Hollow Carbon Sphere Nanoreactors Loaded with PdCu Nanoparticles: Void-Confinement Effects in Liquid-Phase Hydrogenations.

Chao Dong,Run‐Ping Ye,Guang‐Hui Wang,Panpan Su,Jian Liu,Qun Yu

doi:10.1002/anie.202007297

Abstract

Nanoreactors with hollow structures have attracted great interest in catalysis research due to their void‐confinement effects. However, the challenge in unambiguously unraveling these confinement effects is to decouple them from other factors affecting catalysis. Here, we synthesize a pair of hollow carbon sphere (HCS) nanoreactors with presynthesized PdCu nanoparticles encapsulated inside of HCS (PdCu@HCS) and supported outside of HCS (PdCu/HCS), respectively, while keeping other structural features the same. Based on the two comparative nanoreactors, void‐confinement effects in liquid‐phase hydrogenation are investigated in a two‐chamber reactor. It is found that hydrogenations over PdCu@HCS are shape‐selective catalysis, can be accelerated (accumulation of reactants), decelerated (mass transfer limitation), and even inhibited (molecular‐sieving effect); conversion of the intermediate in the void space can be further promoted. Using this principle, a specific imine is selectively produced. This work provides a proof of concept for fundamental catalytic action of the hollow nanoreactors.

Highlights

Nanoreactors with hollow structures have attracted great interest in catalysis research due to their void-confinement effects
In many cases, enhanced catalytic activities or tunable selectivity in reactions over the hollow nanoreactors have been observed compared with their nonhollow analogues, which are ascribed to the void-confinement effects or molecular-sieving effects induced by the hollow structures.[3,4,5]
The excellent catalytic performances are often attributed to the void-confinement effects without any comparative analysis, solely because of the existence of the void spaces

Summary

Introduction

Nanoreactors with hollow structures have attracted great interest in catalysis research due to their void-confinement effects. These results indicate that the two nanoreactors, PdCu@HCS and PdCu/HCS, exhibit similar microporous carbon shells and hollow structures.

Results

Conclusion