PVP-stabilized mono- and bimetallic Ru nanoparticles for selective ring opening

Selective ring opening of naphthenic molecules in oil upgrading should result in no loss in molecular weight. Benzocyclopentane (indan) ring opening was studied under hydrogen atmospheric pressure at 609 K over poly-(vinylpyrrolidone)-stabilized Ru, Ir and Pd monometallic and Ru–Ir and Ru–Pd bimetallic nanocatalysts prepared by simultaneous reductions. The particle size (mostly within 2 nm) and their monodispersity were confirmed by transmission electron microscopy, while X-ray photoelectron spectroscopy indicated the bimetallics' alloy structure. Pd catalysts displayed the lowest activity in the ring opening; Ru showed the highest formation of undesired o-xylene and lights. Monometallic Ir displayed the highest activity and selectivity toward 2-ethyltoluene and n-propylbenzene. In bimetallic structures, higher Ir content led to improved catalytic performance. Next to the monometallic Ir catalyst, the newly developed Ru1Ir4/γ-Al2O3 catalyst (with 1 : 4 molar ratio of Ru to Ir) displayed superior single cleavage selectivity as well as lower cracking activity compared to industrial Pt–Ir catalysts at a comparable indan conversion. The study can pave the way in the development of Pt-free Ru-containing catalysts with narrow size distributions for selective ring opening, especially taking into consideration a possibility of their higher S-resistance as compared to the Pt catalysts.