Supported catalysts based on Pd–In nanoparticles for the liquid-phase hydrogenation of terminal and internal alkynes: 1. formation and structure

Abstract

The formation of Pd–In catalysts synthesized from the heteronuclear acetate complex PdIn(CH₃COO)₅ was studied by temperature-programmed reduction, electron microscopy, IR spectroscopy of adsorbed CO and hydrogen temperature-programmed desorption (H₂-TPD). IR spectroscopy of adsorbed CO and H₂-TPD confirmed the formation of bimetallic Pd–In nanoparticles. It was found that the Pd–In nanoparticle surface contains predominantly Pd atoms separated from one another by indium atoms, which is evidenced by the disappearance of the CO band shift resulting from the lateral dipole–dipole interaction between adsorbed CO molecules and by a significant decrease in the band intensity of CO adsorbed in bridged form. Almost complete inhibition of palladium hydride (PdH_x) provides additional evidence of the formation of Pd–In bimetallic particles.