RESEARCH ARTICLE

Hydroformylation over polyoxometalates supported single-atom Rh catalysts

¹ Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
² School of Materials Science and Engineering, Shaanxi Laboratory of Catalysis, Shaanxi University of Technology, Hanzhong 723001, China
³ School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
⁴ Department of Chemical & Biomolecular Engineering, National University of Singapore, Singapore 117580, Singapore

^* Corresponding authors (emails: qiyu@snut.edu.cn (Qi Yu); ning.yan@nus.edu.sg (Ning Yan))

Received: 30 September 2022
Revised: 3 February 2023
Accepted: 6 February 2023

Abstract

Atomic dispersion of Rh on phosphotungstic acid (PTA) salts was achieved by a self-assembled precipitation method using alkali metal ions as coprecipitation reagents. During styrene hydroformylation, the supported Rh single-atom catalyst (Rh₁/M-PTA, M refers to an alkali metal ion) demonstrated an optimum turnover frequency (TOF) of 1076 h⁻¹. With increasing ionic radius, the pore size of the catalysts increased in the following order: Rh₁/K-PTA<Rh₁/Rb-PTA<Rh₁/Cs-PTA. The catalytic activity showed the same trend, suggesting a positive correlation between pore size and hydroformylation performance. Further experimental data suggested that temperature is an important factor affecting not only the activity but also the selectivity. This study enriches the understanding of the structure and catalytic properties of PTA-supported single-atom materials. The cation-controlled synthesis of catalysts may also be applied to prepare other single-atom catalysts with tunable pore size distributions.