Ru/ZrO<sub>2</sub>催化剂在苯部分加氢反应中的粒径效应
摘要
The particle size effect on partial hydrogenation of benzene to cyclohexene over Ru/ZrO<sub>2</sub> catalysts is reported. Uniform Ru nanoparticles (NPs) with a tunable particle size from 2.4 to 5.4 nm were synthesized by a polyol reduction method and deposited on ZrO<sub>2</sub>. The catalysts were characterized by ultraviolet-visible absorption spectroscopy (UV-Vis), N<sub>2</sub> physisorption, H<sub>2</sub> chemisorption, temperature-programmed desorption of H<sub>2</sub> (H<sub>2</sub>-TPD), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It was found that the type of polyol and the concentration of additive (sodium acetate trihydrate) imposed remarkable effect on the particle size of Ru. A distinct particle size effect occurred in partial hydrogenation of benzene. With the size of the Ru NPs increasing, the hydrogenation activity of benzene increased, and the initial selectivity (<italic>S</italic><sub>0</sub>) to cyclohexene showed a volcanic-type variation tendency, which revealed that the optimal Ru size for obtaining the highest <italic>S</italic><sub>0</sub> is 4.4 nm. The Ru/ZrO<sub>2</sub> catalyst reduced by 1,2-propanediol exhibited the highest <italic>S</italic><sub>0</sub> (82%) and the yield of cyclohexene (39%). Based on the characterization results, the size effect of Ru on the activity and selectivity is discussed.