Rh(0) Nanoparticles: Synthesis, Structure and Catalytic Application in Suzuki–Miyaura Reaction and Hydrogenation of Benzene

Abstract

Rhodium colloids have been prepared by chemical reduction of an aqueous solution of rhodium trichloride with different aliphatic alcohols (from methanol to pentanol) in the presence of polyvinylpyrrolidone (PVP) as the stabilizing agent. The obtained Rh(0) nanoparticles have been characterized structurally by means of X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Catalytic activity of the synthesized Rh/PVP colloids has been evidenced in the Suzuki-Miyaura coupling reaction of phenylboronic acid with bromobenzaldehyde. The choice of the reducing agent and reduction conditions enabled to obtain Rh(0) colloids showing various mean nanoparticle diameters (ranging from 3.8 to 6.0 nm) and different nanoparticle morphologies. These two factors play the decisive role from point of view of catalytic activity of the presented systems. The most active Rh/PVP catalyst, prepared using ethanol as the reducing agent, have also been applied in hydrogenation of benzene to cyclohexane, showing very high activity in this process.

Hydrolysis of Hydrazine Borane for Chemical Hydrogen Storage by Highly Efficient Poly(N-vinyl-2-pyrrolidone)-protected Rhodium Nanoparticles

“…Rh@PVP nanoparticles were prepared by an alcohol reduction method in which PVP serves as both stabilizer and reducing agent [18,19]. To a solution of rhodium(III) chloride trihydrate (0.25 mmol in 50 mL water/ethanol mixture), poly(N-vinyl-2-pyrrolidone) (PVP-40, 2.5 mmol of monomeric units) was added.…”

RhCl(TPPTS)3 supported on iota‐carrageenan as recyclable catalysts for Suzuki cross‐coupling

“…Owing to their profound advantages over homogeneous catalysts, especially the ease with which they can be separated and recycled, heterogeneous metal catalyst synthesis, usually via the heterogenization of homogeneous metal complexes, is of high interest. While numerous palladium‐based heterogeneous catalysts have been introduced for Suzuki cross‐coupling, only a few heterogeneous rhodium catalysts have been prepared, including rhodium nano‐ and micro‐particles supported on Amberlite ion exchange resin and rhodium nano‐particles supported on polyvinylpyrrolidone (PVP) and cellulose …”

Green Synthesis of Rhodium Nanoparticles that are Catalytically Active in Benzene Hydrogenation and 1‐Hexene Hydroformylation

“…Rh NPs are located at the boundary between homogeneous andh eterogeneousc atalysts. [1,16,17,24] Their catalytic activity ands electivity depend on the shape, size, and composition of the stabilizing agents and ligands. [4] Hirai et al reported the use of water-and-alcohol mixtures as reducinga gents in the preparation of Rh,P t, Pd, Os, or Ir NPs.…”

“…[4] Hirai et al reported the use of water-and-alcohol mixtures as reducinga gents in the preparation of Rh,P t, Pd, Os, or Ir NPs. [18][19][20][21][22][23][24] Interestingly,H irai observed that Rh NPs were not obtained in anhydrous methanolo ri nt he absence of PVA. In contrast, RhCl 3 was reduced to Rh NPs after the addition of water to methanol.…”