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

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 H2 over an extended period of time (>6 h), even at high temperatures (for example, 600 °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. Tuning the structures of subnanometric metal clusters is challenging but can unlock unexpected catalytic properties. Here, the authors show that changing the composition of MFI zeolite-encapsulated PtSn subnanometric clusters by adding just a few tin atoms can lead to a remarkable stability enhancement in propane dehydrogenation.