Atomically Dispersed Electron-Rich Ru Species in CoOx for the Efficient Catalytic Hydrogenolysis of 5-Hydroxymethylfurfural

Modulating the electronic environment of single-atom metal catalysts is a promising yet challenging strategy to optimize their catalytic performance. Herein, electron-rich Ru single atoms were successfully confined within a CoOx matrix (Ru0.6CoOx) through a simple manual grinding-reduction strategy. The resulting Ru0.6CoOx catalyst demonstrated exceptional catalytic activity for the hydrogenolysis of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF), affording a nearly quantitative DMF yield with an impressive DMF productivity of 210.2 molDMF·mol–1Ru·h–1 at 160 °C. This productivity outperforms most of the noble metal-based catalysts for DMF production. Notably, Ru0.6CoOx also enabled the efficient conversion of HMF to DMF at a low reaction temperature of 120 °C or using a concentrated HMF solution (up to 20 wt %). Experimental studies combined with density functional theory calculations (DFT) revealed that the electronic interaction between the Ru species and CoOx generates electron-rich Ru single atoms, which serve as active sites to boost the H2 activation. Furthermore, the introduction of single Ru atoms was shown to increase the acidity of Ru0.6CoOx, thereby facilitating the cleavage of the C–OH bond during HMF hydrogenolysis. The boosted H2 activation ability and improved acidity of Ru0.6CoOx contribute significantly to its outstanding catalytic performance. This work provides valuable insights into the preparation of electron-rich single-atom metal catalysts for the catalytic hydrodeoxygenation of biomass-derived chemicals.