriales híbridos basados en complejos metálicos de transición de diferente índole (mono- y multimetálicos) anclados en la superficie del óxido de grafeno u óxido de grafeno modificado con grupos orgánicos. Esta memoria doctoral constituye un trabajo "clásico" desde el punto de vista de estructura de contenidos, los cuales se distribuyen a lo largo de siete capítulos. En el primer capítulo, se exponen las consideraciones generales y aplicaciones de los grafenos y de los materiales híbridos asociados, junto con una clasificación de estrategias de síntesis y estructura química de los óxidos de grafeno objeto de estudio. A continuación, el capítulo segundo aborda los objetivos del presente trabajo de investigación centrados en el estudio de nanomateriales híbridos basados en metales de transición y grafenos. El tercer y cuarto capítulo se centran en la síntesis de óxido de grafeno deslaminado modificando el método de Hummers convencional, que proporciona el soporte laminar sobre el que se anclan covalentemente grupos oxígeno y nitrógeno dadores. Estos grupos permiten la inmovilización coordinativa o axial de un complejo de Mn (III)-salen quiral, para proporcionar nanocatalizadores híbridos dirigidos a la epoxidación enantioselectiva de alquenos proquirales. En el quinto capítulo de esta memoria, se describe la modificación química del óxido de grafeno mediante reacciones de amidación y de acilación de los grupos carboxílicos, y mediante el anclaje covalente de un complejo organometálico de rutenio (II). Los nanomateriales híbridos se estudian en la racemización catalítica del (S)-1-feniletanol, y el catalizador multifuncional enzima (CALB)-Ru-OG en la resolución cinética del 1-feniletanol. El sexto capítulo, se centra en la inmovilización coordinativa de nanoclústeres hexanucleares de haluros de molibdeno (II) en óxido de grafeno, para proporcionar nanohíbridos que se han investigado en el campo de la fotocatálisis y cuya actividad se ha comparado con la obtenida en condiciones homogéneas. Concretamente, se ha abordado la fotorreducción de H2O a H2 y la fotooxidación de determinados sustratos orgánicos, aprovechando las propiedades fotoluminiscentes de los clústeres de molibdeno (II) y las propiedades electrónicas de los materiales grafénicos. La caracterización de los complejos moleculares y de los nanomateriales sintetizados a lo largo de los capítulos 3-6 de la presente tesis se lleva a cabo, mediante técnicas de análisis químico y estructural, espectroscópicas, cromatográficas, de superficie y de imagen El último capítulo y no por ello el menos importante, destaca las conclusiones obtenidas en este trabajo de investigación.Els materials híbrids basats en grafè i complexos de metalls de transició juguen un paper important en la ciència de materials i catàlisi, així com en altres camps tecnològics, segons es destaca en la literatura. En aquesta tesi doctoral s'han desenvolupat nous nanomaterials híbrids basats en complexos metàl·lics de transició de diferent índole (mono- i multimetálicos) ancorats en la superfície de l'òxid de grafè o òxid de grafè modificat amb grups orgànics. Aquesta memòria doctoral constitueix un treball "clàssic" des del punt de vista d'estructura de continguts, els quals es distribueixen al llarg de set capítols. En el primer capítol, s'exposen les consideracions generals i aplicacions dels grafenos i dels materials híbrids associats, juntament amb una classificació d'estratègies de síntesi i estructura química dels òxids de grafè objecte d'estudi. A continuació, el capítol segon aborda els objectius del present treball d'investigació centrats en l'estudi de nanomaterials híbrids basats en metalls de transició i grafenos. El tercer i quart capítol se centren en la síntesi d'òxid de grafè deslaminat modificant el mètode de Hummers convencional, que proporciona el suport laminar sobre el qual s'ancoren covalentment grups oxigen i nitrogen donadors. Aquests grups permeten la immobilització coordinativa o axial d'un complex de Mn (III) -salen quiral, per proporcionar nanocatalitzadors híbrids dirigits a l'epoxidació enantioselectiva d'alquens proquirals. En el cinquè capítol d'aquesta memòria, es descriu la modificació química de l'òxid de grafè mitjançant reaccions de amidació i de acilació dels grups carboxílics, i mitjançant l'ancoratge covalent d'un complex organometàl·lic de ruteni (II). Els nanomaterials híbrids s'estudien a la racemització catalítica del (S) -1-feniletanol, i el catalitzador multifuncional enzim (CALB)-Ru-OG en la resolució cinètica de l'1-feniletanol. El sisè capítol, es centra en la immobilització coordinativa de nanoclústeres hexanuclears de molibdè (II) amb halògens en òxid de grafè, per proporcionar nanohíbrids que s'han investigat en el camp de la fotocatàlisi i l'activitat s'ha comparat amb l'obtinguda en condicions homogènies. Concretament, s'ha abordat la fotoreducció d'H2O a H2 i la fotooxidació de determinats substrats orgànics, aprofitant les propietats fotoluminiscents dels clústers de molibdè (II) i les propietats electròniques dels materials grafénics. La caracterització dels complexos moleculars i dels nanomaterials sintetitzats al llarg dels capítols 3-6 de la present tesi es du a terme, mitjançant tècniques d'anàlisi química i estructural, espectroscòpiques, cromatogràfiques, de superfície i d'imatge. L'últim capítol i no per això menys important, destaca les conclusions obtingudes en aquest treball de recerca.Puche Panadero, M. (2017). Nanomateriales híbridos basados en complejos de metales de transición anclados sobre óxido de grafeno. Aplicaciones catalíticas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86211TESI

