Design Supported Ruthenium Catalysts for the Catalytic Oxidation of (chloro)-Benzene

Ruthenium-based catalysts are commonly known for their roles in the Fischer-Tropsch synthesis as well as the synthesis of ammonia, and these catalysts have also been applied industrially for chlorine gas production via the Deacon Process. Recently, the catalytic properties of ruthenium-based catalysts in the catalytic oxidation of light alkanes and (chloro)-aromatics have attracted significant interest due to their good activities. In this article, we present our work related to design supported ruthenium catalysts for the catalytic oxidation of (chloro)-benzene. In particular, P25-TiO₂, ZrO₂, γ-Al₂O₃ and SiO₂ supported ruthenium catalysts were synthesized and well characterized by XRD, BET, ICP, XPS and TEM. These catalysts were used for benzene oxidation at first. It was found that the Ru/P25-TiO₂ catalyst with inhomogeneous distributed RuO₂ (mainly distributed in the rutile phase of P25-TiO₂) had the best activity among these catalysts. And the total conversion temperature (T₁₀₀) of benzene over the Ru/P25-TiO₂ catalyst was approximately at 230 °C. Accordingly, the Ru/P25-TiO₂ catalyst was tested for chlorobenzene oxidation. Noteworthy, T₁₀₀ of chlorobenzene over the Ru/P25-TiO₂ catalyst was below 280 °C, and the organic by-products formed during the catalytic reaction completely disappeared when T₁₀₀ of the reactant was achieved. Hence, the Ru/P25-TiO₂ catalyst showed substantial advantages than the other reported catalysts in the catalytic oxidation of chlorobenzene. Based on the results of XPS, the active species of Ru/P25-TiO₂ was described as chlorinated RuO₂. The excellent performance of the Ru/P25-TiO₂ catalyst for chlorobenzene oxidation could be attributed to the good thermal stability of RuO₂ in the rutile phase of P25-TiO₂ and chlorine removal capacity of the active species.