Nanoruthenium Readily Reduces Aromatics

By stabilizing ruthenium(0) nanoclusters within a nanozeolite framework, chemists at Middle East Technical University, in Ankara, Turkey, have made a heterogeneous catalyst that exhibits remarkable activity, selectivity, and lifetime in the hydrogenation of aromatics under mild conditions—25 °C and roughly 3 atm of H₂ (J. Am. Chem. Soc., DOI: 10.1021/ja101602d). Because the catalyst works on neat aromatics, it offers a greener hydrogenation than catalysts that require solvents, say Mehmet Zahmakiran, Yalçin Tonbul, and Saim Özkar, who did the research. The team prepared the catalyst via borohydride reduction of a colloidal solution of nanozeolites that have undergone ion exchange with Ru(III). Upon investigating the catalyst’s properties, they discovered that during benzene hydrogenation to cyclohexane the catalyst will undergo 177,200 turnovers during the course of 105 hours before becoming deactivated. That’s the highest total turnover ever reported for this reaction and is 70 times greater than the previous record. In addition to benzene, the catalyst works well with substituted aromatics, such as toluene, o-xylene, and mesitylene. Furthermore, the catalysts are isolable, bottleable, and reusable, making them “superior” to many other hydrogenation catalysts, the researchers note.