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In this work, we will report the generation of Au clusters in a purely siliceous MCM-22 zeolite. The catalytic properties of these Au clusters have been tested for the selective oxidation of cyclohexane to cyclohexanol and cyclohexanone (KA-oil). The Au clusters encapsulated in the MCM-22 zeolite are highly active and selective for the oxidation of cyclohexane to KA-oil, which is superior to Au nanoparticles on the same support. These results suggest that Au clusters are highly active for the activation of oxygen to produce radical species. ; This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the ''Severo Ochoa Program'' (SEV-2016-0683). R. A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through project grant MAT2016-79776-P (AEI/FEDER, UE). ; Peer reviewed

[EN] In this work, we will report the generation of Au clusters in a purely siliceous MCM-22 zeolite. The catalytic properties of these Au clusters have been tested for the selective oxidation of cyclohexane to cyclohexanol and cyclohexanone (KA-oil). The Au clusters encapsulated in the MCM-22 zeolite are highly active and selective for the oxidation of cyclohexane to KA-oil, which is superior to Au nanoparticles on the same support. These results suggest that Au clusters are highly active for the activation of oxygen to produce radical species. ; This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). The authors also thank the Microscopy Service of UPV for kind help with TEM and STEM measurements. Mr J. A. Gaona is greatly acknowledged for his very helpful assistance on the catalytic studies. The XAS data were acquired at European Synchrotron Radiation Facility. The HAADF-HRSTEM studies were conducted in the Laboratorio de Microscopias Avanzadas (LMA) at the Instituto de Nanociencia de Aragon (INA)-Universidad de Zaragoza (Spain), Spanish ICTS National facility. R. A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through project grant MAT2016-79776-P (AEI/FEDER, UE). ; Liu, L.; Arenal, R.; Meira, DM.; Corma Canós, A. (2019). Generation of gold nanoclusters encapsulated in an MCM-22 zeolite for the aerobic oxidation of cyclohexane. Chemical Communications. 55(11):1607-1610. https://doi.org/10.1039/c8cc07185c ; S ; 1607 ; 1610 ; 55 ; 11 ; Claus, P. (2005). Heterogeneously catalysed hydrogenation using gold catalysts. Applied Catalysis A: General, 291(1-2), 222-229. doi:10.1016/j.apcata.2004.12.048 ; Hashmi, A. S. K., & Hutchings, G. J. (2006). Gold Catalysis. Angewandte Chemie International Edition, 45(47), 7896-7936. doi:10.1002/anie.200602454 ; Liu, L., & Corma, A. (2018). Metal Catalysts for ...

1607 1610 55 11 ; S ; [EN] In this work, we will report the generation of Au clusters in a purely siliceous MCM-22 zeolite. The catalytic properties of these Au clusters have been tested for the selective oxidation of cyclohexane to cyclohexanol and cyclohexanone (KA-oil). The Au clusters encapsulated in the MCM-22 zeolite are highly active and selective for the oxidation of cyclohexane to KA-oil, which is superior to Au nanoparticles on the same support. These results suggest that Au clusters are highly active for the activation of oxygen to produce radical species. This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). The authors also thank the Microscopy Service of UPV for kind help with TEM and STEM measurements. Mr J. A. Gaona is greatly acknowledged for his very helpful assistance on the catalytic studies. The XAS data were acquired at European Synchrotron Radiation Facility. The HAADF-HRSTEM studies were conducted in the Laboratorio de Microscopias Avanzadas (LMA) at the Instituto de Nanociencia de Aragon (INA)-Universidad de Zaragoza (Spain), Spanish ICTS National facility. R. A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through project grant MAT2016-79776-P (AEI/FEDER, UE). Liu, L.; Arenal, R.; Meira, DM.; Corma Canós, A. (2019). Generation of gold nanoclusters encapsulated in an MCM-22 zeolite for the aerobic oxidation of cyclohexane. Chemical Communications. 55(11):1607-1610. https://doi.org/10.1039/c8cc07185c Claus, P. (2005). Heterogeneously catalysed hydrogenation using gold catalysts. Applied Catalysis A: General, 291(1-2), 222-229. doi:10.1016/j.apcata.2004.12.048 Hashmi, A. S. K., & Hutchings, G. J. (2006). Gold Catalysis. Angewandte Chemie International Edition, 45(47), 7896-7936. doi:10.1002/anie.200602454 Liu, L., & Corma, A. (2018). Metal Catalysts for Heterogeneous ...

