Abstract
In this work, two single-atom catalysts (SACs) with atomically dispersed RuO2 supported on CrO x were successfully synthesized with a simple reduction strategy for the efficient catalytic oxidation of chlorobenzene (CB). With characterizations like Cs-corrected STEM, XPS, H2-TPR, and O2-TPD, the structure-activity relationship is addressed. The noble metal precursor Ru3+ was anchored with different oxygen species and exposed facets based on the physicochemical properties of catalyst supports. Based on the analysis results, the Ru3+ precursor could be mainly anchored into the surface lattice oxygen of Cr2O3-M over high-index facets (223) and adsorbed oxygen of Cr2O3-P over low-index facets (104), where the precursor Ru3+ was all oxidized to RuO2 when being anchored with the oxygen species of Cr2O3-M and Cr2O3-P, respectively according to XPS analysis. There is a stronger metal-support interaction (SMSI) between Ru ions and the surface lattice oxygen of Cr2O3-M, according to H2-TPR and O2-TPD characterizations. Further, the catalytic performance for CB combustion at a high space velocity of 120 000 mL (g-1 h-1) was tested, and 1RuCr2O3-M performed better than 1RuCr2O3-P in both durability and activity. This could be attributed to the SMSI between single-atom Ru and the lattice oxygen of the 1RuCr2O3-M catalyst and the abundant active sites from the exposed high-index facets. The study provided a novel synthesis strategy for Ru-based SACs with SMSI effect, and the good durability of the catalyst (1RuCr2O3-M) extended the great potential for practical application.