A spectroscopic study to assess the photogeneration of singlet oxygen by graphene oxide

[EN] The photogeneration of singlet oxygen (O-1(2) ) during short irradiation times of graphene oxide (GO) is assessed under visible light with soft irradiation conditions either directly monitoring the phosphorescence emission of O-1(2) at ca. 1275 nm, or indirectly by means of the fluorescent probe 9, 10-anthracene diyl-bis(methylene)dimalonic acid (ABDA). Results obtained using both methodologies lead to the conclusion that O-1(2) generation is negligible under our experimental conditions. In the case of using ABDA very small emission changes were recorded, which could be attributed to other side reactions. Special care should be taken when using this spectroscopic probe to assess the generation of O-1(2), since ABDA and related probes based on the reactivity of the anthracene fluorophore can also detect electron transfer processes. This kind of approaches have been less explored in the field of Materials Science at the nanoscale, and we believe that the knowledge on the lack of generation of O-1(2) by irradiated GO is informative and useful, especially for the assessment of the environmental and biological toxicity of nanomaterials based on GO. (C) 2019 Elsevier B.V. All rights reserved.Ministerio de Economia y Competitividad of Spain (grant CTQ2015-71004-R) and Universitat Jaume I (grant P1.1B2015-76) are thanked for their financial support. C.F-L. thanks the Ministerio de Economia y Competitividad of Spain for a FPI fellowship. Technical support from SCIC of University Jaume I is acknowledged. The Instituto de Tecnologia Quimica (ITQ) thanks the support of the Severo Ochoa Program (SEV-2016-0683), and Consejo Superior de Investigaciones Cientificas (I-Link1063). We would like to thank Dr. Francisco Bosca for his technical assistance with the singlet oxygen emission measurements at the ITQ.Felip-León, C.; Puche Panadero, M.; Miravet, JF.; Galindo, F.; Feliz Rodriguez, M. (2019). A spectroscopic study to assess the photogeneration of singlet oxygen by graphene oxide. Materials Letters. 251:45-51. https://doi.org/10.1016/j.matlet.2019.05.001S455125

Nanostructured Hybrids Based on Tantalum Bromide Octahedral Clusters and Graphene Oxide for Photocatalytic Hydrogen Evolution

