Efficient Heterogeneous Hydroformylation over Zeolite-Encaged Isolated Rhodium Ions

Abstract

Alkene hydroformylation is an extremely important industry process currently accomplished via homogeneous catalysis. Heterogeneous hydroformylation is being avidly pursued as a more economical and sustainable process. Herein, we report the construction of zeolite-encaged rhodium catalyst for efficient hydroformylation. Through a facile in situ hydrothermal strategy, isolated Rhδ+ (δ = 2.5) can be encaged in faujasite and efficiently stabilized via interaction with framework oxygen atoms, producing a Rh@Y model catalyst with well-defined rhodium sites and coordination environment. Rh@Y exhibits high catalytic activity, perfect chemoselectivity, and recyclability in 1-hexene hydroformylation under mild reaction conditions, making it a robust heterogeneous catalyst for potential applications. A state-of-the-art turnover frequency value of 6567 molC=C/molRh/h for Rh@Y can be achieved in 1-hexene hydroformylation at 393 K, outperforming all heterogeneous catalysts and most homogeneous catalysts under comparable conditions. With the well-defined structure of Rh@Y, the detailed mechanism of alkene hydroformylation can be interpreted via theoretical calculations, and the advantages of heterogeneous hydroformylation are well explained. This work provides a promising solution toward efficient heterogeneous noble metal catalysis by encaging stable isolated ions in a zeolite matrix.