In recent years, single metal atoms and metal clusters have attracted a lot of attention because of their high metal dispersity, special electronic structures and uniformity of active sites as heterogeneous catalysts. Lowering the loading amount of metal components (usually below 0.5%) is the most common strategy for the generation of single atoms and clusters with high stability on supports. Meanwhile, supports were revealed to play crucial roles in determining particle morphology and maintaining dispersion. Therefore, it is highly desirable to prepare stable single atoms and clusters with a high metal content, which is still a key challenge. In the present work, a highly dispersed Ru catalyst with 1% loading content were synthesized over an amorphous alumina having 30% pentahedral coordination Al3+ sites through strong metal-support interaction (SMSI). Ru clusters and individual Ru atoms with fine dispersion are clearly observed in the HAADF-STEM images. 27Al solid state MAS-NMR results indicate that coordinative saturation of the pentacoordinate Al3+ sites is the driving force for the strong interaction between catalytic active phase and support. Compared with the Ru catalyst which was loaded on commercial γ-Al2O3, special electronic states of Ru were also showed in the DRIFT spectroscopy with CO and XPS. When the as-prepared Ru/Al2O3 used in benzene hydrogenation reaction, an excellent specific activity (TOF ≈ 7800 h-1) and 100% selectivity for cyclohexane formation were obtained. No decay in the activity and selectivity was observed for 5 cycles. The superior performance can be attributed to the high utilization of the special Ru active sites.

Coordinatively unsaturated Al3+ sites anchored subnanometric ruthenium catalyst for hydrogenation of aromatics

253rd National Meeting (2017)

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