[EN] The generation of hydrogen (H2) using sunlight has become an essential energy alternative for decarbonization. The need for functional nanohybrid materials based on photo- and electroactive materials and accessible raw materials is high in the field of solar fuels. To reach this goal, single-step synthesis of {Ta6Bri12}@GO (GO = graphene oxide) nanohybrids was developed by immobilization of [{Ta6Bri12}Bra2(H2O)a4]·4H2O (i = inner and a = apical positions of the Ta6 octahedron) on GO nanosheets by taking the advantage of the easy ligand exchange of the apical cluster ligands with the oxygen functionalities of GO. The nanohybrids were characterized by spectroscopic, analytical, and morphological techniques. The hybrid formation enhances the yield of photocatalytic H2 from water with respect to their precursors and this is without the presence of precious metals. This enhancement is attributed to the optimal cluster loading onto the GO support and the crucial role of GO in the electron transfer from Ta6 clusters into GO sheets, thus suppressing the charge recombination. In view of the simplicity and versatility of the designed photocatalytic system, octahedral tantalum clusters are promising candidates to develop new and environmentally friendly photocatalysts for H2 evolution.This research was funded by Ministerio de Ciencia e Innovación (MICINN), grant number PGC2018-099744. Parts of this research dealing with metal cluster synthesis and characterization received funding from project RTI2018-096399-A-I00 funded by MCIN/AEI/10.13039/501100011033/ and ¿ERDF A way of making Europe¿. J.S.H. gratefully acknowledges the Consejo Superior de Investigaciones Científicas (CSIC) and Generalitat Valenciana (GVA), Programa Santiago Grisolía, grant number GRISOLIA/2021/054. M.S. received financial support by the Russian Foundation for Basic Research (grant number 20-33-90010) and the Ministry of Science and Higher Education of the Russian Federation (grant number 121031700313¿8). The APC was funded by this journal.Hernandez-Niño, JS.; Shamsurin, M.; Puche Panadero, M.; Sokolov, MN.; Feliz Rodriguez, M. (2022). Nanostructured Hybrids Based on Tantalum Bromide Octahedral Clusters and Graphene Oxide for Photocatalytic Hydrogen Evolution. Nanomaterials. 12(20). https://doi.org/10.3390/nano12203647122

Uniform Ru nanoparticles on N-doped graphene for selective hydrogenation of fatty acids to alcohols

[EN] Ruthenium nanoparticles (Ru NPs) supported on reduced-graphene oxide doped with N (NH2-rGO) was synthesized and used for the selective hydrogenation of fatty acids to alcohols, being the hydrogenation of palmitic acid selected as model. Ru was stabilized forming uniform nanometer size particles on N-doped graphene (Ru/NH2-rGO). The resultant catalyst was very selective for the carbonyl reduction giving 93% of the aliphatic alcohol at 99% conversion. The Ru/NH2-rGO catalysts was more active and selective than the corresponding Ru on non-doped graphene (Ru/rGO) or Ru on carbon (Ru/C). Mechanistic studies points to a dual mechanism for H-2 dissociation, i.e. homolytic and heterolytic cleavage exists on the Ru/NH2-rGO, while only the homolytic H-2 dissociation occurs on Ru/rGO. This heterolytic splitting, which activates the carbonyl groups and facilitates the hydrogenation of aliphatic acids, is due to the presence of basic centres next to the Ru atoms. The presence of N atoms also increases the stability of the catalyst, allowing a reuse up to four times. (C) 2019 Elsevier Inc. All rights reserved.The authors thank Institute de Tecnologia Quimica (ITQ), Consejo Superior de Investigaciones Cientificas (CSIC) and Universitat Politecnica de Valencia (UPV) for the facilities and Severo Ochoa excellence programme, "Juan de la Cierva" programme and Primeros Proyectos de Investigacion (PAID-06-18) for financial support. We gratefully acknowledge Prof. A. Corma for his invaluable contribution to this research. We also thank the Electron Microscopy Service of the UPV for TEM facilities, Jose A. Vidal-Moya (ITQ CSIC-UPV) for NMR measurements and J. Gaona and C. Morales for their assistance in catalytic reactions.Martínez-Prieto, LM.; Puche Panadero, M.; Cerezo-Navarrete, C.; Chaudret, B. (2019). Uniform Ru nanoparticles on N-doped graphene for selective hydrogenation of fatty acids to alcohols. Journal of Catalysis. 377:429-437. https://doi.org/10.1016/j.jcat.2019.07.040S42943737

