Confinement of Atomically Dispersed Pt^δ+ Sites in Zinc-Incorporated Silicalite-1 Zeolite for Enhanced Propane Dehydrogenation

Abstract

For industrial use, propylene production requires efficient and cost-effective propane dehydrogenation (PDH) catalysts. Given the scarcity of platinum and toxicity of chromium, enhancing the catalytic activity and high-temperature stability of zinc-based alternative catalysts bearing a limited amount of Pt would be ideal. Here, we successfully created a low-loaded platinum-confined and zinc-incorporated MFI-type silicalite-1 zeolite catalyst via a facile one-pot synthesis route aided by a micro-liquid film reactor. It was demonstrated that highly dispersed Zn ions were fully incorporated into the S-1 framework, while atomically dispersed Pt δ+ binding to the framework oxygen atoms could be firmly confined in the S-1 micropores. The as-constructed catalyst with only 0.041 wt % Pt loading displayed an impressively ultralow deactivation rate constant of approximately 0.0007 h –1 in the PDH at the WHSV of 2.4 h –1 and 600 °C. More significantly, the catalyst achieved a remarkably high propylene production rate of 188.1 mol C3H6 ·g Pt –1 ·h –1 at the higher WHSV of 12 h –1, far surpassing those of the state-of-the-art PtZn- and PtSn-based catalysts for PDH operated at the medium WHSV values. By combining the multiple characterizations and density functional theory calculations, it was unveiled that the high catalytic efficiency and high-temperature stability of the catalyst was ascribed to the formation of unique atomically dispersed Pt δ+ –O–Zn structures in the catalyst. This work proposes an effective strategy for tuning the nature of active metal sites in zeolites to create high-performance catalysts across diverse heterogeneous catalytic processes.

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