Rhenium Nanostructures Loaded into Amino-Functionalized Resin as a Nanocomposite Catalyst for Hydrogenation of 4-Nitrophenol and 4-Nitroaniline

Abstract

The present work presents a new nanocomposite catalyst with rhenium nanostructures (ReNSs) for the catalytic hydrogenation of 4-nitrophenol and 4-nitroaniline. The catalyst, based on an anion exchange resin with functionality derived from 1,1′-carboimidazole, was obtained in the process involving anion exchange of ReO4– ions followed by their reduction with NaBH4. The amino functionality present in the resin played a primary role in the stabilization of the resultant ReNSs, consisting of ≈1% (w/w) Re in the polymer mass. The synthesized and capped ReNSs were amorphous and had the average size of 3.45 ± 1.85 nm. Then, the obtained catalyst was used in a catalytic reduction of 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA). Following the pseudo-first-order kinetics, 5 mg of the catalyst led to a 90% conversion of 4-NP with the mass-normalized rate constant (km1) of 6.94 × 10−3 min−1 mg−1, while the corresponding value acquired for 4-NA was 7.2 × 10−3 min−1 mg−1, despite the trace amount of Re in the heterogenous catalyst. The obtained material was also conveniently reused.

Keywords

• polymeric nanocomposites
• anion exchange resins
• suspension copolymers
• amines
• 4-nitrophenol
• 4-nitroaniline