Enhanced Photocatalytic Activity and Stability in Hydrogen Evolution of Mo(6)Iodide Clusters Supported on Graphene Oxide

[EN] Catalytic properties of the cluster compound (TBA)2[Mo6Ii8(O2CCH3)a6] (TBA = tetrabutylammonium) and a new hybrid material (TBA)2Mo6Ii8@GO (GO = graphene oxide) in water photoreduction into molecular hydrogen were investigated. New hybrid material (TBA)2Mo6Ii8@GO was prepared by coordinative immobilization of the (TBA)2[Mo6Ii8(O2CCH3)a6] onto GO sheets and characterized by spectroscopic, analytical, and morphological techniques. Liquid and, for the first time, gas phase conditions were chosen for catalytic experiments under UV-Vis irradiation. In liquid water, optimal H2 production yields were obtained after using (TBA)2[Mo6Ii8(O2CCH3)a6] and (TBA)2Mo6Ii8@GO) catalysts after 5 h of irradiation of liquid water. Despite these remarkable catalytic performances, "liquid-phase" catalytic systems have serious drawbacks: the cluster anion evolves to less active cluster species with partial hydrolytic decomposition, and the nanocomposite completely decays in the process. Vapor water photoreduction showed lower catalytic performance but offers more advantages in terms of cluster stability, even after longer radiation exposure times and recyclability of both catalysts. The turnover frequency (TOF) of (TBA)2Mo6Ii8@GO is three times higher than that of the microcrystalline (TBA)2[Mo6Ii8(O2CCH3)a6], in agreement with the better accessibility of catalytic cluster sites for water molecules in the gas phase. This bodes well for the possibility of creating {Mo6I8}4+-based materials as catalysts in hydrogen production technology from water vapor.This research was funded by the Severo Ochoa Program, grant number SEV-2016-0683, Ministerio de Ciencia e Innovacion, grant number PGC2018-099744, Consejo Superior de Investigaciones Cientificas, grant number I-Link1063, and Russian Foundation for Basic Research, grant number 18-33-20056.Puche Panadero, M.; García-Aboal, R.; Mikhaylov, MA.; Sokolov, MN.; Atienzar Corvillo, PE.; Feliz Rodriguez, M. (2020). Enhanced Photocatalytic Activity and Stability in Hydrogen Evolution of Mo(6)Iodide Clusters Supported on Graphene Oxide. Nanomaterials. 10(7). https://doi.org/10.3390/nano1007125910

Graphene oxide as a catalyst for the diastereoselective transfer hydrogenation in the synthesis of prostaglandin derivatives

[EN] Modification of GO by organic molecules changes its catalytic activity in the hydrogen transfer from i-propanol to enones, affecting the selectivity to allyl alcohol and diastereoselectivity to the resulting stereoisomers. It is noteworthy the system does not contain metals and is recyclable.Coman, SM.; Podolean, I.; Tudorache, M.; Cojocaru, B.; Parvulescu, VI.; Puche Panadero, M.; García Gómez, H. (2017). Graphene oxide as a catalyst for the diastereoselective transfer hydrogenation in the synthesis of prostaglandin derivatives. Chemical Communications. 53(74):10271-10274. doi:10.1039/c7cc05105kS1027110274537

The oxidation of trichloroethylene over different mixed oxides derived from hydrotalcites