Identification of active sites in heterogeneous metal catalysts is critical for understanding the reaction mechanism at the molecular level and for designing more efficient catalysts. Because of their structural flexibility, subnanometric metal catalysts, including single atoms and clusters with a few atoms, can exhibit dynamic structural evolution when interacting with substrate molecules, making it difficult to determine the catalytically active sites. In this work, Pt catalysts containing selected types of Pt entities (from single atoms to clusters and nanoparticles) have been prepared, and their evolution has been followed, while they were reacting in a variety of heterogeneous catalytic reactions, including selective hydrogenation reactions, CO oxidation, dehydrogenation of propane, and photocatalytic H2 evolution reaction. By in situ X-ray absorption spectroscopy, in situ IR spectroscopy, and high-resolution electron microscopy techniques, we will show that some characterization techniques carried out in an inadequate way can introduce confusion on the interpretation of coordination environment of highly dispersed Pt species. Finally, the combination of catalytic reactivity and in situ characterization techniques shows that, depending on the catalyst¿reactant interaction and metal¿support interaction, singly dispersed metal atoms can rapidly evolve into metal clusters or nanoparticles, being the working active sites for those abovementioned heterogeneous reactions. ; This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014- 671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). L.L. thanks ITQ for providing a contract. The authors also thank Microscopy Service of UPV for the TEM and STEM measurements. This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under contract no. DE-AC02-06CH11357 and the Canadian Light Source and its funding partners. The HR STEM and STEM−EELS studies were conducted at the Laboratorio de Microscopias Avanzadas, Universidad de Zaragoza, Spain. R.A. acknowledges support from Spanish MINECO grant MAT2016-79776-P (AEI/FEDER, UE), from the Government of Aragon and the European Social Fund (grant number E13_17R, FEDER, UE), and from the European Union H2020 program "ESTEEM3" (grant number 823717). A.V.P. thanks the Spanish Government (Agencia Estatal de Investigacion) and the European Union (European ́ Regional Development Fund) for a grant for young researchers (CTQ2015-74138-JIN, AEI/FEDER/UE).

Preparation of supported metal catalysts with uniform particle size and coordination environment is a challenging and important topic in materials chemistry and catalysis. In this work, we report the regioselective generation of single-site Ir atoms and their evolution into stabilized subnanometric Ir clusters in MWW zeolite, which are located at the 10MR window connecting the two neighboring 12MR supercages. The size of the subnanometric Ir clusters can be controlled by the post-synthesis treatments and maintain below 1 nm even after being reduced at 650 °C, which cannot be readily achieved with samples prepared by conventional impregnation methods. The high structure sensitivity, size-dependence, of catalytic performance in the alkane hydrogenolysis reaction of Ir clusters in the subnanometric regime is evidenced. ; This work has been supported by the European Union through the European Research Council (grant ERC‐AdG‐2014‐671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV‐2016‐0683). The authors also thank Microscopy Service of UPV for the TEM and STEM measurements. High‐resolution STEM measurements were performed at the DME‐UCA node of the ELECMI National Singular Infrastruture, in Cadiz University, with financial support from FEDER/MINECO (MAT2017‐87579‐R and MAT2016‐81118‐P). This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No. DE‐AC02‐06CH11357, and the Canadian Light Source and its funding partners. The financial support from ExxonMobil on this project is also greatly acknowledged.

[EN] Identification of active sites in heterogeneous metal catalysts is critical for understanding the reaction mechanism at the molecular level and for designing more efficient catalysts. Because of their structural flexibility, subnanometric metal catalysts, including single atoms and clusters with a few atoms, can exhibit dynamic structural evolution when interacting with substrate molecules, making it difficult to determine the catalytically active sites. In this work, Pt catalysts containing selected types of Pt entities (from single atoms to clusters and nanoparticles) have been prepared, and their evolution has been followed, while they were reacting in a variety of heterogeneous catalytic reactions, including selective hydrogenation reactions, CO oxidation, dehydrogenation of propane, and photocatalytic H-2 evolution reaction. By in situ X-ray absorption spectroscopy, in situ IR spectroscopy, and high-resolution electron microscopy techniques, we will show that some characterization techniques carried out in an inadequate way can introduce confusion on the interpretation of coordination environment of highly dispersed Pt species. Finally, the combination of catalytic reactivity and in situ characterization techniques shows that, depending on the catalyst-reactant interaction and metal-support interaction, singly dispersed metal atoms can rapidly evolve into metal clusters or nanoparticles, being the working active sites for those abovementioned heterogeneous reactions. ; This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). L.L. thanks ITQ for providing a contract. The authors also thank Microscopy Service of UPV for the TEM and STEM measurements. This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was ...

