Encapsulation of Pt Nanoparticles in ZSM‐5 Zeolite for the Durable Hydrogen‐Water Isotope Exchange

ABSTRACT

Bifunctional Pt‐zeolite catalysts have shown outstanding activity for hydrogen‐water isotope exchange due to the highly‐efficient synergy between metal and Brønsted acid. However, the aggregation and sintering of Pt particles during this reaction impose the great difficulties for their practical applications. Here, the highly dispersed Pt nanoparticles were embedded into framework or channeled within micropores of ZSM‐5 by one‐pot hydrothermal synthesis to form the encapsulated catalysts. For comparison, a supported one with Pt species predominantly dewelled on the extra‐framework was prepared to interrogate their catalytic durabilities during H ₂ ‐HDO isotope exchange. The similarly catalytic efficacy of metal‐acid enables the encapsulated and supported ones to share the same reaction pathway by the protonated water clusters on acid sites to deliver deuteron to reactive ones for the interfacial hydrogen isotope exchange between Pt and water cluster, leading to the measured reaction rate and activation energy to be comparable. During the long‐term running, the encapsulated Pt‐zeolite catalyst exhibits the superior stability with the ignorable activity loss due to the physical constraint effect to suppress the migration of Pt species. However, the absence of this effect upon the supported one causes the severe sintering and agglomeration of metal species, which greatly deteriorates the catalytic exchange.