Size- and structure-controlled mono- and bimetallic Ir–Pd nanoparticles in selective ring opening of indan

Nearly monodispersed 1.6 nm Ir, 2.3 nm Pd nanoparticles, 2.7 nm Pd(core)–Ir(shell) and 2.2 nm Pd–Ir alloys with mixed surface atoms were synthesised in the presence of polyvinylpyrrolidone (PVP) and studied in the atmospheric ring opening of indan. The nanoparticles and supported catalysts were characterised by UV–vis spectroscopy, TGA, TEM, EDX, TPR, XPS, ISS and XANES. The nanoparticle size and structure control allowed insights into the bimetallic catalyst functioning. As soon as two contiguous surface Ir atoms exist on the nanoparticle surface, they display the same catalytic properties, most likely through the dicarbene ring-opening mechanism. Palladium serves only as a dispersing agent in Pd(core)–Ir(shell) structures providing 100% Ir dispersion, or as an inert surface diluting metal in Pd–Ir formulations with mixed nanoparticle surface. The Pd–Ir core–shell structure allows maximum selective ring-opening yield, which is 19% higher than that for the industrial Pt–Ir catalyst.

Ir-Pd bimetallic nanoparticles with controlled alloy and core-shell structures were used in ring-opening (RO) of indan. Pd(core)-Ir(shell) showed the highest selective RO yield among the synthetic and industrial catalysts studied.Figure optionsDownload high-quality image (136 K)Download as PowerPoint slideHighlights
► Size- and structure-controlled Pd/Ir mono- and bimetallic particles were synthesised.
► Two contiguous surface Ir atoms form an active site in indan ring opening (RO).
► Pd serves as an inert surface diluting or Ir dispersing agent.
► Pd(core)Ir(shell) gives 19% higher selective RO yield than industrial PtIr catalyst.