This is the peer reviewed version of the following article: L. Liu, M. Lopez-Haro, D. M. Meira, P. Concepcion, J. J. Calvino, A. Corma, Angew. Chem. Int. Ed. 2020, 59, 15695, which has been published in final form at https://doi.org/10.1002/anie.202005621. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. ; [EN] Preparation of supported metal catalysts with uniform particle size and coordination environment is a challenging and important topic in materials chemistry and catalysis. In this work, we report the regioselective generation of single-site Ir atoms and their evolution into stabilized subnanometric Ir clusters in MWW zeolite, which are located at the 10MR window connecting the two neighboring 12MR supercages. The size of the subnanometric Ir clusters can be controlled by the post-synthesis treatments and maintain below 1 nm even after being reduced at 650 degrees C, which cannot be readily achieved with samples prepared by conventional impregnation methods. The high structure sensitivity, size-dependence, of catalytic performance in the alkane hydrogenolysis reaction of Ir clusters in the subnanometric regime is evidenced. ; This work has been supported by the European Union through the European Research Council (grant ERC-AdG-2014-671093, SynCatMatch) and the Spanish government through the "Severo Ochoa Program" (SEV-2016-0683). The authors also thank Microscopy Service of UPV for the TEM and STEM measurements. High-resolution STEM measurements were performed at the DME-UCA node of the ELECMI National Singular Infrastruture, in Cadiz University, with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No.DE-AC02-06CH11357, and the Canadian Light Source and its funding ...

The Lewis/Brønsted catalytic properties of the Metal-Organic Framework (MOF) nodes can be tuned by simply controlling the solvent employed in the synthetic procedure. In this work, we demonstrate that Hf-MOF-808 can be prepared from a material with a higher amount of Brønsted acid sites,viamodulated hydrothermal synthesis, to a material with a higher proportion of unsaturated Hf Lewis acid sites,viamodulated solvothermal synthesis. The Lewis/Brønsted acid properties of the resultant metallic clusters have been studied by different characterization techniques, including XAS, FTIR and NMR spectroscopies, combined with a DFT study. The different nature of the Hf-MOF-808 materials allows their application as selective catalysts in different target reactions requiring Lewis, Brønsted or Lewis-Brønsted acid pairs. ; This work has been supported by the Spanish Government through the "Severo Ochoa" (SEV-2016-0683, MINECO), MAT2017-82288-C2-1-P (AEI/FEDER, UE) and RTI2018-101033-B-I00 (MCIU/AEI/FEDER, UE). J. M. Salas is acknowledged for his contribution to CD3CN-FTIR experiments. C. W. L. thanks the PRH 50.1 – ANP/FINEP Human Resources Program for the Visiting Researcher Fellowship. This research used resources of the Advanced Photon Source, a user facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357 and by the Canadian Light Source and its funding partners. The Electron Microscopy Service of the UPV is also acknowledged for their help in sample characterization.

[EN] Metal-organic framework (MOF)-driven synthesis is considered as a promising alternative for the development of new catalytic materials with well-designed active sites. This synthetic approach is used here to gradually transform a new bimetallic MOF, with Pd and Fe as the metal components, by the in situ generation of aniline under mild conditions. This methodology results in a compositionally homogeneous nanocomposite formed by Fe-doped Pd nanoparticles that, in turn, are supported on iron oxide-doped carbon. The nanocomposite has been fully characterized by several techniques such as IR and Raman spectroscopy, TEM, XPS, and XAS. The performance of this nanocomposite as an heterogeneous catalyst for hydrogenation of nitroarenes and nitrobenzene coupling with benzaldehyde has been evaluated, proving it to be an efficient and reusable catalyst. ; This work has been supported by the European Union (ERC2016-CoG 724681-S-CAGE), by the Spanish MICINN (Structures of Excellence Severo Ochoa SEV-2016-0683 and Maria de Maeztu CEX2019-000919-M; projects CTQ2017-89528-P, CTQ2015-67592, PGC2018-097277-B-100, and RTI2018-096399A-I00 co-financed by FEDER). We also thank the Generalitat Valenciana (PROMETEO/2018/006 and PROMETEU/2019/066). G.M.E. and P.O.-B. thank MICINN for their "Ramon y Cajal" fellowships. M.G.-M thanks support of a fellowship from "la Caixa" Foundation (LCF/BQ/PI19/11690022) and Generalitat Valenciana (SEJI/2020/036). J.M. thanks MICINN for his PhD fellowship (CTQ2015-67592). The authors also thank the Electron Microscopy Service of Universitat Politicnica de Val~ncia for their support, M. P. Romero for her assistance with TEM measurements and Prof. E. Rodr~guez-Castellin for discussions on the XPS spectra interpretation. This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory and was supported by the U.S. DOE under contract no. DE-AC02-06CH11357, and the Canadian ...