Efficient Catalytic Hydroformylation of Alkenes on Rh/CeO₂ Catalysts Modulated by CeO₂ Morphology

Abstract

The hydroformylation of alkenes represents an economically sustainable and widespread industrial application for high-value-added aldehyde preparation. Herein, a series of cerium oxide (CeO 2 ) catalysts with various morphologies (rods, polyhedra, and octahedra) were prepared using a simple impregnation-reduction method, and Rh active sites were evenly dispersed on the CeO 2 surface. Due to the existence of oxygen vacancies in the catalysts, unsaturated sites were generated, the adsorption energy of CO on the catalyst surfaces was optimized, and the reaction energy barrier was reduced. Thus, the obtained catalysts showed a good catalytic performance. The oxygen vacancy concentration (D/F 2g ) of the three prepared catalysts followed the order: CeO 2 -R-Rh (0.47) > CeO 2 -P-Rh (0.42) > CeO 2 -O-Rh (0.36). CeO 2 -R-Rh showed excellent catalytic styrene hydroformylation activity, with 99% styrene conversion and 98% aldehyde selectivity under a low syngas pressure and phosphate-free ligands. At the same time, CeO 2 -R-Rh showed excellent general applicability for the hydroformylation of various other alkenes, implying a broad scope of potential applications. The strategy presented herein for adjusting catalytic performance through the strong interaction of the metal-oxide-supported interface contributes fresh perspectives to understanding the hydroformylation reaction.