Ceria-Praseodymia Mixed Oxides: Relationships Between Redox Properties and Catalytic Activities Towards NO Oxidation to NO2 and CO-PROX Reactions

A series of CexPr1−xO2−δ catalysts was prepared by co-precipitation method in alkali media. These catalysts were characterized by N2 adsorption–desorption isotherms at −196 °C, X-ray diffraction, thermogravimetry combined with mass spectrometry (TG-MS), and temperature-programmed reduction with H2 and CO (H2-TPR and CO-TPR, respectively). Catalytic tests were performed for temperature programmed NO oxidation to NO2 (from 25 to 750 °C) and for the preferential oxidation of CO in H2 rich stream (CO-PROX reaction) in the range of 150–500 °C. The trends in the order of catalytic activities towards NO oxidation and CO-PROX are correlated with the redox properties of the catalysts and their composition. CexPr1−xO2−δ mixed oxides present very different catalytic behaviours towards NO oxidation and CO-PROX reactions. These experimental trends might be explained by the balance of several factors: the acid character of the NO and CO molecules, the different lattice oxygen mobility of the catalysts, the presence of surface carbonates species in the samples, and the catalysts’ reducibility under H2 and CO. The understanding of the features that govern the activity towards these environmentally relevant oxidation reactions is important in the designing of effective catalysts.The authors gratefully acknowledge the financial support of Generalitat Valenciana (PROMETEOII/2014/010), MINECO (CTQ2015-64801-R, MAT2013-40823-R, CSD2009-00013) and the UE (FEDER funding). X. Chen thanks the program of “Ramón y Cajal” from Ministry of Science and Innovation of Spain

Regioselective Generation of Single-Site Iridium Atoms and Their Evolution into Stabilized Subnanometric Iridium Clusters in MWW Zeolite

