K-promoted Ru-based heterogeneous catalysts for ethylene hydroformylation.

[Display omitted] • A new RuK/Al 2 O 3 heterogeneous hydroformylation catalyst was developed. • RuK possesses higher activity and propanal selectivity than Ru, Rh and Co. • The structure-performance of the RuK and Ru catalysts was investigated. • The synergistic effect of Ru and K facilitates the formation of aldehydes. • K promoted Ru catalysts reduced the hydrogenation of olefins. Hydroformylation is a prototypical C-C coupling reaction of olefins and syngas to produce valuable higher aldehydes. In this study, we investigated the promotional effect of potassium (K) on Ru-based heterogeneous ethylene hydroformylation. The propanal selectivity could reach up to 84.9% at an ethylene (C 2 H 4) conversion of 10.7 % with the addition of K as a promoter. Furthermore, the formation of ethane and the second hydrogenation of olefins were effectively suppressed. Structural characterization results suggested that K promoter could enhance the dispersion of Ru species and increase the electronic density of Ru active sites, thus improving CO adsorption and dissociation. The synergistic effect of Ru and K created a C*-rich and H*-lean local chemical environment, facilitating the formation of aldehydes while effectively reducing the hydrogenation of olefins. This work may provide new insights for development promising Ru-based heterogeneous catalysts for hydroformylation. [ABSTRACT FROM AUTHOR]