Highly Stable Subnanometric\nPt Clusters in All Silica\nK‑Doped Zeolites: Implications for the CO Oxidation Reaction

Small metal clusters can provide improved catalytic activity\ncompared\nwith single metal atoms and larger metal nanoparticles of the same\nelement. The stabilization of metal ensembles of a few atoms is extremely\nchallenging, however, because reductive sintering and oxidative fragmentation\nare phenomena that often occur at low temperatures in reactive atmospheres.\nIn this regard, the CO oxidation reaction is particularly challenging\nbecause CO tends to aggregate noble metals on nonreducible supports,\nsuch as SiO<sub>2</sub>, whereas O<sub>2</sub> triggers the formation\nof (less active) single atoms on reducible supports, such as CeO<sub>2</sub>. Accordingly, state-of-the-art Pt/CeO<sub>2</sub> catalysts\nundergo severe deactivation under practical CO oxidation conditions\nin excess of O<sub>2</sub>. In this contribution, we report a highly\nactive CO oxidation catalyst that is able to overcome both sintering\nand fragmentation instabilities under conditions that make other alternatives\nfail. The catalyst is based on small Pt clusters inside K-MFI that\nbenefit from both strong metal/support interactions at defective sites\nof the zeolite and strong electronic promotion by the support, to\nattain highly stable, highly active, electron-rich Pt clusters.