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 partners. The financial support from ExxonMobil on this project is also greatly acknowledged.Liu, L.; Lopez-Haro, M.; Meira, DM.; Concepción Heydorn, P.; Calvino, JJ.; Corma Canós, A. (2020). Regioselective Generation of Single-Site Iridium Atoms and Their Evolution into Stabilized Subnanometric Iridium Clusters in MWW Zeolite. Angewandte Chemie International Edition. 59(36):15695-15702. https://doi.org/10.1002/anie.202005621S15695157025936Liu, L., & Corma, A. (2018). Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles. Chemical Reviews, 118(10), 4981-5079. doi:10.1021/acs.chemrev.7b00776Thomas, J. M., Raja, R., & Lewis, D. W. (2005). Single-Site Heterogeneous Catalysts. Angewandte Chemie International Edition, 44(40), 6456-6482. doi:10.1002/anie.200462473Thomas, J. M., Raja, R., & Lewis, D. W. (2005). Heterogene Single-Site-Katalysatoren. Angewandte Chemie, 117(40), 6614-6641. doi:10.1002/ange.200462473Wang, A., Li, J., & Zhang, T. (2018). Heterogeneous single-atom catalysis. Nature Reviews Chemistry, 2(6), 65-81. doi:10.1038/s41570-018-0010-1Pelletier, J. D. A., & Basset, J.-M. (2016). Catalysis by Design: Well-Defined Single-Site Heterogeneous Catalysts. Accounts of Chemical Research, 49(4), 664-677. doi:10.1021/acs.accounts.5b00518Pan, Y., Zhang, C., Liu, Z., Chen, C., & Li, Y. (2020). Structural Regulation with Atomic-Level Precision: From Single-Atomic Site to Diatomic and Atomic Interface Catalysis. Matter, 2(1), 78-110. doi:10.1016/j.matt.2019.11.014Gates, B. C., Flytzani-Stephanopoulos, M., Dixon, D. A., & Katz, A. (2017). Atomically dispersed supported metal catalysts: perspectives and suggestions for future research. Catalysis Science & Technology, 7(19), 4259-4275. doi:10.1039/c7cy00881cHoffman, A. S., Debefve, L. M., Zhang, S., Perez-Aguilar, J. E., Conley, E. T., Justl, K. R., … Gates, B. C. (2018). Beating Heterogeneity of Single-Site Catalysts: MgO-Supported Iridium Complexes. ACS Catalysis, 8(4), 3489-3498. doi:10.1021/acscatal.8b00143Oliver-Meseguer, J., Cabrero-Antonino, J. R., Domínguez, I., Leyva-Pérez, A., & Corma, A. (2012). Small Gold Clusters Formed in Solution Give Reaction Turnover Numbers of 10 7 at Room Temperature. Science, 338(6113), 1452-1455. doi:10.1126/science.1227813Corma, A., Concepción, P., Boronat, M., Sabater, M. J., Navas, J., Yacaman, M. J., … Mayoral, A. (2013). Exceptional oxidation activity with size-controlled supported gold clusters of low atomicity. Nature Chemistry, 5(9), 775-781. doi:10.1038/nchem.1721Serna, P., & Gates, B. C. (2014). Molecular Metal Catalysts on Supports: Organometallic Chemistry Meets Surface Science. Accounts of Chemical Research, 47(8), 2612-2620. doi:10.1021/ar500170kLu, J., Aydin, C., Browning, N. D., & Gates, B. C. (2012). Imaging Isolated Gold Atom Catalytic Sites in Zeolite NaY. Angewandte Chemie International Edition, 51(24), 5842-5846. doi:10.1002/anie.201107391Lu, J., Aydin, C., Browning, N. D., & Gates, B. C. (2012). Imaging Isolated Gold Atom Catalytic Sites in Zeolite NaY. Angewandte Chemie, 124(24), 5944-5948. doi:10.1002/ange.201107391Liu, L., & Corma, A. (2020). Evolution of Isolated Atoms and Clusters in Catalysis. Trends in Chemistry, 2(4), 383-400. doi:10.1016/j.trechm.2020.02.003Pan, C., Pelzer, K., Philippot, K., Chaudret, B., Dassenoy, F., Lecante, P., & Casanove, M.-J. (2001). Ligand-Stabilized Ruthenium Nanoparticles:  Synthesis, Organization, and Dynamics. Journal of the American Chemical Society, 123(31), 7584-7593. doi:10.1021/ja003961mMartínez-Prieto, L. M., & Chaudret, B. (2018). Organometallic Ruthenium Nanoparticles: Synthesis, Surface Chemistry, and Insights into Ligand Coordination. Accounts of Chemical Research, 51(2), 376-384. doi:10.1021/acs.accounts.7b00378Liu, L., Díaz, U., Arenal, R., Agostini, G., Concepción, P., & Corma, A. (2016). Generation of subnanometric platinum with high stability during transformation of a 2D zeolite into 3D. Nature Materials, 16(1), 132-138. doi:10.1038/nmat4757Sun, Q., Wang, N., Zhang, T., Bai, R., Mayoral, A., Zhang, P., … Yu, J. (2019). Zeolite‐Encaged