Zeolite-confined nano-RuO2: A green, selective, and efficient catalyst for aerobic alcohol oxidation

Article abstract of DOI:10.1021/ja0282691

The development of green, selective, and efficient catalysts, which can aerobically oxidize a variety of alcohols to their corresponding aldehydes and ketones, is of both economic and environmental significance. We report here the synthesis of a novel aerobic oxidation catalyst, a zeolite-confined nanometersized RuO₂ (RuO₂-FAU), by a one-step hydrothermal method. Using the spatial constraints of the rigid zeolitic framework, we sucessfully incorporated RuO₂ nanoparticles (1.3 ± 0.2 nm) into the supercages of faujasite zeolite. Ru K-edge X-ray absorption fine structure results indicate that the RuO₂ nanoclusters anchored in the zeolite are structurally similar to highly hydrous RuO₂; that is, there is a two-dimensional structure of independent chains, in which RuO₆ octahedra are connected together by two shared oxygen atoms. In our preliminary catalytic studies, we find that the RuO₂ nanoclusters exhibit extraordinarily high activity and selectivity in the aerobic oxidation of alcohols under mild conditions, for example, air and ambient pressure. The physically trapped RuO₂ nanoclusters cannot diffuse out of the relatively narrow channels/pores of the zeolite during the catalytic process, making the catalyst both stable and reusable.