Structural and Catalytic Properties of Alkaline Post‐Treated Ru/ZrO2 Catalysts for Partial Hydrogenation of Benzene to Cyclohexene

Abstract Partial hydrogenation of benzene to cyclohexene is attractive in terms of feedstock accessibility, atomic economy, and operational simplicity. Herein, a series of Ru/ZrO 2 catalysts were prepared by post‐treatment of a binary Ru–Zn/ZrO 2 catalyst using 5–30 wt % NaOH aqueous solutions. Alloying between Ru and Zn was evidenced for the catalyst post‐treated only by water (Ru/ZrO 2 ‐0). Alkaline post‐treatment removed metallic Zn, forming smaller Ru nanoparticles. Concomitantly, the hydrophilicity of the catalysts was increased and maximized on the 10 wt % NaOH‐treated catalyst (Ru/ZrO 2 ‐10). In partial hydrogenation of benzene, the Ru/ZrO 2 ‐0 catalyst displayed the highest turnover frequency but the lowest initial selectivity to cyclohexene, whereas the Ru/ZrO 2 ‐10 catalyst exhibited the highest initial selectivity (86 %) and yield of cyclohexene (51 %) among the catalysts investigated. A quantitative relationship between the initial selectivity to cyclohexene and the hydrophilicity of these catalysts was identified, which rationalizes the significant impact of alkaline post‐treatment on selectivity enhancement in partial hydrogenation of benzene to cyclohexene over Ru/ZrO 2 catalysts.