Single‐Atom Rhodium Catalysts: Highly‐Efficient Hydrogen Generation and Shape‐Selective Tandem Hydrogenation of Nitroarenes. Angewandte Chemie International Edition, 58(51), 18570-18576. doi:10.1002/anie.201912367Sun, Q., Wang, N., Zhang, T., Bai, R., Mayoral, A., Zhang, P., … Yu, J. (2019). Zeolite‐Encaged Single‐Atom Rhodium Catalysts: Highly‐Efficient Hydrogen Generation and Shape‐Selective Tandem Hydrogenation of Nitroarenes. Angewandte Chemie, 131(51), 18743-18749. doi:10.1002/ange.201912367Liu, Y., Li, Z., Yu, Q., Chen, Y., Chai, Z., Zhao, G., … Li, Y. (2019). A General Strategy for Fabricating Isolated Single Metal Atomic Site Catalysts in Y Zeolite. Journal of the American Chemical Society, 141(23), 9305-9311. doi:10.1021/jacs.9b02936Wu, S., Yang, X., & Janiak, C. (2019). Confinement Effects in Zeolite‐Confined Noble Metals. Angewandte Chemie International Edition, 58(36), 12340-12354. doi:10.1002/anie.201900013Wu, S., Yang, X., & Janiak, C. (2019). Confinement Effects in Zeolite‐Confined Noble Metals. Angewandte Chemie, 131(36), 12468-12482. doi:10.1002/ange.201900013Liu, L., Lopez-Haro, M., Lopes, C. W., Li, C., Concepcion, P., Simonelli, L., … Corma, A. (2019). Regioselective generation and reactivity control of subnanometric platinum clusters in zeolites for high-temperature catalysis. Nature Materials, 18(8), 866-873. doi:10.1038/s41563-019-0412-6Camblor, M. A., Corma, A., Díaz-Cabañas, M.-J., & Baerlocher, C. (1998). Synthesis and Structural Characterization of MWW Type Zeolite ITQ-1, the Pure Silica Analog of MCM-22 and SSZ-25. The Journal of Physical Chemistry B, 102(1), 44-51. doi:10.1021/jp972319kYücelen, E., Lazić, I., & Bosch, E. G. T. (2018). Phase contrast scanning transmission electron microscopy imaging of light and heavy atoms at the limit of contrast and resolution. Scientific Reports, 8(1). doi:10.1038/s41598-018-20377-2Liu, L., Wang, N., Zhu, C., Liu, X., Zhu, Y., Guo, P., … Han, Y. (2020). Direct Imaging of Atomically Dispersed Molybdenum that Enables Location of Aluminum in the Framework of Zeolite ZSM‐5. Angewandte Chemie International Edition, 59(2), 819-825. doi:10.1002/anie.201909834Liu, L., Wang, N., Zhu, C., Liu, X., Zhu, Y., Guo, P., … Han, Y. (2019). Direct Imaging of Atomically Dispersed Molybdenum that Enables Location of Aluminum in the Framework of Zeolite ZSM‐5. Angewandte Chemie, 132(2), 829-835. doi:10.1002/ange.201909834Schroeder, C., Mück‐Lichtenfeld, C., Xu, L., Grosso‐Giordano, N. A., Okrut, A., Chen, C., … Koller, H. (2020). A Stable Silanol Triad in the Zeolite Catalyst SSZ‐70. Angewandte Chemie International Edition, 59(27), 10939-10943. doi:10.1002/anie.202001364Schroeder, C., Mück‐Lichtenfeld, C., Xu, L., Grosso‐Giordano, N. A., Okrut, A., Chen, C., … Koller, H. (2020). Stabile Silanoltriaden im Zeolithkatalysator SSZ‐70. Angewandte Chemie, 132(27), 11032-11036. doi:10.1002/ange.202001364Corma, A., Fornes, V., Pergher, S. B., Maesen, T. L. M., & Buglass, J. G. (1998). Delaminated zeolite precursors as selective acidic catalysts. Nature, 396(6709), 353-356. doi:10.1038/24592Leonowicz, M. E., Lawton, J. A., Lawton, S. L., & Rubin, M. K. (1994). MCM-22: A Molecular Sieve with Two Independent Multidimensional Channel Systems. Science, 264(5167), 1910-1913. doi:10.1126/science.264.5167.1910Moliner, M., Gabay, J. E., Kliewer, C. E., Carr, R. T., Guzman, J., Casty, G. L., … Corma, A. (2016). Reversible Transformation of Pt Nanoparticles into Single Atoms inside High-Silica Chabazite Zeolite. Journal of the American Chemical Society, 138(48), 15743-15750. doi:10.1021/jacs.6b10169Liu, L., Zakharov, D. N., Arenal, R., Concepcion, P., Stach, E. A., & Corma, A. (2018). Evolution and stabilization of subnanometric metal species in confined space by in situ TEM. Nature Communications, 9(1). doi:10.1038/s41467-018-03012-6Yan, W., Xi, S., Du, Y., Schreyer, M. K., Tan, S. X., Liu, Y., & Borgna, A. (2018). Heteroatomic Zn-MWW Zeolite Developed for Catalytic Dehydrogenation Reactions: A Combined Experimental and DFT Study. ChemCatChem, 10(14), 3078-3085. doi:10.1002/cctc.201800199De