Nickel Boosts Ring‐Opening Activity of Iridium

Abstract

A variety of bimetallic Ni–Ir catalysts were synthesised by preforming nanoparticles in the presence of polyvinylpyrrolidone, followed by deposition on γ‐alumina and high‐temperature polymer removal. The Ni–Ir (1:1 molar ratio) nanoparticles prepared by the hydrogen‐sacrificial technique (Ir reduction on the preformed Ni nanoparticles with surface Ni hydride) allowed increasing indane ring opening activity per total amount of Ir as compared to monometallic Ir. The simultaneous reduction of Ni and Ir precursors was not as efficient. The catalysts were characterised with UV/Vis spectroscopy, TEM, temperature‐programmed reduction, CO2 temperature‐programmed desorption, CO diffuse reflectance Fourier transform spectroscopy, X‐ray photoelectron spectroscopy and CHN analysis. The study only explored the catalyst’s metal function and allows saving rare and expensive iridium without loss of its outstanding performance as a ring‐opening catalyst.

Reaction Pathways and Intermediates in Selective Ring Opening of Biomass-Derived Heterocyclic Compounds by Iridium

“…As the chemical economy gradually shifts from fossil fuels to renewable resources, it becomes important to develop technologies to upgrade renewable platform molecules to final products of industrial relevance. Renewable heterocyclic molecules 5-hydroxymethylfurfural and furfural can be produced in high yields by depolymerizing and dehydrating lignocellulosic biomass. , Hydrogenolysis of these heterocyclics has been shown to be a viable route toward the production of long-chain hydrocarbons, alcohols, and polyols. − Selective hydrogenolysis of furfural at the C–O bond(s) in the aromatic ring with an iridium catalyst has been shown to be effective in the production of 1,5-pentanediol (1,5-PeD), a valuable precursor for the production of polyesters and polyurethanes. ,− While the hydrogenolysis of furfural to 1,5-PeD has been known for decades, whether the reaction proceeds through the full saturation of the aromatic ring ,− remains a controversial topic. Recent experiments have indicated that the hydrogenolysis of unsaturated homo- and heterocyclics is more facile over that of their saturated equivalents.…”

Encapsulating Ir nanoparticles into UiO-66 for photo-thermal catalytic CO2methanation under ambient pressure

“…S10b †). 45,46 The band at 2007 cm À1 can be ascribed to linear CO adsorption on metallic Ir (Fig. S10a †).…”

Catalytic selective ring opening of polyaromatics for cleaner transportation fuels

“…Transition metal catalysts can open naphthenic ring compounds when the metal ensembles possess hydrogenolysis activity, 91 for example Pt/Al 2 O 3 , Ir/Al 2 O 3 , Ir/SiO 2 , Pt–Ir/Al 2 O 3 , Pt–Ir/SiO 2 , Ru–Pd/Al 2 O 3 , Ru–Ir/Al 2 O 3 and Ni–Ir/Al 2 O 3 . 12,89,92–94 Ring opening is proposed to occur via hydrogenolysis of endocyclic C–C bonds bound to metal sites in three different coordination modes (dicarbene, π-adsorbed olefin or metallocyclobutane) as illustrated in Scheme 3a–c. 63 The selectivity and distribution of ring opening products will depend on which of these intermediates is formed.…”