cs9b03842_si_001.pdf (7.77 MB)
Molecular-Level Proximity of Metal and Acid Sites in Zeolite-Encapsulated Pt Nanoparticles for Selective Multistep Tandem Catalysis
journal contribution
posted on 2020-02-24, 12:33 authored by Hong Je Cho, Doyoung Kim, Shuang Li, Dong Su, Ding Ma, Bingjun XuThe proximity of different catalytic
sites is key to selective
catalysis; however, the controlled placement of multiple types of
active sites is synthetically challenging. In this work, we show that
the framework Al atoms are enriched around intracrystalline mesopores
that encapsulate Pt nanoparticles in H-ZSM-5, referred to as the “halo
effect”. The molecular level proximity between Brønsted
acid and Pt sites is demonstrated by quantitative Fourier-transform
infrared spectroscopy and transmission electron microscopy. The halo
effect enables the selective conversion of furfural to valeric acid
and ethyl valerate (VA/EV) via a 5-step tandem reaction in one pot
with an 86% yield. In contrast, control experiments show that catalysts
with identical metal and acid site densities but without the halo
effect produce only a 5% yield of VA/EV under identical conditions.
The ready access of intermediates to the active sites in the subsequent
reaction enabled by the halo effect is key to the enhanced performance
in tandem catalysis and reduced catalyst deactivation.