Graaf, J., van Dillen, A. ., de Jong, K. ., & Koningsberger, D. . (2001). Preparation of Highly Dispersed Pt Particles in Zeolite Y with a Narrow Particle Size Distribution: Characterization by Hydrogen Chemisorption, TEM, EXAFS Spectroscopy, and Particle Modeling. Journal of Catalysis, 203(2), 307-321. doi:10.1006/jcat.2001.3337Jentys, A. (1999). Estimation of mean size and shape of small metal particles by EXAFS. Physical Chemistry Chemical Physics, 1(17), 4059-4063. doi:10.1039/a904654bLu, J., Serna, P., Aydin, C., Browning, N. D., & Gates, B. C. (2011). Supported Molecular Iridium Catalysts: Resolving Effects of Metal Nuclearity and Supports as Ligands. Journal of the American Chemical Society, 133(40), 16186-16195. doi:10.1021/ja206486jZhao, A., & Gates, B. C. (1996). Hexairidium Clusters Supported on γ-Al2O3:  Synthesis, Structure, and Catalytic Activity for Toluene Hydrogenation. Journal of the American Chemical Society, 118(10), 2458-2469. doi:10.1021/ja952996xNoei, H., Franz, D., Creutzburg, M., Müller, P., Krausert, K., Grånäs, E., … Stierle, A. (2018). Monitoring the Interaction of CO with Graphene Supported Ir Clusters by Vibrational Spectroscopy and Density Functional Theory Calculations. The Journal of Physical Chemistry C, 122(8), 4281-4289. doi:10.1021/acs.jpcc.7b10845Fielicke, A., Gruene, P., Meijer, G., & Rayner, D. M. (2009). The adsorption of CO on transition metal clusters: A case study of cluster surface chemistry. Surface Science, 603(10-12), 1427-1433. doi:10.1016/j.susc.2008.09.064Henninen, T. R., Bon, M., Wang, F., Passerone, D., & Erni, R. (2020). The Structure of Sub‐nm Platinum Clusters at Elevated Temperatures. Angewandte Chemie International Edition, 59(2), 839-845. doi:10.1002/anie.201911068Henninen, T. R., Bon, M., Wang, F., Passerone, D., & Erni, R. (2019). The Structure of Sub‐nm Platinum Clusters at Elevated Temperatures. Angewandte Chemie, 132(2), 849-855. doi:10.1002/ange.201911068Okumura, M., Irie, Y., Kitagawa, Y., Fujitani, T., Maeda, Y., Kasai, T., & Yamaguchi, K. (2006). DFT studies of interaction of Ir cluster with O2, CO and NO. Catalysis Today, 111(3-4), 311-315. doi:10.1016/j.cattod.2005.10.042Flaherty, D. W., & Iglesia, E. (2013). Transition-State Enthalpy and Entropy Effects on Reactivity and Selectivity in Hydrogenolysis of n-Alkanes. Journal of the American Chemical Society, 135(49), 18586-18599. doi:10.1021/ja4093743Talu, O., Sun, M. S., & Shah, D. B. (1998). Diffusivities ofn-alkanes in silicalite by steady-state single-crystal membrane technique. AIChE Journal, 44(3), 681-694. doi:10.1002/aic.690440316Flaherty, D. W., Uzun, A., & Iglesia, E. (2015). Catalytic Ring Opening of Cycloalkanes on Ir Clusters: Alkyl Substitution Effects on the Structure and Stability of C–C Bond Cleavage Transition States. The Journal of Physical Chemistry C, 119(5), 2597-2613. doi:10.1021/jp511688xHibbitts, D. D., Flaherty, D. W., & Iglesia, E. (2015). Role of Branching on the Rate and Mechanism of C–C Cleavage in Alkanes on Metal Surfaces. ACS Catalysis, 6(1), 469-482. doi:10.1021/acscatal.5b01950Majesté, A., Balcon, S., Guérin, M., Kappenstein, C., & Paál, Z. (1999). Hydrogenolysis of n-Hexane on Al2O3-Supported Ir Catalysts of Various Treatments. Journal of Catalysis, 187(2), 486-492. doi:10.1006/jcat.1999.2621Corma, A., Catlow, C. R. A., & Sastre, G. (1998). Diffusion of Linear and Branched C7 Paraffins in ITQ-1 Zeolite. A Molecular Dynamics Study. The Journal of Physical Chemistry B, 102(37), 7085-7090. doi:10.1021/jp9813084Sastre, G., Catlow, C. R. A., & Corma, A. (2002). Influence of the Intermolecular Interactions on the Mobility of Heptane in the Supercages of MCM-22 Zeolite. A Molecular Dynamics Study. The Journal of Physical Chemistry B, 106(5), 956-962. doi:10.1021/jp013589cShi, H., Gutiérrez, O. Y., Haller, G. L., Mei, D., Rousseau, R., & Lercher, J. A. (2013). Structure sensitivity of hydrogenolytic cleavage of endocyclic and exocyclic C–C bonds in methylcyclohexane over supported iridium particles. Journal of Catalysis, 297, 70-78. doi:10.1016/j.jcat.2012.09.01

