Carbon Nanotubes Supported Mono- and Bimetallic Pt and Ru Catalysts for Selective Hydrogenation of Phenylacetylene

Deposition of Pt, Ru, Pt–Ru alloy, Ru@Pt, and Pt@Ru nanoparticles onto carbon nanotubes (CNTs) has been achieved by chemical reduction of the corresponding RuCl3·3H2O and/or H2PtCl6·6H2O by ethylene glycol in the presence of NaOH. The as-prepared catalysts were characterized by X-ray diffraction, H2-temperature programmed reduction, H2-temperature programmed desorption, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. Liquid-phase selective hydrogenation of phenylacetylene was used as a probe reaction to evaluate their catalytic performances. The as-prepared Pt, Ru, Pt–Ru alloy, Ru@Pt, and Pt@Ru nanoparticles fell in the range of 1.5–3.0 nm in diameter, and were uniformly dispersed on the CNTs. All the bimetallic catalysts displayed the characteristic diffraction peaks due to a Pt face-centered cubic structure, but the 2θ values were shifted to slightly higher ones, indicating the formation of alloy or core–shell structures. XPS analysis revealed that the catalysts c...