Sub-nanometric ruthenium clusters prepared by solid-state dispersion for catalytic selective aerobic oxidation of aromatic alcohols

The selective aerobic oxidation of alcohols to corresponding aldehydes is one of the most important challenges in the green chemical industry. In this work, Ru/Al 2 O 3 -SSD catalyst with highly dispersed metallic ruthenium clusters (average particle size of 0.97 nm) was prepared by solid-state dispersion (SSD) for efficient selective aerobic oxidation of aromatic alcohols to aldehydes. Compared with the counterpart catalyst Ru/Al 2 O 3 -IM prepared by wet impregnation (IM), this catalyst has smaller metal particles (0.97 nm vs. 3.4 nm), resulting in a special electronic structure, and exhibits much higher TOF (234 h −1 vs. 98 h −1 ) in the aerobic oxidation reaction of benzyl alcohol at 80 °C. The catalyst also shows excellent catalytic activity in the preparation of vanillin by selective aerobic oxidation of vanillyl alcohol at 100 °C, delivering a vanillin yield of 99%. The solid-state dispersion strategy provides an efficient and facile way for the fabrication of high-performance sub-nanometric metal catalysts. Ru/Al 2 O 3 -SSD catalyst with highly dispersed sub-nanometric Ru clusters was prepared by solid-state dispersion, which exhibits excellent catalytic activity and selectivity for the selective aerobic oxidation of aromatic alcohols. • Highly dispersed ruthenium clusters catalyst Ru/Al 2 O 3 -SSD (average size of 0.97 nm) was prepared by solid-state dispersion. • The Ru/Al 2 O 3 -SSD possesses higher Ru 0 ratio, exhibiting excellent activity in the selective oxidation of aromatic alcohol. • The Ru/Al 2 O 3 -SSD shows excellent activity in the selective oxidation of vanillyl alcohol, delivering a vanillin yield of 99%. • The solid-state dispersion strategy provides an efficient and facile way for the fabrication of high-performance sub-nanometric metal catalysts.