Bimetallic Ru–M/TiO2 (M = Fe, Ni, Cu, Co) nanocomposite catalysts facribated by galvanic replacement: Structural elucidation and catalytic behavior in benzene selective hydrogenation

• Published in: Applied surface science Vol. 456; pp. 1004 - 1013
• Main Authors: Zhou, Gongbing, Dong, Yanlu, He, Daiping
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31.10.2018
• Subjects: Benzene; Cyclohexene; Galvanic replacement; Ruthenium; Surface structure; Galvanic replacement; Ruthenium; Cyclohexene; Benzene; Surface structure
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2018.06.206

The Ru–M/TiO2 catalysts fabricated by galvanic replacement between previously supported metal nanoparticles and Ru cations were highly efficient in benzene selective hydrogenation. [Display omitted] •The Ru–M/TiO2 (M = Fe, Ni, Cu, Co) catalysts were fabricated by galvanic replacement.•The Ru–M/TiO2 catalysts were characterized by a combination of techniques.•The Ru–M/TiO2 catalysts were performed in benzene selective hydrogenation.•Co enabled a highest cyclohexene selectivity (S0 of 85%) and yield (41%).•The effect of sacrificial template on catalytic properties was revealed. On basis of the galvanic replacement between the previously supported Fe, Ni, Cu, and Co nanoparticles (NPs) and Ru salt followed by acid treatment, a novel strategy was developed for the fabrication of bimetallic Ru–M/TiO2 (M = Fe, Ni, Cu, Co) nanocomposite catalysts. The surface structure, composition, chemical state, and acidic properties of the catalysts were comprehensively investigated by transmission electron microscopy, X-ray photoelectron spectroscopic spectrum, and Fourier transformed infrared spectroscopy of adsorbed pyridine. It is identified that the Ru species on the Ru–M/TiO2 catalysts were electron-deficient owing to the electron-donation from Ru to sacrificial templates. In benzene selective hydrogenation to cyclohexene, the turnover frequencies of benzene on the Ru–Fe/TiO2, Ru–Ni/TiO2, and Ru–Co/TiO2 catalysts are similar and higher than that on the Ru–Cu/TiO2 catalyst, whereas the selectivity to cyclohexene increased in the order of Ru–Fe/TiO2 < Ru–Ni/TiO2 < Ru–Cu/TiO2 < Ru–Co/TiO2, attaining a maximum of 85%. The sequence of the electron-deficient degree of Ru on the Ru–M/TiO2 catalysts is identical with that of the cyclohexene selectivity, which rationalized the variation of cyclohexene selectivity since the electron-deficient Ru species may lower the adsorption strength of cyclohexene on the catalysts.