Structural modulation and direct measurement of subnanometric bimetallic PtSn clusters confined in zeolites

Abstract

628 638 3 8 ; S ; [EN] Modulating the structures of subnanometric metal clusters at the atomic level is a great synthetic and characterization challenge in catalysis. Here, we show how the catalytic properties of subnanometric platinum clusters (0.5-0.6 nm) confined in the sinusoidal 10R channels of purely siliceous MFI zeolite are modulated upon introduction of partially reduced tin species that interact with the noble metal at the metal/support interface. The platinum-tin clusters are stable in H(2)over an extended period of time (>6 h), even at high temperatures (for example, 600 degrees C), which is determined by only a few additional tin atoms added to the platinum clusters. The structural features of platinum-tin clusters, which are not immediately visible by conventional characterization techniques but can be established after combination of in situ extended X-ray absorption fine structure, high-angle annular dark-field scanning transmission electron microscopy and CO infrared data, are key to providing a one-order of magnitude lower deactivation rate in the propane dehydrogenation reaction while maintaining high intrinsic (initial) catalytic activity This work was 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 the ITQ for providing a contract. The authors also thank the Microscopy Service of the UPV for the TEM and STEM measurements. The XAS measurements were carried out in the CLAESS beamline of the ALBA synchrotron. We thank Giovanni Agostini for his kind support in the analysis of XAS data. HR-HAADF-STEM measurements were performed at DME-UCA at Cadiz University with financial support from FEDER/MINECO (MAT2017-87579-R and MAT2016-81118-P). C.W.L. thanks CAPES (Science without Frontiers -Process no. 13191/13-6) for a predoctoral fellowship. The financial support from ExxonMobil for this project is also greatly acknowledged. Liu, L.; Lopez-Haro, ...