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

Selective Single‐Site Pd−In Hydrogenation Catalyst for Production of Enhanced Magnetic Resonance Signals using Parahydrogen

“…The dispersion of Pd in the catalysts was determined from the CO uptake in CO chemisorption analysis (assuming a stoichiometry of CO:Pd=1:1). In particular, for the monometallic Pd/Al 2 O 3 catalyst the dispersion was about ≈36 %, but for Pd−In/Al 2 O 3 catalyst the dispersion value was approximately ≈5.6 %.This fact indicates direct influence of In atoms, which do not chemisorb CO, on the nanoparticle surface . Moreover, FTIR spectrum of CO adsorbed on the reference monometallic Pd/Al 2 O 3 sample exhibits two absorption bands, while the spectrum of CO adsorbed on bimetallic Pd−In/Al 2 O 3 catalyst exhibits only one intensive band at 2073 cm −1 attributed to linearly adsorbed CO on metallic Pd (Figure S2).…”

“…The latter is the key to high product selectivity because palladium hydride is the known active species for side reactions such as isomerization or over‐hydrogenation . Pd−In catalyst has been shown to be an effective catalyst for semihydrogenation of a triple to a double carbon‐carbon bond in hydrogenation of acetylene, phenylacetylene, diphenylacetylene and 1‐phenyl‐1‐propyne . Moreover, it was established that Pd was present as single atoms …”

“…Pd−In catalyst has been shown to be an effective catalyst for semihydrogenation of a triple to a double carbon‐carbon bond in hydrogenation of acetylene, phenylacetylene, diphenylacetylene and 1‐phenyl‐1‐propyne . Moreover, it was established that Pd was present as single atoms …”

“…Pd−In/Al 2 O 3 single‐site catalyst was prepared by incipient‐wetness impregnation of Al 2 O 3 with bimetallic acetate complex PdIn(CH 3 COO) 5 with subsequent reduction (for details, see Supporting Information). Recently it was shown that the use of a bimetallic complex as a precursor of the active component combined with high‐temperature reduction enables the formation of bimetallic particles in the catalyst . The size of Pd−In nanoparticles was determined by TEM after pre‐reduction in H 2 atmosphere at 550 °C.…”

“…Pd−In/Al 2 O 3 catalyst was tested earlier in the liquid‐phase hydrogenation of terminal and internal alkynes (phenylacetylene, diphenylacetylene, and 1‐phenyl‐1‐propyne) and demonstrated high selectivity to the formation of alkenes (up to 98 %) …”