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

Regioselective generation and reactivity control of subnanometric platinum clusters in zeolites for high-temperature catalysis

[EN] Subnanometric metal species (single atoms and clusters) have been demonstrated to be unique compared with their nanoparticulate counterparts. However, the poor stabilization of subnanometric metal species towards sintering at high temperature (>500 degrees C) under oxidative or reductive reaction conditions limits their catalytic application. Zeolites can serve as an ideal support to stabilize subnanometric metal catalysts, but it is challenging to localize subnanometric metal species on specific sites and modulate their reactivity. We have achieved a very high preference for localization of highly stable subnanometric Pt and PtSn clusters in the sinusoidal channels of purely siliceous MFI zeolite, as revealed by atomically resolved electron microscopy combining high-angle annular dark-field and integrated differential phase contrast imaging techniques. These catalysts show very high stability, selectivity and activity for the industrially important dehydrogenation of propane to form propylene. This stabilization strategy could be extended to other crystalline porous materials.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 Programme (SEV-2016-0683). L.L. thanks ITQ for providing a contract. The authors also thank the Microscopy Service of UPV for the TEM and STEM measurements. The XAS measurements were carried out in CLAESS beamline at the ALBA synchrotron. HR STEM measurements were performed at DME-UCA in Cadiz University with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). A relevant patent application (European patent application No. 19382024.8) has been presented. C.W.L. thanks CAPES (Science without Frontiers-Process no. 13191/13-6) for a predoctoral fellowship.Liu, L.; Lopez-Haro, M.; Lopes, CW.; Li, C.; Concepción Heydorn, P.; Simonelli, L.; Calvino, JJ.... (2019). Regioselective generation and reactivity control of subnanometric platinum clusters in zeolites for high-temperature catalysis. Nature Materials. 18(8):866-875. https://doi.org/10.1038/s41563-019-0412-6S86687518

NO Oxidation on Lanthanum-Doped Ceria Nanoparticles with Controlled Morphology

The present work aims to assess the impact of morphology and reducibility on lanthanum-doped ceria nanocatalysts with controlled morphology on the NO oxidation reaction. Specifically, samples were prepared using a hydrothermal method incorporating lanthanum at varying molar concentrations (0, 5, 10, and 15 mol.%) into ceria with a controlled morphology (nanocubes and nanorods). The structural, compositional, and redox characterization of these catalysts has been performed via scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (X-EDS), inductively coupled plasma (ICP), hydrogen temperature-programmed reduction (H2-TPR), and oxygen storage capacity (OSC). NO oxidation catalytic tests were conducted, and the results were compared with estimated curves (obtained by considering the proportions of the corresponding components), which revealed the presence of a synergistic effect between lanthanum and ceria. The degree of enhancement was found to depend on both the morphology and the amount of lanthanum incorporated into CeO2. These findings may facilitate the optimization of features concerning ceria-based nanocatalysts for the removal of NOx emissions from exhaust gases.This research was funded by Generalitat Valenciana (CIPROM/2021/070 project), the Spanish Ministry of Science and Innovation/Research Spanish Agency (PID2019-105542RB-I00/AEI/10.13039/501100011033, PID2020-113006RB-I00/AEI/10.13039/501100011033 and PID2020-113809RB-C33 projects), and UE-FEDER funding

Novelty without nobility: Outstanding Ni/Ti-SiO2 catalysts for propylene epoxidation