[EN] The activity of different Mg(Fe/Al), Ni(Fe/Al) and Co(Fe/Al) mixed oxides based on hydrotalcite-like compounds have been studied for the catalytic oxidation of trichloroethylene. It has been shown that the Co catalysts are more active than the Ni catalyst, being the Mg catalysts the less active ones. The activity of all the catalysts improves when iron is substituted by aluminum in the catalyst composition. The best results have been obtained with the CoAl mixed oxide derived from hydrotalcite that is a stable, highly active and selective catalyst. These results have been related with the presence of aluminum in the Co3O4 structure that favors, in the presence of oxygen, the formation of O2 − sites and enhances the acid properties of the catalyst. The combination of both characteristics maximizes the adsorption and oxidation of the TCE.The authors wish to thank financial support from CONACYT (project 154060) and from the Spanish Ministry of Economy and Competitiveness through the Consolider Ingenio Multicat (CSD-2009-00050) and MAT-2012-38567-C02-01 programms. N.B.R. acknowledges Catedra Cemex Sostenibilidad (UPV) for a fellowship.Blanch Raga, N.; Palomares Gimeno, AE.; Martínez Triguero, LJ.; Puche Panadero, M.; Fetter, G.; Bosch, P. (2014). The oxidation of trichloroethylene over different mixed oxides derived from hydrotalcites. Applied Catalysis B: Environmental. 160-61:129-134. https://doi.org/10.1016/j.apcatb.2014.05.014129134160-6

Controlling the selectivity of bimetallic platinum¿ruthenium nanoparticles supported on N-doped graphene by adjusting their metal composition

[EN] Mono and bimetallic platinum-ruthenium nanoparticles have been generated on N-doped graphene (NH2-rGO) following an organometallic approach. Surface and structural studies confirmed the formation of bimetallic MNPs with controlled metal compositions. To evaluate the activity/selectivity of the different materials prepared we used the hydrogenation of acetophenone as a model reaction. We found that both the activity and selectivity of the supported-bimetallic NPs are highly dependent on the support and the atomic composition. The higher the Pt/Ru ratio, the higher the selectivity towards 1-phenylethanol. Indeed, a remarkable activity and selectivity in the hydrogenation of acetophenone was observed for Pt5Ru1@NH2-rGO. The reactivity of these catalysts was also investigated in the hydrogenation of other substrates such as functionalized arenes (i.e. nitrobenzene and benzaldehyde) or hydroxymethylfurfural (HMF), demonstrating that it is possible to control the activity and selectivity of bimetallic Pt-Ru MNPs supported on N-doped graphene by adjusting their metal composition.The authors thank Instituto de Tecnologia Quimica (ITQ), Consejo Superior de Investigaciones Cientificas (CSIC), and Universitat Politecnica de Valencia (UPV) for the facilities, and Severo Ochoa excellence programme (SEV-2016-0683), "Juan de la Cierva" programme (IJCI-2016-27966) and Primero Proyectos de Investigacion (PAID-06-18) for financial support. C. C.-N. gratefully thanks Generalitat Valenciana predoctoral fellowship (GVA: ACIF/2019/076). We also thank the Electron Microscopy Service of the UPV for TEM facilities and A. Garcia Zaragoza for his assistance in catalytic reactions.Cerezo-Navarrete, C.; Mathieu, Y.; Puche Panadero, M.; Morales, C.; Concepción Heydorn, P.; Martínez-Prieto, LM.; Corma Canós, A. (2021). Controlling the selectivity of bimetallic platinum¿ruthenium nanoparticles supported on N-doped graphene by adjusting their metal composition. Catalysis Science & Technology. 11(2):494-505. https://doi.org/10.1039/D0CY02379E49450511

N-Doped graphene as a metal-free catalyst for glucose oxidation to succinic acid

[EN] N-Containing graphenes obtained either by simultaneous amination and reduction of graphene oxide or by pyrolysis of chitosan under an inert atmosphere have been found to act as catalysts for the selective wet oxidation of glucose to succinic acid. Selectivity values over 60% at complete glucose conversion have been achieved by performing the reaction at 160 degrees C and 18 atm O-2 pressure for 20 h. This activity has been attributed to graphenic-type N atoms on graphene. The active N-containing graphene catalysts were used four times without observing a decrease in conversion and selectivity of the process. A mechanism having tartaric and fumaric acids as key intermediates is proposed.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, Grapas and CTQ2015-69153-CO2-R1) and Generalitat Valenciana (Prometeo 2013-014) is gratefully acknowledged. Prof. Simona M. 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