Active and Regioselective Ru Single-Site Heterogeneous Catalysts for Alpha-Olefin Hydroformylation

A heterogeneous ruthenium catalyst consisting of isolated single atoms and disordered clusters stabilized in a N-doped carbon matrix has been synthesized with very good activity and remarkable regioselectivity in the hydroformylation of 1-hexene. The role of the nitrogen heteroatoms has been probed essential to increase the catalyst stability and activity, enabling the stabilization of Ru(II)–N sites according to X-ray photoelectron spectroscopy (XPS) and XANES. Intrinsic size-dependent activity of Ru species of different atomicity has been extracted, correlating the observed reaction rate and the particle size distribution determined by means of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, permitting the identification of single-atom sites as the most active ones. This catalyst appears as a promising alternative with respect to its heterogeneous counterparts, paving the way for designing improved Ru heterogeneous catalysts.