An efficient gas-phase production of propylene oxide (PO) with noble metal-free catalysts could modify the industrial output of this valuable compound. We present a novel catalyst based on well-dispersed Ni nanoparticles loaded on a Ti-SiO2 support for the propylene epoxidation reaction using H2/O2 mixtures. XPS, High Resolution Transmission Electron Microscopy (HRTEM), and UV–Vis corroborate both the small size of Ni particles and the excellent dispersion and incorporation of Ti as tetrahedral single site species into the silica framework. The catalytic results under steady-state conditions at low temperature (200 °C) show high PO selectivity (around 85%) with a substantial propylene conversion (over 6%) and excellent H2 efficiency (~37%) using only 0.5 wt% of Ni on Ti-SiO2 (Ti/Si = 0.01 M ratio). In this work, we have also carried out a preliminary DFT study to gain understanding of the characteristics that make this nickel catalyst active and selective for the propene epoxidation reaction.We thank the Spanish Ministry of Economy and Competitiveness (MINECO), Spanish Ministry of Science, Innovation and Universities, Generalitat Valenciana and FEDER (CTQ2015-66080-R, RTI2018-095291-B-I00, MAT2017-87579-R, and PROMETEO/2018/076) for financial support. JFC thanks MINECO for a researcher formation grant (BES-2016-078079)

Confined Pt11+ Water Clusters in a MOF Catalyze the Low‐Temperature Water–Gas Shift Reaction with both CO2 Oxygen Atoms Coming from Water

The synthesis and reactivity of single metal atoms in a low‐valence state bound to just water, rather than to organic ligands or surfaces, is a major experimental challenge. Herein, we show a gram‐scale wet synthesis of Pt11+ stabilized in a confined space by a crystallographically well‐defined first water sphere, and with a second coordination sphere linked to a metal–organic framework (MOF) through electrostatic and H‐bonding interactions. The role of the water cluster is not only isolating and stabilizing the Pt atoms, but also regulating the charge of the metal and the adsorption of reactants. This is shown for the low‐temperature water–gas shift reaction (WGSR: CO + H2O → CO2 + H2), where both metal coordinated and H‐bonded water molecules trigger a double water attack mechanism to CO and give CO2 with both oxygen atoms coming from water. The stabilized Pt1+ single sites allow performing the WGSR at temperatures as low as 50 °C.This work was supported by the MINECO (Spain) (Projects CTQ2016–75671–P, MAT2013 40823–R, MAT2016–81732–ERC, CTQ2017–86735–P, MAT2017–86992–R, MAT2017–82288–C2–1–P and Excellence Units “Severo Ochoa” and “Maria de Maeztu” SEV–2016–0683 and MDM–2015–0538) the Generalitat Valenciana (PROMETEOII/2014/004) and the Ministero dell’Istruzione, dell’Università e della Ricerca (Italy) and the Junta de Andalucía (FQM–195). M. M. and M.–A. R. C. thanks the MINECO for a predoctoral contract. Thanks are also extended to the Ramón y Cajal Program (E. V. R.–F., E. P. and J.–C. H.–G.) and the “Subprograma atracció de talent–contractes postdoctorals de la Universitat de Valencia” (J. F.–S.). M. L.–H. acknowledges the financial support from the Juan de la Cierva Fellowships Program of MINECO (IJCI–2014–19367)

Developing and understanding Leaching-Resistant cobalt nanoparticles via N/P incorporation for liquid phase hydroformylation

The ultimate target in heterogeneous catalysis is the achievement of robust, resilient and highly efficient materials capable of resisting industrial reaction conditions. Pursuing that goal in liquid-phase hydroformylation poses a unique challenge due to carbon monoxide-induced metal carbonyl species formation, which is directly related to the formation of active homogeneous catalysts by metal leaching. Herein, supported heteroatom-incorporated (P and N) Co nanoparticles were developed to enhance the resistance compared with bare Co nanoparticles. The samples underwent characterization using operando XPS, XAS and HR electron microscopy. Overall, P- and N-doped catalysts increased reusability and suppressed leaching. Among the studied catalysts, the one with N as a dopant, CoNx@NC, presents excellent catalytic results for a Co-based catalyst, with a 94% conversion and a selectivity to aldehydes of 80% in only 7.5 h. Even under milder conditions, this catalyst outperformed existing benchmarks in Turnover Numbers (TON) and productivity. In addition, computational simulations provided atomistic insights, shedding light on the remarkable resistance of small Co clusters interacting with N-doped carbon patches